// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using Microsoft.CodeAnalysis.CSharp.Symbols;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;

namespace Microsoft.CodeAnalysis.CSharp.UnitTests
{
    /// <summary>
    /// Tests related to binding (but not lowering) lock statements.
    /// </summary>
    [CompilerTrait(CompilerFeature.Unsafe)]
    public class UnsafeTests : CompilingTestBase
    {
        private static string GetEscapedNewLine()
        {
            if (Environment.NewLine == "\n")
            {
                return @"\n";
            }
            else if (Environment.NewLine == "\r\n")
            {
                return @"\r\n";
            }
            else
            {
                throw new Exception("Unrecognized new line");
            }
        }

        #region Unsafe regions

        [Fact]
        public void FixedSizeBuffer()
        {
            var text1 = @"
using System;
using System.Runtime.InteropServices;

public static class R
{
    public unsafe struct S
    {
        public fixed byte Buffer[16];
    }
}";
            var comp1 = CreateEmptyCompilation(text1, assemblyName: "assembly1", references: new[] { MscorlibRef_v20 },
                options: TestOptions.UnsafeDebugDll);

            var ref1 = comp1.EmitToImageReference();

            var text2 = @"
using System;

class C
{
    unsafe void M(byte* p)
    {
        R.S* p2 = (R.S*)p;
        IntPtr p3 = M2((IntPtr)p2[0].Buffer);
    }

    unsafe IntPtr M2(IntPtr p) => p;
}";
            var comp2 = CreateCompilationWithMscorlib461(text2,
                references: new[] { ref1 },
                options: TestOptions.UnsafeDebugDll);
            comp2.VerifyDiagnostics(
    // warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'assembly1' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy
    Diagnostic(ErrorCode.WRN_UnifyReferenceMajMin).WithArguments("mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "assembly1", "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "mscorlib").WithLocation(1, 1),
    // warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'assembly1' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy
    Diagnostic(ErrorCode.WRN_UnifyReferenceMajMin).WithArguments("mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "assembly1", "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "mscorlib").WithLocation(1, 1),
    // warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'assembly1' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy
    Diagnostic(ErrorCode.WRN_UnifyReferenceMajMin).WithArguments("mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "assembly1", "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "mscorlib").WithLocation(1, 1),
    // warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'assembly1' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy
    Diagnostic(ErrorCode.WRN_UnifyReferenceMajMin).WithArguments("mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "assembly1", "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "mscorlib").WithLocation(1, 1),
    // warning CS1701: Assuming assembly reference 'mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' used by 'assembly1' matches identity 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' of 'mscorlib', you may need to supply runtime policy
    Diagnostic(ErrorCode.WRN_UnifyReferenceMajMin).WithArguments("mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "assembly1", "mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089", "mscorlib").WithLocation(1, 1));
        }

        [Fact]
        public void FixedSizeBuffer_GenericStruct_01()
        {
            var code = @"
unsafe struct MyStruct<T>
{
    public fixed char buf[16];
    public static void M()
    {
        var ms = new MyStruct<int>();
        var ptr = &ms;
    }
}
";
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void FixedSizeBuffer_GenericStruct_02()
        {
            var code = @"
unsafe struct MyStruct<T>
{
    public fixed T buf[16];
    public static void M()
    {
        var ms = new MyStruct<int>();
        var ptr = &ms;
    }
}
";
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,18): error CS1663: Fixed size buffer type must be one of the following: bool, byte, short, int, long, char, sbyte, ushort, uint, ulong, float or double
                //     public fixed T buf[16];
                Diagnostic(ErrorCode.ERR_IllegalFixedType, "T").WithLocation(4, 18)
            );
        }

        [Fact]
        public void FixedSizeBuffer_GenericStruct_03()
        {
            var code = @"
unsafe struct MyStruct<T> where T : unmanaged
{
    public fixed T buf[16];
    public static void M()
    {
        var ms = new MyStruct<int>();
        var ptr = &ms;
    }
}
";
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,18): error CS1663: Fixed size buffer type must be one of the following: bool, byte, short, int, long, char, sbyte, ushort, uint, ulong, float or double
                //     public fixed T buf[16];
                Diagnostic(ErrorCode.ERR_IllegalFixedType, "T").WithLocation(4, 18)
            );
        }

        [Fact]
        public void FixedSizeBuffer_GenericStruct_04()
        {
            var code = @"
public unsafe struct MyStruct<T>
{
    public T field;
}

unsafe struct OuterStruct
{
    public fixed MyStruct<int> buf[16];
    public static void M()
    {
        var os = new OuterStruct();
        var ptr = &os;
    }
}
";
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,18): error CS1663: Fixed size buffer type must be one of the following: bool, byte, short, int, long, char, sbyte, ushort, uint, ulong, float or double
                //     public fixed MyStruct<int> buf[16];
                Diagnostic(ErrorCode.ERR_IllegalFixedType, "MyStruct<int>").WithLocation(9, 18)
            );
        }

        [Fact]
        public void CompilationNotUnsafe1()
        {
            var text = @"
unsafe class C
{
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll.WithAllowUnsafe(false)).VerifyDiagnostics(
                // (2,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C"));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void CompilationNotUnsafe2()
        {
            var text = @"
class C
{
    unsafe void Goo()
    {
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll.WithAllowUnsafe(false)).VerifyDiagnostics(
                // (4,17): error CS0227: Unsafe code may only appear if compiling with /unsafe
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "Goo"));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void CompilationNotUnsafe3()
        {
            var text = @"
class C
{
    void Goo()
    {
        /*<bind>*/unsafe
        {
            _ = 0;
        }/*</bind>*/
    }
}
";

            string expectedOperationTree = @"
IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
  IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: '_ = 0;')
    Expression: 
      ISimpleAssignmentOperation (OperationKind.SimpleAssignment, Type: System.Int32) (Syntax: '_ = 0')
        Left: 
          IDiscardOperation (Symbol: System.Int32 _) (OperationKind.Discard, Type: System.Int32) (Syntax: '_')
        Right: 
          ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
";
            VerifyOperationTreeAndDiagnosticsForTest<BlockSyntax>(text, expectedOperationTree,
                compilationOptions: TestOptions.UnsafeReleaseDll.WithAllowUnsafe(false),
                expectedDiagnostics: new DiagnosticDescription[] {
                    // file.cs(6,19): error CS0227: Unsafe code may only appear if compiling with /unsafe
                    //         /*<bind>*/unsafe
                    Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(6, 19)
                });

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void IteratorUnsafe1()
        {
            var text = @"
unsafe class C
{
    System.Collections.Generic.IEnumerator<int> Goo()
    {
        yield return 1;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void IteratorUnsafe2()
        {
            var text = @"
class C
{
    unsafe System.Collections.Generic.IEnumerator<int> Goo()
    {
        yield return 1;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (4,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerator<int> Goo()
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "Goo").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(4, 56));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void IteratorUnsafe3()
        {
            var text = @"
class C
{
    System.Collections.Generic.IEnumerator<int> Goo()
    {
        unsafe { }
        yield return 1;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (6,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe { }
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 9));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void IteratorUnsafe4()
        {
            var text = @"
unsafe class C
{
    System.Collections.Generic.IEnumerator<int> Goo()
    {
        unsafe { }
        yield return 1;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (6,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe { }
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 9));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [WorkItem(546657, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/546657")]
        [Fact]
        public void IteratorUnsafe5()
        {
            var text = @"
unsafe class C
{
    System.Collections.Generic.IEnumerator<int> Goo()
    {
        System.Action a = () => { unsafe { } };
        yield return 1;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (6,35): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         System.Action a = () => { unsafe { } };
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 35));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/73280")]
        public void Iterator_UnsafeBlock_LangVersion()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M1()
                    {
                        unsafe // langversion error in C# 12
                        {
                            int* p = null; // unnecessary langversion error in C# 12
                        }
                        yield break;
                    }
                    System.Collections.Generic.IEnumerable<int> M2()
                    {
                        int* p = null; // necessary langversion error in C# 12
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe // langversion error in C# 12
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9),
                // (7,13): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             int* p = null; // unnecessary langversion error in C# 12
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "int*").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 13),
                // (13,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         int* p = null; // necessary langversion error in C# 12
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "int*").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(13, 9));

            var expectedDiagnostics = new[]
            {
                // (13,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         int* p = null; // necessary langversion error in C# 12
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 9)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void Iterator_UnsafeBlock_Local()
        {
            var code = """
                class C
                {
                    public System.Collections.Generic.IEnumerable<int> M()
                    {
                        int x = 1;
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        yield return x;
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - diagnostics inside the unsafe block are unnecessary
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 9),
                // (8,13): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "int *").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(8, 13),
                // (8,22): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "&x").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(8, 22),
                // (9,14): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             *p = *p + 1;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "p").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(9, 14),
                // (9,19): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             *p = *p + 1;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "p").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(9, 19));

            var expectedDiagnostics = new[]
            {
                // (8,23): error CS9239: The '&' operator cannot be used on parameters or local variables in iterator methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_AddressOfInIterator, "x").WithLocation(8, 23)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void Iterator_UnsafeBlock_Parameter()
        {
            var code = """
                class C
                {
                    public System.Collections.Generic.IEnumerable<int> M(int x)
                    {
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        yield return x;
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - diagnostics inside the unsafe block are unnecessary
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9),
                // (7,13): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "int *").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 13),
                // (7,22): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "&x").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(7, 22),
                // (8,14): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             *p = *p + 1;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "p").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(8, 14),
                // (8,19): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             *p = *p + 1;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "p").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(8, 19));

            var expectedDiagnostics = new[]
            {
                // (7,23): error CS9239: The '&' operator cannot be used on parameters or local variables in iterator methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_AddressOfInIterator, "x").WithLocation(7, 23)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void Iterator_UnsafeBlock_Field_01()
        {
            var code = """
                class Program
                {
                    static int _f;
                    static System.Collections.Generic.IEnumerable<int> F()
                    {
                        unsafe
                        {
                            fixed (int* p = &_f) { }
                        }
                        yield break;
                    }
                }
                """;
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void Iterator_UnsafeBlock_Field_02()
        {
            var code = """
                #pragma warning disable CS0649 // field is never assigned to
                unsafe class Program
                {
                    static int* _p;
                    static System.Collections.Generic.IEnumerable<int> F()
                    {
                        unsafe
                        {
                            int* p = _p;
                            p = &p[1];
                        }
                        yield break;
                    }
                }
                """;
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void Iterator_UnsafeBlock_Field_03()
        {
            var code = """
                struct S
                {
                    public int F;
                }
                class Program
                {
                    static System.Collections.Generic.IEnumerable<int> F()
                    {
                        unsafe
                        {
                            S s = default;
                            int* p = &s.F;
                        }
                        yield break;
                    }
                }
                """;
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (12,23): error CS9239: The '&' operator cannot be used on parameters or local variables in iterator methods.
                //             int* p = &s.F;
                Diagnostic(ErrorCode.ERR_AddressOfInIterator, "s.F").WithLocation(12, 23));
        }

        [Fact]
        public void Iterator_UnsafeBlock_Field_04()
        {
            var code = """
                class Program
                {
                    static int _f;
                    static System.Collections.Generic.IEnumerable<int> F()
                    {
                        unsafe
                        {
                            int* p = &_f;
                            (*p)++;
                        }
                        yield break;
                    }
                }
                """;
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,22): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //             int* p = &_f;
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&_f").WithLocation(8, 22));
        }

        [Fact]
        public void Iterator_UnsafeBlock_SizeOf()
        {
            var code = """
                foreach (var x in new C().M()) System.Console.Write(x);

                class C
                {
                    public System.Collections.Generic.IEnumerable<int> M()
                    {
                        int x;
                        unsafe
                        {
                            x = sizeof(nint);
                        }
                        yield return x;
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - diagnostics inside the unsafe block are unnecessary
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(
                // (8,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(8, 9),
                // (10,17): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //             x = sizeof(nint);
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "sizeof(nint)").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(10, 17));

            var expectedOutput = IntPtr.Size.ToString();
            CompileAndVerify(code, expectedOutput: expectedOutput, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CompileAndVerify(code, expectedOutput: expectedOutput, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Fact]
        public void Iterator_UnsafeBlock_YieldBreak()
        {
            var code = """
                class C
                {
                    public System.Collections.Generic.IEnumerable<int> M()
                    {
                        unsafe
                        {
                            yield break;
                        }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9));

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void Iterator_UnsafeBlock_YieldReturn()
        {
            var code = """
                class C
                {
                    public System.Collections.Generic.IEnumerable<int> M()
                    {
                        unsafe
                        {
                            yield return 1;
                        }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         unsafe
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "unsafe").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9));

            var expectedDiagnostics = new[]
            {
                // (7,13): error CS9238: Cannot use 'yield return' in an 'unsafe' block
                //             yield return 1;
                Diagnostic(ErrorCode.ERR_BadYieldInUnsafe, "yield").WithLocation(7, 13)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void Iterator_UnsafeBlock_Async_01()
        {
            var code = """
                await foreach (var x in new C().M()) System.Console.Write(x);

                class C
                {
                    public async System.Collections.Generic.IAsyncEnumerable<int> M()
                    {
                        int x = 1;
                        await System.Threading.Tasks.Task.Yield();
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        yield return x;
                    }
                }
                """ + AsyncStreamsTypes;

            var comp = CreateCompilationWithTasksExtensions(code, options: TestOptions.UnsafeReleaseExe);
            CompileAndVerify(comp, expectedOutput: "1", verify: Verification.Fails).VerifyDiagnostics(
                // (11,23): warning CS9123: The '&' operator should not be used on parameters or local variables in async methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.WRN_AddressOfInAsync, "x").WithLocation(11, 23));
        }

        // Should behave equivalently to AwaitBetweenUnsafeBlocks.
        [Fact]
        public void Iterator_UnsafeBlock_Async_02()
        {
            var code = """
                class C
                {
                    public System.Collections.Generic.IEnumerable<int> M()
                    {
                        int x = 1;
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        yield return x;
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        yield return x;
                        unsafe
                        {
                            int *p = &x;
                            if (*p == 3) yield break;
                        }
                        yield return x;
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (8,23): error CS9239: The '&' operator cannot be used on parameters or local variables in iterator methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_AddressOfInIterator, "x").WithLocation(8, 23),
                // (14,23): error CS9239: The '&' operator cannot be used on parameters or local variables in iterator methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_AddressOfInIterator, "x").WithLocation(14, 23),
                // (20,23): error CS9239: The '&' operator cannot be used on parameters or local variables in iterator methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.ERR_AddressOfInIterator, "x").WithLocation(20, 23)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        // Should behave equivalently to Iterator_UnsafeBlock_Async_02.
        [Fact]
        public void AwaitBetweenUnsafeBlocks()
        {
            var code = """
                using System;
                using System.Threading.Tasks;

                await new C().M();

                class C
                {
                	async Task Report(int x)
                    {
                        Console.Write(x);
                        await Task.Yield();
                    }
                    public async Task M()
                    {
                        int x = 1;
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        await Report(x);
                        unsafe
                        {
                            int *p = &x;
                            *p = *p + 1;
                        }
                        await Report(x);
                        unsafe
                        {
                            int *p = &x;
                            if (*p == 3) return;
                        }
                        await Report(x);
                    }
                }
                """;
            var expectedDiagnostics = new[]
            {
                // (18,23): warning CS9123: The '&' operator should not be used on parameters or local variables in async methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.WRN_AddressOfInAsync, "x").WithLocation(18, 23),
                // (24,23): warning CS9123: The '&' operator should not be used on parameters or local variables in async methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.WRN_AddressOfInAsync, "x").WithLocation(24, 23),
                // (30,23): warning CS9123: The '&' operator should not be used on parameters or local variables in async methods.
                //             int *p = &x;
                Diagnostic(ErrorCode.WRN_AddressOfInAsync, "x").WithLocation(30, 23)
            };
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void Iterator_LocalFunction_Nested()
        {
            var code = """
                class Program
                {
                    static void F()
                    {
                        unsafe
                        {
                            static System.Collections.Generic.IEnumerable<int> G(int x)
                            {
                                unsafe
                                {
                                    x = sizeof(nint);
                                }
                                yield return x;

                                unsafe
                                {
                                    G2(new int*[0]);
                                    static System.Collections.Generic.IEnumerable<int> G2(int*[] x)
                                    {
                                        int y;
                                        unsafe
                                        {
                                            y = *x[0];
                                        }
                                        yield return y;
                                    }
                                }
                            }
                            G(0);
                        }
                    }
                }
                """;
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LambdaInIterator_Async()
        {
            var code = """
                using System.Collections.Generic;
                using System.Threading.Tasks;
                unsafe class C
                {
                    IEnumerable<int> M()
                    {
                        yield return 1;
                        var lam = async () => await Task.Yield();
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - these should ideally be langversion errors
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (8,31): error CS4004: Cannot await in an unsafe context
                //         var lam = async () => await Task.Yield();
                Diagnostic(ErrorCode.ERR_AwaitInUnsafeContext, "await Task.Yield()").WithLocation(8, 31));

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_Async()
        {
            var code = """
                using System.Collections.Generic;
                using System.Threading.Tasks;
                unsafe class C
                {
                    IEnumerable<int> M()
                    {
                        yield return 1;
                        local();
                        async void local() { await Task.Yield(); }
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - these should ideally be langversion errors
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (9,30): error CS4004: Cannot await in an unsafe context
                //         async void local() { await Task.Yield(); }
                Diagnostic(ErrorCode.ERR_AwaitInUnsafeContext, "await Task.Yield()").WithLocation(9, 30));

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LambdaInIterator_Unsafe()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return 1;
                        var lam = () => sizeof(nint);
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - should not be a langversion error since this remains an error in C# 13
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (6,25): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         var lam = () => sizeof(nint);
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "sizeof(nint)").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(6, 25));

            var expectedDiagnostics = new[]
            {
                // (6,25): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         var lam = () => sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(6, 25)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_BreakingChange()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return 1;
                        local();
                        void local() { int* p = null; }
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyEmitDiagnostics();

            var expectedDiagnostics = new[]
            {
                // (7,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         void local() { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(7, 24)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_BreakingChangeWorkaround()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return 1;
                        local();
                        unsafe void local() { int* p = null; }
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyEmitDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_BreakingChange_Property()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> P
                    {
                        get
                        {
                            yield return 1;
                            local();
                            void local() { int* p = null; }
                        }
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyEmitDiagnostics();

            var expectedDiagnostics = new[]
            {
                // (9,28): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //             void local() { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 28)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_BreakingChange_Operator()
        {
            var code = """
                unsafe class C
                {
                    public static System.Collections.Generic.IEnumerable<int> operator+(C c1, C c2)
                    {
                        yield return 1;
                        local();
                        void local() { int* p = null; }
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyEmitDiagnostics();

            var expectedDiagnostics = new[]
            {
                // (7,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         void local() { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(7, 24)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_BreakingChange_Nested_01()
        {
            var code = """
                unsafe class C
                {
                    void M()
                    {
                        local1();
                        System.Collections.Generic.IEnumerable<int> local1()
                        {
                            yield return 1;
                            local2();
                            void local2() { int* p = null; }
                        }
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyEmitDiagnostics();

            var expectedDiagnostics = new[]
            {
                // (10,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //             void local2() { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 29)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunctionInIterator_BreakingChange_Nested_02()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return 1;
                        local1();
                        void local1()
                        {
                            local2();
                            void local2() { int* p = null; }
                        }
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyEmitDiagnostics();

            var expectedDiagnostics = new[]
            {
                // (10,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //             void local2() { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 29)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/73280")]
        public void UnsafeContext_LangVersion()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        int* p = null;
                        yield break;
                    }
                }
                """;

            // https://github.com/dotnet/roslyn/issues/73280 - should not be a langversion error since this remains an error in C# 13
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         int* p = null;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "int*").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9));

            var expectedDiagnostics = new[]
            {
                // (5,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         int* p = null;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 9)
            };

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Method_Signature_Unsafe(bool unsafeClass, bool unsafeMethod)
        {
            if (!unsafeClass && !unsafeMethod)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeMethod ? "unsafe" : "")}} void M(int* p) { }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Method_Signature_Safe()
        {
            var code = """
                class C
                {
                    void M(int* p) { }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(int* p)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 12)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Method_Body_Unsafe(bool unsafeClass, bool unsafeMethod)
        {
            if (!unsafeClass && !unsafeMethod)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeMethod ? "unsafe" : "")}} int M()
                    {
                        return sizeof(nint);
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Method_Body_Safe()
        {
            var code = """
                class C
                {
                    int M()
                    {
                        return sizeof(nint);
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,16): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 16)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Method_Iterator_Signature_UnsafeClass()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M(int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Method_Iterator_Signature_UnsafeMethod(bool unsafeClass)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    unsafe System.Collections.Generic.IEnumerable<int> M(int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerable<int> M(int*[] p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "M").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(3, 56));

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Method_Iterator_Signature_Safe()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> M(int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,51): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     System.Collections.Generic.IEnumerable<int> M(int*[] p)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 51)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Method_Iterator_Body_CSharp12_Safe()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return sizeof(nint);
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 22));
        }

        [Fact]
        public void UnsafeContext_Method_Iterator_Body_CSharp12_Safe_NestedBlock()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        {
                            yield return sizeof(nint);
                        }
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,26): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(6, 26));
        }

        [Fact]
        public void UnsafeContext_Method_Iterator_Body_CSharp12_Unsafe()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return local();
                        int local() => sizeof(nint);
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Method_Iterator_Body_CSharp12_Unsafe_NestedBlock()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        {
                            yield return local();
                        }
                        int local() => sizeof(nint);
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Method_Iterator_Body_CSharp13(bool unsafeClass, bool unsafeMethod)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeMethod ? "unsafe" : "")}} System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return sizeof(nint);
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 22)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Method_Iterator_Body_CSharp13_NestedBlock(bool unsafeClass, bool unsafeMethod)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeMethod ? "unsafe" : "")}} System.Collections.Generic.IEnumerable<int> M()
                    {
                        {
                            yield return sizeof(nint);
                        }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (6,26): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(6, 26)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Operator_Signature_Unsafe(bool unsafeClass, bool unsafeOperator)
        {
            if (!unsafeClass && !unsafeOperator)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeOperator ? "unsafe" : "")}} public static C operator+(C c, int* p)
                    {
                        return c;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Operator_Signature_Safe()
        {
            var code = """
                class C
                {
                    public static C operator+(C c, int* p)
                    {
                        return c;
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,36): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     public static C operator+(C c, int* p)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 36)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Operator_Body_Unsafe(bool unsafeClass, bool unsafeOperator)
        {
            if (!unsafeClass && !unsafeOperator)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeOperator ? "unsafe" : "")}} public static int operator+(C c1, C c2)
                    {
                        return sizeof(nint);
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Operator_Body_Safe()
        {
            var code = """
                class C
                {
                    public static int operator+(C c1, C c2)
                    {
                        return sizeof(nint);
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,16): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 16)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Operator_Iterator_Signature_UnsafeClass()
        {
            var code = """
                unsafe class C
                {
                    public static System.Collections.Generic.IEnumerable<int> operator+(C c, int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Operator_Iterator_Signature_UnsafeOperator(bool unsafeClass)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    public static unsafe System.Collections.Generic.IEnumerable<int> operator+(C c, int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,78): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     public static unsafe System.Collections.Generic.IEnumerable<int> operator+(C c, int*[] p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "+").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(3, 78));

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Operator_Iterator_Signature_Safe()
        {
            var code = """
                class C
                {
                    public static System.Collections.Generic.IEnumerable<int> operator+(C c, int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,78): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     public static System.Collections.Generic.IEnumerable<int> operator+(C c, int*[] p)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 78)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Operator_Iterator_Body_CSharp12_Safe()
        {
            var code = """
                class C
                {
                    public static System.Collections.Generic.IEnumerable<int> operator+(C c1, C c2)
                    {
                        yield return sizeof(nint);
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 22));
        }

        [Fact]
        public void UnsafeContext_Operator_Iterator_Body_CSharp12_Unsafe()
        {
            var code = """
                unsafe class C
                {
                    public static System.Collections.Generic.IEnumerable<int> operator+(C c1, C c2)
                    {
                        yield return local();
                        int local() => sizeof(nint);
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Operator_Iterator_Body_CSharp13(bool unsafeClass, bool unsafeIndexer)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeIndexer ? "unsafe" : "")}} public static System.Collections.Generic.IEnumerable<int> operator+(C c1, C c2)
                    {
                        yield return sizeof(nint);
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 22)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Indexer_Signature_Unsafe(bool unsafeClass, bool unsafeIndexer)
        {
            if (!unsafeClass && !unsafeIndexer)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeIndexer ? "unsafe" : "")}} int this[int* p]
                    {
                        get { return 0; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Indexer_Signature_Safe()
        {
            var code = """
                class C
                {
                    int this[int* p]
                    {
                        get { return 0; }
                        set { }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,14): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     int this[int* p]
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 14)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Indexer_Body_Unsafe(bool unsafeClass, bool unsafeIndexer)
        {
            if (!unsafeClass && !unsafeIndexer)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeIndexer ? "unsafe" : "")}} int this[int x]
                    {
                        get { return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Indexer_Body_Safe()
        {
            var code = """
                class C
                {
                    int this[int x]
                    {
                        get { return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 22),
                // (6,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         set { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 15)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Indexer_Iterator_Signature_UnsafeClass()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> this[int*[] p]
                    {
                        get { yield break; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Indexer_Iterator_Signature_UnsafeIndexer(bool unsafeClass)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    unsafe System.Collections.Generic.IEnumerable<int> this[int*[] p]
                    {
                        get { yield break; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         get { yield break; }
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "get").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9));

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Indexer_Iterator_Signature_Safe()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> this[int*[] p]
                    {
                        get { yield break; }
                        set { }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,54): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     System.Collections.Generic.IEnumerable<int> this[int*[] p]
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 54)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Indexer_Iterator_Body_CSharp12_Safe()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> this[int x]
                    {
                        get { yield return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,28): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { yield return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 28),
                // (6,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         set { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 15));
        }

        [Fact]
        public void UnsafeContext_Indexer_Iterator_Body_CSharp12_Unsafe()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> this[int x]
                    {
                        get
                        {
                            yield return local();
                            int local() => sizeof(nint);
                        }
                        set { int* p = null; }
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Indexer_Iterator_Body_CSharp13_UnsafeSetter(bool unsafeClass, bool unsafeIndexer)
        {
            if (!unsafeClass && !unsafeIndexer)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeIndexer ? "unsafe" : "")}} System.Collections.Generic.IEnumerable<int> this[int x]
                    {
                        get { yield return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,28): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { yield return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 28)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Indexer_Iterator_Body_CSharp13_SafeSetter()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> this[int x]
                    {
                        get { yield return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,28): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { yield return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 28),
                // (6,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         set { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 15)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Property_Signature_Unsafe(bool unsafeClass, bool unsafeProperty)
        {
            if (!unsafeClass && !unsafeProperty)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeProperty ? "unsafe" : "")}} int* P
                    {
                        get { throw null; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Property_Signature_Safe()
        {
            var code = """
                class C
                {
                    int* P
                    {
                        get { throw null; }
                        set { }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     int* P
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 5)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Property_Body_Unsafe(bool unsafeClass, bool unsafeProperty)
        {
            if (!unsafeClass && !unsafeProperty)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeProperty ? "unsafe" : "")}} int P
                    {
                        get { return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Property_Body_Safe()
        {
            var code = """
                class C
                {
                    int P
                    {
                        get { return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 22),
                // (6,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         set { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 15)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Property_Iterator_Signature_UnsafeClass()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int*[]> P
                    {
                        get { yield break; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Property_Iterator_Signature_UnsafeProperty(bool unsafeClass)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    unsafe System.Collections.Generic.IEnumerable<int*[]> P
                    {
                        get { yield break; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //         get { yield break; }
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "get").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(5, 9));

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Property_Iterator_Signature_Safe()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int*[]> P
                    {
                        get { yield break; }
                        set { }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (3,44): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     System.Collections.Generic.IEnumerable<int*[]> P
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 44)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Property_Iterator_Body_CSharp12_Safe()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> P
                    {
                        get { yield return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,28): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { yield return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 28),
                // (6,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         set { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 15));
        }

        [Fact]
        public void UnsafeContext_Property_Iterator_Body_CSharp12_Unsafe()
        {
            var code = """
                unsafe class C
                {
                    System.Collections.Generic.IEnumerable<int> P
                    {
                        get
                        {
                            yield return local();
                            int local() => sizeof(nint);
                        }
                        set { int* p = null; }
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Property_Iterator_Body_CSharp13_UnsafeSetter(bool unsafeClass, bool unsafeProperty)
        {
            if (!unsafeClass && !unsafeProperty)
            {
                return;
            }

            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    {{(unsafeProperty ? "unsafe" : "")}} System.Collections.Generic.IEnumerable<int> P
                    {
                        get { yield return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,28): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { yield return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 28)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Property_Iterator_Body_CSharp13_SafeSetter()
        {
            var code = """
                class C
                {
                    System.Collections.Generic.IEnumerable<int> P
                    {
                        get { yield return sizeof(nint); }
                        set { int* p = null; }
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,28): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         get { yield return sizeof(nint); }
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(5, 28),
                // (6,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         set { int* p = null; }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 15)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Property_Iterator_Signature_UnsafeAccessor(bool unsafeClass)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    System.Collections.Generic.IEnumerable<int> P
                    {
                        unsafe get { yield break; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS8652: The feature 'updated memory safety rules' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version.
                //         unsafe get { yield break; }
                Diagnostic(ErrorCode.ERR_FeatureInPreview, "unsafe").WithArguments("updated memory safety rules").WithLocation(5, 9));

            CreateCompilation(code, parseOptions: TestOptions.RegularPreview, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_Indexer_Iterator_Signature_UnsafeAccessor(bool unsafeClass)
        {
            var code = $$"""
                {{(unsafeClass ? "unsafe" : "")}} class C
                {
                    System.Collections.Generic.IEnumerable<int> this[int x]
                    {
                        unsafe get { yield break; }
                        set { }
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS8652: The feature 'updated memory safety rules' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version.
                //         unsafe get { yield break; }
                Diagnostic(ErrorCode.ERR_FeatureInPreview, "unsafe").WithArguments("updated memory safety rules").WithLocation(5, 9));

            CreateCompilation(code, parseOptions: TestOptions.RegularPreview, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_LocalFunction_Signature_Unsafe(bool unsafeBlock, bool unsafeFunction)
        {
            if (!unsafeBlock && !unsafeFunction)
            {
                return;
            }

            var code = $$"""
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                {{(unsafeBlock ? "unsafe" : "")}}
                {
                    {{(unsafeFunction ? "unsafe" : "")}} void M(int* p) { }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LocalFunction_Signature_Safe()
        {
            var code = """
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                void M(int* p) { }
                """;

            var expectedDiagnostics = new[]
            {
                // (2,8): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // void M(int* p) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 8)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_LocalFunction_Body_Unsafe(bool unsafeBlock, bool unsafeFunction)
        {
            if (!unsafeBlock && !unsafeFunction)
            {
                return;
            }

            var code = $$"""
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                {{(unsafeBlock ? "unsafe" : "")}}
                {
                    {{(unsafeFunction ? "unsafe" : "")}} int M()
                    {
                        return sizeof(nint);
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LocalFunction_Body_Safe()
        {
            var code = """
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                int M()
                {
                    return sizeof(nint);
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (4,12): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //     return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(4, 12)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunction_Iterator_Signature_UnsafeBlock()
        {
            var code = """
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                unsafe
                {
                    System.Collections.Generic.IEnumerable<int> M(int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_LocalFunction_Iterator_Signature_UnsafeFunction(bool unsafeBlock)
        {
            var code = $$"""
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                {{(unsafeBlock ? "unsafe" : "")}}
                {
                    unsafe System.Collections.Generic.IEnumerable<int> M(int*[] p)
                    {
                        yield break;
                    }
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(
                // (4,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerable<int> M(int*[] p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "M").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(4, 56));

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_LocalFunction_Iterator_Signature_Safe()
        {
            var code = """
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                System.Collections.Generic.IEnumerable<int> M(int*[] p)
                {
                    yield break;
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (2,47): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // System.Collections.Generic.IEnumerable<int> M(int*[] p)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 47)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_LocalFunction_Iterator_Body_CSharp12_Safe()
        {
            var code = """
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                System.Collections.Generic.IEnumerable<int> M()
                {
                    yield return sizeof(nint);
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(
                // (4,18): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //     yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(4, 18));
        }

        [Fact]
        public void UnsafeContext_LocalFunction_Iterator_Body_CSharp12_Unsafe()
        {
            var code = """
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                unsafe
                {
                    System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return local();
                        int local() => sizeof(nint);
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Theory, CombinatorialData]
        public void UnsafeContext_LocalFunction_Iterator_Body_CSharp13(bool unsafeBlock, bool unsafeFunction)
        {
            var code = $$"""
                #pragma warning disable CS8321 // The local function 'M' is declared but never used
                {{(unsafeBlock ? "unsafe" : "")}}
                {
                    {{(unsafeFunction ? "unsafe" : "")}} System.Collections.Generic.IEnumerable<int> M()
                    {
                        yield return sizeof(nint);
                    }
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (6,22): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(6, 22)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Lambda_Signature_Unsafe()
        {
            var code = """
                unsafe
                {
                    var lam = (int* p) => { };
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Lambda_Signature_Safe()
        {
            var code = """
                var lam = (int* p) => { };
                """;

            var expectedDiagnostics = new[]
            {
                // (1,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // var lam = (int* p) => { };
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(1, 12),
                // (1,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // var lam = (int* p) => { };
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "p").WithLocation(1, 17)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Lambda_Body_Unsafe()
        {
            var code = """
                unsafe
                {
                    var lam = () =>
                    {
                        return sizeof(nint);
                    };
                }
                """;

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics();
        }

        [Fact]
        public void UnsafeContext_Lambda_Body_Safe()
        {
            var code = """
                var lam = () =>
                {
                    return sizeof(nint);
                };
                """;

            var expectedDiagnostics = new[]
            {
                // (3,12): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //     return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(3, 12)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Lambda_Iterator_Signature_Unsafe()
        {
            var code = """
                unsafe
                {
                    var lam = (int*[] p) =>
                    {
                        yield break;
                    };
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,9): error CS1621: The yield statement cannot be used inside an anonymous method or lambda expression
                //         yield break;
                Diagnostic(ErrorCode.ERR_YieldInAnonMeth, "yield").WithLocation(5, 9)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Lambda_Iterator_Signature_Safe()
        {
            var code = """
                var lam = (int*[] p) =>
                {
                    yield break;
                };
                """;

            var expectedDiagnostics = new[]
            {
                // (1,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // var lam = (int*[] p) =>
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(1, 12),
                // (1,19): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // var lam = (int*[] p) =>
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "p").WithLocation(1, 19),
                // (3,5): error CS1621: The yield statement cannot be used inside an anonymous method or lambda expression
                //     yield break;
                Diagnostic(ErrorCode.ERR_YieldInAnonMeth, "yield").WithLocation(3, 5)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Lambda_Iterator_Body_Unsafe()
        {
            var code = """
                unsafe
                {
                    var lam = () =>
                    {
                        yield return sizeof(nint);
                    };
                }
                """;

            var expectedDiagnostics = new[]
            {
                // (5,9): error CS1621: The yield statement cannot be used inside an anonymous method or lambda expression
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_YieldInAnonMeth, "yield").WithLocation(5, 9)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);

            expectedDiagnostics = [
                // (5,9): error CS1621: The yield statement cannot be used inside an anonymous method or lambda expression
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_YieldInAnonMeth, "yield").WithLocation(5, 9),
                // (5,9): error CS9238: Cannot use 'yield return' in an 'unsafe' block
                //         yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_BadYieldInUnsafe, "yield").WithLocation(5, 9)
            ];

            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeContext_Lambda_Iterator_Body_Safe()
        {
            var code = """
                var lam = () =>
                {
                    yield return sizeof(nint);
                };
                """;

            var expectedDiagnostics = new[]
            {
                // (3,5): error CS1621: The yield statement cannot be used inside an anonymous method or lambda expression
                //     yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_YieldInAnonMeth, "yield").WithLocation(3, 5),
                // (3,18): error CS0233: 'nint' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //     yield return sizeof(nint);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(nint)").WithArguments("nint").WithLocation(3, 18)
            };

            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseExe).VerifyDiagnostics(expectedDiagnostics);
            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseExe, expectedDiagnostics);
        }

        [Fact]
        public void UnsafeBlock_InAsyncMethod()
        {
            var code = """
                using System.Threading.Tasks;
                class C
                {
                    async Task M(int x)
                    {
                        unsafe { x = sizeof(nint); }
                        await Task.Yield();
                    }
                }
                """;
            CreateCompilation(code, parseOptions: TestOptions.Regular12, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
            CreateCompilation(code, parseOptions: TestOptions.Regular13, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void UnsafeModifier()
        {
            var text = @"
unsafe class C
{
    unsafe C() { }
    unsafe ~C() { }
    unsafe static void Static() { }
    unsafe void Instance() { }
    unsafe struct Inner { }
    unsafe int field = 1;
    unsafe event System.Action Event;
    unsafe int Property { get; set; }
    unsafe int this[int x] { get { return field; } set { } }
    unsafe public static C operator +(C c1, C c2) { return c1; }
    unsafe public static implicit operator int(C c) { return 0; }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (10,32): warning CS0067: The event 'C.Event' is never used
                //     unsafe event System.Action Event;
                Diagnostic(ErrorCode.WRN_UnreferencedEvent, "Event").WithArguments("C.Event"));
        }

        [Fact]
        public void TypeIsUnsafe()
        {
            var text = @"
unsafe class C<T>
{
    int* f0;
    int** f1;
    int*[] f2;
    int*[][] f3;
    C<int*> f4;
    C<int**> f5;
    C<int*[]> f6;
    C<int*[][]> f7;
}
";

            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            compilation.VerifyDiagnostics(
                // (8,13): error CS0306: The type 'int*' may not be used as a type argument
                //     C<int*> f4;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "f4").WithArguments("int*").WithLocation(8, 13),
                // (9,14): error CS0306: The type 'int**' may not be used as a type argument
                //     C<int**> f5;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "f5").WithArguments("int**").WithLocation(9, 14),

                // (4,10): warning CS0169: The field 'C<T>.f0' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f0").WithArguments("C<T>.f0"),
                // (5,11): warning CS0169: The field 'C<T>.f1' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f1").WithArguments("C<T>.f1"),
                // (6,12): warning CS0169: The field 'C<T>.f2' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f2").WithArguments("C<T>.f2"),
                // (7,14): warning CS0169: The field 'C<T>.f3' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f3").WithArguments("C<T>.f3"),
                // (8,13): warning CS0169: The field 'C<T>.f4' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f4").WithArguments("C<T>.f4"),
                // (9,14): warning CS0169: The field 'C<T>.f5' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f5").WithArguments("C<T>.f5"),
                // (10,15): warning CS0169: The field 'C<T>.f6' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f6").WithArguments("C<T>.f6"),
                // (11,17): warning CS0169: The field 'C<T>.f7' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedField, "f7").WithArguments("C<T>.f7"));

            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            var fieldTypes = Enumerable.Range(0, 8).Select(i => type.GetMember<FieldSymbol>("f" + i).TypeWithAnnotations).ToArray();

            Assert.True(fieldTypes[0].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[1].Type.IsPointerOrFunctionPointer());
            Assert.False(fieldTypes[2].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[2].Type.ContainsPointerOrFunctionPointer());
            Assert.False(fieldTypes[3].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[3].Type.ContainsPointerOrFunctionPointer());

            Assert.False(fieldTypes[4].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[4].Type.ContainsPointerOrFunctionPointer());
            Assert.False(fieldTypes[5].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[5].Type.ContainsPointerOrFunctionPointer());
            Assert.False(fieldTypes[6].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[6].Type.ContainsPointerOrFunctionPointer());
            Assert.False(fieldTypes[7].Type.IsPointerOrFunctionPointer());
            Assert.True(fieldTypes[7].Type.ContainsPointerOrFunctionPointer());
        }

        [Fact]
        public void UnsafeFieldTypes()
        {
            var template = @"
{0} class C
{{
    public {1} int* f = null, g = null;
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     public  int* f = null, g = null;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*")
                );
        }

        [Fact]
        public void UnsafeLocalTypes()
        {
            var template = @"
{0} class C
{{
    void M()
    {{
        {1} 
        {{
            int* f = null, g = null;
        }}
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"));
        }

        [Fact]
        public void UnsafeMethodSignatures()
        {
            var template = @"
{0} interface I
{{
    {1} int* M(long* p, byte* q);
}}

{0} class C
{{
    {1} int* M(long* p, byte* q) {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"),
                // (4,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"),
                // (4,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),

                // (9,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"),
                // (9,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"),
                // (9,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"));
        }

        [Fact]
        public void DelegateSignatures()
        {
            var template = @"
{0} class C
{{
    {1} delegate int* M(long* p, byte* q);
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"),
                // (4,31): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"),
                // (4,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"));
        }

        [Fact]
        public void UnsafeConstructorSignatures()
        {
            var template = @"
{0} class C
{{
    {1} C(long* p, byte* q) {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,8): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"),
                // (4,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"));
        }

        [Fact]
        public void UnsafeOperatorSignatures()
        {
            var template = @"
{0} class C
{{
    public static {1} C operator +(C c, int* p) {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"));
        }

        [Fact]
        public void UnsafeConversionSignatures()
        {
            var template = @"
{0} class C
{{
    public static {1} explicit operator C(int* p) {{ throw null; }}
    public static {1} explicit operator byte*(C c) {{ throw null; }}
    public static {1} implicit operator C(short* p) {{ throw null; }}
    public static {1} implicit operator long*(C c) {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,40): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (5,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"),
                // (6,40): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "short*"),
                // (7,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"));
        }

        [Fact]
        public void UnsafePropertySignatures()
        {
            var template = @"
{0} interface I
{{
    {1} int* P {{ get; set; }}
}}

{0} class C
{{
    {1} int* P {{ get; set; }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (9,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"));
        }

        [Fact]
        public void UnsafeIndexerSignatures()
        {
            var template = @"
{0} interface I
{{
    {1} int* this[long* p, byte* q] {{ get; set; }}
}}

{0} class C
{{
    {1} int* this[long* p, byte* q] {{ get {{ throw null; }} set {{ throw null; }} }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (4,16): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"),
                // (4,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"),
                // (9,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (9,16): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*"),
                // (9,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "byte*"));
        }

        [Fact]
        public void UnsafeEventSignatures()
        {
            var template = @"
{0} interface I
{{
    {1} event int* E;
}}

{0} class C
{{
    {1} event int* E1;
    {1} event int* E2 {{ add {{ }} remove {{ }} }}
}}
";
            DiagnosticDescription[] expectedWithoutUnsafe =
            {
                // (4,17): error CS0066: 'I.E': event must be of a delegate type
                Diagnostic(ErrorCode.ERR_EventNotDelegate, "E").WithArguments("I.E").WithLocation(4, 17),
                // (9,17): error CS0066: 'C.E1': event must be of a delegate type
                Diagnostic(ErrorCode.ERR_EventNotDelegate, "E1").WithArguments("C.E1").WithLocation(9, 17),
                // (10,17): error CS0066: 'C.E2': event must be of a delegate type
                Diagnostic(ErrorCode.ERR_EventNotDelegate, "E2").WithArguments("C.E2").WithLocation(10, 17),
                // (9,17): warning CS0067: The event 'C.E1' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedEvent, "E1").WithArguments("C.E1").WithLocation(9, 17)
            };

            DiagnosticDescription[] expectedWithUnsafe =
            {
                // (4,23): error CS0066: 'I.E': event must be of a delegate type
                Diagnostic(ErrorCode.ERR_EventNotDelegate, "E").WithArguments("I.E").WithLocation(4, 23),
                // (9,23): error CS0066: 'C.E1': event must be of a delegate type
                Diagnostic(ErrorCode.ERR_EventNotDelegate, "E1").WithArguments("C.E1").WithLocation(9, 23),
                // (10,23): error CS0066: 'C.E2': event must be of a delegate type
                Diagnostic(ErrorCode.ERR_EventNotDelegate, "E2").WithArguments("C.E2").WithLocation(10, 23),
                // (9,23): warning CS0067: The event 'C.E1' is never used
                Diagnostic(ErrorCode.WRN_UnreferencedEvent, "E1").WithArguments("C.E1").WithLocation(9, 23)
            };

            CompareUnsafeDiagnostics(template, expectedWithoutUnsafe, expectedWithoutUnsafe, expectedWithoutUnsafe,
                expectedWithUnsafeOnMembersOnlyPreview: expectedWithUnsafe,
                expectedWithUnsafeOnTypeAndMembersPreview: expectedWithUnsafe);
        }

        [Fact]
        public void UnsafeTypeArguments()
        {
            var template = """
                {0} interface I<T>
                {{
                    {1} void Test(I<int*> i);
                }}

                {0} class C<T>
                {{
                    {1} void Test(C<int*> c) {{ }}
                }}
                """;

            CompareUnsafeDiagnostics(template,
                new[]
                {
                    // (3,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      void Test(I<int*> i);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 18),
                    // (3,24): error CS0306: The type 'int*' may not be used as a type argument
                    //      void Test(I<int*> i);
                    Diagnostic(ErrorCode.ERR_BadTypeArgument, "i").WithArguments("int*").WithLocation(3, 24),
                    // (8,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      void Test(C<int*> c) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(8, 18),
                    // (8,24): error CS0306: The type 'int*' may not be used as a type argument
                    //      void Test(C<int*> c) { }
                    Diagnostic(ErrorCode.ERR_BadTypeArgument, "c").WithArguments("int*").WithLocation(8, 24)
                },
                new[]
                {
                    // (3,30): error CS0306: The type 'int*' may not be used as a type argument
                    //     unsafe void Test(I<int*> i);
                    Diagnostic(ErrorCode.ERR_BadTypeArgument, "i").WithArguments("int*"),
                    // (8,30): error CS0306: The type 'int*' may not be used as a type argument
                    //     unsafe void Test(C<int*> c) { }
                    Diagnostic(ErrorCode.ERR_BadTypeArgument, "c").WithArguments("int*"),
                },
                expectedWithoutUnsafePreview:
                [
                    // (3,24): error CS0306: The type 'int*' may not be used as a type argument
                    //      void Test(I<int*> i);
                    Diagnostic(ErrorCode.ERR_BadTypeArgument, "i").WithArguments("int*").WithLocation(3, 24),
                    // (8,24): error CS0306: The type 'int*' may not be used as a type argument
                    //      void Test(C<int*> c) { }
                    Diagnostic(ErrorCode.ERR_BadTypeArgument, "c").WithArguments("int*").WithLocation(8, 24)
                ]);
        }

        [Fact]
        public void UnsafeExpressions1()
        {
            var template = @"
{0} class C
{{
    void Test()
    {{
        {1}
        {{
            Unsafe(); //CS0214
        }}

        {1}
        {{
            var x = Unsafe(); //CS0214
        }}

        {1}
        {{
            var x = Unsafe(); //CS0214
            var y = Unsafe(); //CS0214 suppressed
        }}

        {1}
        {{
            Unsafe(null); //CS0214
        }}
    }}

    {1} int* Unsafe() {{ return null; }} //CS0214
    {1} void Unsafe(int* p) {{ }} //CS0214
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (28,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int* Unsafe() { return null; } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(28, 6),
                    // (29,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      void Unsafe(int* p) { } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(29, 18),
                    // (8,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(8, 13),
                    // (13,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             var x = Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(13, 21),
                    // (18,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             var x = Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(18, 21),
                    // (19,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             var y = Unsafe(); //CS0214 suppressed
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(19, 21),
                    // (24,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             Unsafe(null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(24, 20),
                    // (24,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             Unsafe(null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe(null)").WithLocation(24, 13)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (8,13): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //             Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(8, 13),
                    // (13,21): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //             var x = Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(13, 21),
                    // (18,21): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //             var x = Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(18, 21),
                    // (19,21): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //             var y = Unsafe(); //CS0214 suppressed
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(19, 21),
                    // (24,13): error CS9363: 'C.Unsafe(int*)' must be used in an unsafe context because it has pointers in its signature
                    //             Unsafe(null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe(null)").WithArguments("C.Unsafe(int*)").WithLocation(24, 13),
                ]);
        }

        [Fact]
        public void UnsafeExpressions2()
        {
            var template = @"
{0} class C
{{
    {1} int* Field = Unsafe(); //CS0214 * 2

    {1} C()
    {{
        Unsafe(); //CS0214
    }}

    {1} ~C()
    {{
        Unsafe(); //CS0214
    }}

    {1} void Test()
    {{
        Unsafe(); //CS0214
    }}

    {1} event System.Action E
    {{
        add {{ Unsafe(); }} //CS0214
        remove {{ Unsafe(); }} //CS0214
    }}

    {1} int P
    {{
        set {{ Unsafe(); }} //CS0214
    }}

    {1} int this[int x]
    {{
        set {{ Unsafe(); }} //CS0214
    }}

    {1} public static implicit operator int(C c)
    {{
        Unsafe(); //CS0214
        return 0;
    }}

    {1} public static C operator +(C c)
    {{
        Unsafe(); //CS0214
        return c;
    }}

    {1} static int* Unsafe() {{ return null; }} //CS0214
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int* Field = Unsafe(); //CS0214 * 2
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 6),
                    // (4,19): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int* Field = Unsafe(); //CS0214 * 2
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(4, 19),
                    // (8,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(8, 9),
                    // (13,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(13, 9),
                    // (18,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(18, 9),
                    // (23,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         add { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(23, 15),
                    // (24,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         remove { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(24, 18),
                    // (29,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         set { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(29, 15),
                    // (34,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         set { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(34, 15),
                    // (39,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(39, 9),
                    // (45,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(45, 9),
                    // (49,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static int* Unsafe() { return null; } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(49, 13)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (4,19): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //      int* Field = Unsafe(); //CS0214 * 2
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(4, 19),
                    // (8,9): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(8, 9),
                    // (13,9): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(13, 9),
                    // (18,9): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(18, 9),
                    // (23,15): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         add { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(23, 15),
                    // (24,18): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         remove { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(24, 18),
                    // (29,15): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         set { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(29, 15),
                    // (34,15): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         set { Unsafe(); } //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(34, 15),
                    // (39,9): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(39, 9),
                    // (45,9): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(45, 9),
                ]);
        }

        [Fact]
        public void UnsafeExpressions3()
        {
            var template = @"
{0} class C
{{
    {1} void Test(int* p = Unsafe()) //CS0214 * 2
    {{
        System.Action a1 = () => Unsafe(); //CS0214

        System.Action a2 = () =>
        {{
            Unsafe(); //CS0214
        }};
    }}

    {1} static int* Unsafe() {{ return null; }} //CS0214
}}
";

            DiagnosticDescription[] expectedWithoutUnsafe =
            {
                // (4,16): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      void Test(int* p = Unsafe()) //CS0214 * 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 16),
                // (4,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      void Test(int* p = Unsafe()) //CS0214 * 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(4, 25),
                // (4,25): error CS1736: Default parameter value for 'p' must be a compile-time constant
                //      void Test(int* p = Unsafe()) //CS0214 * 2
                Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "Unsafe()").WithArguments("p").WithLocation(4, 25),
                // (6,34): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         System.Action a1 = () => Unsafe(); //CS0214
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(6, 34),
                // (10,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //             Unsafe(); //CS0214
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Unsafe()").WithLocation(10, 13),
                // (14,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      static int* Unsafe() { return null; } //CS0214
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(14, 13)
            };

            DiagnosticDescription[] expectedWithUnsafe =
            {
                // (4,25): error CS1736: Default parameter value for 'p' must be a compile-time constant
                //      void Test(int* p = Unsafe()) //CS0214 * 2
                Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "Unsafe()").WithArguments("p")
            };

            CompareUnsafeDiagnostics(template, expectedWithoutUnsafe, expectedWithUnsafe,
                expectedWithoutUnsafePreview:
                [
                    // (4,25): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //      void Test(int* p = Unsafe()) //CS0214 * 2
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(4, 25),
                    // (4,25): error CS1736: Default parameter value for 'p' must be a compile-time constant
                    //      void Test(int* p = Unsafe()) //CS0214 * 2
                    Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "Unsafe()").WithArguments("p").WithLocation(4, 25),
                    // (6,34): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //         System.Action a1 = () => Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(6, 34),
                    // (10,13): error CS9363: 'C.Unsafe()' must be used in an unsafe context because it has pointers in its signature
                    //             Unsafe(); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Unsafe()").WithArguments("C.Unsafe()").WithLocation(10, 13),
                ]);
        }

        [Fact]
        public void UnsafeIteratorSignatures()
        {
            var template = @"
{0} class C
{{
    {1} System.Collections.Generic.IEnumerable<int> Iterator(int* p)
    {{
        yield return 1;
    }}
}}
";

            var withoutUnsafe = string.Format(template, "", "");
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // CONSIDER: We should probably suppress CS0214 (like Dev10 does) because it's
                // confusing, but we don't have a good way to do so, because we don't know that
                // the method is an iterator until we bind the body and we certainly don't want
                // to do that just to figure out the types of the parameters.

                // (4,59): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (4,64): error CS1637: Iterators cannot have pointer type parameters
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p"));

            CreateCompilation(withoutUnsafe, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,64): error CS1637: Iterators cannot have pointer type parameters
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p"));
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,64): error CS1637: Iterators cannot have pointer type parameters
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p"));

            var withUnsafeOnType = string.Format(template, "unsafe", "");
            CreateCompilation(withUnsafeOnType, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,64): error CS1637: Iterators cannot have pointer type parameters
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p"));

            var withUnsafeOnMembers = string.Format(template, "", "unsafe");
            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (4,70): error CS1637: Iterators cannot have pointer type parameters
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int* p)
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p").WithLocation(4, 70),
                // (4,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int* p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "Iterator").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(4, 56)); //this is for putting "unsafe" on an iterator, not for the parameter type

            var expectedDiagnostics = new[]
            {
                // (4,70): error CS1637: Iterators cannot have pointer type parameters
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int* p)
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p").WithLocation(4, 70)
            };

            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);

            var withUnsafeOnTypeAndMembers = string.Format(template, "unsafe", "unsafe");
            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (4,70): error CS1637: Iterators cannot have pointer type parameters
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int* p)
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p").WithLocation(4, 70),
                // (4,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int* p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "Iterator").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(4, 56)); //this is for putting "unsafe" on an iterator, not for the parameter type

            expectedDiagnostics = [
                // (4,70): error CS1637: Iterators cannot have pointer type parameters
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int* p)
                Diagnostic(ErrorCode.ERR_UnsafeIteratorArgType, "p").WithLocation(4, 70)
            ];

            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void UnsafeIteratorSignatures_PointerArray()
        {
            var template = @"
{0} class C
{{
    {1} System.Collections.Generic.IEnumerable<int> Iterator(int*[] p)
    {{
        yield return 1;
    }}
}}
";

            var withoutUnsafe = string.Format(template, "", "");
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,59): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      System.Collections.Generic.IEnumerable<int> Iterator(int*[] p)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 59)
                );

            CreateCompilation(withoutUnsafe, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();

            var withUnsafeOnType = string.Format(template, "unsafe", "");
            CreateCompilation(withUnsafeOnType, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();

            var withUnsafeOnMembers = string.Format(template, "", "unsafe");
            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (4,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int*[] p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "Iterator").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(4, 56)
                );

            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();

            var withUnsafeOnTypeAndMembers = string.Format(template, "unsafe", "unsafe");
            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (4,56): error CS9202: Feature 'ref and unsafe in async and iterator methods' is not available in C# 12.0. Please use language version 13.0 or greater.
                //     unsafe System.Collections.Generic.IEnumerable<int> Iterator(int*[] p)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion12, "Iterator").WithArguments("ref and unsafe in async and iterator methods", "13.0").WithLocation(4, 56)
                );

            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular13).VerifyEmitDiagnostics();
            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll).VerifyEmitDiagnostics();
        }

        [Fact]
        public void UnsafeInAttribute1()
        {
            var text = @"
unsafe class Attr : System.Attribute
{
    [Attr(null)] // Dev10: doesn't matter that the type and member are both 'unsafe'
    public unsafe Attr(int* i)
    {
    }
}
";
            // CONSIDER: Dev10 reports CS0214 (unsafe) and CS0182 (not a constant), but this makes
            // just as much sense.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,6): error CS0181: Attribute constructor parameter 'i' has type 'int*', which is not a valid attribute parameter type
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "Attr").WithArguments("i", "int*"));
        }

        [Fact]
        public void UnsafeInAttribute2()
        {
            var text = @"
unsafe class Attr : System.Attribute
{
    [Attr(Unsafe() == null)] // Not a constant
    public unsafe Attr(bool b)
    {
    }

    static int* Unsafe()
    {
        return null;
    }
}
";
            // CONSIDER: Dev10 reports both CS0214 (unsafe) and CS0182 (not a constant), but this makes
            // just as much sense.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,11): error CS0182: An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type
                Diagnostic(ErrorCode.ERR_BadAttributeArgument, "Unsafe() == null"));
        }

        [Fact]
        public void TypeofNeverUnsafe()
        {
            var text = @"
class C<T>
{
    void Test()
    {
        System.Type t;

        t = typeof(int*);
        t = typeof(int**);
        t = typeof(int*[]);
        t = typeof(int*[][]);

        t = typeof(C<int*>); // CS0306
        t = typeof(C<int**>); // CS0306
        t = typeof(C<int*[]>);
        t = typeof(C<int*[][]>);
    }
}
";
            CreateCompilation(text).VerifyDiagnostics(
                // (13,22): error CS0306: The type 'int*' may not be used as a type argument
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "int*").WithArguments("int*"),
                // (14,22): error CS0306: The type 'int**' may not be used as a type argument
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "int**").WithArguments("int**"));
        }

        [Fact]
        public void UnsafeOnEnum()
        {
            var text = @"
unsafe enum E
{
    A
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (2,13): error CS0106: The modifier 'unsafe' is not valid for this item
                Diagnostic(ErrorCode.ERR_BadMemberFlag, "E").WithArguments("unsafe"));
        }

        [WorkItem(543834, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/543834")]
        [Fact]
        public void UnsafeOnDelegates()
        {
            var text = @"
public unsafe delegate void TestDelegate();
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll.WithAllowUnsafe(false)).VerifyDiagnostics(
                // (2,29): error CS0227: Unsafe code may only appear if compiling with /unsafe
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "TestDelegate"));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [WorkItem(543835, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/543835")]
        [Fact]
        public void UnsafeOnConstField()
        {
            var text = @"
public class Main
{
    unsafe public const int number = 0;
}
";

            CreateCompilation(text).VerifyDiagnostics(
                // (4,29): error CS0106: The modifier 'unsafe' is not valid for this item
                Diagnostic(ErrorCode.ERR_BadMemberFlag, "number").WithArguments("unsafe"));

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,29): error CS0106: The modifier 'unsafe' is not valid for this item
                Diagnostic(ErrorCode.ERR_BadMemberFlag, "number").WithArguments("unsafe"));
        }

        [Fact]
        public void UnsafeOnExplicitInterfaceImplementation()
        {
            var text = @"
interface I
{
    int P { get; set; }
    void M();
    event System.Action E;
}

class C : I
{
    unsafe int I.P { get; set; }
    unsafe void I.M() { }
    unsafe event System.Action I.E { add { } remove { } }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [WorkItem(544417, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544417")]
        [Fact]
        public void UnsafeCallParamArrays()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        {{ Goo(); }}
        {{ Goo(null); }}
        {{ Goo((int*)1); }}
        {{ Goo(new int*[2]); }}
    }}

    {1} static void Goo(params int*[] x) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (12,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void Goo(params int*[] x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 29),
                    // (6,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo()").WithLocation(6, 11),
                    // (7,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(7, 15),
                    // (7,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo(null)").WithLocation(7, 11),
                    // (8,16): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(8, 16),
                    // (8,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(8, 15),
                    // (8,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo((int*)1)").WithLocation(8, 11),
                    // (9,19): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 19),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new int*[2]").WithLocation(9, 15),
                    // (9,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo(new int*[2])").WithLocation(9, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (6,11): error CS9363: 'C.Goo(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo()").WithArguments("C.Goo(params int*[])").WithLocation(6, 11),
                    // (7,11): error CS9363: 'C.Goo(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo(null)").WithArguments("C.Goo(params int*[])").WithLocation(7, 11),
                    // (8,11): error CS9363: 'C.Goo(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo((int*)1)").WithArguments("C.Goo(params int*[])").WithLocation(8, 11),
                    // (9,11): error CS9363: 'C.Goo(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo(new int*[2])").WithArguments("C.Goo(params int*[])").WithLocation(9, 11),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeCallOptionalParameters()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        {{ Goo(); }}
        {{ Goo(null); }}
        {{ Goo((int*)1); }}
    }}

    {1} static void Goo(int* p = null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void Goo(int* p = null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(11, 22),
                    // (6,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo()").WithLocation(6, 11),
                    // (7,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(7, 15),
                    // (7,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo(null)").WithLocation(7, 11),
                    // (8,16): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(8, 16),
                    // (8,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(8, 15),
                    // (8,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo((int*)1)").WithLocation(8, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (6,11): error CS9363: 'C.Goo(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo()").WithArguments("C.Goo(int*)").WithLocation(6, 11),
                    // (7,11): error CS9363: 'C.Goo(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo(null)").WithArguments("C.Goo(int*)").WithLocation(7, 11),
                    // (8,11): error CS9363: 'C.Goo(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { Goo((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo((int*)1)").WithArguments("C.Goo(int*)").WithLocation(8, 11),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeDelegateCallParamArrays()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        D d = null;
        {{ d(); }}
        {{ d(null); }}
        {{ d((int*)1); }}
        {{ d(new int*[2]); }}
    }}

    {1} delegate void D(params int*[] x);
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate void D(params int*[] x);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 29),
                    // (7,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d()").WithLocation(7, 11),
                    // (8,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(8, 13),
                    // (8,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d(null)").WithLocation(8, 11),
                    // (9,14): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 14),
                    // (9,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(9, 13),
                    // (9,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d((int*)1)").WithLocation(9, 11),
                    // (10,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 17),
                    // (10,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new int*[2]").WithLocation(10, 13),
                    // (10,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d(new int*[2])").WithLocation(10, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,11): error CS9363: 'C.D.Invoke(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d()").WithArguments("C.D.Invoke(params int*[])").WithLocation(7, 11),
                    // (8,11): error CS9363: 'C.D.Invoke(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d(null)").WithArguments("C.D.Invoke(params int*[])").WithLocation(8, 11),
                    // (9,11): error CS9363: 'C.D.Invoke(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d((int*)1)").WithArguments("C.D.Invoke(params int*[])").WithLocation(9, 11),
                    // (10,11): error CS9363: 'C.D.Invoke(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d(new int*[2])").WithArguments("C.D.Invoke(params int*[])").WithLocation(10, 11),
                ]);
        }

        [Fact]
        public void UnsafeDelegateCallParamArrays_Nested()
        {
            var template = @"
class Container<T> {{ }}
{0} class C
{{
    {1} static void Main()
    {{
        D d = null;
        {{ d(); }}
        {{ d(null); }}
        {{ d(new Container<int*[]>[2]); }}
    }}

    {1} delegate void D(params Container<int*[]>[] x);
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,39): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate void D(params Container<int*[]>[] x);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 39),
                    // (8,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d()").WithLocation(8, 11),
                    // (9,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(9, 13),
                    // (9,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d(null)").WithLocation(9, 11),
                    // (10,27): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 27),
                    // (10,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new Container<int*[]>[2]").WithLocation(10, 13),
                    // (10,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d(new Container<int*[]>[2])").WithLocation(10, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (8,11): error CS9363: 'C.D.Invoke(params Container<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d()").WithArguments("C.D.Invoke(params Container<int*[]>[])").WithLocation(8, 11),
                    // (9,11): error CS9363: 'C.D.Invoke(params Container<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d(null)").WithArguments("C.D.Invoke(params Container<int*[]>[])").WithLocation(9, 11),
                    // (10,11): error CS9363: 'C.D.Invoke(params Container<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d(new Container<int*[]>[2])").WithArguments("C.D.Invoke(params Container<int*[]>[])").WithLocation(10, 11),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeDelegateCallOptionalParameters()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        D d = null;
        {{ d(); }}
        {{ d(null); }}
        {{ d((int*)1); }}
    }}

    {1} delegate void D(int* p = null);
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (12,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate void D(int* p = null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 22),
                    // (7,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d()").WithLocation(7, 11),
                    // (8,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(8, 13),
                    // (8,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d(null)").WithLocation(8, 11),
                    // (9,14): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 14),
                    // (9,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(9, 13),
                    // (9,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "d((int*)1)").WithLocation(9, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,11): error CS9363: 'C.D.Invoke(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { d(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d()").WithArguments("C.D.Invoke(int*)").WithLocation(7, 11),
                    // (8,11): error CS9363: 'C.D.Invoke(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { d(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d(null)").WithArguments("C.D.Invoke(int*)").WithLocation(8, 11),
                    // (9,11): error CS9363: 'C.D.Invoke(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { d((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "d((int*)1)").WithArguments("C.D.Invoke(int*)").WithLocation(9, 11),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeObjectCreationParamArrays()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        C c;
        {{ c = new C(); }}
        {{ c = new C(null); }}
        {{ c = new C((int*)1); }}
        {{ c = new C(new int*[2]); }}
    }}

    {1} C(params int*[] x) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      C(params int*[] x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 15),
                    // (7,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C()").WithLocation(7, 15),
                    // (8,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(8, 21),
                    // (8,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C(null)").WithLocation(8, 15),
                    // (9,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 22),
                    // (9,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(9, 21),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C((int*)1)").WithLocation(9, 15),
                    // (10,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 25),
                    // (10,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new int*[2]").WithLocation(10, 21),
                    // (10,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C(new int*[2])").WithLocation(10, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,15): error CS9363: 'C.C(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C()").WithArguments("C.C(params int*[])").WithLocation(7, 15),
                    // (8,15): error CS9363: 'C.C(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C(null)").WithArguments("C.C(params int*[])").WithLocation(8, 15),
                    // (9,15): error CS9363: 'C.C(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C((int*)1)").WithArguments("C.C(params int*[])").WithLocation(9, 15),
                    // (10,15): error CS9363: 'C.C(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(new int*[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C(new int*[2])").WithArguments("C.C(params int*[])").WithLocation(10, 15),
                ]);
        }

        [Fact]
        public void UnsafeObjectCreationParamArrays_Nested()
        {
            var template = @"
class Container<T> {{ }}
{0} class C
{{
    {1} static void Main()
    {{
        C c;
        {{ c = new C(); }}
        {{ c = new C(null); }}
        {{ c = new C(new Container<int*[]>[2]); }}
    }}

    {1} C(params Container<int*[]>[] x) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      C(params Container<int*[]>[] x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 25),
                    // (8,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C()").WithLocation(8, 15),
                    // (9,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(9, 21),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C(null)").WithLocation(9, 15),
                    // (10,35): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 35),
                    // (10,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new Container<int*[]>[2]").WithLocation(10, 21),
                    // (10,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C(new Container<int*[]>[2])").WithLocation(10, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (8,15): error CS9363: 'C.C(params Container<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C()").WithArguments("C.C(params Container<int*[]>[])").WithLocation(8, 15),
                    // (9,15): error CS9363: 'C.C(params Container<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C(null)").WithArguments("C.C(params Container<int*[]>[])").WithLocation(9, 15),
                    // (10,15): error CS9363: 'C.C(params Container<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(new Container<int*[]>[2]); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C(new Container<int*[]>[2])").WithArguments("C.C(params Container<int*[]>[])").WithLocation(10, 15),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeObjectCreationOptionalParameters()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        C c;
        {{ c = new C(); }}
        {{ c = new C(null); }}
        {{ c = new C((int*)1); }}
    }}

    {1} C(int* p = null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (12,8): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      C(int* p = null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 8),
                    // (7,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C()").WithLocation(7, 15),
                    // (8,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(8, 21),
                    // (8,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C(null)").WithLocation(8, 15),
                    // (9,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 22),
                    // (9,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(9, 21),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new C((int*)1)").WithLocation(9, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,15): error CS9363: 'C.C(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C()").WithArguments("C.C(int*)").WithLocation(7, 15),
                    // (8,15): error CS9363: 'C.C(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C(null); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C(null)").WithArguments("C.C(int*)").WithLocation(8, 15),
                    // (9,15): error CS9363: 'C.C(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { c = new C((int*)1); }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "new C((int*)1)").WithArguments("C.C(int*)").WithLocation(9, 15),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeIndexerParamArrays()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        C c = new C();
        {{ int x = c[1]; }} // NOTE: as in dev10, this does not produce an error (would for a call).
        {{ int x = c[1, null]; }} // NOTE: as in dev10, this does not produce an error (would for a call).
        {{ int x = c[1, (int*)1]; }}
        {{ int x = c[1, new int*[2]]; }}
    }}

    {1} int this[int x, params int*[] a] {{ get {{ return 0; }} set {{ }} }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int this[int x, params int*[] a] { get { return 0; } set { } }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 29),
                    // (9,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, (int*)1]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 25),
                    // (9,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, (int*)1]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(9, 24),
                    // (10,28): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, new int*[2]]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(10, 28),
                    // (10,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, new int*[2]]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new int*[2]").WithLocation(10, 24)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,19): error CS9363: 'C.this[int, params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1]; } // NOTE: as in dev10, this does not produce an error (would for a call).
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1]").WithArguments("C.this[int, params int*[]].get").WithLocation(7, 19),
                    // (8,19): error CS9363: 'C.this[int, params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, null]; } // NOTE: as in dev10, this does not produce an error (would for a call).
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, null]").WithArguments("C.this[int, params int*[]].get").WithLocation(8, 19),
                    // (9,19): error CS9363: 'C.this[int, params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, (int*)1]; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, (int*)1]").WithArguments("C.this[int, params int*[]].get").WithLocation(9, 19),
                    // (10,19): error CS9363: 'C.this[int, params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, new int*[2]]; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, new int*[2]]").WithArguments("C.this[int, params int*[]].get").WithLocation(10, 19),
                ],
                verifyPreviewDiagnosticsAreSubset: false);
        }

        [Fact]
        public void UnsafeIndexerParamArrays_Nested()
        {
            var template = @"
class Container<T> {{ }}

{0} class C
{{
    {1} static void Main()
    {{
        C c = new C();
        {{ int x = c[1]; }} // NOTE: as in dev10, this does not produce an error (would for a call).
        {{ int x = c[1, null]; }} // NOTE: as in dev10, this does not produce an error (would for a call).
        {{ int x = c[1, new Container<int*[]>[2]]; }}
    }}

    {1} int this[int x, params Container<int*[]>[] a] {{ get {{ return 0; }} set {{ }} }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (14,39): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int this[int x, params Container<int*[]>[] a] { get { return 0; } set { } }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(14, 39),
                    // (11,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, new Container<int*[]>[2]]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(11, 38),
                    // (11,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, new Container<int*[]>[2]]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "new Container<int*[]>[2]").WithLocation(11, 24)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,19): error CS9363: 'C.this[int, params Container<int*[]>[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1]; } // NOTE: as in dev10, this does not produce an error (would for a call).
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1]").WithArguments("C.this[int, params Container<int*[]>[]].get").WithLocation(9, 19),
                    // (10,19): error CS9363: 'C.this[int, params Container<int*[]>[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, null]; } // NOTE: as in dev10, this does not produce an error (would for a call).
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, null]").WithArguments("C.this[int, params Container<int*[]>[]].get").WithLocation(10, 19),
                    // (11,19): error CS9363: 'C.this[int, params Container<int*[]>[]].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, new Container<int*[]>[2]]; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, new Container<int*[]>[2]]").WithArguments("C.this[int, params Container<int*[]>[]].get").WithLocation(11, 19),
                ],
                verifyPreviewDiagnosticsAreSubset: false);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeIndexerOptionalParameters()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        C c = new C();
        {{ int x = c[1]; }} // NOTE: as in dev10, this does not produce an error (would for a call).
        {{ int x = c[1, null]; }} // NOTE: as in dev10, this does not produce an error (would for a call).
        {{ int x = c[1, (int*)1]; }}
    }}

    {1} int this[int x, int* p = null] {{ get {{ return 0; }} set {{ }} }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (12,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int this[int x, int* p = null] { get { return 0; } set { } }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 22),
                    // (9,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, (int*)1]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(9, 25),
                    // (9,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { int x = c[1, (int*)1]; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "(int*)1").WithLocation(9, 24)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,19): error CS9363: 'C.this[int, int*].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1]; } // NOTE: as in dev10, this does not produce an error (would for a call).
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1]").WithArguments("C.this[int, int*].get").WithLocation(7, 19),
                    // (8,19): error CS9363: 'C.this[int, int*].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, null]; } // NOTE: as in dev10, this does not produce an error (would for a call).
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, null]").WithArguments("C.this[int, int*].get").WithLocation(8, 19),
                    // (9,19): error CS9363: 'C.this[int, int*].get' must be used in an unsafe context because it has pointers in its signature
                    //         { int x = c[1, (int*)1]; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "c[1, (int*)1]").WithArguments("C.this[int, int*].get").WithLocation(9, 19),
                ],
                verifyPreviewDiagnosticsAreSubset: false);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeAttributeParamArrays()
        {
            var template = @"
[A]
{0} class A : System.Attribute
{{
    {1} A(params int*[] a) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                new[]
                {
                // CONSIDER: this differs slightly from dev10, but is clearer.
                // (2,2): error CS0181: Attribute constructor parameter 'a' has type 'int*[]', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("a", "int*[]").WithLocation(2, 2),

                // (5,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      A(params int*[] a) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 15)
                },
                new[]
                {
                // CONSIDER: this differs slightly from dev10, but is clearer.
                // (2,2): error CS0181: Attribute constructor parameter 'a' has type 'int*[]', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("a", "int*[]").WithLocation(2, 2)
                },
                expectedWithoutUnsafePreview:
                [
                // (2,2): error CS0181: Attribute constructor parameter 'a' has type 'int*[]', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("a", "int*[]").WithLocation(2, 2),
                // (2,2): error CS9363: 'A.A(params int*[])' must be used in an unsafe context because it has pointers in its signature
                // [A]
                Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "A").WithArguments("A.A(params int*[])").WithLocation(2, 2),
                ],
                expectedWithUnsafeOnMembersOnlyPreview:
                [
                // (2,2): error CS0181: Attribute constructor parameter 'a' has type 'int*[]', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("a", "int*[]").WithLocation(2, 2),
                // (2,2): error CS9363: 'A.A(params int*[])' must be used in an unsafe context because it has pointers in its signature
                // [A]
                Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "A").WithArguments("A.A(params int*[])").WithLocation(2, 2),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeAttributeOptionalParameters()
        {
            var template = @"
[A]
{0} class A : System.Attribute
{{
    {1} A(int* p = null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                new[]
                {
                // CONSIDER: this differs slightly from dev10, but is clearer.
                // (2,2): error CS0181: Attribute constructor parameter 'p' has type 'int*', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("p", "int*").WithLocation(2, 2),

                // (5,8): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      A(int* p = null) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 8)
                },
                new[]
                {
                // CONSIDER: this differs slightly from dev10, but is clearer.
                // (2,2): error CS0181: Attribute constructor parameter 'p' has type 'int*', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("p", "int*").WithLocation(2, 2)
                },
                expectedWithoutUnsafePreview:
                [
                // (2,2): error CS0181: Attribute constructor parameter 'p' has type 'int*', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("p", "int*").WithLocation(2, 2),
                // (2,2): error CS9363: 'A.A(int*)' must be used in an unsafe context because it has pointers in its signature
                // [A]
                Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "A").WithArguments("A.A(int*)").WithLocation(2, 2),
                ],
                expectedWithUnsafeOnMembersOnlyPreview:
                [
                // (2,2): error CS0181: Attribute constructor parameter 'p' has type 'int*', which is not a valid attribute parameter type
                // [A]
                Diagnostic(ErrorCode.ERR_BadAttributeParamType, "A").WithArguments("p", "int*").WithLocation(2, 2),
                // (2,2): error CS9363: 'A.A(int*)' must be used in an unsafe context because it has pointers in its signature
                // [A]
                Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "A").WithArguments("A.A(int*)").WithLocation(2, 2),
                ]);
        }

        [WorkItem(544938, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544938")]
        [Fact]
        public void UnsafeDelegateAssignment_Parameter()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        D d;
        {{ d = delegate {{ }}; }}
        {{ d = null; }}
        {{ d = Goo; }}
    }}

    {1} delegate void D(int* x = null);
    {1} static void Goo(int* x = null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo").WithLocation(9, 15),

                    // (12,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate void D(int* x = null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 22),
                    // (13,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void Goo(int* x = null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 22)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,15): error CS9363: 'C.Goo(int*)' must be used in an unsafe context because it has pointers in its signature
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo").WithArguments("C.Goo(int*)").WithLocation(9, 15),
                ]);
        }

        [Fact]
        public void UnsafeDelegateAssignment_ReturnType()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        D d;
        {{ d = delegate {{ throw null; }}; }}
        {{ d = null; }}
        {{ d = Goo; }}
    }}

    {1} delegate int* D();
    {1} static int* Goo() {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo").WithLocation(9, 15),

                    // (12,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate int* D();
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 15),
                    // (13,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static int* Goo() { throw null; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 13)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,15): error CS9363: 'C.Goo()' must be used in an unsafe context because it has pointers in its signature
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo").WithArguments("C.Goo()").WithLocation(9, 15),
                ]);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67330")]
        public void UnsafeDelegateAssignment_PointerArray_Parameter()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        D d;
        {{ d = delegate {{ }}; }}
        {{ d = null; }}
        {{ d = Goo; }}
    }}

    {1} delegate void D(int*[] x = null);
    {1} static void Goo(int*[] x = null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void Goo(int*[] x = null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 22),
                    // (12,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate void D(int*[] x = null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 22),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo").WithLocation(9, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,15): error CS9363: 'C.Goo(int*[])' must be used in an unsafe context because it has pointers in its signature
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo").WithArguments("C.Goo(int*[])").WithLocation(9, 15),
                ]);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67330")]
        public void UnsafeDelegateAssignment_PointerArray_Return()
        {
            var template = @"
{0} class C
{{
    {1} static void Main()
    {{
        D d;
        {{ d = delegate {{ throw null; }}; }}
        {{ d = null; }}
        {{ d = Goo; }}
    }}

    {1} delegate int*[] D();
    {1} static int*[] Goo() {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static int*[] Goo() { throw null; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 13),
                    // (12,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate int*[] D();
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 15),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo").WithLocation(9, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,15): error CS9363: 'C.Goo()' must be used in an unsafe context because it has pointers in its signature
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo").WithArguments("C.Goo()").WithLocation(9, 15),
                ]);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67330")]
        public void UnsafeDelegateAssignment_PointerArray_Nested_Parameter()
        {
            var template = @"
{0} class C<T>
{{
    {1} static void Main()
    {{
        D d;
        {{ d = delegate {{ }}; }}
        {{ d = null; }}
        {{ d = Goo; }}
    }}

    {1} delegate void D(C<int*[]> x = null);
    {1} static void Goo(C<int*[]> x = null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void Goo(C<int*[]> x = null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 24),
                    // (12,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate void D(C<int*[]> x = null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 24),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo").WithLocation(9, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,15): error CS9363: 'C<T>.Goo(C<int*[]>)' must be used in an unsafe context because it has pointers in its signature
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo").WithArguments("C<T>.Goo(C<int*[]>)").WithLocation(9, 15),
                ]);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67330")]
        public void UnsafeDelegateAssignment_PointerArray_Nested_Return()
        {
            var template = @"
{0} class C<T>
{{
    {1} static void Main()
    {{
        D d;
        {{ d = delegate {{ throw null; }}; }}
        {{ d = null; }}
        {{ d = Goo; }}
    }}

    {1} delegate C<int*[]> D();
    {1} static C<int*[]> Goo() {{ throw null; }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (13,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static C<int*[]> Goo() { throw null; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 15),
                    // (12,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      delegate C<int*[]> D();
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(12, 17),
                    // (9,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo").WithLocation(9, 15)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,15): error CS9363: 'C<T>.Goo()' must be used in an unsafe context because it has pointers in its signature
                    //         { d = Goo; }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo").WithArguments("C<T>.Goo()").WithLocation(9, 15),
                ]);
        }

        private static void CompareUnsafeDiagnostics(string template, params DiagnosticDescription[] expectedWithoutUnsafe)
        {
            // In preview langversion, pointer types and sizeof are safe,
            // so filter out ERR_UnsafeNeeded and ERR_SizeofUnsafe for preview expected diagnostics.
            var expectedWithoutUnsafePreview = Array.FindAll(expectedWithoutUnsafe,
                d => !d.Code.Equals((int)ErrorCode.ERR_UnsafeNeeded) && !d.Code.Equals((int)ErrorCode.ERR_SizeofUnsafe));
            CompareUnsafeDiagnostics(template, expectedWithoutUnsafe, expectedWithUnsafe: [], expectedWithoutUnsafePreview: expectedWithoutUnsafePreview);
        }

        private static void CompareUnsafeDiagnostics(
            string template,
            DiagnosticDescription[] expectedWithoutUnsafe,
            DiagnosticDescription[] expectedWithUnsafe,
            DiagnosticDescription[] expectedWithoutUnsafePreview,
            DiagnosticDescription[] expectedWithUnsafeOnMembersOnlyPreview = null,
            DiagnosticDescription[] expectedWithUnsafeOnTypeAndMembersPreview = null,
            bool verifyPreviewDiagnosticsAreSubset = true)
        {
            // NOTE: ERR_UnsafeNeeded is not affected by the presence/absence of the /unsafe flag.
            var withoutUnsafe = string.Format(template, "", "");

            // With old langversion, pointer types require unsafe context.
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.Regular14).VerifyDiagnostics(expectedWithoutUnsafe);
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedWithoutUnsafe);

            // With preview langversion, pointer types are safe.
            var previewExpected = expectedWithoutUnsafePreview ?? expectedWithoutUnsafe;
            CreateCompilation(withoutUnsafe).VerifyDiagnostics(previewExpected);
            CreateCompilation(withoutUnsafe, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(previewExpected);

            // RegularNext should match preview behavior.
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.RegularNext).VerifyDiagnostics(previewExpected);
            CreateCompilation(withoutUnsafe, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(previewExpected);

            var withUnsafeOnType = string.Format(template, "unsafe", "");
            CreateCompilation(withUnsafeOnType, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedWithUnsafe);

            var withUnsafeOnMembers = string.Format(template, "", "unsafe");
            CreateCompilation(withUnsafeOnMembers, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedWithUnsafeOnMembersOnlyPreview ?? expectedWithUnsafe);

            var withUnsafeOnTypeAndMembers = string.Format(template, "unsafe", "unsafe");
            CreateCompilation(withUnsafeOnTypeAndMembers, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedWithUnsafeOnTypeAndMembersPreview ?? expectedWithUnsafe);

            // Verify that there are no breaks, i.e., we are not marking more calls unsafe.
            // Some expected diagnostics don't have location, but that should only happen in trivial cases (hence the `if`).
            if (verifyPreviewDiagnosticsAreSubset && expectedWithoutUnsafePreview.Length != 0 && !expectedWithoutUnsafePreview.SequenceEqual(expectedWithoutUnsafe))
            {
                Assert.Subset(expectedWithoutUnsafe.Select(d => d.LocationLine).ToHashSet(), expectedWithoutUnsafePreview.Select(d => d.LocationLine).ToHashSet());
            }
        }

        /// <summary>
        /// Tests that diagnostics are reported with old langversion and correctly filtered in preview.
        /// In preview, pointer types and sizeof are safe, so ERR_UnsafeNeeded and ERR_SizeofUnsafe are filtered.
        /// </summary>
        private static void VerifyUnsafeContextDiagnostics(string code, CSharpCompilationOptions options, DiagnosticDescription[] expectedDiagnostics, DiagnosticDescription[] expectedPreviewDiagnostics = null)
        {
            expectedPreviewDiagnostics ??= Array.FindAll(expectedDiagnostics,
                d => !d.Code.Equals((int)ErrorCode.ERR_UnsafeNeeded) && !d.Code.Equals((int)ErrorCode.ERR_SizeofUnsafe));
            CreateCompilation(code, parseOptions: TestOptions.Regular14, options: options).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(code, options: options).VerifyDiagnostics(expectedPreviewDiagnostics);
            CreateCompilation(code, parseOptions: TestOptions.RegularNext, options: options).VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [WorkItem(544097, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544097")]
        [Fact]
        public void MethodCallWithNullAsPointerArg()
        {
            var template = @"
{0} class Test
{{
    {1} static void Goo(void* p) {{ }}
    {1} static void Main()
    {{
        Goo(null);
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void Goo(void* p) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(4, 22),
                    // (7,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Goo(null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(7, 13),
                    // (7,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         Goo(null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Goo(null)").WithLocation(7, 9)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,9): error CS9363: 'Test.Goo(void*)' must be used in an unsafe context because it has pointers in its signature
                    //         Goo(null);
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "Goo(null)").WithArguments("Test.Goo(void*)").WithLocation(7, 9),
                ]);
        }

        [Fact]
        public void MethodCallWithNullAsPointerArrayArg()
        {
            var template = @"
{0} class Test
{{
    {1} static void M(void*[] p) {{ }}
    {1} static void Main()
    {{
        M(null);
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void M(void*[] p) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(4, 20),
                    // (7,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         M(null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(null)").WithLocation(7, 9),
                    // (7,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         M(null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(7, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (7,9): error CS9363: 'Test.M(void*[])' must be used in an unsafe context because it has pointers in its signature
                    //         M(null);
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(null)").WithArguments("Test.M(void*[])").WithLocation(7, 9),
                ]);
        }

        [Fact]
        public void MethodCallWithNullAsPointerArrayArg_Nested()
        {
            var template = @"
class C<T> {{ }}
{0} class Test
{{
    {1} static void M(C<void*[]>[] p) {{ }}
    {1} static void Main()
    {{
        M(null);
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (5,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      static void M(C<void*[]>[] p) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(5, 22),
                    // (8,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         M(null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(null)").WithLocation(8, 9),
                    // (8,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         M(null);
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(8, 11)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (8,9): error CS9363: 'Test.M(C<void*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //         M(null);
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(null)").WithArguments("Test.M(C<void*[]>[])").WithLocation(8, 9),
                ]);
        }

        [WorkItem(544097, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544097")]
        [Fact]
        public void MethodCallWithUnsafeArgument()
        {
            var template = @"
{0} class Test
{{
    {1} int M(params int*[] p) {{ return 0; }}
    {1} public static implicit operator int*(Test t) {{ return null; }}

    {1} void M()
    {{
        {{
            int x = M(null); //CS0214
        }}
        {{
            int x = M(null, null); //CS0214
        }}
        {{
            int x = M(this); //CS0214
        }}
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (5,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public static implicit operator int*(Test t) { return null; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 38),
                    // (4,19): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int M(params int*[] p) { return 0; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 19),
                    // (10,23): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(10, 23),
                    // (10,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(null)").WithLocation(10, 21),
                    // (13,23): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null, null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(13, 23),
                    // (13,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null, null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(13, 29),
                    // (13,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null, null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(null, null)").WithLocation(13, 21),
                    // (16,23): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(this); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "this").WithLocation(16, 23),
                    // (16,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(this); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(this)").WithLocation(16, 21)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (10,21): error CS9363: 'Test.M(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(null)").WithArguments("Test.M(params int*[])").WithLocation(10, 21),
                    // (13,21): error CS9363: 'Test.M(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(null, null); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(null, null)").WithArguments("Test.M(params int*[])").WithLocation(13, 21),
                    // (16,21): error CS9363: 'Test.M(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(this); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(this)").WithArguments("Test.M(params int*[])").WithLocation(16, 21),
                    // (16,23): error CS9363: 'Test.implicit operator int*(Test)' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(this); //CS0214
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this").WithArguments("Test.implicit operator int*(Test)").WithLocation(16, 23),
                ]);
        }

        [Fact]
        public void MethodCallWithUnsafeArgument_Nested()
        {
            var template = @"
class C<T> {{ }}
{0} class Test
{{
    {1} int M(params int*[] p) {{ return 0; }} // 1
    {1} public static implicit operator int*(Test t) {{ return null; }} // 2

    {1} void M()
    {{
        {{
            int x = M(null); // 3
        }}
        {{
            int x = M(null, null); // 4
        }}
        {{
            int x = M(this); // 5
        }}
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (6,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public static implicit operator int*(Test t) { return null; } // 2
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 38),
                    // (5,19): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int M(params int*[] p) { return 0; } // 1
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 19),
                    // (11,23): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null); // 3
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(11, 23),
                    // (11,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null); // 3
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(null)").WithLocation(11, 21),
                    // (14,23): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null, null); // 4
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(14, 23),
                    // (14,29): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null, null); // 4
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(14, 29),
                    // (14,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(null, null); // 4
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(null, null)").WithLocation(14, 21),
                    // (17,23): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(this); // 5
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "this").WithLocation(17, 23),
                    // (17,21): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //             int x = M(this); // 5
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "M(this)").WithLocation(17, 21)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (11,21): error CS9363: 'Test.M(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(null); // 3
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(null)").WithArguments("Test.M(params int*[])").WithLocation(11, 21),
                    // (14,21): error CS9363: 'Test.M(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(null, null); // 4
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(null, null)").WithArguments("Test.M(params int*[])").WithLocation(14, 21),
                    // (17,21): error CS9363: 'Test.M(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(this); // 5
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "M(this)").WithArguments("Test.M(params int*[])").WithLocation(17, 21),
                    // (17,23): error CS9363: 'Test.implicit operator int*(Test)' must be used in an unsafe context because it has pointers in its signature
                    //             int x = M(this); // 5
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this").WithArguments("Test.implicit operator int*(Test)").WithLocation(17, 23),
                ]);
        }

        [WorkItem(544097, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544097")]
        [Fact]
        public void IndexerAccessWithUnsafeArgument()
        {
            var template = @"
{0} class Test
{{
    {1} int this[params int*[] p] {{ get {{ return 0; }} set {{ }} }}
    {1} public static implicit operator int*(Test t) {{ return null; }}

    {1} void M()
    {{
        {{
            int x = this[null]; //CS0214 seems appropriate, but dev10 accepts
        }}
        {{
            int x = this[null, null]; //CS0214 seems appropriate, but dev10 accepts
        }}
        {{
            int x = this[this]; //CS0214 seems appropriate, but dev10 accepts
        }}
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int this[params int*[] p] { get { return 0; } set { } }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 22),
                    // (5,38): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public static implicit operator int*(Test t) { return null; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 38)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (10,21): error CS9363: 'Test.this[params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[null]; //CS0214 seems appropriate, but dev10 accepts
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this[null]").WithArguments("Test.this[params int*[]].get").WithLocation(10, 21),
                    // (13,21): error CS9363: 'Test.this[params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[null, null]; //CS0214 seems appropriate, but dev10 accepts
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this[null, null]").WithArguments("Test.this[params int*[]].get").WithLocation(13, 21),
                    // (16,21): error CS9363: 'Test.this[params int*[]].get' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[this]; //CS0214 seems appropriate, but dev10 accepts
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this[this]").WithArguments("Test.this[params int*[]].get").WithLocation(16, 21),
                    // (16,26): error CS9363: 'Test.implicit operator int*(Test)' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[this]; //CS0214 seems appropriate, but dev10 accepts
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this").WithArguments("Test.implicit operator int*(Test)").WithLocation(16, 26),
                ],
                verifyPreviewDiagnosticsAreSubset: false);
        }

        [Fact]
        public void IndexerAccessWithUnsafeArgument_Nested()
        {
            var template = @"
class C<T> {{ }}
{0} class Test
{{
    {1} int this[params C<int*[]>[] p] {{ get {{ return 0; }} set {{ }} }}
    {1} public static implicit operator C<int*[]>(Test t) {{ return null; }}

    {1} void M()
    {{
        {{
            int x = this[null];
        }}
        {{
            int x = this[null, null];
        }}
        {{
            int x = this[this];
        }}
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (5,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      int this[params C<int*[]>[] p] { get { return 0; } set { } }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 24),
                    // (6,40): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public static implicit operator C<int*[]>(Test t) { return null; }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 40)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (11,21): error CS9363: 'Test.this[params C<int*[]>[]].get' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[null];
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this[null]").WithArguments("Test.this[params C<int*[]>[]].get").WithLocation(11, 21),
                    // (14,21): error CS9363: 'Test.this[params C<int*[]>[]].get' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[null, null];
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this[null, null]").WithArguments("Test.this[params C<int*[]>[]].get").WithLocation(14, 21),
                    // (17,21): error CS9363: 'Test.this[params C<int*[]>[]].get' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[this];
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this[this]").WithArguments("Test.this[params C<int*[]>[]].get").WithLocation(17, 21),
                    // (17,26): error CS9363: 'Test.implicit operator C<int*[]>(Test)' must be used in an unsafe context because it has pointers in its signature
                    //             int x = this[this];
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "this").WithArguments("Test.implicit operator C<int*[]>(Test)").WithLocation(17, 26),
                ],
                verifyPreviewDiagnosticsAreSubset: false);
        }

        [WorkItem(544097, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544097")]
        [Fact]
        public void ConstructorInitializerWithUnsafeArgument()
        {
            var template = @"
{0} class Base
{{
    {1} public Base(int* p) {{ }}
}}

{0} class Derived : Base
{{
    {1} public Derived() : base(null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Base(int* p) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 18),
                    // (9,30): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(9, 30),
                    // (9,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "base").WithLocation(9, 25)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,23): error CS9363: 'Base.Base(int*)' must be used in an unsafe context because it has pointers in its signature
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, ": base(null)").WithArguments("Base.Base(int*)").WithLocation(9, 23),
                ]);
        }

        [Fact]
        public void ConstructorInitializerWithUnsafeArgument_PointerArray()
        {
            var template = @"
{0} class Base
{{
    {1} public Base(int*[] p) {{ }}
}}

{0} class Derived : Base
{{
    {1} public Derived() : base(null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Base(int*[] p) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 18),
                    // (9,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "base").WithLocation(9, 25),
                    // (9,30): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(9, 30)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,23): error CS9363: 'Base.Base(int*[])' must be used in an unsafe context because it has pointers in its signature
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, ": base(null)").WithArguments("Base.Base(int*[])").WithLocation(9, 23),
                ]);
        }

        [Fact]
        public void ConstructorInitializerWithUnsafeArgument_PointerArray_Nested()
        {
            var template = @"
class C<T> {{ }}
{0} class Base
{{
    {1} public Base(C<int*[]>[] p) {{ }}
}}

{0} class Derived : Base
{{
    {1} public Derived() : base(null) {{ }}
}}
";

            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (5,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Base(C<int*[]>[] p) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 20),
                    // (10,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "base").WithLocation(10, 25),
                    // (10,30): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "null").WithLocation(10, 30)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (10,23): error CS9363: 'Base.Base(C<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //      public Derived() : base(null) { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, ": base(null)").WithArguments("Base.Base(C<int*[]>[])").WithLocation(10, 23),
                ]);
        }

        [WorkItem(544286, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544286")]
        [Fact]
        public void UnsafeLambdaParameterType()
        {
            var template = @"
{0} class Program
{{
    {1} delegate void F(int* x);
    
    {1} static void Main()
    {{
        F e = x => {{ }};
    }}
}}
";

            CompareUnsafeDiagnostics(template,
                // (4,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //      delegate void F(int* x);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (8,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         F e = x => { };
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x"));
        }

        #endregion Unsafe regions

        #region Variables that need fixing

        [Fact]
        public void FixingVariables_Parameters()
        {
            var text = @"
class C
{
    void M(int x, ref int y, out int z, params int[] p)
    {
        M(x, ref y, out z, p);
    }
}
";
            var expected = @"
Yes, Call 'M(x, ref y, out z, p)' requires fixing.
Yes, ThisReference 'M' requires fixing.
No, Parameter 'x' does not require fixing. It has an underlying symbol 'x'
Yes, Parameter 'y' requires fixing.
Yes, Parameter 'z' requires fixing.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Locals()
        {
            var text = @"
class C
{
    void M(params object[] p)
    {
        C c = null;
        int x = 0;
        M(c, x);
    }
}
";
            var expected = @"
Yes, TypeExpression 'C' requires fixing.
Yes, Conversion 'null' requires fixing.
Yes, Literal 'null' requires fixing.
Yes, TypeExpression 'int' requires fixing.
Yes, Literal '0' requires fixing.
Yes, Call 'M(c, x)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 'c' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'x' requires fixing.
No, Local 'x' does not require fixing. It has an underlying symbol 'x'
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Fields1()
        {
            var text = @"
class C
{
    public S1 s;
    public C c;

    void M(params object[] p)
    {
        C c = new C();
        S1 s = new S1();

        M(this, this.s, this.s.s, this.s.c, this.c.s, this.c.c);
        M(c, c.s, c.s.s, c.s.c, c.c.s, c.c.c);
        M(s, s.s, s.s.i);
    }
}

struct S1
{
    public S2 s;
    public C c;
}

struct S2
{
    public int i;
}
";
            var expected = @"
Yes, TypeExpression 'C' requires fixing.
Yes, ObjectCreationExpression 'new C()' requires fixing.
Yes, TypeExpression 'S1' requires fixing.
Yes, ObjectCreationExpression 'new S1()' requires fixing.
Yes, Call 'M(this, this.s, this.s.s, this.s.c, this.c.s, this.c.c)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 'this' requires fixing.
Yes, ThisReference 'this' requires fixing.
Yes, Conversion 'this.s' requires fixing.
Yes, FieldAccess 'this.s' requires fixing.
Yes, ThisReference 'this' requires fixing.
Yes, Conversion 'this.s.s' requires fixing.
Yes, FieldAccess 'this.s.s' requires fixing.
Yes, FieldAccess 'this.s' requires fixing.
Yes, ThisReference 'this' requires fixing.
Yes, Conversion 'this.s.c' requires fixing.
Yes, FieldAccess 'this.s.c' requires fixing.
Yes, FieldAccess 'this.s' requires fixing.
Yes, ThisReference 'this' requires fixing.
Yes, Conversion 'this.c.s' requires fixing.
Yes, FieldAccess 'this.c.s' requires fixing.
Yes, FieldAccess 'this.c' requires fixing.
Yes, ThisReference 'this' requires fixing.
Yes, Conversion 'this.c.c' requires fixing.
Yes, FieldAccess 'this.c.c' requires fixing.
Yes, FieldAccess 'this.c' requires fixing.
Yes, ThisReference 'this' requires fixing.
Yes, Call 'M(c, c.s, c.s.s, c.s.c, c.c.s, c.c.c)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 'c' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'c.s' requires fixing.
Yes, FieldAccess 'c.s' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'c.s.s' requires fixing.
Yes, FieldAccess 'c.s.s' requires fixing.
Yes, FieldAccess 'c.s' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'c.s.c' requires fixing.
Yes, FieldAccess 'c.s.c' requires fixing.
Yes, FieldAccess 'c.s' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'c.c.s' requires fixing.
Yes, FieldAccess 'c.c.s' requires fixing.
Yes, FieldAccess 'c.c' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'c.c.c' requires fixing.
Yes, FieldAccess 'c.c.c' requires fixing.
Yes, FieldAccess 'c.c' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Call 'M(s, s.s, s.s.i)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 's' requires fixing.
No, Local 's' does not require fixing. It has an underlying symbol 's'
Yes, Conversion 's.s' requires fixing.
No, FieldAccess 's.s' does not require fixing. It has an underlying symbol 's'
No, Local 's' does not require fixing. It has an underlying symbol 's'
Yes, Conversion 's.s.i' requires fixing.
No, FieldAccess 's.s.i' does not require fixing. It has an underlying symbol 's'
No, FieldAccess 's.s' does not require fixing. It has an underlying symbol 's'
No, Local 's' does not require fixing. It has an underlying symbol 's'
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Fields2()
        {
            var text = @"
class Base
{
    public int i;
}

class Derived : Base
{
    void M()
    {
        base.i = 0;
    }
}
";
            var expected = @"
Yes, AssignmentOperator 'base.i = 0' requires fixing.
Yes, FieldAccess 'base.i' requires fixing.
Yes, BaseReference 'base' requires fixing.
Yes, Literal '0' requires fixing.
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Fields3()
        {
            var text = @"
struct S
{
    static int i;

    void M()
    {
        S.i = 0;
    }
}
";
            var expected = @"
Yes, AssignmentOperator 'S.i = 0' requires fixing.
Yes, FieldAccess 'S.i' requires fixing.
Yes, TypeExpression 'S' requires fixing.
Yes, Literal '0' requires fixing.
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Fields4()
        {
            var text = @"
struct S
{
    int i;

    void M(params object[] p)
    {
        // rvalues always require fixing.
        M(new S().i, default(S).i, MakeS().i, (new S[1])[0].i);
    }

    S MakeS() 
    { 
        return default(S); 
    }
}
";
            var expected = @"
Yes, Call 'M(new S().i, default(S).i, MakeS().i, (new S[1])[0].i)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 'new S().i' requires fixing.
Yes, FieldAccess 'new S().i' requires fixing.
Yes, ObjectCreationExpression 'new S()' requires fixing.
Yes, Conversion 'default(S).i' requires fixing.
Yes, FieldAccess 'default(S).i' requires fixing.
Yes, DefaultExpression 'default(S)' requires fixing.
Yes, Conversion 'MakeS().i' requires fixing.
Yes, FieldAccess 'MakeS().i' requires fixing.
Yes, Call 'MakeS()' requires fixing.
Yes, ThisReference 'MakeS' requires fixing.
Yes, Conversion '(new S[1])[0].i' requires fixing.
Yes, FieldAccess '(new S[1])[0].i' requires fixing.
Yes, ArrayAccess '(new S[1])[0]' requires fixing.
Yes, ArrayCreation 'new S[1]' requires fixing.
Yes, Literal '1' requires fixing.
Yes, Literal '0' requires fixing.
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Events()
        {
            var text = @"
struct S
{
    public event System.Action E;
    public event System.Action F { add { } remove { } }

    void M(params object[] p)
    {
        C c = new C();
        S s = new S();

        M(c.E, c.F); //note: note legal to pass F
        M(s.E, s.F); //note: note legal to pass F
    }
}

class C
{
    public event System.Action E;
    public event System.Action F { add { } remove { } }
}
";
            var expected = @"
Yes, TypeExpression 'C' requires fixing.
Yes, ObjectCreationExpression 'new C()' requires fixing.
Yes, TypeExpression 'S' requires fixing.
Yes, ObjectCreationExpression 'new S()' requires fixing.
Yes, Call 'M(c.E, c.F)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 'c.E' requires fixing.
Yes, BadExpression 'c.E' requires fixing.
Yes, EventAccess 'c.E' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'c.F' requires fixing.
Yes, BadExpression 'c.F' requires fixing.
Yes, EventAccess 'c.F' requires fixing.
No, Local 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Call 'M(s.E, s.F)' requires fixing.
Yes, ThisReference 'M' requires fixing.
Yes, Conversion 's.E' requires fixing.
No, EventAccess 's.E' does not require fixing. It has an underlying symbol 's'
No, Local 's' does not require fixing. It has an underlying symbol 's'
Yes, Conversion 's.F' requires fixing.
Yes, BadExpression 's.F' requires fixing.
Yes, EventAccess 's.F' requires fixing.
No, Local 's' does not require fixing. It has an underlying symbol 's'
".Trim();

            CheckIfVariablesNeedFixing(text, expected, expectError: true);
        }

        [Fact]
        public void FixingVariables_Lambda1()
        {
            var text = @"
class C
{
    void M(params object[] p)
    {
        int i = 0; // NOTE: does not require fixing even though it will be hoisted - lambdas handled separately.
        i++;
        System.Action a = () =>
        {
            int j = i;
            j++;
        };
    }
}
";
            var expected = string.Format(@"
Yes, TypeExpression 'int' requires fixing.
Yes, Literal '0' requires fixing.
Yes, IncrementOperator 'i++' requires fixing.
No, Local 'i' does not require fixing. It has an underlying symbol 'i'
Yes, TypeExpression 'System.Action' requires fixing.
Yes, Conversion '() =>{0}        {{{0}            int j = i;{0}            j++;{0}        }}' requires fixing.
Yes, Lambda '() =>{0}        {{{0}            int j = i;{0}            j++;{0}        }}' requires fixing.
Yes, TypeExpression 'int' requires fixing.
No, Local 'i' does not require fixing. It has an underlying symbol 'i'
Yes, IncrementOperator 'j++' requires fixing.
No, Local 'j' does not require fixing. It has an underlying symbol 'j'
", GetEscapedNewLine()).Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Lambda2()
        {
            var text = @"
class C
{
    void M()
    {
        int i = 0; // NOTE: does not require fixing even though it will be hoisted - lambdas handled separately.
        i++;
        System.Func<int, System.Func<int, int>> a = p => q => p + q + i;
    }
}
";
            var expected = @"
Yes, TypeExpression 'int' requires fixing.
Yes, Literal '0' requires fixing.
Yes, IncrementOperator 'i++' requires fixing.
No, Local 'i' does not require fixing. It has an underlying symbol 'i'
Yes, TypeExpression 'System.Func<int, System.Func<int, int>>' requires fixing.
Yes, Conversion 'p => q => p + q + i' requires fixing.
Yes, Lambda 'p => q => p + q + i' requires fixing.
Yes, Conversion 'q => p + q + i' requires fixing.
Yes, Lambda 'q => p + q + i' requires fixing.
Yes, BinaryOperator 'p + q + i' requires fixing.
Yes, BinaryOperator 'p + q' requires fixing.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
No, Parameter 'q' does not require fixing. It has an underlying symbol 'q'
No, Local 'i' does not require fixing. It has an underlying symbol 'i'
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_Dereference()
        {
            var text = @"
struct S
{
    int i;

    unsafe void Test(S* p)
    {
        S s;
        s = *p;
        s = p[0];

        int j;
        j = (*p).i;
        j = p[0].i;
        j = p->i;
    }
}
";
            var expected = @"
Yes, TypeExpression 'S' requires fixing.
Yes, AssignmentOperator 's = *p' requires fixing.
No, Local 's' does not require fixing. It has an underlying symbol 's'
No, PointerIndirectionOperator '*p' does not require fixing. It has no underlying symbol.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
Yes, AssignmentOperator 's = p[0]' requires fixing.
No, Local 's' does not require fixing. It has an underlying symbol 's'
No, PointerElementAccess 'p[0]' does not require fixing. It has no underlying symbol.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
Yes, Literal '0' requires fixing.
Yes, TypeExpression 'int' requires fixing.
Yes, AssignmentOperator 'j = (*p).i' requires fixing.
No, Local 'j' does not require fixing. It has an underlying symbol 'j'
No, FieldAccess '(*p).i' does not require fixing. It has no underlying symbol.
No, PointerIndirectionOperator '*p' does not require fixing. It has no underlying symbol.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
Yes, AssignmentOperator 'j = p[0].i' requires fixing.
No, Local 'j' does not require fixing. It has an underlying symbol 'j'
No, FieldAccess 'p[0].i' does not require fixing. It has no underlying symbol.
No, PointerElementAccess 'p[0]' does not require fixing. It has no underlying symbol.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
Yes, Literal '0' requires fixing.
Yes, AssignmentOperator 'j = p->i' requires fixing.
No, Local 'j' does not require fixing. It has an underlying symbol 'j'
No, FieldAccess 'p->i' does not require fixing. It has no underlying symbol.
No, PointerIndirectionOperator 'p' does not require fixing. It has no underlying symbol.
No, Parameter 'p' does not require fixing. It has an underlying symbol 'p'
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_StackAlloc()
        {
            var text = @"
struct S
{
    unsafe void Test()
    {
        int* p = stackalloc int[1];
    }
}
";
            var expected = @"
Yes, TypeExpression 'int*' requires fixing.
No, ConvertedStackAllocExpression 'stackalloc int[1]' does not require fixing. It has no underlying symbol.
Yes, Literal '1' requires fixing.
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_TypeParameters1()
        {
            var text = @"
class C
{
    public C c;

    void M<T>(T t, C c) where T : C
    {
        M(t, t.c);
    }
}
";
            var expected = @"
Yes, Call 'M(t, t.c)' requires fixing.
Yes, ThisReference 'M' requires fixing.
No, Parameter 't' does not require fixing. It has an underlying symbol 't'
Yes, FieldAccess 't.c' requires fixing.
No, Parameter 't' does not require fixing. It has an underlying symbol 't'
".Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_TypeParameters2()
        {
            var text = @"
class D : C<S>
{
    public override void M<U>(U u, int j)
    {
        M(u, u.i); // effective base type (System.ValueType) does not have a member 'i'
    }
}

abstract class C<T>
{
    public abstract void M<U>(U u, int i) where U : T;
}

struct S
{
    public int i;
}
";
            var expected = @"
Yes, Call 'M(u, u.i)' requires fixing.
Yes, ThisReference 'M' requires fixing.
No, Parameter 'u' does not require fixing. It has an underlying symbol 'u'
Yes, BadExpression 'u.i' requires fixing.
No, Parameter 'u' does not require fixing. It has an underlying symbol 'u'
".Trim();

            CheckIfVariablesNeedFixing(text, expected, expectError: true);
        }

        [Fact]
        public void FixingVariables_RangeVariables1()
        {
            var text = @"
using System.Linq;

class C
{
    void M(int[] array)
    {
        var result = 
            from i in array 
            from j in array 
            select i + j;
    }
}
";
            var expected = string.Format(@"
Yes, TypeExpression 'var' requires fixing.
Yes, QueryClause 'from i in array {0}            from j in array {0}            select i + j' requires fixing.
Yes, QueryClause 'select i + j' requires fixing.
Yes, QueryClause 'from j in array' requires fixing.
Yes, Call 'from j in array' requires fixing.
Yes, Conversion 'from i in array' requires fixing.
Yes, QueryClause 'from i in array' requires fixing.
No, Parameter 'array' does not require fixing. It has an underlying symbol 'array'
Yes, QueryClause 'from j in array' requires fixing.
Yes, Conversion 'array' requires fixing.
Yes, Lambda 'array' requires fixing.
Yes, Conversion 'array' requires fixing.
No, Parameter 'array' does not require fixing. It has an underlying symbol 'array'
Yes, Conversion 'i + j' requires fixing.
Yes, Lambda 'i + j' requires fixing.
Yes, BinaryOperator 'i + j' requires fixing.
No, RangeVariable 'i' does not require fixing. It has an underlying symbol 'i'
No, Parameter 'i' does not require fixing. It has an underlying symbol 'i'
No, RangeVariable 'j' does not require fixing. It has an underlying symbol 'j'
No, Parameter 'j' does not require fixing. It has an underlying symbol 'j'
", GetEscapedNewLine()).Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        [Fact]
        public void FixingVariables_RangeVariables2()
        {
            var text = @"
using System;

class Test
{
    void M(C c)
    {
        var result = from x in c
                     where x > 0 //int
                     where x.Length < 2 //string
                     select char.IsLetter(x); //char
    }
}

class C
{
    public D Where(Func<int, bool> predicate)
    {
        return new D();
    }
}

class D
{
    public char[] Where(Func<string, bool> predicate)
    {
        return new char[10];
    }
}

static class Extensions
{
    public static object Select(this char[] array, Func<char, bool> func)
    {
        return null;
    }
}
";

            var expected = string.Format(@"
Yes, TypeExpression 'var' requires fixing.
Yes, QueryClause 'from x in c{0}                     where x > 0 //int{0}                     where x.Length < 2 //string{0}                     select char.IsLetter(x)' requires fixing.
Yes, QueryClause 'select char.IsLetter(x)' requires fixing.
Yes, Call 'select char.IsLetter(x)' requires fixing.
Yes, QueryClause 'where x.Length < 2' requires fixing.
Yes, Call 'where x.Length < 2' requires fixing.
Yes, QueryClause 'where x > 0' requires fixing.
Yes, Call 'where x > 0' requires fixing.
Yes, QueryClause 'from x in c' requires fixing.
No, Parameter 'c' does not require fixing. It has an underlying symbol 'c'
Yes, Conversion 'x > 0' requires fixing.
Yes, Lambda 'x > 0' requires fixing.
Yes, BinaryOperator 'x > 0' requires fixing.
No, RangeVariable 'x' does not require fixing. It has an underlying symbol 'x'
No, Parameter 'x' does not require fixing. It has an underlying symbol 'x'
Yes, Literal '0' requires fixing.
Yes, Conversion 'x.Length < 2' requires fixing.
Yes, Lambda 'x.Length < 2' requires fixing.
Yes, BinaryOperator 'x.Length < 2' requires fixing.
Yes, PropertyAccess 'x.Length' requires fixing.
No, RangeVariable 'x' does not require fixing. It has an underlying symbol 'x'
No, Parameter 'x' does not require fixing. It has an underlying symbol 'x'
Yes, Literal '2' requires fixing.
Yes, Conversion 'char.IsLetter(x)' requires fixing.
Yes, Lambda 'char.IsLetter(x)' requires fixing.
Yes, Call 'char.IsLetter(x)' requires fixing.
Yes, TypeExpression 'char' requires fixing.
No, RangeVariable 'x' does not require fixing. It has an underlying symbol 'x'
No, Parameter 'x' does not require fixing. It has an underlying symbol 'x'
", GetEscapedNewLine()).Trim();

            CheckIfVariablesNeedFixing(text, expected);
        }

        private static void CheckIfVariablesNeedFixing(string text, string expected, bool expectError = false)
        {
            var compilation = CreateCompilationWithMscorlib40AndSystemCore(text, options: TestOptions.UnsafeReleaseDll);
            var compilationDiagnostics = compilation.GetDiagnostics();
            if (expectError != compilationDiagnostics.Any(diag => diag.Severity == DiagnosticSeverity.Error))
            {
                compilationDiagnostics.Verify();
                Assert.True(false);
            }

            var tree = compilation.SyntaxTrees.Single();
            var methodDecl = tree.GetCompilationUnitRoot().DescendantNodes().OfType<MethodDeclarationSyntax>().First();
            var methodBody = methodDecl.Body;
            var model = compilation.GetSemanticModel(tree);
            var binder = ((CSharpSemanticModel)model).GetEnclosingBinder(methodBody.SpanStart);

            Assert.NotNull(binder);
            Assert.Equal(SymbolKind.Method, binder.ContainingMemberOrLambda.Kind);

            var unusedDiagnostics = DiagnosticBag.GetInstance();
            var block = binder.BindEmbeddedBlock(methodBody, unusedDiagnostics);
            unusedDiagnostics.Free();

            var builder = ArrayBuilder<string>.GetInstance();

            CheckFixingVariablesVisitor.Process(block, binder, builder);

            var actual = string.Join(Environment.NewLine, builder);

            Assert.Equal(expected, actual);

            builder.Free();
        }

        private class CheckFixingVariablesVisitor : BoundTreeWalkerWithStackGuard
        {
            private readonly Binder _binder;
            private readonly ArrayBuilder<string> _builder;

            private CheckFixingVariablesVisitor(Binder binder, ArrayBuilder<string> builder)
            {
                _binder = binder;
                _builder = builder;
            }

            public static void Process(BoundBlock block, Binder binder, ArrayBuilder<string> builder)
            {
                var visitor = new CheckFixingVariablesVisitor(binder, builder);
                visitor.Visit(block);
            }

            public override BoundNode Visit(BoundNode node)
            {
                var expr = node as BoundExpression;
                if (expr != null && !expr.IsParamsArrayOrCollection)
                {
                    var text = node.Syntax.ToString();
                    if (!string.IsNullOrEmpty(text))
                    {
                        text = SymbolDisplay.FormatLiteral(text, quote: false);

                        if (_binder.IsMoveableVariable(expr, out Symbol accessedLocalOrParameterOpt))
                        {
                            _builder.Add($"Yes, {expr.Kind} '{text}' requires fixing.");
                        }
                        else
                        {
                            _builder.Add(string.Concat($"No, {expr.Kind} '{text}' does not require fixing.", accessedLocalOrParameterOpt is null
                                ? " It has no underlying symbol."
                                : $" It has an underlying symbol '{accessedLocalOrParameterOpt.Name}'"));
                        }
                    }
                }

                return base.Visit(node);
            }

            protected override bool ConvertInsufficientExecutionStackExceptionToCancelledByStackGuardException()
            {
                return false;
            }

            public override BoundNode VisitArrayCreation(BoundArrayCreation node)
            {
                if (node.IsParamsArrayOrCollection)
                {
                    this.VisitList(node.InitializerOpt.Initializers);
                    return null;
                }

                return base.VisitArrayCreation(node);
            }
        }

        #endregion Variables that need fixing

        #region IsManagedType

        [Fact]
        public void IsManagedType_Array()
        {
            var text = @"
class C
{
    int[] f1;
    int[,] f2;
    int[][] f3;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_Pointer()
        {
            var text = @"
unsafe class C
{
    int* f1;
    int** f2;
    void* f3;
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => !field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_Dynamic()
        {
            var text = @"
class C
{
    dynamic f1;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_Error()
        {
            var text = @"
class C<T>
{
    C f1;
    C<int, int> f2;
    Garbage f3;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_TypeParameter()
        {
            var text = @"
class C<T, U> where U : struct
{
    T f1;
    U f2;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_AnonymousType()
        {
            var text = @"
class C
{
    void M()
    {
        var local1 = new { };
        var local2 = new { F = 1 };
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            Assert.True(tree.GetCompilationUnitRoot().DescendantNodes().OfType<AnonymousObjectCreationExpressionSyntax>().
                Select(syntax => model.GetTypeInfo(syntax).Type).All(type => type.GetSymbol().IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_Class()
        {
            var text = @"
class Outer
{
    Outer f1;
    Outer.Inner f2;
    string f3;    

    class Inner { }
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("Outer");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_GenericClass()
        {
            var text = @"
class Outer<T>
{
    Outer<T> f1;
    Outer<T>.Inner f2;
    Outer<int> f1;
    Outer<string>.Inner f2;

    class Inner { }
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("Outer");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => field.Type.IsManagedTypeNoUseSiteDiagnostics));
        }

        [Fact]
        public void IsManagedType_ManagedSpecialTypes()
        {
            var text = @"
class C
{
    object f1;
    string f2;
    System.Collections.IEnumerable f3;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            foreach (var field in type.GetMembers().OfType<FieldSymbol>())
            {
                Assert.True(field.Type.IsManagedTypeNoUseSiteDiagnostics, field.ToString());
            }
        }

        [Fact]
        public void IsManagedType_NonManagedSpecialTypes()
        {
            var text = @"
class C
{
    bool f1;
    char f2;
    sbyte f3;
    byte f4;
    short f5;
    ushort f6;
    int f7;
    uint f8;
    long f9;
    ulong f10;
    decimal f11;
    float f12;
    double f13;
    System.IntPtr f14;
    System.UIntPtr f15;
    int? f16;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");

            Assert.True(type.GetMembers().OfType<FieldSymbol>().All(field => !field.Type.IsManagedTypeNoUseSiteDiagnostics));
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetField("f16").Type.ManagedKindNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_Void()
        {
            var text = @"
class C
{
    void M() { }
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");
            var method = type.GetMember<MethodSymbol>("M");

            Assert.False(method.ReturnType.IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_Enum()
        {
            var text = @"
enum E { A }

class C
{
    enum E { A }
}

class D<T>
{
    enum E { A }
}

struct S
{
    enum E { A }
}

struct R<T>
{
    enum E { A }
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("E").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("C").GetMember<NamedTypeSymbol>("E").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("D").GetMember<NamedTypeSymbol>("E").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S").GetMember<NamedTypeSymbol>("E").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("R").GetMember<NamedTypeSymbol>("E").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_EmptyStruct()
        {
            var text = @"
struct S { }

struct P<T> { }

class C
{
    struct S { }
}

class D<T>
{
    struct S { }
}

struct Q
{
    struct S { }
}

struct R<T>
{
    struct S { }
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.Unmanaged, globalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("P").IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, globalNamespace.GetMember<NamedTypeSymbol>("P").ManagedKindNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("C").GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("D").GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("Q").GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("R").GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_SubstitutedStruct()
        {
            var text = @"
class C<U>
{
    S<U> f1;
    S<int> f2;
    S<U>.R f3;
    S<int>.R f4;
    S<U>.R2 f5;
    S<int>.R2 f6;
}

struct S<T>
{
    struct R { }
    internal struct R2 { }
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");
            Assert.False(type.GetMember<FieldSymbol>("f1").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f1").Type.ManagedKindNoUseSiteDiagnostics);
            Assert.False(type.GetMember<FieldSymbol>("f2").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f2").Type.ManagedKindNoUseSiteDiagnostics);

            // these are managed due to S`1.R being ErrorType due to protection level (CS0169)
            Assert.True(type.GetMember<FieldSymbol>("f3").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.Managed, type.GetMember<FieldSymbol>("f3").Type.ManagedKindNoUseSiteDiagnostics);
            Assert.True(type.GetMember<FieldSymbol>("f4").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.Managed, type.GetMember<FieldSymbol>("f4").Type.ManagedKindNoUseSiteDiagnostics);

            Assert.False(type.GetMember<FieldSymbol>("f5").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f5").Type.ManagedKindNoUseSiteDiagnostics);
            Assert.False(type.GetMember<FieldSymbol>("f6").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f6").Type.ManagedKindNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_GenericStruct()
        {
            var text = @"
class C<U>
{
    S<object> f1;
    S<int> f2;
}

struct S<T>
{
    T field;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");
            Assert.True(type.GetMember<FieldSymbol>("f1").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.Managed, type.GetMember<FieldSymbol>("f1").Type.ManagedKindNoUseSiteDiagnostics);
            Assert.False(type.GetMember<FieldSymbol>("f2").Type.IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f2").Type.ManagedKindNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_GenericStruct_ErrorTypeArg()
        {
            var text = @"
class C<U>
{
    S<Widget> f1;
}

struct S<T>
{
    T field;
}
";
            var compilation = CreateCompilation(text);
            var type = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C");
            Assert.True(type.GetMember<FieldSymbol>("f1").Type.IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_NonEmptyStruct()
        {
            var text = @"
struct S1
{
    int f;
}

struct S2
{
    object f;
}

struct S3
{
    S1 s;
}

struct S4
{
    S2 s;
}

struct S5
{
    S1 s1;
    S2 s2;
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S1").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S2").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S3").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S4").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S5").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_StaticFieldStruct()
        {
            var text = @"
struct S1
{
    static object o;
    int f;
}

struct S2
{
    static object o;
    object f;
}

struct S3
{
    static object o;
    S1 s;
}

struct S4
{
    static object o;
    S2 s;
}

struct S5
{
    static object o;
    S1 s1;
    S2 s2;
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S1").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S2").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S3").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S4").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S5").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_AutoPropertyStruct()
        {
            var text = @"
struct S1
{
    int f { get; set; }
}

struct S2
{
    object f { get; set; }
}

struct S3
{
    S1 s { get; set; }
}

struct S4
{
    S2 s { get; set; }
}

struct S5
{
    S1 s1 { get; set; }
    S2 s2 { get; set; }
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S1").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S2").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S3").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S4").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S5").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_PropertyStruct()
        {
            var text = @"
struct S1
{
    object o { get { return null; } set { } }
    int f { get; set; }
}

struct S2
{
    object o { get { return null; } set { } }
    object f { get; set; }
}

struct S3
{
    object o { get { return null; } set { } }
    S1 s { get; set; }
}

struct S4
{
    object o { get { return null; } set { } }
    S2 s { get; set; }
}

struct S5
{
    object o { get { return null; } set { } }
    S1 s1 { get; set; }
    S2 s2 { get; set; }
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S1").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S2").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S3").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S4").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S5").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_EventStruct()
        {
            var text = @"
struct S1
{
    event System.Action E; // has field
}

struct S2
{
    event System.Action E { add { } remove { } } // no field
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("S1").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S2").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_ExpandingStruct()
        {
            var text = @"
struct X<T> { public T t; }
struct W<T> { X<W<W<T>>> x; }
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("X").IsManagedTypeNoUseSiteDiagnostics); // because of X.t
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("W").IsManagedTypeNoUseSiteDiagnostics);
            Assert.Equal(ManagedKind.UnmanagedWithGenerics, globalNamespace.GetMember<NamedTypeSymbol>("W").ManagedKindNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_CyclicStruct()
        {
            var text = @"
struct S
{
    S s;
}

struct R
{
    object o;
    S s;
}
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("R").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_CyclicStructChain()
        {
            var text = @"
struct Q { R r; }
struct R { A a; object o }
struct S { A a; }

//cycle
struct A { B b; }
struct B { C c; }
struct C { D d; }
struct D { A a; }
";
            var compilation = CreateCompilation(text);
            var globalNamespace = compilation.GlobalNamespace;
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("Q").IsManagedTypeNoUseSiteDiagnostics);
            Assert.True(globalNamespace.GetMember<NamedTypeSymbol>("R").IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(globalNamespace.GetMember<NamedTypeSymbol>("S").IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact]
        public void IsManagedType_SpecialClrTypes()
        {
            var text = @"
class C { }
";
            var compilation = CreateCompilation(text);
            Assert.False(compilation.GetSpecialType(SpecialType.System_ArgIterator).IsManagedTypeNoUseSiteDiagnostics);
            Assert.False(compilation.GetSpecialType(SpecialType.System_RuntimeArgumentHandle).IsManagedTypeNoUseSiteDiagnostics);
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void IsManagedType_TypedReference()
        {
            var libSrc = @"
public unsafe class C
{
    public static System.TypedReference* M(System.TypedReference* r)
    {
        return r;
    }
}
";
            var libComp = CreateCompilation(libSrc, options: TestOptions.UnsafeDebugDll);
            Assert.True(libComp.GetSpecialType(SpecialType.System_TypedReference).IsManagedTypeNoUseSiteDiagnostics);
            libComp.VerifyEmitDiagnostics(
                // (4,42): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('TypedReference')
                //     public static System.TypedReference* M(System.TypedReference* r)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "M").WithArguments("System.TypedReference").WithLocation(4, 42),
                // (4,67): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('TypedReference')
                //     public static System.TypedReference* M(System.TypedReference* r)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "r").WithArguments("System.TypedReference").WithLocation(4, 67)
                );

            var src = """
unsafe class D
{
    System.TypedReference* M(System.TypedReference* r)
    {
        return C.M(r);
    }
}
""";
            var comp = CreateCompilation(src, options: TestOptions.UnsafeDebugDll, references: new[] { libComp.EmitToImageReference() });
            comp.VerifyDiagnostics(
                // (3,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('TypedReference')
                //     System.TypedReference* M(System.TypedReference* r)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "M").WithArguments("System.TypedReference").WithLocation(3, 28),
                // (3,53): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('TypedReference')
                //     System.TypedReference* M(System.TypedReference* r)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "r").WithArguments("System.TypedReference").WithLocation(3, 53)
                );

            var method = comp.GetMember<MethodSymbol>("C.M");
            var returnType = method.ReturnType;
            Assert.True(returnType.IsPointerType());
            Assert.Equal(SpecialType.System_TypedReference, ((PointerTypeSymbol)returnType).PointedAtType.SpecialType);

            var parameterType = method.GetParameterType(0);
            Assert.True(parameterType.IsPointerType());
            Assert.Equal(SpecialType.System_TypedReference, ((PointerTypeSymbol)parameterType).PointedAtType.SpecialType);
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_InArray()
        {
            var src = @"
public class C
{
    public static System.TypedReference[] M(System.TypedReference[] r)
    {
        return r;
    }
}
";
            var comp = CreateCompilation(src);
            comp.VerifyEmitDiagnostics(
                // (4,19): error CS0611: Array elements cannot be of type 'TypedReference'
                //     public static System.TypedReference[] M(System.TypedReference[] r)
                Diagnostic(ErrorCode.ERR_ArrayElementCantBeRefAny, "System.TypedReference").WithArguments("System.TypedReference").WithLocation(4, 19),
                // (4,45): error CS0611: Array elements cannot be of type 'TypedReference'
                //     public static System.TypedReference[] M(System.TypedReference[] r)
                Diagnostic(ErrorCode.ERR_ArrayElementCantBeRefAny, "System.TypedReference").WithArguments("System.TypedReference").WithLocation(4, 45)
                );
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_InLocal()
        {
            var src = @"
public unsafe class C
{
    public static void M()
    {
        System.TypedReference* trp = null;
        System.TypedReference tr = default;
        M2(*trp);
        M2(tr);
    }
    public static void M2(System.TypedReference tr) { }
}
";
            var comp = CreateCompilation(src, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                // (6,9): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('TypedReference')
                //         System.TypedReference* trp = null;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "System.TypedReference*").WithArguments("System.TypedReference").WithLocation(6, 9)
                );
            var verifier = CompileAndVerify(comp, verify: Verification.Skipped);
            verifier.VerifyIL("C.M", """
{
  // Code size       32 (0x20)
  .maxstack  1
  .locals init (System.TypedReference* V_0, //trp
                System.TypedReference V_1) //tr
  IL_0000:  nop
  IL_0001:  ldc.i4.0
  IL_0002:  conv.u
  IL_0003:  stloc.0
  IL_0004:  ldloca.s   V_1
  IL_0006:  initobj    "System.TypedReference"
  IL_000c:  ldloc.0
  IL_000d:  ldobj      "System.TypedReference"
  IL_0012:  call       "void C.M2(System.TypedReference)"
  IL_0017:  nop
  IL_0018:  ldloc.1
  IL_0019:  call       "void C.M2(System.TypedReference)"
  IL_001e:  nop
  IL_001f:  ret
}
""");
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_ByValue()
        {
            var libSrc = @"
public class C
{
    public static System.TypedReference M(System.TypedReference r)
    {
        return r;
    }
}
";
            var comp = CreateCompilation(libSrc);
            Assert.True(comp.GetSpecialType(SpecialType.System_TypedReference).IsManagedTypeNoUseSiteDiagnostics);
            comp.VerifyEmitDiagnostics(
                // (4,19): error CS1599: The return type of a method, delegate, or function pointer cannot be 'TypedReference'
                //     public static System.TypedReference M(System.TypedReference r)
                Diagnostic(ErrorCode.ERR_MethodReturnCantBeRefAny, "System.TypedReference").WithArguments("System.TypedReference").WithLocation(4, 19)
                );
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_ByRef()
        {
            var libSrc = @"
public class C
{
    public static ref System.TypedReference M(ref System.TypedReference r)
    {
        return ref r;
    }
}
";
            var comp = CreateCompilation(libSrc);
            Assert.True(comp.GetSpecialType(SpecialType.System_TypedReference).IsManagedTypeNoUseSiteDiagnostics);
            comp.VerifyEmitDiagnostics(
                // (4,19): error CS1599: The return type of a method, delegate, or function pointer cannot be 'TypedReference'
                //     public static ref System.TypedReference M(ref System.TypedReference r)
                Diagnostic(ErrorCode.ERR_MethodReturnCantBeRefAny, "ref System.TypedReference").WithArguments("System.TypedReference").WithLocation(4, 19),
                // (4,47): error CS1601: Cannot make reference to variable of type 'TypedReference'
                //     public static ref System.TypedReference M(ref System.TypedReference r)
                Diagnostic(ErrorCode.ERR_MethodArgCantBeRefAny, "ref System.TypedReference r").WithArguments("System.TypedReference").WithLocation(4, 47)
                );
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_AsTypeArgument()
        {
            var libSrc = @"
public class C<T>
{
    public static void M(C<System.TypedReference> c) { }
}
";
            var comp = CreateCompilation(libSrc);
            Assert.True(comp.GetSpecialType(SpecialType.System_TypedReference).IsManagedTypeNoUseSiteDiagnostics);
            comp.VerifyEmitDiagnostics(
                // (4,51): error CS0306: The type 'TypedReference' may not be used as a type argument
                //     public static void M(C<System.TypedReference> c) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "c").WithArguments("System.TypedReference").WithLocation(4, 51)
                );
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_Field()
        {
            var libSrc = @"
public ref struct C
{
    public System.TypedReference field;
    public ref System.TypedReference field2;
}
";
            var comp = CreateCompilation(libSrc, targetFramework: TargetFramework.Net70);
            comp.VerifyEmitDiagnostics(
                // (4,12): error CS0610: Field or property cannot be of type 'TypedReference'
                //     public System.TypedReference field;
                Diagnostic(ErrorCode.ERR_FieldCantBeRefAny, "System.TypedReference").WithArguments("System.TypedReference").WithLocation(4, 12),
                // (5,12): error CS9050: A ref field cannot refer to a ref struct.
                //     public ref System.TypedReference field2;
                Diagnostic(ErrorCode.ERR_RefFieldCannotReferToRefStruct, "ref System.TypedReference").WithLocation(5, 12),
                // (5,12): error CS0610: Field or property cannot be of type 'TypedReference'
                //     public ref System.TypedReference field2;
                Diagnostic(ErrorCode.ERR_FieldCantBeRefAny, "ref System.TypedReference").WithArguments("System.TypedReference").WithLocation(5, 12)
                );
        }

        [Fact, WorkItem(65530, "https://github.com/dotnet/roslyn/issues/65530")]
        public void TypedReference_AsGenericConstraint()
        {
            var libSrc = @"
public class C<T> where T : System.TypedReference
{
}
";
            var comp = CreateCompilation(libSrc);
            Assert.True(comp.GetSpecialType(SpecialType.System_TypedReference).IsManagedTypeNoUseSiteDiagnostics);
            comp.VerifyEmitDiagnostics(
                // (2,29): error CS0701: 'TypedReference' is not a valid constraint. A type used as a constraint must be an interface, a non-sealed class or a type parameter.
                // public class C<T> where T : System.TypedReference
                Diagnostic(ErrorCode.ERR_BadBoundType, "System.TypedReference").WithArguments("System.TypedReference").WithLocation(2, 29)
                );
        }

        [Fact]
        public void WRN_ManagedAddr_ShallowRecursive()
        {
            var text = @"
public unsafe struct S1
{
    public S1* s; //CS0208
    public object o;
}

public unsafe struct S2
{
    public S2* s; //fine
    public int i;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,16): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S1')
                //     public S1* s; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "s").WithArguments("S1").WithLocation(4, 16));
        }

        [Fact]
        public void WRN_ManagedAddr_DeepRecursive()
        {
            var text = @"
public unsafe struct A
{
    public B** bb; //CS0208
    public object o;

    public struct B
    {
        public C*[] cc; //CS0208

        public struct C
        {
            public A*[,][] aa; //CS0208
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,16): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('A.B')
                //     public B** bb; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "bb").WithArguments("A.B").WithLocation(4, 16),
                // (9,21): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('A.B.C')
                //         public C*[] cc; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "cc").WithArguments("A.B.C").WithLocation(9, 21),
                // (13,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('A')
                //             public A*[,][] aa; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "aa").WithArguments("A").WithLocation(13, 28));
        }

        [Fact]
        public void WRN_ManagedAddr_Alias()
        {
            var text = @"
using Alias = S;

public unsafe struct S
{
    public Alias* s; //CS0208
    public object o;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,19): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     public Alias* s; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "s").WithArguments("S").WithLocation(6, 19));
        }

        [Fact()]
        public void WRN_ManagedAddr_Members()
        {
            var text = @"
public unsafe struct S
{
    S* M() { return M(); }
    void M(S* p) { }

    S* P { get; set; }
    
    S* this[int x] { get { return M(); } set { } }
    int this[S* p] { get { return 0; } set { } }

    public S* s; //CS0208
    public object o;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,15): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     void M(S* p) { }
                Diagnostic(ErrorCode.WRN_ManagedAddr, "p").WithArguments("S").WithLocation(5, 15),
                // (12,15): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     public S* s; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "s").WithArguments("S").WithLocation(12, 15),
                // (4,8): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     S* M() { return M(); }
                Diagnostic(ErrorCode.WRN_ManagedAddr, "M").WithArguments("S").WithLocation(4, 8),
                // (7,8): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     S* P { get; set; }
                Diagnostic(ErrorCode.WRN_ManagedAddr, "P").WithArguments("S").WithLocation(7, 8),
                // (9,8): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     S* this[int x] { get { return M(); } set { } }
                Diagnostic(ErrorCode.WRN_ManagedAddr, "this").WithArguments("S").WithLocation(9, 8),
                // (10,17): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //     int this[S* p] { get { return 0; } set { } }
                Diagnostic(ErrorCode.WRN_ManagedAddr, "p").WithArguments("S").WithLocation(10, 17));
        }

        [Fact]
        public void WRN_ManagedAddr_ArrayPointer()
        {
            var text = @"
public unsafe struct S
{
    public int[]* s;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,19): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('int[]')
                //     public int[]* s;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "s").WithArguments("int[]").WithLocation(4, 19));
        }

        [WorkItem(10195, "https://github.com/dotnet/roslyn/issues/10195")]
        [Fact]
        public void PointerToStructInPartialMethodSignature()
        {
            string text =
@"unsafe partial struct S
{
    partial void M(S *p) { }
    partial void M(S *p);
}";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void IsUnmanagedTypeSemanticModel()
        {
            var tree = SyntaxFactory.ParseSyntaxTree(@"
struct S1 { }
struct S2 { public S1 F1; }
struct S3 { public object F1; }
struct S4<T> { public T F1; }
struct S5<T> where T : unmanaged { public T F1; }
enum E1 { }
class C<T>
{
    unsafe void M<U>() where U : unmanaged
    {
        var s1 = new S1();
        var s2 = new S2();
        var s3 = new S3();
        var s4_0 = new S4<int>();
        var s4_1 = new S4<object>();
        var s4_2 = new S4<U>();
        var s5 = new S5<int>();
        var i0 = 0;
        var e1 = new E1();
        var o1 = new object();
        var c1 = new C<int>;
        var t1 = default(T);
        var u1 = default(U);
        void* p1 = null;
        var a1 = new { X = 0 };
        var a2 = new int[1];
        var t2 = (0, 0);
    }
}");
            var comp = CreateCompilation(tree);
            var model = comp.GetSemanticModel(tree);
            var root = tree.GetRoot();
            // The spec states the following are unmanaged types:
            // sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal, or bool.
            // Any enum_type.
            // Any pointer_type.
            // Any user-defined struct_type that contains fields of unmanaged_types only.
            // A type parameter with an unmanaged constraint
            Assert.True(getLocalType("s1").IsUnmanagedType);
            Assert.True(getLocalType("s2").IsUnmanagedType);
            Assert.False(getLocalType("s3").IsUnmanagedType);
            Assert.True(getLocalType("s4_0").IsUnmanagedType);
            Assert.False(getLocalType("s4_1").IsUnmanagedType);
            Assert.True(getLocalType("s4_2").IsUnmanagedType);
            Assert.True(getLocalType("s5").IsUnmanagedType);
            Assert.True(getLocalType("i0").IsUnmanagedType);
            Assert.True(getLocalType("e1").IsUnmanagedType);
            Assert.False(getLocalType("o1").IsUnmanagedType);
            Assert.False(getLocalType("c1").IsUnmanagedType);
            Assert.False(getLocalType("t1").IsUnmanagedType);
            Assert.True(getLocalType("u1").IsUnmanagedType);
            Assert.True(getLocalType("p1").IsUnmanagedType);
            Assert.False(getLocalType("a1").IsUnmanagedType);
            Assert.False(getLocalType("a2").IsUnmanagedType);
            Assert.True(getLocalType("t2").IsUnmanagedType);

            ITypeSymbol getLocalType(string name)
            {
                var decl = root.DescendantNodes()
                    .OfType<VariableDeclaratorSyntax>()
                    .Single(n => n.Identifier.ValueText == name);
                return ((ILocalSymbol)model.GetDeclaredSymbol(decl)).Type;
            }
        }

        [Fact]
        public void GenericStructPrivateFieldInMetadata()
        {
            var externalCode = @"
public struct External<T>
{
    private T field;
}
";
            var metadata = CreateCompilation(externalCode).EmitToImageReference();

            var code = @"
public class C
{
    public unsafe void M<T, U>() where T : unmanaged
    {
        var good = new External<int>();
        var goodPtr = &good;

        var good2 = new External<T>();
        var goodPtr2 = &good2;

        var bad = new External<object>();
        var badPtr = &bad;

        var bad2 = new External<U>();
        var badPtr2 = &bad2;
    }
}
";
            var tree = SyntaxFactory.ParseSyntaxTree(code, TestOptions.Regular);
            var compilation = CreateCompilation(tree, new[] { metadata }, TestOptions.UnsafeReleaseDll);

            compilation.VerifyDiagnostics(
                // (13,22): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('External<object>')
                //         var badPtr = &bad;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&bad").WithArguments("External<object>").WithLocation(13, 22),
                // (16,23): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('External<U>')
                //         var badPtr2 = &bad2;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&bad2").WithArguments("External<U>").WithLocation(16, 23)
            );

            var model = compilation.GetSemanticModel(tree);
            var root = tree.GetRoot();

            Assert.True(getLocalType("good").IsUnmanagedType);
            Assert.True(getLocalType("good2").IsUnmanagedType);
            Assert.False(getLocalType("bad").IsUnmanagedType);
            Assert.False(getLocalType("bad2").IsUnmanagedType);

            ITypeSymbol getLocalType(string name)
            {
                var decl = root.DescendantNodes()
                    .OfType<VariableDeclaratorSyntax>()
                    .Single(n => n.Identifier.ValueText == name);
                return ((ILocalSymbol)model.GetDeclaredSymbol(decl)).Type;
            }
        }

        #endregion IsManagedType

        #region AddressOf operand kinds

        [Fact]
        public void AddressOfExpressionKinds_Simple()
        {
            var text = @"
unsafe class C
{
    void M(int param)
    {
        int local;
        int* p;
        p = &param;
        p = &local;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void AddressOfExpressionKinds_Dereference()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int x;
        int* p = &x;
        p = &(*p);
        p = &p[0];
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void AddressOfExpressionKinds_Struct()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        S1 s;
        S1* p1 = &s;
        S2* p2 = &s.s;
        S3* p3 = &s.s.s;
        int* p4 = &s.s.s.x;

        p2 = &(p1->s);
        p3 = &(p2->s);
        p4 = &(p3->x);

        p2 = &((*p1).s);
        p3 = &((*p2).s);
        p4 = &((*p3).x);
    }
}

struct S1
{
    public S2 s;
}

struct S2
{
    public S3 s;
}

struct S3
{
    public int x;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [WorkItem(529267, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/529267")]
        [Fact]
        public void AddressOfExpressionKinds_RangeVariable()
        {
            var text = @"
using System.Linq;

unsafe class C
{
    int M(int param)
    {
        var z = from x in new int[2] select Goo(&x);

        return 0;
    }

    int Goo(int* p) { return 0; }
}
";
            // NOTE: this is a breaking change - dev10 allows this.
            CreateCompilationWithMscorlib40AndSystemCore(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,50): error CS0211: Cannot take the address of the given expression
                //         var z = from x in new int[2] select Goo(&x);
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "x"));
        }

        [WorkItem(22306, "https://github.com/dotnet/roslyn/issues/22306")]
        [Fact]
        public void AddressOfExpressionKinds_ReadOnlyLocal()
        {
            var text = @"
class Test { static void Main() { } }

unsafe class C
{
    int[] array;

    void M()
    {
        int* p;

        const int x = 1;
        p = &x; //CS0211

        foreach (int y in new int[1])
        {
            p = &y; 
        }

        using (S s = new S())
        {
            S* sp = &s; 
        }

        fixed (int* a = &array[0])
        {
            int** pp = &a; 
        }
    }
}

struct S : System.IDisposable
{
    public void Dispose() { }
}
";
            CreateCompilationWithMscorlib40AndSystemCore(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (13,14): error CS0211: Cannot take the address of the given expression
                //         p = &x; //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "x").WithLocation(13, 14),
                // (6,11): warning CS0649: Field 'C.array' is never assigned to, and will always have its default value null
                //     int[] array;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "array").WithArguments("C.array", "null").WithLocation(6, 11)
                );
        }

        [Fact]
        public void AddressOfExpressionKinds_Failure()
        {
            var text = @"
class Base
{
    public int f = 2;
}

unsafe class C : Base
{
    event System.Action E;
    event System.Action F { add { } remove { } }
    int instanceField;
    int staticField;
    int this[int x] { get { return 0; } set { } }
    int P { get; set; }

    int M(int param)
    {
        int local;
        int[] array = new int[1];
        System.Func<int> func = () => 1;

        int* p;
        p = &1; //CS0211 (can't addr)
        p = &array[0]; //CS0212 (need fixed)
        p = &(local = 1); //CS0211
        p = &goo; //CS0103 (no goo)
        p = &base.f; //CS0212
        p = &(local + local); //CS0211
        p = &M(local); //CS0211
        p = &func(); //CS0211
        p = &(local += local); //CS0211
        p = &(local == 0 ? local : param); //CS0211
        p = &((int)param); //CS0211
        p = &default(int); //CS0211
        p = &delegate { return 1; }; //CS0211
        p = &instanceField; //CS0212
        p = &staticField; //CS0212
        p = &(local++); //CS0211
        p = &this[0]; //CS0211
        p = &(() => 1); //CS0211
        p = &M; //CS0211
        p = &(new System.Int32()); //CS0211
        p = &P; //CS0211
        p = &sizeof(int); //CS0211
        p = &this.instanceField; //CS0212
        p = &(+local); //CS0211

        int** pp;
        pp = &(&local); //CS0211

        var q = &(new { }); //CS0208, CS0211 (managed)
        var r = &(new int[1]); //CS0208, CS0211 (managed)
        var s = &(array as object); //CS0208, CS0211 (managed)
        var t = &E; //CS0208
        var u = &F; //CS0079 (can't use event like that)
        var v = &(E += null); //CS0211
        var w = &(F += null); //CS0211
        var x = &(array is object); //CS0211
        var y = &(array ?? array); //CS0208, CS0211 (managed)
        var aa = &this; //CS0208
        var bb = &typeof(int); //CS0208, CS0211 (managed)
        var cc = &Color.Red; //CS0211

        return 0;
    }

    int Goo(int* p) { return 0; }

    static void Main() { }
}

unsafe struct S
{
    S(int x)
    {
        var aa = &this; //CS0212 (need fixed)
    }
}

enum Color
{
    Red,
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (76,18): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         var aa = &this; //CS0212 (need fixed)
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&this").WithLocation(76, 18),
                // (23,14): error CS0211: Cannot take the address of the given expression
                //         p = &1; //CS0211 (can't addr)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "1").WithLocation(23, 14),
                // (24,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &array[0]; //CS0212 (need fixed)
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&array[0]").WithLocation(24, 13),
                // (25,15): error CS0211: Cannot take the address of the given expression
                //         p = &(local = 1); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "local = 1").WithLocation(25, 15),
                // (26,14): error CS0103: The name 'goo' does not exist in the current context
                //         p = &goo; //CS0103 (no goo)
                Diagnostic(ErrorCode.ERR_NameNotInContext, "goo").WithArguments("goo").WithLocation(26, 14),
                // (27,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &base.f; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&base.f").WithLocation(27, 13),
                // (28,15): error CS0211: Cannot take the address of the given expression
                //         p = &(local + local); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "local + local").WithLocation(28, 15),
                // (29,14): error CS0211: Cannot take the address of the given expression
                //         p = &M(local); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "M(local)").WithLocation(29, 14),
                // (30,14): error CS0211: Cannot take the address of the given expression
                //         p = &func(); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "func()").WithLocation(30, 14),
                // (31,15): error CS0211: Cannot take the address of the given expression
                //         p = &(local += local); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "local += local").WithLocation(31, 15),
                // (32,15): error CS0211: Cannot take the address of the given expression
                //         p = &(local == 0 ? local : param); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "local == 0 ? local : param").WithLocation(32, 15),
                // (33,15): error CS0211: Cannot take the address of the given expression
                //         p = &((int)param); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "(int)param").WithLocation(33, 15),
                // (34,14): error CS0211: Cannot take the address of the given expression
                //         p = &default(int); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "default(int)").WithLocation(34, 14),
                // (35,14): error CS0211: Cannot take the address of the given expression
                //         p = &delegate { return 1; }; //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "delegate { return 1; }").WithLocation(35, 14),
                // (36,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &instanceField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&instanceField").WithLocation(36, 13),
                // (37,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &staticField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&staticField").WithLocation(37, 13),
                // (38,15): error CS0211: Cannot take the address of the given expression
                //         p = &(local++); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "local++").WithLocation(38, 15),
                // (39,14): error CS0211: Cannot take the address of the given expression
                //         p = &this[0]; //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "this[0]").WithLocation(39, 14),
                // (40,15): error CS0211: Cannot take the address of the given expression
                //         p = &(() => 1); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "() => 1").WithLocation(40, 15),
                // (41,13): error CS8812: Cannot convert &method group 'M' to non-function pointer type 'int*'.
                //         p = &M; //CS0211
                Diagnostic(ErrorCode.ERR_AddressOfToNonFunctionPointer, "&M").WithArguments("M", "int*").WithLocation(41, 13),
                // (42,15): error CS0211: Cannot take the address of the given expression
                //         p = &(new System.Int32()); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "new System.Int32()").WithLocation(42, 15),
                // (43,14): error CS0211: Cannot take the address of the given expression
                //         p = &P; //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "P").WithLocation(43, 14),
                // (44,14): error CS0211: Cannot take the address of the given expression
                //         p = &sizeof(int); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "sizeof(int)").WithLocation(44, 14),
                // (45,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &this.instanceField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&this.instanceField").WithLocation(45, 13),
                // (46,15): error CS0211: Cannot take the address of the given expression
                //         p = &(+local); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "+local").WithLocation(46, 15),
                // (49,16): error CS0211: Cannot take the address of the given expression
                //         pp = &(&local); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "&local").WithLocation(49, 16),
                // (51,19): error CS0211: Cannot take the address of the given expression
                //         var q = &(new { }); //CS0208, CS0211 (managed)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "new { }").WithLocation(51, 19),
                // (52,19): error CS0211: Cannot take the address of the given expression
                //         var r = &(new int[1]); //CS0208, CS0211 (managed)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "new int[1]").WithLocation(52, 19),
                // (53,19): error CS0211: Cannot take the address of the given expression
                //         var s = &(array as object); //CS0208, CS0211 (managed)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "array as object").WithLocation(53, 19),
                // (54,17): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('Action')
                //         var t = &E; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&E").WithArguments("System.Action").WithLocation(54, 17),
                // (54,17): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         var t = &E; //CS0208
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&E").WithLocation(54, 17),
                // (55,18): error CS0079: The event 'C.F' can only appear on the left hand side of += or -=
                //         var u = &F; //CS0079 (can't use event like that)
                Diagnostic(ErrorCode.ERR_BadEventUsageNoField, "F").WithArguments("C.F").WithLocation(55, 18),
                // (56,19): error CS0211: Cannot take the address of the given expression
                //         var v = &(E += null); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "E += null").WithLocation(56, 19),
                // (57,19): error CS0211: Cannot take the address of the given expression
                //         var w = &(F += null); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "F += null").WithLocation(57, 19),
                // (58,19): error CS0211: Cannot take the address of the given expression
                //         var x = &(array is object); //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "array is object").WithLocation(58, 19),
                // (59,19): error CS0211: Cannot take the address of the given expression
                //         var y = &(array ?? array); //CS0208, CS0211 (managed)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "array ?? array").WithLocation(59, 19),
                // (60,19): error CS0211: Cannot take the address of the given expression
                //         var aa = &this; //CS0208
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "this").WithLocation(60, 19),
                // (61,19): error CS0211: Cannot take the address of the given expression
                //         var bb = &typeof(int); //CS0208, CS0211 (managed)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "typeof(int)").WithLocation(61, 19),
                // (62,19): error CS0211: Cannot take the address of the given expression
                //         var cc = &Color.Red; //CS0211
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "Color.Red").WithLocation(62, 19)
            );
        }

        #endregion AddressOf operand kinds

        #region AddressOf diagnostics

        [Fact]
        public void AddressOfManaged()
        {
            var text = @"
unsafe class C
{
    void M<T>(T t)
    {
        var p0 = &t; // 1

        C c = new C();
        var p1 = &c; // 2

        S s = new S();
        var p2 = &s; // 3
        
        var anon = new { };
        var p3 = &anon; // 4
    }
}

public struct S
{
    public string s;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,18): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //         var p0 = &t; // 1
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&t").WithArguments("T").WithLocation(6, 18),
                // (9,18): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('C')
                //         var p1 = &c; // 2
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&c").WithArguments("C").WithLocation(9, 18),
                // (12,18): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //         var p2 = &s; // 3
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&s").WithArguments("S").WithLocation(12, 18),
                // (15,18): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('<empty anonymous type>')
                //         var p3 = &anon; // 4
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&anon").WithArguments("<empty anonymous type>").WithLocation(15, 18));
        }

        [Fact]
        public void AddressOfManaged_Cycle()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        S s = new S();
        var p = &s; //CS0208
    }
}

public struct S
{
    public S s; //CS0523
    public object o;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (13,14): error CS0523: Struct member 'S.s' of type 'S' causes a cycle in the struct layout
                //     public S s; //CS0523
                Diagnostic(ErrorCode.ERR_StructLayoutCycle, "s").WithArguments("S.s", "S").WithLocation(13, 14),
                // (7,17): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //         var p = &s; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&s").WithArguments("S").WithLocation(7, 17));
        }

        [Fact]
        public void AddressOfVariablesThatRequireFixing()
        {
            var text = @"
class Base
{
    public int instanceField;
    public int staticField;
}

unsafe class Derived : Base
{
    void M(ref int refParam, out int outParam)
    {
        Derived d = this;
        int[] array = new int[2];

        int* p;
        
        p = &instanceField; //CS0212
        p = &this.instanceField; //CS0212
        p = &base.instanceField; //CS0212
        p = &d.instanceField; //CS0212
        
        p = &staticField; //CS0212
        p = &this.staticField; //CS0212
        p = &base.staticField; //CS0212
        p = &d.staticField; //CS0212

        p = &array[0]; //CS0212

        p = &refParam; //CS0212
        p = &outParam; //CS0212
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (17,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &instanceField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&instanceField"),
                // (18,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &this.instanceField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&this.instanceField"),
                // (19,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &base.instanceField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&base.instanceField"),
                // (20,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &d.instanceField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&d.instanceField"),
                // (22,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &staticField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&staticField"),
                // (23,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &this.staticField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&this.staticField"),
                // (24,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &base.staticField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&base.staticField"),
                // (25,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &d.staticField; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&d.staticField"),
                // (27,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &array[0]; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&array[0]"),
                // (29,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &refParam; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&refParam"),
                // (30,13): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         p = &outParam; //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&outParam"));
        }

        [Fact]
        public void AddressOfInitializes()
        {
            var text = @"
public struct S
{
    public int x;
    public int y;
}

unsafe class C
{
    void M()
    {
        S s;
        int* p = &s.x;
        int x = s.x; //fine
        int y = s.y; //cs0170 (uninitialized)
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (15,17): error CS0170: Use of possibly unassigned field 'y'
                //         int y = s.y; //cs0170 (uninitialized)
                Diagnostic(ErrorCode.ERR_UseDefViolationField, "s.y").WithArguments("y"));
        }

        [Fact]
        public void AddressOfCapturedLocal1()
        {
            var text = @"
unsafe class C
{
    void M(System.Action a)
    {
        int x;
        int* p = &x; //before capture
        M(() => { x++; });
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,11): error CS1686: Local 'x' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         M(&x, () => { x++; });
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&x").WithArguments("x"));
        }

        [Fact]
        public void AddressOfCapturedLocal2()
        {
            var text = @"
unsafe class C
{
    void M(System.Action a)
    {
        int x = 1;
        M(() => { x++; });
        int* p = &x; //after capture
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,18): error CS1686: Local 'x' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         int* p = &x;
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&x").WithArguments("x"));
        }

        [Fact]
        public void AddressOfCapturedLocal3()
        {
            var text = @"
unsafe class C
{
    void M(System.Action a)
    {
        int x;
        M(() => { int* p = &x; }); // in lambda
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,28): error CS1686: Local 'x' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         M(() => { int* p = &x; }); // in lambda
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&x").WithArguments("x"));
        }

        [Fact]
        public void AddressOfCapturedLocal4()
        {
            var text = @"
unsafe class C
{
    void M(System.Action a)
    {
        int x;
        int* p = &x; //only report the first
        M(() => { p = &x; });
        p = &x;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,28): error CS1686: Local 'x' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         M(() => { int* p = &x; }); // in lambda
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&x").WithArguments("x"));
        }

        [Fact]
        public void AddressOfCapturedStructField1()
        {
            var text = @"
unsafe struct S
{
    int x;    

    void M(System.Action a)
    {
        S s;
        int* p = &s.x; //before capture
        M(() => { s.x++; });
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,18): error CS1686: Local 's' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         int* p = &s.x; //before capture
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&s.x").WithArguments("s"));
        }

        [Fact]
        public void AddressOfCapturedStructField2()
        {
            var text = @"
unsafe struct S
{
    int x;    

    void M(System.Action a)
    {
        S s;
        s.x = 1;
        M(() => { s.x++; });
        int* p = &s.x; //after capture
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (11,18): error CS1686: Local 's' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         int* p = &s.x; //after capture
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&s.x").WithArguments("s"));
        }

        [Fact]
        public void AddressOfCapturedStructField3()
        {
            var text = @"
unsafe struct S
{
    int x;    

    void M(System.Action a)
    {
        S s;
        M(() => { int* p = &s.x; }); // in lambda
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,28): error CS1686: Local 's' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         M(() => { int* p = &s.x; }); // in lambda
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&s.x").WithArguments("s"));
        }

        [Fact]
        public void AddressOfCapturedStructField4()
        {
            var text = @"
unsafe struct S
{
    int x;    

    void M(System.Action a)
    {
        S s;
        int* p = &s.x; //only report the first
        M(() => { p = &s.x; });
        p = &s.x;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,18): error CS1686: Local 's' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //         int* p = &s.x; //only report the first
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&s.x").WithArguments("s"));
        }

        [Fact]
        public void AddressOfCapturedParameters()
        {
            var text = @"
unsafe struct S
{
    int x;    

    void M(int x, S s, System.Action a)
    {
        M(x, s, () => 
        {
            int* p1 = &x;
            int* p2 = &s.x;
        });
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (10,23): error CS1686: Local 'x' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //             int* p1 = &x;
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&x").WithArguments("x"),
                // (11,23): error CS1686: Local 's' or its members cannot have their address taken and be used inside an anonymous method or lambda expression
                //             int* p2 = &s.x;
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "&s.x").WithArguments("s")
                );
        }

        [WorkItem(657083, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/657083")]
        [Fact]
        public void CaptureStructWithFixedArray()
        {
            var text = @"
unsafe public struct Test
{
    private delegate int D();
    public fixed int i[1];
    public int goo()
    {
        Test t = this;
        t.i[0] = 5;
        D d = () => t.i[0];
        return d();
    }
}";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                Diagnostic(ErrorCode.ERR_LocalCantBeFixedAndHoisted, "t.i").WithArguments("t")
                );
        }

        [Fact]
        public void AddressOfCapturedFixed1()
        {
            var text = @"
unsafe class C
{
    int x;    

    void M(System.Action a)
    {
        fixed(int* p = &x) //fine - error only applies to variables that require fixing
        {
            M(() => x++);
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void AddressOfCapturedFixed2()
        {
            var text = @"
unsafe class C
{
    void M(ref int x, System.Action a)
    {
        fixed (int* p = &x) //fine - error only applies to variables that require fixing
        {
            M(ref x, () => x++);
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,28): error CS1628: Cannot use ref or out parameter 'x' inside an anonymous method, lambda expression, or query expression
                //             M(ref x, () => x++);
                Diagnostic(ErrorCode.ERR_AnonDelegateCantUse, "x").WithArguments("x"));
        }

        [WorkItem(543989, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/543989")]
        [Fact]
        public void AddressOfInsideAnonymousTypes()
        {
            var text = @"
public class C
{
    public static void Main()
    {
        int x = 10;
        unsafe
        {
            var t = new { p1 = &x };
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                //(9,27): error CS0828: Cannot assign int* to anonymous type property
                //             p1 = &x
                Diagnostic(ErrorCode.ERR_AnonymousTypePropertyAssignedBadValue, "p1 = &x").WithArguments("int*"));
        }

        [WorkItem(22306, "https://github.com/dotnet/roslyn/issues/22306")]
        [WorkItem(544537, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544537")]
        [Fact]
        public void AddressOfStaticReadonlyFieldInsideFixed()
        {
            var text = @"
public class Test
{
    static readonly int R1 = 45;

    unsafe public static void Main()
    {
        fixed (int* v1 = &R1) { }
    }
}
";

            CreateCompilationWithMscorlib40AndSystemCore(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        #endregion AddressOf diagnostics

        #region AddressOf SemanticModel tests

        [Fact]
        public void AddressOfSemanticModelAPIs()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int x;
        int* p = &x;
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<PrefixUnaryExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.AddressOfExpression, syntax.Kind());

            var symbolInfo = model.GetSymbolInfo(syntax);
            Assert.Null(symbolInfo.Symbol);
            Assert.Equal(CandidateReason.None, symbolInfo.CandidateReason);
            Assert.Equal(0, symbolInfo.CandidateSymbols.Length);

            var typeInfo = model.GetTypeInfo(syntax);
            var type = typeInfo.Type;
            var conv = model.GetConversion(syntax);
            Assert.NotNull(type);
            Assert.Equal(type, typeInfo.ConvertedType);
            Assert.Equal(Conversion.Identity, conv);
            Assert.Equal(TypeKind.Pointer, type.TypeKind);
            Assert.Equal(SpecialType.System_Int32, ((IPointerTypeSymbol)type).PointedAtType.SpecialType);

            var declaredSymbol = model.GetDeclaredSymbol(syntax.Ancestors().OfType<VariableDeclaratorSyntax>().First());
            Assert.NotNull(declaredSymbol);
            Assert.Equal(SymbolKind.Local, declaredSymbol.Kind);
            Assert.Equal("p", declaredSymbol.Name);
            Assert.Equal(type, ((ILocalSymbol)declaredSymbol).Type);
        }

        [Fact]
        public void SpeculativelyBindPointerToManagedType()
        {
            var text = @"
unsafe struct S
{
    public object o;
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<FieldDeclarationSyntax>().Single();
            Assert.Equal(SyntaxKind.FieldDeclaration, syntax.Kind());

            model.GetSpeculativeTypeInfo(syntax.SpanStart, SyntaxFactory.ParseTypeName("S*"), SpeculativeBindingOption.BindAsTypeOrNamespace);

            // Specifically don't see diagnostic from speculative binding.
            compilation.VerifyDiagnostics(
                // (4,19): warning CS0649: Field 'S.o' is never assigned to, and will always have its default value null
                //     public object o;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "o").WithArguments("S.o", "null"));
        }

        [WorkItem(544346, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544346")]
        [Fact]
        public void AddressOfLambdaExpr1()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        var i1 = &()=>5;
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<PrefixUnaryExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.AddressOfExpression, syntax.Kind());
            Assert.Equal("&()", syntax.ToString()); //NOTE: not actually lambda

            var symbolInfo = model.GetSymbolInfo(syntax);
            Assert.Null(symbolInfo.Symbol);
            Assert.Equal(CandidateReason.None, symbolInfo.CandidateReason);
            Assert.Equal(0, symbolInfo.CandidateSymbols.Length);

            var typeInfo = model.GetTypeInfo(syntax);
            var type = typeInfo.Type;
            var conv = model.GetConversion(syntax);
            Assert.NotNull(type);
            Assert.Equal(type, typeInfo.ConvertedType);
            Assert.Equal(Conversion.Identity, conv);

            Assert.Equal("?*", typeInfo.Type.ToTestDisplayString());
            Assert.Equal(TypeKind.Pointer, typeInfo.Type.TypeKind);
            Assert.Equal(TypeKind.Error, ((IPointerTypeSymbol)typeInfo.Type).PointedAtType.TypeKind);
        }

        [WorkItem(544346, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544346")]
        [Fact]
        public void AddressOfLambdaExpr2()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        var i1 = &(()=>5);
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<PrefixUnaryExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.AddressOfExpression, syntax.Kind());
            Assert.Equal("&(()=>5)", syntax.ToString());

            var symbolInfo = model.GetSymbolInfo(syntax);
            Assert.Null(symbolInfo.Symbol);
            Assert.Equal(CandidateReason.None, symbolInfo.CandidateReason);
            Assert.Equal(0, symbolInfo.CandidateSymbols.Length);

            var typeInfo = model.GetTypeInfo(syntax);
            var type = typeInfo.Type;
            var conv = model.GetConversion(syntax);
            Assert.NotNull(type);
            Assert.Equal(type, typeInfo.ConvertedType);
            Assert.Equal(Conversion.Identity, conv);

            Assert.Equal("?*", typeInfo.Type.ToTestDisplayString());
            Assert.Equal(TypeKind.Pointer, typeInfo.Type.TypeKind);
            Assert.Equal(TypeKind.Error, ((IPointerTypeSymbol)typeInfo.Type).PointedAtType.TypeKind);
        }

        [WorkItem(544346, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544346")]
        [Fact]
        public void AddressOfMethodGroup()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        var i1 = &M;
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            compilation.VerifyDiagnostics(
                // (6,13): error CS0815: Cannot assign &method group to an implicitly-typed variable
                //         var i1 = &M;
                Diagnostic(ErrorCode.ERR_ImplicitlyTypedVariableAssignedBadValue, "i1 = &M").WithArguments("&method group").WithLocation(6, 13)
            );
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<PrefixUnaryExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.AddressOfExpression, syntax.Kind());

            var symbolInfo = model.GetSymbolInfo(syntax);
            Assert.Null(symbolInfo.Symbol);
            Assert.Equal(CandidateReason.OverloadResolutionFailure, symbolInfo.CandidateReason);
            Assert.Equal("void C.M()", symbolInfo.CandidateSymbols.Single().ToTestDisplayString());

            var typeInfo = model.GetTypeInfo(syntax);
            var type = typeInfo.Type;
            var conv = model.GetConversion(syntax);
            Assert.Null(type);
            Assert.Equal(type, typeInfo.ConvertedType);
            Assert.Equal(Conversion.Identity, conv);
        }

        #endregion AddressOf SemanticModel tests

        #region Dereference diagnostics

        [Fact]
        public void DereferenceSuccess()
        {
            var text = @"
unsafe class C
{
    int M(int* p)
    {
        return *p;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void DereferenceNullLiteral()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int x = *null;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,17): error CS0193: The * or -> operator must be applied to a pointer
                //         int x = *null;
                Diagnostic(ErrorCode.ERR_PtrExpected, "*null"));
        }

        [Fact]
        public void DereferenceNonPointer()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int p = 1;
        int x = *p;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,17): error CS0193: The * or -> operator must be applied to a pointer
                //         int x = *p;
                Diagnostic(ErrorCode.ERR_PtrExpected, "*p"));
        }

        [Fact]
        public void DereferenceVoidPointer()
        {
            var text = @"
unsafe class C
{
    void M(void* p)
    {
        var x = *p;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,17): error CS0242: The operation in question is undefined on void pointers
                //         var x = *p;
                Diagnostic(ErrorCode.ERR_VoidError, "*p"));
        }

        [Fact]
        public void DereferenceUninitialized()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int* p;
        int x = *p;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,18): error CS0165: Use of unassigned local variable 'p'
                //         int x = *p;
                Diagnostic(ErrorCode.ERR_UseDefViolation, "p").WithArguments("p"));
        }

        #endregion Dereference diagnostics

        #region Dereference SemanticModel tests

        [Fact]
        public void DereferenceSemanticModelAPIs()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int x;
        int* p = &x;
        x = *p;
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<PrefixUnaryExpressionSyntax>().Last();
            Assert.Equal(SyntaxKind.PointerIndirectionExpression, syntax.Kind());

            var symbolInfo = model.GetSymbolInfo(syntax);
            Assert.Null(symbolInfo.Symbol);
            Assert.Equal(CandidateReason.None, symbolInfo.CandidateReason);
            Assert.Equal(0, symbolInfo.CandidateSymbols.Length);

            var typeInfo = model.GetTypeInfo(syntax);
            var type = typeInfo.Type;
            var conv = model.GetConversion(syntax);
            Assert.NotNull(type);
            Assert.Equal(type, typeInfo.ConvertedType);
            Assert.Equal(Conversion.Identity, conv);
            Assert.Equal(SpecialType.System_Int32, type.SpecialType);
        }

        #endregion Dereference SemanticModel tests

        #region PointerMemberAccess diagnostics

        [Fact]
        public void PointerMemberAccessSuccess()
        {
            var text = @"
unsafe class C
{
    string M(int* p)
    {
        return p->ToString();
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerMemberAccessAddress()
        {
            var text = @"
unsafe struct S
{
    int x;

    void M(S* sp)
    {
        int* ip = &(sp->x);
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerMemberAccessNullLiteral()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        string x = null->ToString(); //Roslyn: CS0193 / Dev10: CS0023
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,20): error CS0193: The * or -> operator must be applied to a pointer
                //         string x = null->ToString(); //Roslyn: CS0193 / Dev10: CS0023
                Diagnostic(ErrorCode.ERR_PtrExpected, "null->ToString"));
        }

        [Fact]
        public void PointerMemberAccessMethodGroup()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        string x = M->ToString(); //Roslyn: CS0193 / Dev10: CS0023
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,20): error CS0193: The * or -> operator must be applied to a pointer
                //         string x = M->ToString(); //Roslyn: CS0193 / Dev10: CS0023
                Diagnostic(ErrorCode.ERR_PtrExpected, "M->ToString"));
        }

        [Fact]
        public void PointerMemberAccessLambda()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        string x = (z => z)->ToString(); //Roslyn: CS0193 / Dev10: CS0023
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,20): error CS0193: The * or -> operator must be applied to a pointer
                //         string x = (z => z)->ToString(); //Roslyn: CS0193 / Dev10: CS0023
                Diagnostic(ErrorCode.ERR_PtrExpected, "(z => z)->ToString"));
        }

        [Fact]
        public void PointerMemberAccessNonPointer()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int p = 1;
        int x = p->GetHashCode();
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,17): error CS0193: The * or -> operator must be applied to a pointer
                //         int x = p->GetHashCode();
                Diagnostic(ErrorCode.ERR_PtrExpected, "p->GetHashCode"));
        }

        [Fact]
        public void PointerMemberAccessVoidPointer()
        {
            var text = @"
unsafe class C
{
    void M(void* p)
    {
        var x = p->GetHashCode();
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,17): error CS0242: The operation in question is undefined on void pointers
                //         var x = p->GetHashCode();
                Diagnostic(ErrorCode.ERR_VoidError, "p->GetHashCode"));
        }

        [Fact]
        public void PointerMemberAccessUninitialized()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        int* p;
        int x = p->GetHashCode();
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,18): error CS0165: Use of unassigned local variable 'p'
                //         int x = *p;
                Diagnostic(ErrorCode.ERR_UseDefViolation, "p").WithArguments("p"));
        }

        [Fact]
        public void PointerMemberAccessMemberKinds()
        {
            var text = @"
unsafe struct S
{
    int InstanceField;
    static int StaticField;

    int InstanceProperty { get; set; }
    static int StaticProperty { get; set; }

    // No syntax for indexer access.
    //int this[int x] { get { return 0; } set { } }

    void InstanceMethod() { }
    static void StaticMethod() { }

    // No syntax for type member access.
    //delegate void Delegate();
    //struct Type { }

    static void Main()
    {
        S s;
        S* p = &s;

        p->InstanceField = 1;
        p->StaticField = 1; //CS0176

        p->InstanceProperty = 2;
        p->StaticProperty = 2; //CS0176

        p->InstanceMethod();
        p->StaticMethod(); //CS0176

        p->ExtensionMethod();

        System.Action a;
        a = p->InstanceMethod;
        a = p->StaticMethod; //CS0176
        a = p->ExtensionMethod; //CS1113
    }
}

static class Extensions
{
    public static void ExtensionMethod(this S s)
    {
    }
}
";
            CreateCompilationWithMscorlib40AndSystemCore(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (26,9): error CS0176: Member 'S.StaticField' cannot be accessed with an instance reference; qualify it with a type name instead
                //         p->StaticField = 1; //CS0176
                Diagnostic(ErrorCode.ERR_ObjectProhibited, "p->StaticField").WithArguments("S.StaticField").WithLocation(26, 9),
                // (29,9): error CS0176: Member 'S.StaticProperty' cannot be accessed with an instance reference; qualify it with a type name instead
                //         p->StaticProperty = 2; //CS0176
                Diagnostic(ErrorCode.ERR_ObjectProhibited, "p->StaticProperty").WithArguments("S.StaticProperty").WithLocation(29, 9),
                // (32,9): error CS0176: Member 'S.StaticMethod()' cannot be accessed with an instance reference; qualify it with a type name instead
                //         p->StaticMethod(); //CS0176
                Diagnostic(ErrorCode.ERR_ObjectProhibited, "p->StaticMethod").WithArguments("S.StaticMethod()").WithLocation(32, 9),
                // (38,13): error CS0176: Member 'S.StaticMethod()' cannot be accessed with an instance reference; qualify it with a type name instead
                //         a = p->StaticMethod; //CS0176
                Diagnostic(ErrorCode.ERR_ObjectProhibited, "p->StaticMethod").WithArguments("S.StaticMethod()").WithLocation(38, 13),
                // (39,13): error CS1113: Extension method 'Extensions.ExtensionMethod(S)' defined on value type 'S' cannot be used to create delegates
                //         a = p->ExtensionMethod; //CS1113
                Diagnostic(ErrorCode.ERR_ValueTypeExtDelegate, "p->ExtensionMethod").WithArguments("Extensions.ExtensionMethod(S)", "S").WithLocation(39, 13)
                );
        }

        // NOTE: a type with events is managed, so this is always an error case.
        [Fact]
        public void PointerMemberAccessEvents()
        {
            var text = @"
unsafe struct S
{
    event System.Action InstanceFieldLikeEvent;
    static event System.Action StaticFieldLikeEvent;

    event System.Action InstanceCustomEvent { add { } remove { } }
    static event System.Action StaticCustomEvent { add { } remove { } }

    static void Main()
    {
        S s;
        S* p = &s; //CS0208

        p->InstanceFieldLikeEvent += null;
        p->StaticFieldLikeEvent += null; //CS0176

        p->InstanceCustomEvent += null;
        p->StaticCustomEvent += null; //CS0176
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (13,9): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //         S* p = &s; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "S*").WithArguments("S").WithLocation(13, 9),
                // (13,16): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //         S* p = &s; //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "&s").WithArguments("S").WithLocation(13, 16),
                // (16,9): error CS0176: Member 'S.StaticFieldLikeEvent' cannot be accessed with an instance reference; qualify it with a type name instead
                //         p->StaticFieldLikeEvent += null; //CS0176
                Diagnostic(ErrorCode.ERR_ObjectProhibited, "p->StaticFieldLikeEvent").WithArguments("S.StaticFieldLikeEvent").WithLocation(16, 9),
                // (19,9): error CS0176: Member 'S.StaticCustomEvent' cannot be accessed with an instance reference; qualify it with a type name instead
                //         p->StaticCustomEvent += null; //CS0176
                Diagnostic(ErrorCode.ERR_ObjectProhibited, "p->StaticCustomEvent").WithArguments("S.StaticCustomEvent").WithLocation(19, 9),
                // (5,32): warning CS0067: The event 'S.StaticFieldLikeEvent' is never used
                //     static event System.Action StaticFieldLikeEvent;
                Diagnostic(ErrorCode.WRN_UnreferencedEvent, "StaticFieldLikeEvent").WithArguments("S.StaticFieldLikeEvent").WithLocation(5, 32),
                // (4,25): warning CS0067: The event 'S.InstanceFieldLikeEvent' is never used
                //     event System.Action InstanceFieldLikeEvent;
                Diagnostic(ErrorCode.WRN_UnreferencedEvent, "InstanceFieldLikeEvent").WithArguments("S.InstanceFieldLikeEvent").WithLocation(4, 25)
                );
        }

        #endregion PointerMemberAccess diagnostics

        #region PointerMemberAccess SemanticModel tests

        [Fact]
        public void PointerMemberAccessSemanticModelAPIs()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        S s;
        S* p = &s;
        p->M();
    }
}

struct S
{
    public void M() { }
    public void M(int x) { }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<MemberAccessExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.PointerMemberAccessExpression, syntax.Kind());

            var receiverSyntax = syntax.Expression;
            var methodGroupSyntax = syntax;
            var callSyntax = syntax.Parent;

            var structType = compilation.GlobalNamespace.GetMember<TypeSymbol>("S");
            var structPointerType = new PointerTypeSymbol(TypeWithAnnotations.Create(structType));
            var structMethod1 = structType.GetMembers("M").OfType<MethodSymbol>().Single(m => m.ParameterCount == 0);
            var structMethod2 = structType.GetMembers("M").OfType<MethodSymbol>().Single(m => m.ParameterCount == 1);

            var receiverSummary = model.GetSemanticInfoSummary(receiverSyntax);
            var receiverSymbol = receiverSummary.Symbol;
            Assert.Equal(SymbolKind.Local, receiverSymbol.Kind);
            Assert.Equal(structPointerType.GetPublicSymbol(), ((ILocalSymbol)receiverSymbol).Type);
            Assert.Equal("p", receiverSymbol.Name);
            Assert.Equal(CandidateReason.None, receiverSummary.CandidateReason);
            Assert.Equal(0, receiverSummary.CandidateSymbols.Length);
            Assert.Equal(structPointerType, receiverSummary.Type.GetSymbol());
            Assert.Equal(structPointerType, receiverSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, receiverSummary.ImplicitConversion.Kind);
            Assert.Equal(0, receiverSummary.MethodGroup.Length);

            var methodGroupSummary = model.GetSemanticInfoSummary(methodGroupSyntax);
            Assert.Equal(structMethod1, methodGroupSummary.Symbol.GetSymbol());
            Assert.Equal(CandidateReason.None, methodGroupSummary.CandidateReason);
            Assert.Equal(0, methodGroupSummary.CandidateSymbols.Length);
            Assert.Null(methodGroupSummary.Type);
            Assert.Null(methodGroupSummary.ConvertedType);
            Assert.Equal(ConversionKind.Identity, methodGroupSummary.ImplicitConversion.Kind);
            Assert.True(methodGroupSummary.MethodGroup.SetEquals(ImmutableArray.Create<IMethodSymbol>(structMethod1.GetPublicSymbol(), structMethod2.GetPublicSymbol()), EqualityComparer<IMethodSymbol>.Default));

            var callSummary = model.GetSemanticInfoSummary(callSyntax);
            Assert.Equal(structMethod1, callSummary.Symbol.GetSymbol());
            Assert.Equal(CandidateReason.None, callSummary.CandidateReason);
            Assert.Equal(0, callSummary.CandidateSymbols.Length);
            Assert.Equal(SpecialType.System_Void, callSummary.Type.SpecialType);
            Assert.Equal(SpecialType.System_Void, callSummary.ConvertedType.SpecialType);
            Assert.Equal(ConversionKind.Identity, callSummary.ImplicitConversion.Kind);
            Assert.Equal(0, callSummary.MethodGroup.Length);
        }

        [Fact]
        public void PointerMemberAccessSemanticModelAPIs_ErrorScenario()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        S s;
        S* p = &s;
        s->M(); //should be 'p'
    }
}

struct S
{
    public void M() { }
    public void M(int x) { }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<MemberAccessExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.PointerMemberAccessExpression, syntax.Kind());

            var receiverSyntax = syntax.Expression;
            var methodGroupSyntax = syntax;
            var callSyntax = syntax.Parent;

            var structType = compilation.GlobalNamespace.GetMember<TypeSymbol>("S");
            var structMethod1 = structType.GetMembers("M").OfType<MethodSymbol>().Single(m => m.ParameterCount == 0);
            var structMethod2 = structType.GetMembers("M").OfType<MethodSymbol>().Single(m => m.ParameterCount == 1);
            var structMethods = ImmutableArray.Create<MethodSymbol>(structMethod1, structMethod2);

            var receiverSummary = model.GetSemanticInfoSummary(receiverSyntax);
            var receiverSymbol = receiverSummary.Symbol;
            Assert.Equal(SymbolKind.Local, receiverSymbol.Kind);
            Assert.Equal(structType.GetPublicSymbol(), ((ILocalSymbol)receiverSymbol).Type);
            Assert.Equal("s", receiverSymbol.Name);
            Assert.Equal(CandidateReason.None, receiverSummary.CandidateReason);
            Assert.Equal(0, receiverSummary.CandidateSymbols.Length);
            Assert.Equal(structType, receiverSummary.Type.GetSymbol());
            Assert.Equal(structType, receiverSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, receiverSummary.ImplicitConversion.Kind);
            Assert.Equal(0, receiverSummary.MethodGroup.Length);

            var methodGroupSummary = model.GetSemanticInfoSummary(methodGroupSyntax);
            Assert.Equal(structMethod1, methodGroupSummary.Symbol.GetSymbol()); // Have enough info for overload resolution.
            Assert.Null(methodGroupSummary.Type);
            Assert.Null(methodGroupSummary.ConvertedType);
            Assert.Equal(ConversionKind.Identity, methodGroupSummary.ImplicitConversion.Kind);
            Assert.True(methodGroupSummary.MethodGroup.SetEquals(structMethods.GetPublicSymbols(), EqualityComparer<IMethodSymbol>.Default));

            var callSummary = model.GetSemanticInfoSummary(callSyntax);
            Assert.Equal(structMethod1, callSummary.Symbol.GetSymbol()); // Have enough info for overload resolution.
            Assert.Equal(SpecialType.System_Void, callSummary.Type.SpecialType);
            Assert.Equal(callSummary.Type, callSummary.ConvertedType);
            Assert.Equal(ConversionKind.Identity, callSummary.ImplicitConversion.Kind);
            Assert.Equal(0, callSummary.MethodGroup.Length);
        }

        #endregion PointerMemberAccess SemanticModel tests

        #region PointerElementAccess

        [Fact]
        public void PointerElementAccess_NoIndices()
        {
            var text = @"
unsafe struct S
{
    void M(S* p)
    {
        S s = p[];
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,17): error CS0443: Syntax error; value expected
                //         S s = p[];
                Diagnostic(ErrorCode.ERR_ValueExpected, "]"));
        }

        [Fact]
        public void PointerElementAccess_MultipleIndices()
        {
            var text = @"
unsafe struct S
{
    void M(S* p)
    {
        S s = p[1, 2];
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,15): error CS0196: A pointer must be indexed by only one value
                //         S s = p[1, 2];
                Diagnostic(ErrorCode.ERR_PtrIndexSingle, "p[1, 2]"));
        }

        [Fact]
        public void PointerElementAccess_RefIndex()
        {
            var text = @"
unsafe struct S
{
    void M(S* p)
    {
        int x = 1;
        S s = p[ref x];
    }
}
";
            // Dev10 gives an unhelpful syntax error.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,21): error CS1615: Argument 1 should not be passed with the 'ref' keyword
                //         S s = p[ref x];
                Diagnostic(ErrorCode.ERR_BadArgExtraRef, "x").WithArguments("1", "ref"));
        }

        [Fact]
        public void PointerElementAccess_OutIndex()
        {
            var text = @"
unsafe struct S
{
    void M(S* p)
    {
        int x = 1;
        S s = p[out x];
    }
}
";
            // Dev10 gives an unhelpful syntax error.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,21): error CS1615: Argument 1 should not be passed with the 'out' keyword
                //         S s = p[out x];
                Diagnostic(ErrorCode.ERR_BadArgExtraRef, "x").WithArguments("1", "out"));
        }

        [Fact]
        public void PointerElementAccess_NamedOffset()
        {
            var text = @"
unsafe struct S
{
    void M(S* p)
    {
        int x = 1;
        S s = p[index: x];
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,15): error CS1742: An array access may not have a named argument specifier
                //         S s = p[index: x];
                Diagnostic(ErrorCode.ERR_NamedArgumentForArray, "p[index: x]"));
        }

        [Fact]
        public void PointerElementAccess_VoidPointer()
        {
            var text = @"
unsafe struct S
{
    void M(void* p)
    {
        p[0] = null;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,9): error CS0242: The operation in question is undefined on void pointers
                //         p[0] = null;
                Diagnostic(ErrorCode.ERR_VoidError, "p"));
        }

        [Fact, WorkItem(27945, "https://github.com/dotnet/roslyn/issues/27945")]
        public void TakingAddressOfPointerFieldsIsLegal_Static()
        {
            CreateCompilation(@"
unsafe class C
{
    static int* x;

    static void Main()
    {
        fixed (int* y = new int[1])
        {
            x = y;
        }

        int* element = &x[0];
        *element = 5;
    }
}", options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact, WorkItem(27945, "https://github.com/dotnet/roslyn/issues/27945")]
        public void TakingAddressOfPointerFieldsIsLegal_Instance()
        {
            CreateCompilation(@"
unsafe class C
{
    int* x;

    void Calculate()
    {
        fixed (int* y = new int[1])
        {
            x = y;
        }

        int* element = &x[0];
        *element = 5;
    }
}", options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact, WorkItem(27945, "https://github.com/dotnet/roslyn/issues/27945")]
        public void TakingAddressOfPointerFieldsIsLegal_Local()
        {
            CreateCompilation(@"
unsafe class C
{
    static void Main()
    {
        int* x;

        fixed (int* y = new int[1])
        {
            x = y;
        }

        int* element = &x[0];
        *element = 5;
    }
}", options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        #endregion PointerElementAccess diagnostics

        #region PointerElementAccess SemanticModel tests

        [Fact]
        public void PointerElementAccessSemanticModelAPIs()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        const int size = 3;
        fixed(int* p = new int[size])
        {
            for (int i = 0; i < size; i++)
            {
                p[i] = i * i;
            }
        }
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ElementAccessExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.ElementAccessExpression, syntax.Kind());

            var receiverSyntax = syntax.Expression;
            var indexSyntax = syntax.ArgumentList.Arguments.Single().Expression;
            var accessSyntax = syntax;

            var intType = compilation.GetSpecialType(SpecialType.System_Int32);
            var intPointerType = new PointerTypeSymbol(TypeWithAnnotations.Create(intType));

            var receiverSummary = model.GetSemanticInfoSummary(receiverSyntax);
            var receiverSymbol = receiverSummary.Symbol;
            Assert.Equal(SymbolKind.Local, receiverSymbol.Kind);
            Assert.Equal(intPointerType.GetPublicSymbol(), ((ILocalSymbol)receiverSymbol).Type);
            Assert.Equal("p", receiverSymbol.Name);
            Assert.Equal(CandidateReason.None, receiverSummary.CandidateReason);
            Assert.Equal(0, receiverSummary.CandidateSymbols.Length);
            Assert.Equal(intPointerType, receiverSummary.Type.GetSymbol());
            Assert.Equal(intPointerType, receiverSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, receiverSummary.ImplicitConversion.Kind);
            Assert.Equal(0, receiverSummary.MethodGroup.Length);

            var indexSummary = model.GetSemanticInfoSummary(indexSyntax);
            var indexSymbol = indexSummary.Symbol;
            Assert.Equal(SymbolKind.Local, indexSymbol.Kind);
            Assert.Equal(intType.GetPublicSymbol(), ((ILocalSymbol)indexSymbol).Type);
            Assert.Equal("i", indexSymbol.Name);
            Assert.Equal(CandidateReason.None, indexSummary.CandidateReason);
            Assert.Equal(0, indexSummary.CandidateSymbols.Length);
            Assert.Equal(intType, indexSummary.Type.GetSymbol());
            Assert.Equal(intType, indexSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, indexSummary.ImplicitConversion.Kind);
            Assert.Equal(0, indexSummary.MethodGroup.Length);

            var accessSummary = model.GetSemanticInfoSummary(accessSyntax);
            Assert.Null(accessSummary.Symbol);
            Assert.Equal(CandidateReason.None, accessSummary.CandidateReason);
            Assert.Equal(0, accessSummary.CandidateSymbols.Length);
            Assert.Equal(intType, accessSummary.Type.GetSymbol());
            Assert.Equal(intType, accessSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, accessSummary.ImplicitConversion.Kind);
            Assert.Equal(0, accessSummary.MethodGroup.Length);
        }

        [Fact]
        public void PointerElementAccessSemanticModelAPIs_Fixed_Unmovable()
        {
            var text = @"
unsafe class C
{
    struct S1
    {
        public fixed int f[10];
    }

    void M()
    {
        S1 p = default;

        p.f[i] = 123;
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ElementAccessExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.ElementAccessExpression, syntax.Kind());

            var receiverSyntax = syntax.Expression;
            var indexSyntax = syntax.ArgumentList.Arguments.Single().Expression;
            var accessSyntax = syntax;

            var intType = compilation.GetSpecialType(SpecialType.System_Int32);
            var intPointerType = new PointerTypeSymbol(TypeWithAnnotations.Create(intType));

            var receiverSummary = model.GetSemanticInfoSummary(receiverSyntax);
            var receiverSymbol = receiverSummary.Symbol;
            Assert.Equal(SymbolKind.Field, receiverSymbol.Kind);
            Assert.Equal(intPointerType.GetPublicSymbol(), ((IFieldSymbol)receiverSymbol).Type);
            Assert.Equal("f", receiverSymbol.Name);
            Assert.Equal(CandidateReason.None, receiverSummary.CandidateReason);
            Assert.Equal(0, receiverSummary.CandidateSymbols.Length);
            Assert.Equal(intPointerType, receiverSummary.Type.GetSymbol());
            Assert.Equal(intPointerType, receiverSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, receiverSummary.ImplicitConversion.Kind);
            Assert.Equal(0, receiverSummary.MethodGroup.Length);

            var indexSummary = model.GetSemanticInfoSummary(indexSyntax);
            var indexSymbol = indexSummary.Symbol;
            Assert.Null(indexSymbol);

            var accessSummary = model.GetSemanticInfoSummary(accessSyntax);
            Assert.Null(accessSummary.Symbol);
            Assert.Equal(CandidateReason.None, accessSummary.CandidateReason);
            Assert.Equal(0, accessSummary.CandidateSymbols.Length);
            Assert.Equal(intType, accessSummary.Type.GetSymbol());
            Assert.Equal(intType, accessSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, accessSummary.ImplicitConversion.Kind);
            Assert.Equal(0, accessSummary.MethodGroup.Length);
        }

        [Fact]
        public void PointerElementAccessSemanticModelAPIs_Fixed_Movable()
        {
            var text = @"
unsafe class C
{
    struct S1
    {
        public fixed int f[10];
    }

    S1 p = default;
    void M()
    {
        p.f[i] = 123;
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ElementAccessExpressionSyntax>().Single();
            Assert.Equal(SyntaxKind.ElementAccessExpression, syntax.Kind());

            var receiverSyntax = syntax.Expression;
            var indexSyntax = syntax.ArgumentList.Arguments.Single().Expression;
            var accessSyntax = syntax;

            var intType = compilation.GetSpecialType(SpecialType.System_Int32);
            var intPointerType = new PointerTypeSymbol(TypeWithAnnotations.Create(intType));

            var receiverSummary = model.GetSemanticInfoSummary(receiverSyntax);
            var receiverSymbol = receiverSummary.Symbol;
            Assert.Equal(SymbolKind.Field, receiverSymbol.Kind);
            Assert.Equal(intPointerType.GetPublicSymbol(), ((IFieldSymbol)receiverSymbol).Type);
            Assert.Equal("f", receiverSymbol.Name);
            Assert.Equal(CandidateReason.None, receiverSummary.CandidateReason);
            Assert.Equal(0, receiverSummary.CandidateSymbols.Length);
            Assert.Equal(intPointerType, receiverSummary.Type.GetSymbol());
            Assert.Equal(intPointerType, receiverSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, receiverSummary.ImplicitConversion.Kind);
            Assert.Equal(0, receiverSummary.MethodGroup.Length);

            var indexSummary = model.GetSemanticInfoSummary(indexSyntax);
            var indexSymbol = indexSummary.Symbol;
            Assert.Null(indexSymbol);

            var accessSummary = model.GetSemanticInfoSummary(accessSyntax);
            Assert.Null(accessSummary.Symbol);
            Assert.Equal(CandidateReason.None, accessSummary.CandidateReason);
            Assert.Equal(0, accessSummary.CandidateSymbols.Length);
            Assert.Equal(intType, accessSummary.Type.GetSymbol());
            Assert.Equal(intType, accessSummary.ConvertedType.GetSymbol());
            Assert.Equal(ConversionKind.Identity, accessSummary.ImplicitConversion.Kind);
            Assert.Equal(0, accessSummary.MethodGroup.Length);
        }

        #endregion PointerElementAccess SemanticModel tests

        #region Pointer conversion tests

        [Fact]
        public void NullLiteralConversion()
        {
            var text = @"
unsafe struct S
{
    void M()
    {
        byte* b = null;
        int* i = null;
        S* s = null;
        void* v = null;
    }
}
";

            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            compilation.VerifyDiagnostics();

            foreach (var nullSyntax in tree.GetCompilationUnitRoot().DescendantTokens().Where(token => token.IsKind(SyntaxKind.NullKeyword)))
            {
                var node = (ExpressionSyntax)nullSyntax.Parent;
                var typeInfo = model.GetTypeInfo(node);
                var conv = model.GetConversion(node);
                Assert.Null(typeInfo.Type);
                Assert.Equal(TypeKind.Pointer, typeInfo.ConvertedType.TypeKind);
                Assert.Equal(ConversionKind.ImplicitNullToPointer, conv.Kind);
            }
        }

        [Fact]
        public void VoidPointerConversion1()
        {
            var text = @"
unsafe struct S
{
    void M()
    {
        byte* b = null;
        int* i = null;
        S* s = null;

        void* v1 = b;
        void* v2 = i;
        void* v3 = s;
    }
}
";

            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            compilation.VerifyDiagnostics();

            foreach (var declarationSyntax in tree.GetCompilationUnitRoot().DescendantNodes().OfType<VariableDeclarationSyntax>().Where(syntax => syntax.GetFirstToken().IsKind(SyntaxKind.VoidKeyword)))
            {
                var value = declarationSyntax.Variables.Single().Initializer.Value;
                var typeInfo = model.GetTypeInfo(value);

                var type = typeInfo.Type;
                Assert.Equal(TypeKind.Pointer, type.TypeKind);
                Assert.NotEqual(SpecialType.System_Void, ((IPointerTypeSymbol)type).PointedAtType.SpecialType);

                var convertedType = typeInfo.ConvertedType;
                Assert.Equal(TypeKind.Pointer, convertedType.TypeKind);
                Assert.Equal(SpecialType.System_Void, ((IPointerTypeSymbol)convertedType).PointedAtType.SpecialType);

                var conv = model.GetConversion(value);
                Assert.Equal(ConversionKind.ImplicitPointerToVoid, conv.Kind);
            }
        }

        [Fact]
        public void VoidPointerConversion2()
        {
            var text = @"
unsafe struct S
{
    void M()
    {
        void* v = null;
        void* vv1 = &v;
        void** vv2 = &v;
        void* vv3 = vv2;
        void** vv4 = vv3;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (10,22): error CS0266: Cannot implicitly convert type 'void*' to 'void**'. An explicit conversion exists (are you missing a cast?)
                //         void** vv4 = vv3;
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "vv3").WithArguments("void*", "void**"));
        }

        [Fact]
        public void ExplicitPointerConversion()
        {
            var text = @"
unsafe struct S
{
    void M(int* i, byte* b, void* v, int** ii, byte** bb, void** vv)
    {
        i = (int*)b;
        i = (int*)v;
        i = (int*)ii;
        i = (int*)bb;
        i = (int*)vv;

        b = (byte*)i;
        b = (byte*)v;
        b = (byte*)ii;
        b = (byte*)bb;
        b = (byte*)vv;

        v = (void*)i;
        v = (void*)b;
        v = (void*)ii;
        v = (void*)bb;
        v = (void*)vv;

        ii = (int**)i;
        ii = (int**)b;
        ii = (int**)v;
        ii = (int**)bb;
        ii = (int**)vv;

        bb = (byte**)i;
        bb = (byte**)b;
        bb = (byte**)v;
        bb = (byte**)ii;
        bb = (byte**)vv;

        vv = (void**)i;
        vv = (void**)b;
        vv = (void**)v;
        vv = (void**)ii;
        vv = (void**)bb;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void ExplicitPointerNumericConversion()
        {
            var text = @"
unsafe struct S
{
    void M(int* pi, void* pv, sbyte sb, byte b, short s, ushort us, int i, uint ui, long l, ulong ul)
    {
        sb = (sbyte)pi;
        b = (byte)pi;
        s = (short)pi;
        us = (ushort)pi;
        i = (int)pi;
        ui = (uint)pi;
        l = (long)pi;
        ul = (ulong)pi;

        sb = (sbyte)pv;
        b = (byte)pv;
        s = (short)pv;
        us = (ushort)pv;
        i = (int)pv;
        ui = (uint)pv;
        l = (long)pv;
        ul = (ulong)pv;

        pi = (int*)sb;
        pi = (int*)b;
        pi = (int*)s;
        pi = (int*)us;
        pi = (int*)i;
        pi = (int*)ui;
        pi = (int*)l;
        pi = (int*)ul;

        pv = (void*)sb;
        pv = (void*)b;
        pv = (void*)s;
        pv = (void*)us;
        pv = (void*)i;
        pv = (void*)ui;
        pv = (void*)l;
        pv = (void*)ul;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void ExplicitPointerNumericConversion_Illegal()
        {
            var text = @"
unsafe struct S
{
    void M(int* pi, void* pv, bool b, char c, double d, decimal e, float f)
    {
        b = (bool)pi;
        c = (char)pi;
        d = (double)pi;
        e = (decimal)pi;
        f = (float)pi;

        b = (bool)pv;
        c = (char)pv;
        d = (double)pv;
        e = (decimal)pv;
        f = (float)pv;

        pi = (int*)b;
        pi = (int*)c;
        pi = (int*)d;
        pi = (int*)d;
        pi = (int*)f;

        pv = (void*)b;
        pv = (void*)c;
        pv = (void*)d;
        pv = (void*)e;
        pv = (void*)f;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,13): error CS0030: Cannot convert type 'int*' to 'bool'
                //         b = (bool)pi;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(bool)pi").WithArguments("int*", "bool"),
                // (7,13): error CS0030: Cannot convert type 'int*' to 'char'
                //         c = (char)pi;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(char)pi").WithArguments("int*", "char"),
                // (8,13): error CS0030: Cannot convert type 'int*' to 'double'
                //         d = (double)pi;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(double)pi").WithArguments("int*", "double"),
                // (9,13): error CS0030: Cannot convert type 'int*' to 'decimal'
                //         e = (decimal)pi;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(decimal)pi").WithArguments("int*", "decimal"),
                // (10,13): error CS0030: Cannot convert type 'int*' to 'float'
                //         f = (float)pi;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(float)pi").WithArguments("int*", "float"),
                // (12,13): error CS0030: Cannot convert type 'void*' to 'bool'
                //         b = (bool)pv;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(bool)pv").WithArguments("void*", "bool"),
                // (13,13): error CS0030: Cannot convert type 'void*' to 'char'
                //         c = (char)pv;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(char)pv").WithArguments("void*", "char"),
                // (14,13): error CS0030: Cannot convert type 'void*' to 'double'
                //         d = (double)pv;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(double)pv").WithArguments("void*", "double"),
                // (15,13): error CS0030: Cannot convert type 'void*' to 'decimal'
                //         e = (decimal)pv;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(decimal)pv").WithArguments("void*", "decimal"),
                // (16,13): error CS0030: Cannot convert type 'void*' to 'float'
                //         f = (float)pv;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(float)pv").WithArguments("void*", "float"),
                // (18,14): error CS0030: Cannot convert type 'bool' to 'int*'
                //         pi = (int*)b;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)b").WithArguments("bool", "int*"),
                // (19,14): error CS0030: Cannot convert type 'char' to 'int*'
                //         pi = (int*)c;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)c").WithArguments("char", "int*"),
                // (20,14): error CS0030: Cannot convert type 'double' to 'int*'
                //         pi = (int*)d;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)d").WithArguments("double", "int*"),
                // (21,14): error CS0030: Cannot convert type 'double' to 'int*'
                //         pi = (int*)d;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)d").WithArguments("double", "int*"),
                // (22,14): error CS0030: Cannot convert type 'float' to 'int*'
                //         pi = (int*)f;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)f").WithArguments("float", "int*"),
                // (24,14): error CS0030: Cannot convert type 'bool' to 'void*'
                //         pv = (void*)b;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)b").WithArguments("bool", "void*"),
                // (25,14): error CS0030: Cannot convert type 'char' to 'void*'
                //         pv = (void*)c;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)c").WithArguments("char", "void*"),
                // (26,14): error CS0030: Cannot convert type 'double' to 'void*'
                //         pv = (void*)d;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)d").WithArguments("double", "void*"),
                // (27,14): error CS0030: Cannot convert type 'decimal' to 'void*'
                //         pv = (void*)e;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)e").WithArguments("decimal", "void*"),
                // (28,14): error CS0030: Cannot convert type 'float' to 'void*'
                //         pv = (void*)f;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)f").WithArguments("float", "void*"));
        }

        [Fact]
        public void ExplicitPointerNumericConversion_Nullable()
        {
            var text = @"
unsafe struct S
{
    void M(int* pi, void* pv, sbyte? sb, byte? b, short? s, ushort? us, int? i, uint? ui, long? l, ulong? ul)
    {
        sb = (sbyte?)pi;
        b = (byte?)pi;
        s = (short?)pi;
        us = (ushort?)pi;
        i = (int?)pi;
        ui = (uint?)pi;
        l = (long?)pi;
        ul = (ulong?)pi;

        sb = (sbyte?)pv;
        b = (byte?)pv;
        s = (short?)pv;
        us = (ushort?)pv;
        i = (int?)pv;
        ui = (uint?)pv;
        l = (long?)pv;
        ul = (ulong?)pv;

        pi = (int*)sb;
        pi = (int*)b;
        pi = (int*)s;
        pi = (int*)us;
        pi = (int*)i;
        pi = (int*)ui;
        pi = (int*)l;
        pi = (int*)ul;

        pv = (void*)sb;
        pv = (void*)b;
        pv = (void*)s;
        pv = (void*)us;
        pv = (void*)i;
        pv = (void*)ui;
        pv = (void*)l;
        pv = (void*)ul;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (24,14): error CS0030: Cannot convert type 'sbyte?' to 'int*'
                //         pi = (int*)sb;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)sb").WithArguments("sbyte?", "int*"),
                // (25,14): error CS0030: Cannot convert type 'byte?' to 'int*'
                //         pi = (int*)b;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)b").WithArguments("byte?", "int*"),
                // (26,14): error CS0030: Cannot convert type 'short?' to 'int*'
                //         pi = (int*)s;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)s").WithArguments("short?", "int*"),
                // (27,14): error CS0030: Cannot convert type 'ushort?' to 'int*'
                //         pi = (int*)us;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)us").WithArguments("ushort?", "int*"),
                // (28,14): error CS0030: Cannot convert type 'int?' to 'int*'
                //         pi = (int*)i;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)i").WithArguments("int?", "int*"),
                // (29,14): error CS0030: Cannot convert type 'uint?' to 'int*'
                //         pi = (int*)ui;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)ui").WithArguments("uint?", "int*"),
                // (30,14): error CS0030: Cannot convert type 'long?' to 'int*'
                //         pi = (int*)l;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)l").WithArguments("long?", "int*"),
                // (31,14): error CS0030: Cannot convert type 'ulong?' to 'int*'
                //         pi = (int*)ul;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)ul").WithArguments("ulong?", "int*"),
                // (33,14): error CS0030: Cannot convert type 'sbyte?' to 'void*'
                //         pv = (void*)sb;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)sb").WithArguments("sbyte?", "void*"),
                // (34,14): error CS0030: Cannot convert type 'byte?' to 'void*'
                //         pv = (void*)b;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)b").WithArguments("byte?", "void*"),
                // (35,14): error CS0030: Cannot convert type 'short?' to 'void*'
                //         pv = (void*)s;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)s").WithArguments("short?", "void*"),
                // (36,14): error CS0030: Cannot convert type 'ushort?' to 'void*'
                //         pv = (void*)us;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)us").WithArguments("ushort?", "void*"),
                // (37,14): error CS0030: Cannot convert type 'int?' to 'void*'
                //         pv = (void*)i;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)i").WithArguments("int?", "void*"),
                // (38,14): error CS0030: Cannot convert type 'uint?' to 'void*'
                //         pv = (void*)ui;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)ui").WithArguments("uint?", "void*"),
                // (39,14): error CS0030: Cannot convert type 'long?' to 'void*'
                //         pv = (void*)l;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)l").WithArguments("long?", "void*"),
                // (40,14): error CS0030: Cannot convert type 'ulong?' to 'void*'
                //         pv = (void*)ul;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(void*)ul").WithArguments("ulong?", "void*"));
        }

        [Fact]
        public void PointerArrayConversion()
        {
            var text = @"
using System;

unsafe class C
{
    void M(int*[] api, void*[] apv, Array a)
    {
        a = api;
        a.GetValue(0); //runtime error
        a = apv;
        a.GetValue(0); //runtime error

        api = a; //CS0266
        apv = a; //CS0266

        api = (int*[])a;
        apv = (void*[])a;

        apv = api; //CS0029
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (13,15): error CS0266: Cannot implicitly convert type 'System.Array' to 'int*[]'. An explicit conversion exists (are you missing a cast?)
                //         api = a; //CS0266
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "a").WithArguments("System.Array", "int*[]"),
                // (14,15): error CS0266: Cannot implicitly convert type 'System.Array' to 'void*[]'. An explicit conversion exists (are you missing a cast?)
                //         apv = a; //CS0266
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "a").WithArguments("System.Array", "void*[]"),
                // (19,15): error CS0029: Cannot implicitly convert type 'int*[]' to 'void*[]'
                //         apv = api; //CS0029
                Diagnostic(ErrorCode.ERR_NoImplicitConv, "api").WithArguments("int*[]", "void*[]"));
        }

        [Fact]
        public void PointerArrayToListConversion()
        {
            var text = @"
using System.Collections.Generic;

unsafe class C
{
    void M(int*[] api, void*[] apv)
    {
        To(api);
        To(apv);

        api = From(api[0]);
        apv = From(apv[0]);
    }

    void To<T>(IList<T> list)
    {
    }

    IList<T> From<T>(T t)
    {
        return null;
    }
}
";

            // NOTE: dev10 also reports some rather silly cascading CS0266s.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,9): error CS0306: The type 'int*' may not be used as a type argument
                //         To(api);
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "To").WithArguments("int*"),
                // (9,9): error CS0306: The type 'void*' may not be used as a type argument
                //         To(apv);
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "To").WithArguments("void*"),
                // (11,15): error CS0306: The type 'int*' may not be used as a type argument
                //         api = From(api[0]);
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "From").WithArguments("int*"),
                // (12,15): error CS0306: The type 'void*' may not be used as a type argument
                //         apv = From(apv[0]);
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "From").WithArguments("void*"));
        }

        [Fact]
        public void PointerArrayToEnumerableConversion()
        {
            var text = @"
using System.Collections;

unsafe class C
{
    void M(int*[] api, void*[] apv)
    {
        IEnumerable e = api;
        e = apv;
    }
}
";

            // NOTE: as in Dev10, there's a runtime error if you try to access an element.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        #endregion Pointer conversion tests

        #region Pointer arithmetic tests

        [Fact]
        public void PointerArithmetic_LegalNumeric()
        {
            var text = @"
unsafe class C
{
    void M(byte* p, int i, uint ui, long l, ulong ul)
    {
        p = p + i;
        p = i + p;
        p = p - i;

        p = p + ui;
        p = ui + p;
        p = p - ui;

        p = p + l;
        p = l + p;
        p = p - l;
        
        p = p + ul;
        p = ul + p;
        p = p - ul;
    }
}
";

            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            compilation.VerifyDiagnostics();

            var methodSymbol = compilation.GlobalNamespace.GetMember<NamedTypeSymbol>("C").GetMember<MethodSymbol>("M");
            var pointerType = methodSymbol.Parameters[0].Type;
            Assert.Equal(TypeKind.Pointer, pointerType.TypeKind);

            foreach (var binOpSyntax in tree.GetCompilationUnitRoot().DescendantNodes().OfType<BinaryExpressionSyntax>())
            {
                var summary = model.GetSemanticInfoSummary(binOpSyntax);

                if (binOpSyntax.Kind() == SyntaxKind.SimpleAssignmentExpression)
                {
                    Assert.Null(summary.Symbol);
                }
                else
                {
                    Assert.NotNull(summary.Symbol);
                    var summaryMethod = (IMethodSymbol)summary.Symbol;
                    Assert.Equal(MethodKind.BuiltinOperator, summaryMethod.MethodKind);

                    var synthesizedMethod = compilation.CreateBuiltinOperator(
                        summaryMethod.Name, summaryMethod.ReturnType, summaryMethod.Parameters[0].Type, summaryMethod.Parameters[1].Type);
                    Assert.Equal(synthesizedMethod, summaryMethod);
                }

                Assert.Equal(0, summary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, summary.CandidateReason);
                Assert.Equal(pointerType, summary.Type.GetSymbol());
                Assert.Equal(pointerType, summary.ConvertedType.GetSymbol());
                Assert.Equal(Conversion.Identity, summary.ImplicitConversion);
                Assert.Equal(0, summary.MethodGroup.Length);
                Assert.Null(summary.Alias);
                Assert.False(summary.IsCompileTimeConstant);
                Assert.False(summary.ConstantValue.HasValue);
            }
        }

        [Fact]
        public void PointerArithmetic_LegalPointer()
        {
            var text = @"
unsafe class C
{
    void M(byte* p)
    {
        var diff = p - p;
    }
}
";

            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            compilation.VerifyDiagnostics();

            foreach (var binOpSyntax in tree.GetCompilationUnitRoot().DescendantNodes().OfType<BinaryExpressionSyntax>())
            {
                var summary = model.GetSemanticInfoSummary(binOpSyntax);
                Assert.Equal("System.Int64 System.Byte*.op_Subtraction(System.Byte* left, System.Byte* right)", summary.Symbol.ToTestDisplayString());
                Assert.Equal(0, summary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, summary.CandidateReason);
                Assert.Equal(SpecialType.System_Int64, summary.Type.SpecialType);
                Assert.Equal(SpecialType.System_Int64, summary.ConvertedType.SpecialType);
                Assert.Equal(Conversion.Identity, summary.ImplicitConversion);
                Assert.Equal(0, summary.MethodGroup.Length);
                Assert.Null(summary.Alias);
                Assert.False(summary.IsCompileTimeConstant);
                Assert.False(summary.ConstantValue.HasValue);
            }
        }

        [Fact]
        public void PointerArithmetic_IllegalNumericSubtraction()
        {
            var text = @"
unsafe class C
{
    void M(byte* p, int i, uint ui, long l, ulong ul)
    {
        p = i - p;
        p = ui - p;
        p = l - p;
        p = ul - p;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,13): error CS0019: Operator '-' cannot be applied to operands of type 'int' and 'byte*'
                //         p = i - p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i - p").WithArguments("-", "int", "byte*"),
                // (7,13): error CS0019: Operator '-' cannot be applied to operands of type 'uint' and 'byte*'
                //         p = ui - p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "ui - p").WithArguments("-", "uint", "byte*"),
                // (8,13): error CS0019: Operator '-' cannot be applied to operands of type 'long' and 'byte*'
                //         p = l - p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "l - p").WithArguments("-", "long", "byte*"),
                // (9,13): error CS0019: Operator '-' cannot be applied to operands of type 'ulong' and 'byte*'
                //         p = ul - p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "ul - p").WithArguments("-", "ulong", "byte*"));
        }

        [Fact]
        public void PointerArithmetic_IllegalPointerSubtraction()
        {
            var text = @"
unsafe class C
{
    void M(byte* b, int* i, byte** bb, int** ii)
    {
        long l;

        l = b - i;
        l = b - bb;
        l = b - ii;

        l = i - b;
        l = i - bb;
        l = i - ii;

        l = bb - b;
        l = bb - i;
        l = bb - ii;

        l = ii - b;
        l = ii - i;
        l = ii - bb;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,13): error CS0019: Operator '-' cannot be applied to operands of type 'byte*' and 'int*'
                //         l = b - i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "b - i").WithArguments("-", "byte*", "int*"),
                // (9,13): error CS0019: Operator '-' cannot be applied to operands of type 'byte*' and 'byte**'
                //         l = b - bb;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "b - bb").WithArguments("-", "byte*", "byte**"),
                // (10,13): error CS0019: Operator '-' cannot be applied to operands of type 'byte*' and 'int**'
                //         l = b - ii;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "b - ii").WithArguments("-", "byte*", "int**"),
                // (12,13): error CS0019: Operator '-' cannot be applied to operands of type 'int*' and 'byte*'
                //         l = i - b;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i - b").WithArguments("-", "int*", "byte*"),
                // (13,13): error CS0019: Operator '-' cannot be applied to operands of type 'int*' and 'byte**'
                //         l = i - bb;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i - bb").WithArguments("-", "int*", "byte**"),
                // (14,13): error CS0019: Operator '-' cannot be applied to operands of type 'int*' and 'int**'
                //         l = i - ii;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i - ii").WithArguments("-", "int*", "int**"),
                // (16,13): error CS0019: Operator '-' cannot be applied to operands of type 'byte**' and 'byte*'
                //         l = bb - b;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "bb - b").WithArguments("-", "byte**", "byte*"),
                // (17,13): error CS0019: Operator '-' cannot be applied to operands of type 'byte**' and 'int*'
                //         l = bb - i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "bb - i").WithArguments("-", "byte**", "int*"),
                // (18,13): error CS0019: Operator '-' cannot be applied to operands of type 'byte**' and 'int**'
                //         l = bb - ii;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "bb - ii").WithArguments("-", "byte**", "int**"),
                // (20,13): error CS0019: Operator '-' cannot be applied to operands of type 'int**' and 'byte*'
                //         l = ii - b;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "ii - b").WithArguments("-", "int**", "byte*"),
                // (21,13): error CS0019: Operator '-' cannot be applied to operands of type 'int**' and 'int*'
                //         l = ii - i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "ii - i").WithArguments("-", "int**", "int*"),
                // (22,13): error CS0019: Operator '-' cannot be applied to operands of type 'int**' and 'byte**'
                //         l = ii - bb;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "ii - bb").WithArguments("-", "int**", "byte**"));
        }

        [Fact]
        public void PointerArithmetic_OtherOperators()
        {
            var text = @"
unsafe class C
{
    void M(byte* p, int i)
    {
        var r01 = p * i;
        var r02 = i * p;
        var r03 = p / i;
        var r04 = i / p;
        var r05 = p % i;
        var r06 = i % p;
        var r07 = p << i;
        var r08 = i << p;
        var r09 = p >> i;
        var r10 = i >> p;
        var r11 = p & i;
        var r12 = i & p;
        var r13 = p | i;
        var r14 = i | p;
        var r15 = p ^ i;
        var r16 = i ^ p;
        var r17 = p >>> i;
        var r18 = i >>> p;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,19): error CS0019: Operator '*' cannot be applied to operands of type 'byte*' and 'int'
                //         var r01 = p * i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p * i").WithArguments("*", "byte*", "int"),
                // (7,19): error CS0019: Operator '*' cannot be applied to operands of type 'int' and 'byte*'
                //         var r02 = i * p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i * p").WithArguments("*", "int", "byte*"),
                // (8,19): error CS0019: Operator '/' cannot be applied to operands of type 'byte*' and 'int'
                //         var r03 = p / i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p / i").WithArguments("/", "byte*", "int"),
                // (9,19): error CS0019: Operator '/' cannot be applied to operands of type 'int' and 'byte*'
                //         var r04 = i / p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i / p").WithArguments("/", "int", "byte*"),
                // (10,19): error CS0019: Operator '%' cannot be applied to operands of type 'byte*' and 'int'
                //         var r05 = p % i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p % i").WithArguments("%", "byte*", "int"),
                // (11,19): error CS0019: Operator '%' cannot be applied to operands of type 'int' and 'byte*'
                //         var r06 = i % p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i % p").WithArguments("%", "int", "byte*"),
                // (12,19): error CS0019: Operator '<<' cannot be applied to operands of type 'byte*' and 'int'
                //         var r07 = p << i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p << i").WithArguments("<<", "byte*", "int"),
                // (13,19): error CS0019: Operator '<<' cannot be applied to operands of type 'int' and 'byte*'
                //         var r08 = i << p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i << p").WithArguments("<<", "int", "byte*"),
                // (14,19): error CS0019: Operator '>>' cannot be applied to operands of type 'byte*' and 'int'
                //         var r09 = p >> i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p >> i").WithArguments(">>", "byte*", "int"),
                // (15,19): error CS0019: Operator '>>' cannot be applied to operands of type 'int' and 'byte*'
                //         var r10 = i >> p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i >> p").WithArguments(">>", "int", "byte*"),
                // (16,19): error CS0019: Operator '&' cannot be applied to operands of type 'byte*' and 'int'
                //         var r11 = p & i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p & i").WithArguments("&", "byte*", "int"),
                // (17,19): error CS0019: Operator '&' cannot be applied to operands of type 'int' and 'byte*'
                //         var r12 = i & p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i & p").WithArguments("&", "int", "byte*"),
                // (18,19): error CS0019: Operator '|' cannot be applied to operands of type 'byte*' and 'int'
                //         var r13 = p | i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p | i").WithArguments("|", "byte*", "int"),
                // (19,19): error CS0019: Operator '|' cannot be applied to operands of type 'int' and 'byte*'
                //         var r14 = i | p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i | p").WithArguments("|", "int", "byte*"),
                // (20,19): error CS0019: Operator '^' cannot be applied to operands of type 'byte*' and 'int'
                //         var r15 = p ^ i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p ^ i").WithArguments("^", "byte*", "int"),
                // (21,19): error CS0019: Operator '^' cannot be applied to operands of type 'int' and 'byte*'
                //         var r16 = i ^ p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i ^ p").WithArguments("^", "int", "byte*"),
                // (22,19): error CS0019: Operator '>>>' cannot be applied to operands of type 'byte*' and 'int'
                //         var r17 = p >>> i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p >>> i").WithArguments(">>>", "byte*", "int").WithLocation(22, 19),
                // (23,19): error CS0019: Operator '>>>' cannot be applied to operands of type 'int' and 'byte*'
                //         var r18 = i >>> p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "i >>> p").WithArguments(">>>", "int", "byte*").WithLocation(23, 19)
                );
        }

        [Fact]
        public void PointerArithmetic_NumericWidening()
        {
            var text = @"
unsafe class C
{
    void M(int* p, sbyte sb, byte b, short s, ushort us)
    {
        p = p + sb;
        p = p + b;
        p = p + s;
        p = p + us;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerArithmetic_NumericUDC()
        {
            var text = @"
unsafe class C
{
    void M(int* p)
    {
        p = p + this;
    }

    public static implicit operator int(C c)
    {
        return 0;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerArithmetic_Nullable()
        {
            var text = @"
unsafe class C
{
    void M(int* p, int? i)
    {
        p = p + i;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,13): error CS0019: Operator '+' cannot be applied to operands of type 'int*' and 'int?'
                //         p = p + i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p + i").WithArguments("+", "int*", "int?"));
        }

        [Fact]
        public void PointerArithmetic_Compound()
        {
            var text = @"
unsafe class C
{
    void M(int* p, int i)
    {
        p++;
        ++p;
        p--;
        --p;
        p += i;
        p -= i;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerArithmetic_VoidPointer()
        {
            var text = @"
unsafe class C
{
    void M(void* p)
    {
        var diff = p - p;
        p = p + 1;
        p = p - 1;
        p = 1 + p;
        p = 1 - p;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,20): error CS0242: The operation in question is undefined on void pointers
                //         var diff = p - p;
                Diagnostic(ErrorCode.ERR_VoidError, "p - p"),
                // (7,13): error CS0242: The operation in question is undefined on void pointers
                //         p = p + 1;
                Diagnostic(ErrorCode.ERR_VoidError, "p + 1"),
                // (8,13): error CS0242: The operation in question is undefined on void pointers
                //         p = p - 1;
                Diagnostic(ErrorCode.ERR_VoidError, "p - 1"),
                // (9,13): error CS0242: The operation in question is undefined on void pointers
                //         p = 1 + p;
                Diagnostic(ErrorCode.ERR_VoidError, "1 + p"),
                // (10,13): error CS0242: The operation in question is undefined on void pointers
                //         p = 1 - p;
                Diagnostic(ErrorCode.ERR_VoidError, "1 - p"),
                // (10,13): error CS0019: Operator '-' cannot be applied to operands of type 'int' and 'void*'
                //         p = 1 - p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "1 - p").WithArguments("-", "int", "void*"));
        }

        [Fact]
        public void PointerArithmetic_VoidPointerPointer()
        {
            var text = @"
unsafe class C
{
    void M(void** p) //void** is not a void pointer
    {
        var diff = p - p;
        p = p + 1;
        p = p - 1;
        p = 1 + p;
        p = 1 - p;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (10,13): error CS0019: Operator '-' cannot be applied to operands of type 'int' and 'void**'
                //         p = 1 - p;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "1 - p").WithArguments("-", "int", "void**"));
        }

        #endregion Pointer arithmetic tests

        #region Pointer comparison tests

        [WorkItem(546712, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/546712")]
        [Fact]
        public void PointerComparison_Null()
        {
            // We had a bug whereby overload resolution was failing if the null
            // was on the left. This test regresses the bug.
            var text = @"
unsafe struct S
{
    bool M(byte* pb, S* ps)
    {
        return null != pb && null == ps;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerComparison_Pointer()
        {
            var text = @"
unsafe class C
{
    void M(byte* b, int* i, void* v)
    {
        bool result;
        byte* b2 = b;
        int* i2 = i;
        void* v2 = v;

        result = b == b2;
        result = b == i2;
        result = b == v2;

        result = i != i2;
        result = i != v2;
        result = i != b2;

        result = v <= v2;
        result = v <= b2;
        result = v <= i2;

        result = b >= b2;
        result = b >= i2;
        result = b >= v2;
        
        result = i < i2;
        result = i < v2;
        result = i < b2;
        
        result = v > v2;
        result = v > b2;
        result = v > i2;
    }
}
";

            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            compilation.VerifyDiagnostics();

            foreach (var binOpSyntax in tree.GetCompilationUnitRoot().DescendantNodes().OfType<BinaryExpressionSyntax>())
            {
                var summary = model.GetSemanticInfoSummary(binOpSyntax);

                if (binOpSyntax.Kind() == SyntaxKind.SimpleAssignmentExpression)
                {
                    Assert.Null(summary.Symbol);
                }
                else
                {
                    Assert.NotNull(summary.Symbol);
                    var summaryMethod = (IMethodSymbol)summary.Symbol;
                    Assert.Equal(MethodKind.BuiltinOperator, summaryMethod.MethodKind);

                    var synthesizedMethod = compilation.CreateBuiltinOperator(
                        summaryMethod.Name, summaryMethod.ReturnType, summaryMethod.Parameters[0].Type, summaryMethod.Parameters[1].Type);
                    Assert.Equal(synthesizedMethod, summaryMethod);
                }

                Assert.Equal(0, summary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, summary.CandidateReason);
                Assert.Equal(SpecialType.System_Boolean, summary.Type.SpecialType);
                Assert.Equal(SpecialType.System_Boolean, summary.ConvertedType.SpecialType);
                Assert.Equal(Conversion.Identity, summary.ImplicitConversion);
                Assert.Equal(0, summary.MethodGroup.Length);
                Assert.Null(summary.Alias);
                Assert.False(summary.IsCompileTimeConstant);
                Assert.False(summary.ConstantValue.HasValue);
            }
        }

        [Fact]
        public void PointerComparison_PointerPointer()
        {
            var text = @"
unsafe class C
{
    void M(byte* b, byte** bb)
    {
        bool result;

        result = b == bb;
        result = b != bb;
        result = b <= bb;
        result = b >= bb;
        result = b < bb;
        result = b > bb;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void PointerComparison_Numeric()
        {
            var text = @"
unsafe class C
{
    void M(char* p, int i, uint ui, long l, ulong ul)
    {
        bool result;

        result = p == i;
        result = p != i;
        result = p <= i;
        result = p >= i;
        result = p < i;
        result = p > i;

        result = p == ui;
        result = p != ui;
        result = p <= ui;
        result = p >= ui;
        result = p < ui;
        result = p > ui;

        result = p == l;
        result = p != l;
        result = p <= l;
        result = p >= l;
        result = p < l;
        result = p > l;

        result = p == ul;
        result = p != ul;
        result = p <= ul;
        result = p >= ul;
        result = p < ul;
        result = p > ul;
    }
}
";

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,18): error CS0019: Operator '==' cannot be applied to operands of type 'char*' and 'int'
                //         result = p == i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p == i").WithArguments("==", "char*", "int"),
                // (9,18): error CS0019: Operator '!=' cannot be applied to operands of type 'char*' and 'int'
                //         result = p != i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p != i").WithArguments("!=", "char*", "int"),
                // (10,18): error CS0019: Operator '<=' cannot be applied to operands of type 'char*' and 'int'
                //         result = p <= i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p <= i").WithArguments("<=", "char*", "int"),
                // (11,18): error CS0019: Operator '>=' cannot be applied to operands of type 'char*' and 'int'
                //         result = p >= i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p >= i").WithArguments(">=", "char*", "int"),
                // (12,18): error CS0019: Operator '<' cannot be applied to operands of type 'char*' and 'int'
                //         result = p < i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p < i").WithArguments("<", "char*", "int"),
                // (13,18): error CS0019: Operator '>' cannot be applied to operands of type 'char*' and 'int'
                //         result = p > i;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p > i").WithArguments(">", "char*", "int"),
                // (15,18): error CS0019: Operator '==' cannot be applied to operands of type 'char*' and 'uint'
                //         result = p == ui;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p == ui").WithArguments("==", "char*", "uint"),
                // (16,18): error CS0019: Operator '!=' cannot be applied to operands of type 'char*' and 'uint'
                //         result = p != ui;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p != ui").WithArguments("!=", "char*", "uint"),
                // (17,18): error CS0019: Operator '<=' cannot be applied to operands of type 'char*' and 'uint'
                //         result = p <= ui;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p <= ui").WithArguments("<=", "char*", "uint"),
                // (18,18): error CS0019: Operator '>=' cannot be applied to operands of type 'char*' and 'uint'
                //         result = p >= ui;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p >= ui").WithArguments(">=", "char*", "uint"),
                // (19,18): error CS0019: Operator '<' cannot be applied to operands of type 'char*' and 'uint'
                //         result = p < ui;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p < ui").WithArguments("<", "char*", "uint"),
                // (20,18): error CS0019: Operator '>' cannot be applied to operands of type 'char*' and 'uint'
                //         result = p > ui;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p > ui").WithArguments(">", "char*", "uint"),
                // (22,18): error CS0019: Operator '==' cannot be applied to operands of type 'char*' and 'long'
                //         result = p == l;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p == l").WithArguments("==", "char*", "long"),
                // (23,18): error CS0019: Operator '!=' cannot be applied to operands of type 'char*' and 'long'
                //         result = p != l;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p != l").WithArguments("!=", "char*", "long"),
                // (24,18): error CS0019: Operator '<=' cannot be applied to operands of type 'char*' and 'long'
                //         result = p <= l;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p <= l").WithArguments("<=", "char*", "long"),
                // (25,18): error CS0019: Operator '>=' cannot be applied to operands of type 'char*' and 'long'
                //         result = p >= l;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p >= l").WithArguments(">=", "char*", "long"),
                // (26,18): error CS0019: Operator '<' cannot be applied to operands of type 'char*' and 'long'
                //         result = p < l;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p < l").WithArguments("<", "char*", "long"),
                // (27,18): error CS0019: Operator '>' cannot be applied to operands of type 'char*' and 'long'
                //         result = p > l;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p > l").WithArguments(">", "char*", "long"),
                // (29,18): error CS0019: Operator '==' cannot be applied to operands of type 'char*' and 'ulong'
                //         result = p == ul;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p == ul").WithArguments("==", "char*", "ulong"),
                // (30,18): error CS0019: Operator '!=' cannot be applied to operands of type 'char*' and 'ulong'
                //         result = p != ul;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p != ul").WithArguments("!=", "char*", "ulong"),
                // (31,18): error CS0019: Operator '<=' cannot be applied to operands of type 'char*' and 'ulong'
                //         result = p <= ul;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p <= ul").WithArguments("<=", "char*", "ulong"),
                // (32,18): error CS0019: Operator '>=' cannot be applied to operands of type 'char*' and 'ulong'
                //         result = p >= ul;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p >= ul").WithArguments(">=", "char*", "ulong"),
                // (33,18): error CS0019: Operator '<' cannot be applied to operands of type 'char*' and 'ulong'
                //         result = p < ul;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p < ul").WithArguments("<", "char*", "ulong"),
                // (34,18): error CS0019: Operator '>' cannot be applied to operands of type 'char*' and 'ulong'
                //         result = p > ul;
                Diagnostic(ErrorCode.ERR_BadBinaryOps, "p > ul").WithArguments(">", "char*", "ulong"));
        }

        #endregion Pointer comparison tests

        #region Fixed statement diagnostics

        [Fact]
        public void ERR_BadFixedInitType()
        {
            var text = @"
unsafe class C
{
    int x;

    void M()
    {
        fixed (int p = &x) //not a pointer
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,20): error CS0209: The type of a local declared in a fixed statement must be a pointer type
                //         fixed (int p = &x) //not a pointer
                Diagnostic(ErrorCode.ERR_BadFixedInitType, "p = &x"));
        }

        [Fact]
        public void ERR_FixedMustInit()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        fixed (int* p) //missing initializer
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,21): error CS0210: You must provide an initializer in a fixed or using statement declaration
                //         fixed (int* p) //missing initializer
                Diagnostic(ErrorCode.ERR_FixedMustInit, "p"));
        }

        [Fact]
        public void ERR_ImplicitlyTypedLocalCannotBeFixed1()
        {
            var text = @"
unsafe class C
{
    int x;

    void M()
    {
        fixed (var p = &x) //implicitly typed
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,20): error CS0821: Implicitly-typed local variables cannot be fixed
                //         fixed (var p = &x) //implicitly typed
                Diagnostic(ErrorCode.ERR_ImplicitlyTypedLocalCannotBeFixed, "p = &x"));
        }

        [Fact]
        public void ERR_ImplicitlyTypedLocalCannotBeFixed2()
        {
            var text = @"
unsafe class C
{
    int x;

    void M()
    {
        fixed (var p = &x) //not implicitly typed
        {
        }
    }
}

class @var
{
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,20): error CS0209: The type of a local declared in a fixed statement must be a pointer type
                //         fixed (var p = &x) //not implicitly typed
                Diagnostic(ErrorCode.ERR_BadFixedInitType, "p = &x"));
        }

        [Fact]
        public void ERR_MultiTypeInDeclaration()
        {
            var text = @"
unsafe class C
{
    int x;

    void M()
    {
        fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,29): error CS1044: Cannot use more than one type in a for, using, fixed, or declaration statement
                //         fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
                Diagnostic(ErrorCode.ERR_MultiTypeInDeclaration, "var"),

                // (8,33): error CS1026: ) expected
                //         fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
                Diagnostic(ErrorCode.ERR_CloseParenExpected, "q"),
                // (8,38): error CS1002: ; expected
                //         fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
                Diagnostic(ErrorCode.ERR_SemicolonExpected, ")"),
                // (8,38): error CS1513: } expected
                //         fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
                Diagnostic(ErrorCode.ERR_RbraceExpected, ")"),
                // (8,29): error CS0210: You must provide an initializer in a fixed or using statement declaration
                //         fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
                Diagnostic(ErrorCode.ERR_FixedMustInit, "var"),
                // (8,33): error CS0103: The name 'q' does not exist in the current context
                //         fixed (int* p = &x, var q = p) //multiple declarations (vs declarators)
                Diagnostic(ErrorCode.ERR_NameNotInContext, "q").WithArguments("q"));
        }

        [Fact]
        public void ERR_BadCastInFixed_String()
        {
            var text = @"
unsafe class C
{
    public NotString n;

    void M()
    {
        fixed (char* p = (string)""hello"")
        {
        }

        fixed (char* p = (string)n)
        {
        }
    }
}

class NotString
{
    unsafe public static implicit operator string(NotString n)
    {
        return null;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,22): warning CS0649: Field 'C.n' is never assigned to, and will always have its default value null
                //     public NotString n;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "n").WithArguments("C.n", "null"));
        }

        [Fact]
        public void ERR_BadCastInFixed_Array()
        {
            var text = @"
unsafe class C
{
    public NotArray n;

    void M()
    {
        fixed (byte* p = (byte[])new byte[0])
        {
        }

        fixed (int* p = (int[])n)
        {
        }
    }
}

class NotArray
{
    unsafe public static implicit operator int[](NotArray n)
    {
        return null;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,21): warning CS0649: Field 'C.n' is never assigned to, and will always have its default value null
                //     public NotArray n;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "n").WithArguments("C.n", "null"));
        }

        [Fact]
        public void ERR_BadCastInFixed_Pointer()
        {
            var text = @"
unsafe class C
{
    public byte x;
    public NotPointer n;

    void M()
    {
        fixed (byte* p = (byte*)&x)
        {
        }

        fixed (int* p = n) //CS0213 (confusing, but matches dev10)
        {
        }

        fixed (int* p = (int*)n)
        {
        }
    }
}

class NotPointer
{
    unsafe public static implicit operator int*(NotPointer n)
    {
        return null;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,26): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (byte* p = (byte*)&x)
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "(byte*)&x").WithLocation(9, 26),
                // (13,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = n) //CS0213 (confusing, but matches dev10)
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "n").WithLocation(13, 25),
                // (17,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = (int*)n)
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "(int*)n").WithLocation(17, 25),
                // (5,23): warning CS0649: Field 'C.n' is never assigned to, and will always have its default value null
                //     public NotPointer n;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "n").WithArguments("C.n", "null").WithLocation(5, 23)
            );
        }

        [Fact]
        public void ERR_FixedLocalInLambda()
        {
            var text = @"
using System;

unsafe class C
{
    char c = 'a';
    char[] a = new char[1];

    static void Main()
    {
        C c = new C();
        fixed (char* p = &c.c, q = c.a, r = ""hello"")
        {
            System.Action a;
            a = () => Console.WriteLine(*p);
            a = () => Console.WriteLine(*q);
            a = () => Console.WriteLine(*r);
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (15,42): error CS1764: Cannot use fixed local 'p' inside an anonymous method, lambda expression, or query expression
                //             a = () => Console.WriteLine(*p);
                Diagnostic(ErrorCode.ERR_FixedLocalInLambda, "p").WithArguments("p"),
                // (16,42): error CS1764: Cannot use fixed local 'q' inside an anonymous method, lambda expression, or query expression
                //             a = () => Console.WriteLine(*q);
                Diagnostic(ErrorCode.ERR_FixedLocalInLambda, "q").WithArguments("q"),
                // (17,42): error CS1764: Cannot use fixed local 'r' inside an anonymous method, lambda expression, or query expression
                //             a = () => Console.WriteLine(*r);
                Diagnostic(ErrorCode.ERR_FixedLocalInLambda, "r").WithArguments("r"));
        }

        [Fact]
        public void NormalAddressOfInFixedStatement()
        {
            var text = @"
class Program
{
    int x;
    int[] a;

    unsafe static void Main()
    {
        Program p = new Program();
        int q;
        fixed (int* px = (&(p.a[*(&q)]))) //fine
        {
        }

        fixed (int* px = &(p.a[*(&p.x)])) //CS0212
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (15,34): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         fixed (int* px = &(p.a[*(&p.x)])) //CS0212
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&p.x"),
                // (5,11): warning CS0649: Field 'Program.a' is never assigned to, and will always have its default value null
                //     int[] a;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "a").WithArguments("Program.a", "null"));
        }

        [Fact]
        public void StackAllocInFixedStatement()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        fixed (int* p = stackalloc int[2]) //CS0213 - already fixed
        {
        }
    }
}
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(
                // (6,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = stackalloc int[2]) //CS0213 - already fixed
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "stackalloc int[2]").WithLocation(6, 25));
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = stackalloc int[2]) //CS0213 - already fixed
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "stackalloc int[2]").WithLocation(6, 25));
        }

        [Fact]
        public void FixedInitializerRefersToPreviousVariable()
        {
            var text = @"
unsafe class C
{
    int f;
    int[] a;

    void Goo()
    {
        fixed (int* q = &f, r = &q[1]) //CS0213
        {
        }

        fixed (int* q = &f, r = &a[*q]) //fine
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,33): error CS0213: You cannot use the fixed statement to take the address of an already fixed expression
                //         fixed (int* q = &f, r = &q[1]) //CS0213
                Diagnostic(ErrorCode.ERR_FixedNotNeeded, "&q[1]"),

                // (5,11): warning CS0649: Field 'C.a' is never assigned to, and will always have its default value null
                //     int[] a;
                Diagnostic(ErrorCode.WRN_UnassignedInternalField, "a").WithArguments("C.a", "null"));
        }

        [Fact]
        public void NormalInitializerType_Null()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        fixed (int* p = null)
        {
        }

        fixed (int* p = &null)
        {
        }

        fixed (int* p = _)
        {
        }

        fixed (int* p = &_)
        {
        }

        fixed (int* p = ()=>throw null)
        {
        }

        fixed (int* p = &(()=>throw null))
        {
        }
    }
}
";
            // Confusing, but matches Dev10.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = null)
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "null").WithLocation(6, 25),
                // (10,26): error CS0211: Cannot take the address of the given expression
                //         fixed (int* p = &null)
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "null").WithLocation(10, 26),
                // (14,25): error CS0103: The name '_' does not exist in the current context
                //         fixed (int* p = _)
                Diagnostic(ErrorCode.ERR_NameNotInContext, "_").WithArguments("_").WithLocation(14, 25),
                // (18,26): error CS0103: The name '_' does not exist in the current context
                //         fixed (int* p = &_)
                Diagnostic(ErrorCode.ERR_NameNotInContext, "_").WithArguments("_").WithLocation(18, 26),
                // (22,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = ()=>throw null)
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "()=>throw null").WithLocation(22, 25),
                // (26,27): error CS0211: Cannot take the address of the given expression
                //         fixed (int* p = &(()=>throw null))
                Diagnostic(ErrorCode.ERR_InvalidAddrOp, "()=>throw null").WithLocation(26, 27)
                );
        }

        [Fact]
        public void NormalInitializerType_Lambda()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        fixed (int* p = (x => x))
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,26): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = (x => x))
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "x => x").WithLocation(6, 26));
        }

        [Fact]
        public void NormalInitializerType_MethodGroup()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        fixed (int* p = Main)
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,25): error CS9385: The given expression cannot be used in a fixed statement
                //         fixed (int* p = Main)
                Diagnostic(ErrorCode.ERR_ExprCannotBeFixed, "Main").WithLocation(6, 25));
        }

        [Fact]
        public void NormalInitializerType_String()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        string s = ""hello"";

        fixed (char* p = s) //fine
        {
        }

        fixed (void* p = s) //fine
        {
        }

        fixed (int* p = s) //can't convert char* to int*
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (16,25): error CS0266: Cannot implicitly convert type 'char*' to 'int*'. An explicit conversion exists (are you missing a cast?)
                //         fixed (int* p = s) //can't convert char* to int*
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "s").WithArguments("char*", "int*"));
        }

        [Fact]
        public void NormalInitializerType_ArrayOfManaged()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        string[] a = new string[2];

        fixed (void* p = a) //string* is not a valid type
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,26): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //         fixed (void* p = a) //string* is not a valid type
                Diagnostic(ErrorCode.WRN_ManagedAddr, "a").WithArguments("string").WithLocation(8, 26));
        }

        [Fact]
        public void NormalInitializerType_ArrayOfGenericStruct()
        {
            var text = @"
public struct MyStruct<T>
{
    public T field;
}

class Program
{
    unsafe static void Main()
    {
        var a = new MyStruct<int>[2];
        a[0].field = 42;

        fixed (MyStruct<int>* p = a)
        {
            System.Console.Write(p->field);
        }
    }
}
";
            CompileAndVerify(text, options: TestOptions.UnsafeReleaseExe, verify: Verification.Skipped, expectedOutput: "42");
        }

        [Fact]
        public void NormalInitializerType_ArrayOfGenericStruct_RequiresCSharp8()
        {
            var text = @"
public struct MyStruct<T>
{
    public T field;
}

class Program
{
    unsafe static void Main()
    {
        var a = new MyStruct<int>[2];

        fixed (void* p = a)
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(
                // (13,26): error CS8652: The feature 'unmanaged constructed types' is not available in C# 7.3. Please use language version 8.0 or greater.
                //         fixed (void* p = a)
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "a").WithArguments("unmanaged constructed types", "8.0").WithLocation(13, 26));
        }

        [Fact]
        public void NormalInitializerType_Array()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        char[] a = new char[2];

        fixed (char* p = a) //fine
        {
        }

        fixed (void* p = a) //fine
        {
        }

        fixed (int* p = a) //can't convert char* to int*
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (16,25): error CS0266: Cannot implicitly convert type 'char*' to 'int*'. An explicit conversion exists (are you missing a cast?)
                //         fixed (int* p = a) //can't convert char* to int*
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "a").WithArguments("char*", "int*"));
        }

        [Fact]
        public void NormalInitializerType_MultiDimensionalArray()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        char[,] a = new char[2,2];

        fixed (char* p = a) //fine
        {
        }

        fixed (void* p = a) //fine
        {
        }

        fixed (int* p = a) //can't convert char* to int*
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (16,25): error CS0266: Cannot implicitly convert type 'char*' to 'int*'. An explicit conversion exists (are you missing a cast?)
                //         fixed (int* p = a) //can't convert char* to int*
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "a").WithArguments("char*", "int*"));
        }

        [Fact]
        public void NormalInitializerType_JaggedArray()
        {
            var text = @"
class Program
{
    unsafe static void Main()
    {
        char[][] a = new char[2][];

        fixed (void* p = a) //char[]* is not a valid type
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (8,26): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('char[]')
                //         fixed (void* p = a) //char[]* is not a valid type
                Diagnostic(ErrorCode.WRN_ManagedAddr, "a").WithArguments("char[]").WithLocation(8, 26));
        }

        #endregion Fixed statement diagnostics

        #region Fixed statement semantic model tests

        [Fact]
        public void FixedSemanticModelDeclaredSymbols()
        {
            var text = @"
using System;

unsafe class C
{
    char c = 'a';
    char[] a = new char[1];

    static void Main()
    {
        C c = new C();
        fixed (char* p = &c.c, q = c.a, r = ""hello"")
        {
        }
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var declarators = tree.GetCompilationUnitRoot().DescendantNodes().OfType<VariableDeclaratorSyntax>().Reverse().Take(3).Reverse().ToArray();
            var declaredSymbols = declarators.Select(syntax => (ILocalSymbol)model.GetDeclaredSymbol(syntax)).ToArray();

            foreach (var symbol in declaredSymbols)
            {
                Assert.NotNull(symbol);
                Assert.Equal(LocalDeclarationKind.FixedVariable, symbol.GetSymbol().DeclarationKind);
                Assert.True(((ILocalSymbol)symbol).IsFixed);
                ITypeSymbol type = symbol.Type;
                Assert.Equal(TypeKind.Pointer, type.TypeKind);
                Assert.Equal(SpecialType.System_Char, ((IPointerTypeSymbol)type).PointedAtType.SpecialType);
            }
        }

        [Fact]
        public void FixedSemanticModelSymbolInfo()
        {
            var text = @"
using System;

unsafe class C
{
    char c = 'a';
    char[] a = new char[1];

    static void Main()
    {
        C c = new C();
        fixed (char* p = &c.c, q = c.a, r = ""hello"")
        {
            Console.WriteLine(*p);
            Console.WriteLine(*q);
            Console.WriteLine(*r);
        }
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var stringSymbol = compilation.GetSpecialType(SpecialType.System_String);
            var charSymbol = compilation.GetSpecialType(SpecialType.System_Char);
            var charPointerSymbol = new PointerTypeSymbol(TypeWithAnnotations.Create(charSymbol));

            const int numSymbols = 3;
            var declarators = tree.GetCompilationUnitRoot().DescendantNodes().OfType<VariableDeclaratorSyntax>().Reverse().Take(numSymbols).Reverse().ToArray();
            var dereferences = tree.GetCompilationUnitRoot().DescendantNodes().Where(syntax => syntax.IsKind(SyntaxKind.PointerIndirectionExpression)).ToArray();
            Assert.Equal(numSymbols, dereferences.Length);

            var declaredSymbols = declarators.Select(syntax => (ILocalSymbol)model.GetDeclaredSymbol(syntax)).ToArray();

            var initializerSummaries = declarators.Select(syntax => model.GetSemanticInfoSummary(syntax.Initializer.Value)).ToArray();

            for (int i = 0; i < numSymbols; i++)
            {
                var summary = initializerSummaries[i];
                Assert.Equal(0, summary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, summary.CandidateReason);
                Assert.Equal(charPointerSymbol, summary.ConvertedType.GetSymbol());
                Assert.Equal(Conversion.Identity, summary.ImplicitConversion);
                Assert.Equal(0, summary.MethodGroup.Length);
                Assert.Null(summary.Alias);
            }

            var summary0 = initializerSummaries[0];
            Assert.Null(summary0.Symbol);
            Assert.Equal(charPointerSymbol, summary0.Type.GetSymbol());

            var summary1 = initializerSummaries[1];
            var arraySymbol = compilation.GlobalNamespace.GetMember<TypeSymbol>("C").GetMember<FieldSymbol>("a");
            Assert.Equal(arraySymbol, summary1.Symbol.GetSymbol());
            Assert.Equal(arraySymbol.Type, summary1.Type.GetSymbol());

            var summary2 = initializerSummaries[2];
            Assert.Null(summary2.Symbol);
            Assert.Equal(stringSymbol, summary2.Type.GetSymbol());

            var accessSymbolInfos = dereferences.Select(syntax => model.GetSymbolInfo(((PrefixUnaryExpressionSyntax)syntax).Operand)).ToArray();

            for (int i = 0; i < numSymbols; i++)
            {
                SymbolInfo info = accessSymbolInfos[i];
                Assert.Equal(declaredSymbols[i], info.Symbol);
                Assert.Equal(0, info.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, info.CandidateReason);
            }
        }

        [Fact]
        public void FixedSemanticModelSymbolInfoConversions()
        {
            var text = @"
using System;

unsafe class C
{
    char c = 'a';
    char[] a = new char[1];

    static void Main()
    {
        C c = new C();
        fixed (void* p = &c.c, q = c.a, r = ""hello"")
        {
        }
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var stringSymbol = compilation.GetSpecialType(SpecialType.System_String);
            var charSymbol = compilation.GetSpecialType(SpecialType.System_Char);
            var charPointerSymbol = new PointerTypeSymbol(TypeWithAnnotations.Create(charSymbol));
            var voidSymbol = compilation.GetSpecialType(SpecialType.System_Void);
            var voidPointerSymbol = new PointerTypeSymbol(TypeWithAnnotations.Create(voidSymbol));

            const int numSymbols = 3;
            var declarators = tree.GetCompilationUnitRoot().DescendantNodes().OfType<VariableDeclaratorSyntax>().Reverse().Take(numSymbols).Reverse().ToArray();
            var initializerSummaries = declarators.Select(syntax => model.GetSemanticInfoSummary(syntax.Initializer.Value)).ToArray();

            for (int i = 0; i < numSymbols; i++)
            {
                var summary = initializerSummaries[i];
                Assert.Equal(0, summary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, summary.CandidateReason);
                Assert.Equal(0, summary.MethodGroup.Length);
                Assert.Null(summary.Alias);
            }

            var summary0 = initializerSummaries[0];
            Assert.Null(summary0.Symbol);
            Assert.Equal(charPointerSymbol, summary0.Type.GetSymbol());
            Assert.Equal(voidPointerSymbol, summary0.ConvertedType.GetSymbol());
            Assert.Equal(Conversion.PointerToVoid, summary0.ImplicitConversion);

            var summary1 = initializerSummaries[1];
            var arraySymbol = compilation.GlobalNamespace.GetMember<TypeSymbol>("C").GetMember<FieldSymbol>("a");
            Assert.Equal(arraySymbol, summary1.Symbol.GetSymbol());
            Assert.Equal(arraySymbol.Type, summary1.Type.GetSymbol());
            Assert.Equal(voidPointerSymbol, summary1.ConvertedType.GetSymbol());
            Assert.Equal(Conversion.PointerToVoid, summary1.ImplicitConversion);

            var summary2 = initializerSummaries[2];
            Assert.Null(summary2.Symbol);
            Assert.Equal(stringSymbol, summary2.Type.GetSymbol());
            Assert.Equal(voidPointerSymbol, summary2.ConvertedType.GetSymbol());
            Assert.Equal(Conversion.PointerToVoid, summary2.ImplicitConversion);
        }

        #endregion Fixed statement semantic model tests

        #region sizeof diagnostic tests

        [Fact]
        public void SizeOfManaged()
        {
            var text = @"
unsafe class C
{
    void M<T>(T t)
    {
        int x;
        x = sizeof(T); //CS0208
        x = sizeof(C); //CS0208
        x = sizeof(S); //CS0208
    }
}

public struct S
{
    public string s;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,13): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //         x = sizeof(T); //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "sizeof(T)").WithArguments("T").WithLocation(7, 13),
                // (8,13): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('C')
                //         x = sizeof(C); //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "sizeof(C)").WithArguments("C").WithLocation(8, 13),
                // (9,13): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('S')
                //         x = sizeof(S); //CS0208
                Diagnostic(ErrorCode.WRN_ManagedAddr, "sizeof(S)").WithArguments("S").WithLocation(9, 13));
        }

        [Fact]
        public void SizeOfUnsafe1()
        {
            var template = @"
{0} struct S
{{
    {1} void M()
    {{
        int x;
        x = sizeof(S); // Type isn't unsafe, but expression is.
    }}
}}
";
            CompareUnsafeDiagnostics(template,
                // (7,13): error CS0233: 'S' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)
                //         x = sizeof(S);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(S)").WithArguments("S"));
        }

        [Fact]
        public void SizeOfUnsafe2()
        {
            var template = @"
{0} class C
{{
    {1} void M()
    {{
        int x;
        x = sizeof(int*);
        x = sizeof(int**);
        x = sizeof(void*);
        x = sizeof(void**);
    }}
}}
";
            // CONSIDER: Dev10 reports ERR_SizeofUnsafe for each sizeof, but that seems redundant.
            CompareUnsafeDiagnostics(template,
                // (7,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         x = sizeof(int*);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (7,13): error CS0233: 'int*' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)
                //         x = sizeof(int*);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(int*)").WithArguments("int*"),
                // (8,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         x = sizeof(int**);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (8,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         x = sizeof(int**);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int**"),
                // (8,13): error CS0233: 'int**' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)
                //         x = sizeof(int**);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(int**)").WithArguments("int**"),
                // (9,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         x = sizeof(void*);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*"),
                // (9,13): error CS0233: 'void*' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)
                //         x = sizeof(void*);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(void*)").WithArguments("void*"),
                // (10,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         x = sizeof(void**);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*"),
                // (10,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         x = sizeof(void**);
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void**"),
                // (10,13): error CS0233: 'void**' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)
                //         x = sizeof(void**);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(void**)").WithArguments("void**")
                );
        }

        [Fact]
        public void SizeOfUnsafeInIterator()
        {
            var text = @"
struct S
{
    System.Collections.Generic.IEnumerable<int> M()
    {
        yield return sizeof(S);
    }
}
";

            var expectedDiagnostics = new[]
            {
                // (6,22): error CS0233: 'S' does not have a predefined size, therefore sizeof can only be used in an unsafe context
                //         yield return sizeof(S);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(S)").WithArguments("S").WithLocation(6, 22)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(text, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(text, parseOptions: TestOptions.Regular14).VerifyDiagnostics(expectedDiagnostics);

            CreateCompilation(text).VerifyDiagnostics();
            CreateCompilation(text, parseOptions: TestOptions.RegularNext).VerifyDiagnostics();
        }

        [Fact]
        public void SizeOfNonType1()
        {
            var text = @"
unsafe struct S
{
    void M()
    {
        S s = new S();
        int i = 0;

        i = sizeof(s);
        i = sizeof(i);
        i = sizeof(M);
    }
}
";
            // Not identical to Dev10, but same meaning.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,20): error CS0118: 's' is a variable but is used like a type
                //         i = sizeof(s);
                Diagnostic(ErrorCode.ERR_BadSKknown, "s").WithArguments("s", "variable", "type"),
                // (10,20): error CS0118: 'i' is a variable but is used like a type
                //         i = sizeof(i);
                Diagnostic(ErrorCode.ERR_BadSKknown, "i").WithArguments("i", "variable", "type"),
                // (11,20): error CS0246: The type or namespace name 'M' could not be found (are you missing a using directive or an assembly reference?)
                //         i = sizeof(M);
                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "M").WithArguments("M"),
                // (6,11): warning CS0219: The variable 's' is assigned but its value is never used
                //         S s = new S();
                Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "s").WithArguments("s"));
        }

        [Fact]
        public void SizeOfNonType2()
        {
            var text = @"
unsafe struct S
{
    void M()
    {
        int i;
        i = sizeof(void);
        i = sizeof(this); //parser error
        i = sizeof(x => x); //parser error
    }
}
";
            // Not identical to Dev10, but same meaning.
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,20): error CS1547: Keyword 'void' cannot be used in this context
                //         i = sizeof(void);
                Diagnostic(ErrorCode.ERR_NoVoidHere, "void"),
                // (8,20): error CS1031: Type expected
                //         i = sizeof(this); //parser error
                Diagnostic(ErrorCode.ERR_TypeExpected, "this"),
                // (8,20): error CS1026: ) expected
                //         i = sizeof(this); //parser error
                Diagnostic(ErrorCode.ERR_CloseParenExpected, "this"),
                // (8,20): error CS1002: ; expected
                //         i = sizeof(this); //parser error
                Diagnostic(ErrorCode.ERR_SemicolonExpected, "this"),
                // (8,24): error CS1002: ; expected
                //         i = sizeof(this); //parser error
                Diagnostic(ErrorCode.ERR_SemicolonExpected, ")"),
                // (8,24): error CS1513: } expected
                //         i = sizeof(this); //parser error
                Diagnostic(ErrorCode.ERR_RbraceExpected, ")"),
                // (9,22): error CS1026: ) expected
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_CloseParenExpected, "=>"),
                // (9,22): error CS1002: ; expected
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_SemicolonExpected, "=>"),
                // (9,22): error CS1513: } expected
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_RbraceExpected, "=>"),
                // (9,26): error CS1002: ; expected
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_SemicolonExpected, ")"),
                // (9,26): error CS1513: } expected
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_RbraceExpected, ")"),
                // (9,20): error CS0246: The type or namespace name 'x' could not be found (are you missing a using directive or an assembly reference?)
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "x").WithArguments("x"),
                // (9,25): error CS0103: The name 'x' does not exist in the current context
                //         i = sizeof(x => x); //parser error
                Diagnostic(ErrorCode.ERR_NameNotInContext, "x").WithArguments("x"));
        }

        [Fact, WorkItem(529318, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/529318")]
        public void SizeOfNull()
        {
            string text = @"
class Program
{
    int F1 = sizeof(null);
}
";
            CreateCompilation(text, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,21): error CS1031: Type expected
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_TypeExpected, "null"),
                // (4,21): error CS1026: ) expected
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_CloseParenExpected, "null"),
                // (4,21): error CS1003: Syntax error, ',' expected
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_SyntaxError, "null").WithArguments(","),
                // (4,14): error CS0233: '?' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_SizeofUnsafe, "sizeof(").WithArguments("?"));

            var expectedPreviewDiagnostics = new[]
            {
                // (4,21): error CS1031: Type expected
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_TypeExpected, "null"),
                // (4,21): error CS1026: ) expected
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_CloseParenExpected, "null"),
                // (4,21): error CS1003: Syntax error, ',' expected
                //     int F1 = sizeof(null);
                Diagnostic(ErrorCode.ERR_SyntaxError, "null").WithArguments(","),
            };
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedPreviewDiagnostics);
            CreateCompilation(text, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        #endregion sizeof diagnostic tests

        #region sizeof semantic model tests

        private static readonly Dictionary<SpecialType, int> s_specialTypeSizeOfMap = new Dictionary<SpecialType, int>
        {
            { SpecialType.System_SByte, 1 },
            { SpecialType.System_Byte, 1 },
            { SpecialType.System_Int16, 2 },
            { SpecialType.System_UInt16, 2 },
            { SpecialType.System_Int32, 4 },
            { SpecialType.System_UInt32, 4 },
            { SpecialType.System_Int64, 8 },
            { SpecialType.System_UInt64, 8 },
            { SpecialType.System_Char, 2 },
            { SpecialType.System_Single, 4 },
            { SpecialType.System_Double, 8 },
            { SpecialType.System_Boolean, 1 },
            { SpecialType.System_Decimal, 16 },
        };

        [Fact]
        public void SizeOfSemanticModelSafe()
        {
            var text = @"
class Program
{
    static void Main()
    {
        int x;
        x = sizeof(sbyte);
        x = sizeof(byte);
        x = sizeof(short);
        x = sizeof(ushort);
        x = sizeof(int);
        x = sizeof(uint);
        x = sizeof(long);
        x = sizeof(ulong);
        x = sizeof(char);
        x = sizeof(float);
        x = sizeof(double);
        x = sizeof(bool);
        x = sizeof(decimal); //Supported by dev10, but not spec.
    }
}
";
            // NB: not unsafe
            var compilation = CreateCompilation(text);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntaxes = tree.GetCompilationUnitRoot().DescendantNodes().OfType<SizeOfExpressionSyntax>();

            foreach (var syntax in syntaxes)
            {
                var typeSummary = model.GetSemanticInfoSummary(syntax.Type);
                var type = typeSummary.Symbol as ITypeSymbol;

                Assert.NotNull(type);
                Assert.Equal(0, typeSummary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, typeSummary.CandidateReason);
                Assert.NotEqual(SpecialType.None, type.SpecialType);
                Assert.Equal(type, typeSummary.Type);
                Assert.Equal(type, typeSummary.ConvertedType);
                Assert.Equal(Conversion.Identity, typeSummary.ImplicitConversion);
                Assert.Null(typeSummary.Alias);
                Assert.False(typeSummary.IsCompileTimeConstant);
                Assert.False(typeSummary.ConstantValue.HasValue);

                var sizeOfSummary = model.GetSemanticInfoSummary(syntax);

                Assert.Null(sizeOfSummary.Symbol);
                Assert.Equal(0, sizeOfSummary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, sizeOfSummary.CandidateReason);
                Assert.Equal(SpecialType.System_Int32, sizeOfSummary.Type.SpecialType);
                Assert.Equal(sizeOfSummary.Type, sizeOfSummary.ConvertedType);
                Assert.Equal(Conversion.Identity, sizeOfSummary.ImplicitConversion);
                Assert.Equal(0, sizeOfSummary.MethodGroup.Length);
                Assert.Null(sizeOfSummary.Alias);
                Assert.True(sizeOfSummary.IsCompileTimeConstant);
                Assert.Equal(s_specialTypeSizeOfMap[type.SpecialType], sizeOfSummary.ConstantValue);
            }
        }

        [Fact]
        public void SizeOfSemanticModelEnum()
        {
            var text = @"
class Program
{
    static void Main()
    {
        int x;
        x = sizeof(E1);
        x = sizeof(E2);
    }
}

enum E1 : short
{
    A
}

enum E2 : long
{
    A
}
";
            // NB: not unsafe
            var compilation = CreateCompilation(text);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntaxes = tree.GetCompilationUnitRoot().DescendantNodes().OfType<SizeOfExpressionSyntax>();

            foreach (var syntax in syntaxes)
            {
                var typeSummary = model.GetSemanticInfoSummary(syntax.Type);
                var type = typeSummary.Symbol as ITypeSymbol;

                Assert.NotNull(type);
                Assert.Equal(0, typeSummary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, typeSummary.CandidateReason);
                Assert.Equal(TypeKind.Enum, type.TypeKind);
                Assert.Equal(type, typeSummary.Type);
                Assert.Equal(type, typeSummary.ConvertedType);
                Assert.Equal(Conversion.Identity, typeSummary.ImplicitConversion);
                Assert.Null(typeSummary.Alias);
                Assert.False(typeSummary.IsCompileTimeConstant);
                Assert.False(typeSummary.ConstantValue.HasValue);

                var sizeOfSummary = model.GetSemanticInfoSummary(syntax);

                Assert.Null(sizeOfSummary.Symbol);
                Assert.Equal(0, sizeOfSummary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, sizeOfSummary.CandidateReason);
                Assert.Equal(SpecialType.System_Int32, sizeOfSummary.Type.SpecialType);
                Assert.Equal(sizeOfSummary.Type, sizeOfSummary.ConvertedType);
                Assert.Equal(Conversion.Identity, sizeOfSummary.ImplicitConversion);
                Assert.Equal(0, sizeOfSummary.MethodGroup.Length);
                Assert.Null(sizeOfSummary.Alias);
                Assert.True(sizeOfSummary.IsCompileTimeConstant);
                Assert.Equal(s_specialTypeSizeOfMap[type.GetEnumUnderlyingType().SpecialType], sizeOfSummary.ConstantValue);
            }
        }

        [Fact]
        public void SizeOfSemanticModelUnsafe()
        {
            var text = @"
struct Outer
{
    unsafe static void Main()
    {
        int x;
        x = sizeof(Outer);
        x = sizeof(Inner);
        x = sizeof(Outer*);
        x = sizeof(Inner*);
        x = sizeof(Outer**);
        x = sizeof(Inner**);
    }

    struct Inner
    {
    }
}
";
            // NB: not unsafe
            var compilation = CreateCompilation(text);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var syntaxes = tree.GetCompilationUnitRoot().DescendantNodes().OfType<SizeOfExpressionSyntax>();

            foreach (var syntax in syntaxes)
            {
                var typeSummary = model.GetSemanticInfoSummary(syntax.Type);
                var type = typeSummary.Symbol as ITypeSymbol;

                Assert.NotNull(type);
                Assert.Equal(0, typeSummary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, typeSummary.CandidateReason);
                Assert.Equal(SpecialType.None, type.SpecialType);
                Assert.Equal(type, typeSummary.Type);
                Assert.Equal(type, typeSummary.ConvertedType);
                Assert.Equal(Conversion.Identity, typeSummary.ImplicitConversion);
                Assert.Null(typeSummary.Alias);
                Assert.False(typeSummary.IsCompileTimeConstant);
                Assert.False(typeSummary.ConstantValue.HasValue);

                var sizeOfSummary = model.GetSemanticInfoSummary(syntax);

                Assert.Null(sizeOfSummary.Symbol);
                Assert.Equal(0, sizeOfSummary.CandidateSymbols.Length);
                Assert.Equal(CandidateReason.None, sizeOfSummary.CandidateReason);
                Assert.Equal(SpecialType.System_Int32, sizeOfSummary.Type.SpecialType);
                Assert.Equal(sizeOfSummary.Type, sizeOfSummary.ConvertedType);
                Assert.Equal(Conversion.Identity, sizeOfSummary.ImplicitConversion);
                Assert.Equal(0, sizeOfSummary.MethodGroup.Length);
                Assert.Null(sizeOfSummary.Alias);
                Assert.False(sizeOfSummary.IsCompileTimeConstant);
                Assert.False(sizeOfSummary.ConstantValue.HasValue);
            }
        }

        #endregion sizeof semantic model tests

        #region stackalloc diagnostic tests

        [Fact]
        public void StackAllocUnsafe()
        {
            var template = @"
{0} struct S
{{
    {1} void M()
    {{
        int* p = stackalloc int[1];
    }}
}}
";
            CompareUnsafeDiagnostics(template,
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         int* p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*"),
                // (6,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         int* p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "stackalloc int[1]")
                );
        }

        [Fact]
        public void StackAllocUnsafeInIterator()
        {
            var text = @"
struct S
{
    System.Collections.Generic.IEnumerable<int> M()
    {
        var p = stackalloc int[1];
        yield return 1;
    }
}
";

            var expectedDiagnostics = new[]
            {
                // (6,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "stackalloc int[1]").WithLocation(6, 17)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(text, parseOptions: TestOptions.Regular13).VerifyDiagnostics(expectedDiagnostics);
            CreateCompilation(text, parseOptions: TestOptions.Regular14).VerifyDiagnostics(expectedDiagnostics);

            CreateCompilation(text).VerifyDiagnostics();
            CreateCompilation(text, parseOptions: TestOptions.RegularNext).VerifyDiagnostics();
        }

        [Fact]
        public void ERR_NegativeStackAllocSize()
        {
            var text = @"
unsafe struct S
{
    void M()
    {
        int* p = stackalloc int[-1];
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,33): error CS0247: Cannot use a negative size with stackalloc
                //         int* p = stackalloc int[-1];
                Diagnostic(ErrorCode.ERR_NegativeStackAllocSize, "-1"));
        }

        [Fact]
        public void ERR_StackallocInCatchFinally_Catch()
        {
            var text = @"
unsafe class C
{
    int x = M(() =>
    {
        try
        {
            int* p = stackalloc int[1]; //fine
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                catch
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
        catch
        {
            int* p = stackalloc int[1]; //CS0255
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                catch
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
    });

    static int M(System.Action action)
    {
        try
        {
            int* p = stackalloc int[1]; //fine
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                catch
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
        catch
        {
            int* p = stackalloc int[1]; //CS0255
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                catch
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
        return 0;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (17,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (23,22): error CS0255: stackalloc may not be used in a catch or finally block
                //             int* p = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (32,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (51,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (57,22): error CS0255: stackalloc may not be used in a catch or finally block
                //             int* p = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (66,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"));
        }

        [Fact]
        public void ERR_StackallocInCatchFinally_Finally()
        {
            var text = @"
unsafe class C
{
    int x = M(() =>
    {
        try
        {
            int* p = stackalloc int[1]; //fine
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                finally
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
        finally
        {
            int* p = stackalloc int[1]; //CS0255
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                finally
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
    });

    static int M(System.Action action)
    {
        try
        {
            int* p = stackalloc int[1]; //fine
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                finally
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
        finally
        {
            int* p = stackalloc int[1]; //CS0255
            System.Action a = () =>
            {
                try
                {
                    int* q = stackalloc int[1]; //fine
                }
                finally
                {
                    int* q = stackalloc int[1]; //CS0255
                }
            };
        }
        return 0;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (17,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (23,22): error CS0255: stackalloc may not be used in a catch or finally block
                //             int* p = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (32,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (51,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (57,22): error CS0255: stackalloc may not be used in a catch or finally block
                //             int* p = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"),
                // (66,30): error CS0255: stackalloc may not be used in a catch or finally block
                //                     int* q = stackalloc int[1]; //CS0255
                Diagnostic(ErrorCode.ERR_StackallocInCatchFinally, "stackalloc int[1]"));
        }

        [Fact]
        public void ERR_BadStackAllocExpr()
        {
            var text = @"
unsafe class C
{
    static void Main()
    {
        int* p = stackalloc int;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,29): error CS1575: A stackalloc expression requires [] after type
                //         int* p = stackalloc int;
                Diagnostic(ErrorCode.ERR_BadStackAllocExpr, "int"));
        }

        [Fact]
        public void StackAllocCountType()
        {
            var text = @"
unsafe class C
{
    static void Main()
    {
        { int* p = stackalloc int[1]; } //fine
        { int* p = stackalloc int[1L]; } //CS0266 (could cast), even though constant value is fine
        { int* p = stackalloc int['c']; } //fine
        { int* p = stackalloc int[""hello""]; } // CS0029 (no conversion)
        { int* p = stackalloc int[Main]; } //CS0428 (method group conversion)
        { int* p = stackalloc int[x => x]; } //CS1660 (lambda conversion)
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (7,35): error CS0266: Cannot implicitly convert type 'long' to 'int'. An explicit conversion exists (are you missing a cast?)
                //         { int* p = stackalloc int[1L]; } //CS0266 (could cast), even though constant value is fine
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "1L").WithArguments("long", "int").WithLocation(7, 35),
                // (9,35): error CS0029: Cannot implicitly convert type 'string' to 'int'
                //         { int* p = stackalloc int["hello"]; } // CS0029 (no conversion)
                Diagnostic(ErrorCode.ERR_NoImplicitConv, @"""hello""").WithArguments("string", "int").WithLocation(9, 35),
                // (10,35): error CS0428: Cannot convert method group 'Main' to non-delegate type 'int'. Did you intend to invoke the method?
                //         { int* p = stackalloc int[Main]; } //CS0428 (method group conversion)
                Diagnostic(ErrorCode.ERR_MethGrpToNonDel, "Main").WithArguments("Main", "int").WithLocation(10, 35),
                // (11,37): error CS1660: Cannot convert lambda expression to type 'int' because it is not a delegate type
                //         { int* p = stackalloc int[x => x]; } //CS1660 (lambda conversion)
                Diagnostic(ErrorCode.ERR_AnonMethToNonDel, "=>").WithArguments("lambda expression", "int").WithLocation(11, 37));
        }

        [Fact]
        public void StackAllocCountQuantity()
        {
            // These all give unhelpful parser errors in Dev10.  Let's see if we can do better.
            var text = @"
unsafe class C
{
    static void Main()
    {
        { int* p = stackalloc int[]; }
        { int* p = stackalloc int[1, 1]; }
        { int* p = stackalloc int[][]; }
        { int* p = stackalloc int[][1]; }
        { int* p = stackalloc int[1][]; }
        { int* p = stackalloc int[1][1]; }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,34): error CS1586: Array creation must have array size or array initializer
                //         { int* p = stackalloc int[]; }
                Diagnostic(ErrorCode.ERR_MissingArraySize, "[]").WithLocation(6, 34),
                // (7,31): error CS1575: A stackalloc expression requires [] after type
                //         { int* p = stackalloc int[1, 1]; }
                Diagnostic(ErrorCode.ERR_BadStackAllocExpr, "int[1, 1]").WithLocation(7, 31),
                // (8,31): error CS0208: Cannot take the address of, get the size of, or declare a pointer to a managed type ('int[]')
                //         { int* p = stackalloc int[][]; }
                Diagnostic(ErrorCode.ERR_ManagedAddr, "int").WithArguments("int[]").WithLocation(8, 31),
                // (8,31): error CS1575: A stackalloc expression requires [] after type
                //         { int* p = stackalloc int[][]; }
                Diagnostic(ErrorCode.ERR_BadStackAllocExpr, "int[][]").WithLocation(8, 31),
                // (9,31): error CS0208: Cannot take the address of, get the size of, or declare a pointer to a managed type ('int[]')
                //         { int* p = stackalloc int[][1]; }
                Diagnostic(ErrorCode.ERR_ManagedAddr, "int").WithArguments("int[]").WithLocation(9, 31),
                // (9,31): error CS1575: A stackalloc expression requires [] after type
                //         { int* p = stackalloc int[][1]; }
                Diagnostic(ErrorCode.ERR_BadStackAllocExpr, "int[][1]").WithLocation(9, 31),
                // (10,31): error CS0208: Cannot take the address of, get the size of, or declare a pointer to a managed type ('int[]')
                //         { int* p = stackalloc int[1][]; }
                Diagnostic(ErrorCode.ERR_ManagedAddr, "int").WithArguments("int[]").WithLocation(10, 31),
                // (10,31): error CS1575: A stackalloc expression requires [] after type
                //         { int* p = stackalloc int[1][]; }
                Diagnostic(ErrorCode.ERR_BadStackAllocExpr, "int[1][]").WithLocation(10, 31),
                // (11,31): error CS0208: Cannot take the address of, get the size of, or declare a pointer to a managed type ('int[]')
                //         { int* p = stackalloc int[1][1]; }
                Diagnostic(ErrorCode.ERR_ManagedAddr, "int").WithArguments("int[]").WithLocation(11, 31),
                // (11,31): error CS1575: A stackalloc expression requires [] after type
                //         { int* p = stackalloc int[1][1]; }
                Diagnostic(ErrorCode.ERR_BadStackAllocExpr, "int[1][1]").WithLocation(11, 31)
                );
        }

        [Fact]
        public void StackAllocExplicitConversion()
        {
            var text = @"
unsafe class C
{
    static void Main()
    {
        { var p = (int*)stackalloc int[1]; }
        { var p = (void*)stackalloc int[1]; }
        { var p = (C)stackalloc int[1]; }
    }

    public static implicit operator C(int* p)
    {
        return null;
    }
}
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(
                // (6,19): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'int*' is not possible.
                //         { var p = (int*)stackalloc int[1]; }
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "(int*)stackalloc int[1]").WithArguments("int", "int*").WithLocation(6, 19),
                // (7,19): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'void*' is not possible.
                //         { var p = (void*)stackalloc int[1]; }
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "(void*)stackalloc int[1]").WithArguments("int", "void*").WithLocation(7, 19),
                // (8,19): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'C' is not possible.
                //         { var p = (C)stackalloc int[1]; }
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "(C)stackalloc int[1]").WithArguments("int", "C").WithLocation(8, 19));
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular8).VerifyDiagnostics(
                // (6,19): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'int*' is not possible.
                //         { var p = (int*)stackalloc int[1]; }
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "(int*)stackalloc int[1]").WithArguments("int", "int*").WithLocation(6, 19),
                // (7,19): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'void*' is not possible.
                //         { var p = (void*)stackalloc int[1]; }
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "(void*)stackalloc int[1]").WithArguments("int", "void*").WithLocation(7, 19),
                // (8,19): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'C' is not possible.
                //         { var p = (C)stackalloc int[1]; }
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "(C)stackalloc int[1]").WithArguments("int", "C").WithLocation(8, 19));
        }

        [Fact]
        public void StackAllocNotExpression_FieldInitializer()
        {
            var text = @"
unsafe class C
{
    int* p = stackalloc int[1];
}
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(
                // (4,14): error CS8652: The feature 'stackalloc in nested expressions' is not available in C# 7.3. Please use language version 8.0 or greater.
                //     int* p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "stackalloc").WithArguments("stackalloc in nested expressions", "8.0").WithLocation(4, 14)
                );
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular8).VerifyDiagnostics(
                // (4,14): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'int*' is not possible.
                //     int* p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "stackalloc int[1]").WithArguments("int", "int*").WithLocation(4, 14)
            );
        }

        [Fact]
        public void StackAllocNotExpression_DefaultParameterValue()
        {
            var text = @"
unsafe class C
{
    void M(int* p = stackalloc int[1])
    {
    }
}
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,21): error CS1736: Default parameter value for 'p' must be a compile-time constant
                //     void M(int* p = stackalloc int[1])
                Diagnostic(ErrorCode.ERR_DefaultValueMustBeConstant, "stackalloc int[1]").WithArguments("p").WithLocation(4, 21)
            );
        }

        [Fact]
        public void StackAllocNotExpression_ForLoop()
        {
            var text = @"
unsafe class C
{
    void M()
    {
        for (int* p = stackalloc int[1]; p != null; p++) //fine
        {
        }
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void StackAllocNotExpression_GlobalDeclaration_01()
        {
            var text = @"
unsafe int* p = stackalloc int[1];
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Script).VerifyDiagnostics(
                // (2,17): error CS8346: Conversion of a stackalloc expression of type 'int' to type 'int*' is not possible.
                // unsafe int* p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_StackAllocConversionNotPossible, "stackalloc int[1]").WithArguments("int", "int*").WithLocation(2, 17)
            );
        }

        [Fact]
        public void StackAllocNotExpression_GlobalDeclaration_02()
        {
            var text = @"
using System;
Span<int> p = stackalloc int[1];
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Script).VerifyDiagnostics(
                // (3,1): error CS8345: Field or auto-implemented property cannot be of type 'Span<int>' unless it is an instance member of a ref struct.
                // Span<int> p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_FieldAutoPropCantBeByRefLike, "Span<int>").WithArguments("System.Span<int>").WithLocation(3, 1)
            );
        }

        [Fact]
        public void StackAllocNotExpression_GlobalDeclaration_03()
        {
            var text = @"
var p = stackalloc int[1];
";
            CreateCompilationWithMscorlibAndSpan(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Script).VerifyDiagnostics(
                // (2,1): error CS8345: Field or auto-implemented property cannot be of type 'Span<int>' unless it is an instance member of a ref struct.
                // var p = stackalloc int[1];
                Diagnostic(ErrorCode.ERR_FieldAutoPropCantBeByRefLike, "var").WithArguments("System.Span<int>").WithLocation(2, 1)
            );
        }

        #endregion stackalloc diagnostic tests

        #region stackalloc semantic model tests

        [Fact]
        public void StackAllocSemanticModel()
        {
            var text = @"
class C
{
    unsafe static void Main()
    {
        const short count = 20;
        void* p = stackalloc char[count];
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var stackAllocSyntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<StackAllocArrayCreationExpressionSyntax>().Single();
            var arrayTypeSyntax = (ArrayTypeSyntax)stackAllocSyntax.Type;
            var typeSyntax = arrayTypeSyntax.ElementType;
            var countSyntax = arrayTypeSyntax.RankSpecifiers.Single().Sizes.Single();

            var stackAllocSummary = model.GetSemanticInfoSummary(stackAllocSyntax);
            Assert.Equal(SpecialType.System_Char, ((IPointerTypeSymbol)stackAllocSummary.Type).PointedAtType.SpecialType);
            Assert.Equal(SpecialType.System_Void, ((IPointerTypeSymbol)stackAllocSummary.ConvertedType).PointedAtType.SpecialType);
            Assert.Equal(Conversion.PointerToVoid, stackAllocSummary.ImplicitConversion);
            Assert.Null(stackAllocSummary.Symbol);
            Assert.Equal(0, stackAllocSummary.CandidateSymbols.Length);
            Assert.Equal(CandidateReason.None, stackAllocSummary.CandidateReason);
            Assert.Equal(0, stackAllocSummary.MethodGroup.Length);
            Assert.Null(stackAllocSummary.Alias);
            Assert.False(stackAllocSummary.IsCompileTimeConstant);
            Assert.False(stackAllocSummary.ConstantValue.HasValue);

            var typeSummary = model.GetSemanticInfoSummary(typeSyntax);
            Assert.Equal(SpecialType.System_Char, typeSummary.Type.SpecialType);
            Assert.Equal(typeSummary.Type, typeSummary.ConvertedType);
            Assert.Equal(Conversion.Identity, typeSummary.ImplicitConversion);
            Assert.Equal(typeSummary.Symbol, typeSummary.Type);
            Assert.Equal(0, typeSummary.CandidateSymbols.Length);
            Assert.Equal(CandidateReason.None, typeSummary.CandidateReason);
            Assert.Equal(0, typeSummary.MethodGroup.Length);
            Assert.Null(typeSummary.Alias);
            Assert.False(typeSummary.IsCompileTimeConstant);
            Assert.False(typeSummary.ConstantValue.HasValue);

            var countSummary = model.GetSemanticInfoSummary(countSyntax);
            Assert.Equal(SpecialType.System_Int16, countSummary.Type.SpecialType);
            Assert.Equal(SpecialType.System_Int32, countSummary.ConvertedType.SpecialType);
            Assert.Equal(Conversion.ImplicitNumeric, countSummary.ImplicitConversion);
            var countSymbol = (ILocalSymbol)countSummary.Symbol;
            Assert.Equal(countSummary.Type, countSymbol.Type);
            Assert.Equal("count", countSymbol.Name);
            Assert.Equal(0, countSummary.CandidateSymbols.Length);
            Assert.Equal(CandidateReason.None, countSummary.CandidateReason);
            Assert.Equal(0, countSummary.MethodGroup.Length);
            Assert.Null(countSummary.Alias);
            Assert.True(countSummary.IsCompileTimeConstant);
            Assert.True(countSummary.ConstantValue.HasValue);
            Assert.Equal((short)20, countSummary.ConstantValue.Value);
        }

        #endregion stackalloc semantic model tests

        #region PointerTypes tests

        [WorkItem(5712, "https://github.com/dotnet/roslyn/issues/5712")]
        [Fact]
        public void PathologicalRefStructPtrMultiDimensionalArray()
        {
            var text = @"
class C
{
  class Goo3 { 
     internal struct Struct1<U> {} 
  }

  unsafe void NMethodCecilNameHelper_Parameter_AllTogether<U>(ref Goo3.Struct1<int>**[][,,] ppi) { }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeDebugDll).VerifyDiagnostics();
        }

        [WorkItem(543990, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/543990")]
        [Fact]
        public void PointerTypeInVolatileField()
        {
            string text = @"
unsafe class Test 
{
	static volatile int *px;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,23): warning CS0169: The field 'Test.px' is never used
                // 	static volatile int *px;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "px").WithArguments("Test.px"));
        }

        [Fact, WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544003")]
        public void PointerTypesAsTypeArgs_NoUnsafeContext()
        {
            string text = @"
class A
{
    public class B{}
}
class C<T> : A
{
    private static C<T*[]>.B b;
}
";
            var expected = new[]
            {
                // (8,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b")
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);

            CreateCompilation(text, options: TestOptions.ReleaseDll.WithUpdatedMemorySafetyRules()).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll.WithUpdatedMemorySafetyRules()).VerifyDiagnostics(expected);

            expected = new[]
            {
                // (8,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "T*").WithLocation(8, 22),
                // (8,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(8, 30)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);
        }

        [Fact, WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544003")]
        public void PointerTypesAsTypeArgs_UnsafeContext()
        {
            string text = @"
class A
{
    public class B{}
}
unsafe class C<T> : A
{
    private static C<T*[]>.B b;
}
";

            var expected = new[]
            {
                // (6,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // unsafe class C<T> : A
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C").WithLocation(6, 14),
                // (8,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(8, 30)
            };

            var expectedWithUnsafe = new[]
            {
                // (8,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(8, 30)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expectedWithUnsafe);

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expectedWithUnsafe);

            CreateCompilation(text).VerifyDiagnostics(expected);

            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(expectedWithUnsafe);
        }

        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544003")]
        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544232")]
        [Fact]
        public void PointerTypesAsTypeArgs2_NoUnsafeContext()
        {
            string text = @"
class A
{
    public class B{}
}
class C<T> : A
{
    // Dev10 and Roslyn both do not report an error here because they don't look for ERR_ManagedAddr until
    // late in the binding process - at which point the type has been resolved to A.B.
    private static C<T*[]>.B b;

    // Workarounds
    private static B b1;
    private static A.B b2;

    // Dev10 and Roslyn produce the same diagnostic here.
    private static C<T*[]> c;
}
";
            var expected = new[]
            {
                // (17,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("T").WithLocation(17, 28),
                // (14,24): warning CS0169: The field 'C<T>.b2' is never used
                //     private static A.B b2;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b2").WithArguments("C<T>.b2").WithLocation(14, 24),
                // (13,22): warning CS0169: The field 'C<T>.b1' is never used
                //     private static B b1;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b1").WithArguments("C<T>.b1").WithLocation(13, 22),
                // (10,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 30),
                // (17,28): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(17, 28)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);

            expected = new[]
            {
                // (17,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "T*").WithLocation(17, 22),
                // (10,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "T*").WithLocation(10, 22),
                // (17,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("T").WithLocation(17, 28),
                // (17,28): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(17, 28),
                // (14,24): warning CS0169: The field 'C<T>.b2' is never used
                //     private static A.B b2;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b2").WithArguments("C<T>.b2").WithLocation(14, 24),
                // (13,22): warning CS0169: The field 'C<T>.b1' is never used
                //     private static B b1;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b1").WithArguments("C<T>.b1").WithLocation(13, 22),
                // (10,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 30)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);
        }

        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544003")]
        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544232")]
        [Fact]
        public void PointerTypesAsTypeArgs2_UnsafeContext()
        {
            string text = @"
class A
{
    public class B{}
}
unsafe class C<T> : A
{
    // Dev10 and Roslyn both do not report an error here because they don't look for ERR_ManagedAddr until
    // late in the binding process - at which point the type has been resolved to A.B.
    private static C<T*[]>.B b;

    // Workarounds
    private static B b1;
    private static A.B b2;

    // Dev10 and Roslyn produce the same diagnostic here.
    private static C<T*[]> c;
}
";

            CreateCompilation(text, parseOptions: TestOptions.Regular11).VerifyDiagnostics(
                // (6,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // unsafe class C<T> : A
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C").WithLocation(6, 14),
                // (17,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("T").WithLocation(17, 28),
                // (14,24): warning CS0169: The field 'C<T>.b2' is never used
                //     private static A.B b2;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b2").WithArguments("C<T>.b2").WithLocation(14, 24),
                // (10,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 30),
                // (17,28): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(17, 28),
                // (13,22): warning CS0169: The field 'C<T>.b1' is never used
                //     private static B b1;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b1").WithArguments("C<T>.b1").WithLocation(13, 22));
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular11).VerifyDiagnostics(
                // (10,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 30),
                // (13,22): warning CS0169: The field 'C<T>.b1' is never used
                //     private static B b1;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b1").WithArguments("C<T>.b1").WithLocation(13, 22),
                // (14,24): warning CS0169: The field 'C<T>.b2' is never used
                //     private static A.B b2;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b2").WithArguments("C<T>.b2").WithLocation(14, 24),
                // (17,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("T").WithLocation(17, 28),
                // (17,28): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(17, 28));

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (6,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // unsafe class C<T> : A
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C").WithLocation(6, 14),
                // (17,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("T").WithLocation(17, 28),
                // (17,28): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(17, 28),
                // (13,22): warning CS0169: The field 'C<T>.b1' is never used
                //     private static B b1;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b1").WithArguments("C<T>.b1").WithLocation(13, 22),
                // (14,24): warning CS0169: The field 'C<T>.b2' is never used
                //     private static A.B b2;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b2").WithArguments("C<T>.b2").WithLocation(14, 24),
                // (10,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 30));
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (10,30): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<T*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 30),
                // (13,22): warning CS0169: The field 'C<T>.b1' is never used
                //     private static B b1;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b1").WithArguments("C<T>.b1").WithLocation(13, 22),
                // (14,24): warning CS0169: The field 'C<T>.b2' is never used
                //     private static A.B b2;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b2").WithArguments("C<T>.b2").WithLocation(14, 24),
                // (17,28): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('T')
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("T").WithLocation(17, 28),
                // (17,28): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<T*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(17, 28));
        }

        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544003")]
        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544232")]
        [Fact]
        public void PointerTypesAsTypeArgs3_NoUnsafeContext()
        {
            string text = @"
class A
{
    public class B{}
}
class C<T> : A
{
    // Dev10 and Roslyn both do not report an error here because they don't look for ERR_ManagedAddr until
    // late in the binding process - at which point the type has been resolved to A.B.
    private static C<string*[]>.B b;

    // Dev10 and Roslyn produce the same diagnostic here.
    private static C<string*[]> c;
}
";
            var expected = new[]
            {
                // (13,33): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("string").WithLocation(13, 33),
                // (10,35): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 35),
                // (13,33): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(13, 33)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular11).VerifyDiagnostics(expected);

            expected = new[]
            {
                // (13,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "string*").WithLocation(13, 22),
                // (10,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "string*").WithLocation(10, 22),
                // (13,33): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("string").WithLocation(13, 33),
                // (13,33): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(13, 33),
                // (10,35): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 35)
            };

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(expected);
        }

        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544003")]
        [WorkItem("http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544232")]
        [Fact]
        public void PointerTypesAsTypeArgs3_UnsafeContext()
        {
            string text = @"
class A
{
    public class B{}
}
unsafe class C<T> : A
{
    // Dev10 and Roslyn both do not report an error here because they don't look for ERR_ManagedAddr until
    // late in the binding process - at which point the type has been resolved to A.B.
    private static C<string*[]>.B b;

    // Dev10 and Roslyn produce the same diagnostic here.
    private static C<string*[]> c;
}
";

            CreateCompilation(text, parseOptions: TestOptions.Regular11).VerifyDiagnostics(
                // (6,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // unsafe class C<T> : A
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C").WithLocation(6, 14),
                // (13,33): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("string").WithLocation(13, 33),
                // (13,33): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(13, 33),
                // (10,35): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 35));
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular11).VerifyDiagnostics(
                // (10,35): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 35),
                // (13,33): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("string").WithLocation(13, 33),
                // (13,33): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(13, 33));

            CreateCompilation(text, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (6,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // unsafe class C<T> : A
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C").WithLocation(6, 14),
                // (13,33): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("string").WithLocation(13, 33),
                // (13,33): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(13, 33),
                // (10,35): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 35));
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular12).VerifyDiagnostics(
                // (10,35): warning CS0169: The field 'C<T>.b' is never used
                //     private static C<string*[]>.B b;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "b").WithArguments("C<T>.b").WithLocation(10, 35),
                // (13,33): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_ManagedAddr, "c").WithArguments("string").WithLocation(13, 33),
                // (13,33): warning CS0169: The field 'C<T>.c' is never used
                //     private static C<string*[]> c;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "c").WithArguments("C<T>.c").WithLocation(13, 33));
        }

        [Fact]
        [WorkItem(37051, "https://github.com/dotnet/roslyn/issues/37051")]
        public void GenericPointer_Override()
        {
            var csharp = @"
public unsafe class A
{
    public virtual T* M<T>() where T : unmanaged => throw null!;
}

public unsafe class B : A
{
    public override T* M<T>() => throw null!;
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        #endregion PointerTypes tests

        #region misc unsafe tests

        [Fact, WorkItem(543988, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/543988")]
        public void UnsafeFieldInitializerInStruct()
        {
            string sourceCode = @"
public struct Test
{
    static unsafe int*[] myArray = new int*[100];
}
";
            var tree = Parse(sourceCode);
            var comp = CreateCompilation(tree, options: TestOptions.UnsafeReleaseDll);
            var model = comp.GetSemanticModel(tree);

            model.GetDiagnostics().Verify();
        }

        [Fact, WorkItem(544143, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544143")]
        public void ConvertFromPointerToSelf()
        {
            string text = @"
struct C
{
    unsafe static public implicit operator long*(C* i)
    {
        return null;
    }
    unsafe static void Main()
    {
        C c = new C();
    }
}
";
            var comp = CreateCompilation(text, options: TestOptions.UnsafeReleaseExe);
            comp.VerifyDiagnostics(
                // (4,44): error CS0556: User-defined conversion must convert to or from the enclosing type
                //     unsafe static public implicit operator long*(C* i)
                Diagnostic(ErrorCode.ERR_ConversionNotInvolvingContainedType, "long*"),
                // (10,11): warning CS0219: The variable 'c' is assigned but its value is never used
                //         C c = new C();
                Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "c").WithArguments("c"));

            var tree = comp.SyntaxTrees.Single();
            var model = comp.GetSemanticModel(tree);

            var parameterSyntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ParameterSyntax>().Single();

            var info = model.GetSemanticInfoSummary(parameterSyntax.Type);
        }

        [Fact]
        public void PointerVolatileField()
        {
            string text = @"
unsafe class C
{
    volatile int* p; //Spec section 18.2 specifically allows this.
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (4,19): warning CS0169: The field 'C.p' is never used
                //     volatile int* p; //Spec section 18.2 specifically allows this.
                Diagnostic(ErrorCode.WRN_UnreferencedField, "p").WithArguments("C.p"));
        }

        [Fact]
        public void SemanticModelPointerArrayForeachInfo()
        {
            var text = @"
using System;

unsafe class C
{
    static void Main()
    {
        foreach(int* element in new int*[3])
        {
        }
    }
}
";
            var compilation = CreateCompilation(text, options: TestOptions.UnsafeReleaseDll);
            var tree = compilation.SyntaxTrees.Single();
            var model = compilation.GetSemanticModel(tree);

            var foreachSyntax = tree.GetCompilationUnitRoot().DescendantNodes().OfType<ForEachStatementSyntax>().Single();

            // Reports members of non-generic interfaces (pointers can't be type arguments).
            var info = model.GetForEachStatementInfo(foreachSyntax);
            Assert.Equal(default(ForEachStatementInfo), info);
        }

        [Fact, WorkItem(544336, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/544336")]
        public void PointerTypeAsDelegateParamInAnonMethod()
        {
            // It is legal to use a delegate with pointer types in a "safe" context
            // provided that you do not actually make a parameter of unsafe type!
            string sourceCode = @"
unsafe delegate int D(int* p);
class C 
{
	static void Main()
	{
		D d = delegate { return 1;};
	}
}
";
            var tree = Parse(sourceCode);
            var comp = CreateCompilation(tree, options: TestOptions.UnsafeReleaseDll);
            var model = comp.GetSemanticModel(tree);

            model.GetDiagnostics().Verify();
        }

        [Fact(Skip = "529402"), WorkItem(529402, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/529402")]
        public void DotOperatorOnPointerTypes()
        {
            string text = @"
unsafe class Program
{
    static void Main(string[] args)
    {
        int* i1 = null;
        i1.ToString();
    }
}
";
            var comp = CreateCompilation(text, options: TestOptions.ReleaseExe);
            comp.VerifyDiagnostics(
                // (7,9): error CS0023: Operator '.' cannot be applied to operand of type 'int*'
                //        i1.ToString();
                Diagnostic(ErrorCode.ERR_BadUnaryOp, "i1.ToString").WithArguments(".", "int*"));
        }

        [Fact, WorkItem(545028, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/545028")]
        public void PointerToEnumInGeneric()
        {
            string text = @"
class C<T>
{
    enum E { }
    unsafe E* ptr;
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,15): warning CS0169: The field 'C<T>.ptr' is never used
                //     unsafe E* ptr;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "ptr").WithArguments("C<T>.ptr"));
        }

        [Fact]
        public void InvalidAsConversions()
        {
            string text = @"
using System;

public class Test
{
    unsafe void M<T>(T t)
    {
        int* p = null;
        Console.WriteLine(t as int*); // CS0244
        Console.WriteLine(p as T); // Dev10 reports CS0244 here as well, but CS0413 seems reasonable
        Console.WriteLine(null as int*); // CS0244
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (9,27): error CS0244: Neither 'is' nor 'as' is valid on pointer types
                //         Console.WriteLine(t as int*); // pointer
                Diagnostic(ErrorCode.ERR_PointerInAsOrIs, "t as int*"),
                // (10,27): error CS0413: The type parameter 'T' cannot be used with the 'as' operator because it does not have a class type constraint nor a 'class' constraint
                //         Console.WriteLine(p as T); // pointer
                Diagnostic(ErrorCode.ERR_AsWithTypeVar, "p as T").WithArguments("T"),
                // (11,27): error CS0244: Neither 'is' nor 'as' is valid on pointer types
                //         Console.WriteLine(null as int*); // pointer
                Diagnostic(ErrorCode.ERR_PointerInAsOrIs, "null as int*"));
        }

        [Fact]
        public void UnsafeConstructorInitializer()
        {
            string template = @"
{0} class A
{{
    {1} public A(params int*[] x) {{ }}
}}
 
{0} class B : A
{{
    {1} B(int x) {{ }}
    {1} B(double x) : base() {{ }}
}}
";
            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (4,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public A(params int*[] x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(4, 22),
                    // (9,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      B(int x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "B").WithLocation(9, 6),
                    // (10,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      B(double x) : base() { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "base").WithLocation(10, 20)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (9,6): error CS9363: 'A.A(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //      B(int x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "B(int x) { }").WithArguments("A.A(params int*[])").WithLocation(9, 6),
                    // (10,18): error CS9363: 'A.A(params int*[])' must be used in an unsafe context because it has pointers in its signature
                    //      B(double x) : base() { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, ": base()").WithArguments("A.A(params int*[])").WithLocation(10, 18),
                ]);
        }

        [Fact]
        public void UnsafeConstructorInitializer_NestedPointer()
        {
            string template = @"
class C<T> {{ }}

{0} class A
{{
    {1} public A(params C<int*[]>[] x) {{ }}
}}
 
{0} class B : A
{{
    {1} B(int x) {{ }}
    {1} B(double x) : base() {{ }}
}}
";
            CompareUnsafeDiagnostics(template,
                expectedWithoutUnsafe:
                [
                    // (6,24): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      public A(params C<int*[]>[] x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 24),
                    // (11,6): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      B(int x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "B").WithLocation(11, 6),
                    // (12,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //      B(double x) : base() { }
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "base").WithLocation(12, 20)
                ],
                expectedWithUnsafe: [],
                expectedWithoutUnsafePreview:
                [
                    // (11,6): error CS9363: 'A.A(params C<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //      B(int x) { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, "B(int x) { }").WithArguments("A.A(params C<int*[]>[])").WithLocation(11, 6),
                    // (12,18): error CS9363: 'A.A(params C<int*[]>[])' must be used in an unsafe context because it has pointers in its signature
                    //      B(double x) : base() { }
                    Diagnostic(ErrorCode.ERR_UnsafeMemberOperationCompat, ": base()").WithArguments("A.A(params C<int*[]>[])").WithLocation(12, 18),
                ]);
        }

        [WorkItem(545985, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/545985")]
        [Fact]
        public void UnboxPointer()
        {
            var text = @"
class C
{
    unsafe void Goo(object obj)
    {
        var x = (int*)obj;
    }
}
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,17): error CS0030: Cannot convert type 'object' to 'int*'
                //         var x = (int*)obj;
                Diagnostic(ErrorCode.ERR_NoExplicitConv, "(int*)obj").WithArguments("object", "int*"));
        }

        [Fact]
        public void FixedBuffersNoDefiniteAssignmentCheck()
        {
            var text = @"
    unsafe struct struct_ForTestingDefiniteAssignmentChecking        
    {
        //Definite Assignment Checking
        public fixed int FixedbuffInt[1024];
    }
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void FixedBuffersNoErrorsOnValidTypes()
        {
            var text = @"
    unsafe struct struct_ForTestingDefiniteAssignmentChecking        
    {
    public fixed bool _Type1[10]; 
    public fixed byte _Type12[10]; 
    public fixed int _Type2[10]; 
    public fixed short _Type3[10]; 
    public fixed long _Type4[10]; 
    public fixed char _Type5[10]; 
    public fixed sbyte _Type6[10]; 
    public fixed ushort _Type7[10]; 
    public fixed uint _Type8[10]; 
    public fixed ulong _Type9[10]; 
    public fixed float _Type10[10]; 
    public fixed double _Type11[10];  
    }
";
            CreateCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact()]
        [WorkItem(547030, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547030")]
        public void FixedBuffersUsageScenarioInRange()
        {
            var text = @"
using System;

unsafe struct s
{
    public fixed bool  _buffer[5]; // This is a fixed buffer.
}

class Program
{
    static s _fixedBufferExample = new s();  

    static void Main()
    {
        // Store values in the fixed buffer.
        // ... The load the values from the fixed buffer.
        Store();
        Load();
   }

    unsafe static void Store()
    {
        // Put the fixed buffer in unmovable memory.
        // ... Then assign some elements.
        fixed (bool* buffer = _fixedBufferExample._buffer)
        {
            buffer[0] = true;
            buffer[1] = false;
            buffer[2] = true;
        }
    }

    unsafe static void Load()
    {
        // Put in unmovable memory.
        // ... Then load some values from the memory.
        fixed (bool* buffer = _fixedBufferExample._buffer)
        {
            Console.Write(buffer[0]);
            Console.Write(buffer[1]);
            Console.Write(buffer[2]);
        }
    }

}
";
            var compilation = CompileAndVerify(text, options: TestOptions.UnsafeReleaseExe, verify: Verification.Fails);

            compilation.VerifyIL("Program.Store", @"
{
  // Code size       34 (0x22)
  .maxstack  3
  .locals init (pinned bool& V_0)
  IL_0000:  ldsflda    ""s Program._fixedBufferExample""
  IL_0005:  ldflda     ""bool* s._buffer""
  IL_000a:  ldflda     ""bool s.<_buffer>e__FixedBuffer.FixedElementField""
  IL_000f:  stloc.0
  IL_0010:  ldloc.0
  IL_0011:  conv.u
  IL_0012:  dup
  IL_0013:  ldc.i4.1
  IL_0014:  stind.i1
  IL_0015:  dup
  IL_0016:  ldc.i4.1
  IL_0017:  add
  IL_0018:  ldc.i4.0
  IL_0019:  stind.i1
  IL_001a:  ldc.i4.2
  IL_001b:  add
  IL_001c:  ldc.i4.1
  IL_001d:  stind.i1
  IL_001e:  ldc.i4.0
  IL_001f:  conv.u
  IL_0020:  stloc.0
  IL_0021:  ret
}
");
            compilation.VerifyIL("Program.Load", @"
{
  // Code size       46 (0x2e)
  .maxstack  3
  .locals init (pinned bool& V_0)
  IL_0000:  ldsflda    ""s Program._fixedBufferExample""
  IL_0005:  ldflda     ""bool* s._buffer""
  IL_000a:  ldflda     ""bool s.<_buffer>e__FixedBuffer.FixedElementField""
  IL_000f:  stloc.0
  IL_0010:  ldloc.0
  IL_0011:  conv.u
  IL_0012:  dup
  IL_0013:  ldind.u1
  IL_0014:  call       ""void System.Console.Write(bool)""
  IL_0019:  dup
  IL_001a:  ldc.i4.1
  IL_001b:  add
  IL_001c:  ldind.u1
  IL_001d:  call       ""void System.Console.Write(bool)""
  IL_0022:  ldc.i4.2
  IL_0023:  add
  IL_0024:  ldind.u1
  IL_0025:  call       ""void System.Console.Write(bool)""
  IL_002a:  ldc.i4.0
  IL_002b:  conv.u
  IL_002c:  stloc.0
  IL_002d:  ret
}
");
        }

        [Fact()]
        [WorkItem(547030, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547030")]
        public void FixedBuffersUsagescenarioOutOfRange()
        {
            // This should work as no range checking for unsafe code.
            //however the fact that we are writing bad unsafe code has potential for encountering problems            
            var text = @"
using System;

unsafe struct s
{
    public fixed bool  _buffer[5]; // This is a fixed buffer.
}

class Program
{
    static s _fixedBufferExample = new s();  

    static void Main()
    {
        // Store values in the fixed buffer.
        // ... The load the values from the fixed buffer.
        Store();
        Load();
   }

    unsafe static void Store()
    {
        // Put the fixed buffer in unmovable memory.
        // ... Then assign some elements.
        fixed (bool* buffer = _fixedBufferExample._buffer)
        {
            buffer[0] = true;
            buffer[8] = false;
            buffer[10] = true;
        }
    }

    unsafe static void Load()
    {
        // Put in unmovable memory.
        // ... Then load some values from the memory.
        fixed (bool* buffer = _fixedBufferExample._buffer)
        {
            Console.Write(buffer[0]);
            Console.Write(buffer[8]);
            Console.Write(buffer[10]);
        }
    }

}
";
            //IL Baseline rather than execute because I'm intentionally writing outside of bounds of buffer
            // This will compile without warning but runtime behavior is unpredictable.

            var compilation = CompileAndVerify(text, options: TestOptions.UnsafeReleaseExe, verify: Verification.Fails);
            compilation.VerifyIL("Program.Load", @"
{
  // Code size       47 (0x2f)
  .maxstack  3
  .locals init (pinned bool& V_0)
  IL_0000:  ldsflda    ""s Program._fixedBufferExample""
  IL_0005:  ldflda     ""bool* s._buffer""
  IL_000a:  ldflda     ""bool s.<_buffer>e__FixedBuffer.FixedElementField""
  IL_000f:  stloc.0
  IL_0010:  ldloc.0
  IL_0011:  conv.u
  IL_0012:  dup
  IL_0013:  ldind.u1
  IL_0014:  call       ""void System.Console.Write(bool)""
  IL_0019:  dup
  IL_001a:  ldc.i4.8
  IL_001b:  add
  IL_001c:  ldind.u1
  IL_001d:  call       ""void System.Console.Write(bool)""
  IL_0022:  ldc.i4.s   10
  IL_0024:  add
  IL_0025:  ldind.u1
  IL_0026:  call       ""void System.Console.Write(bool)""
  IL_002b:  ldc.i4.0
  IL_002c:  conv.u
  IL_002d:  stloc.0
  IL_002e:  ret
}");

            compilation.VerifyIL("Program.Store", @"
{
  // Code size       35 (0x23)
  .maxstack  3
  .locals init (pinned bool& V_0)
  IL_0000:  ldsflda    ""s Program._fixedBufferExample""
  IL_0005:  ldflda     ""bool* s._buffer""
  IL_000a:  ldflda     ""bool s.<_buffer>e__FixedBuffer.FixedElementField""
  IL_000f:  stloc.0
  IL_0010:  ldloc.0
  IL_0011:  conv.u
  IL_0012:  dup
  IL_0013:  ldc.i4.1
  IL_0014:  stind.i1
  IL_0015:  dup
  IL_0016:  ldc.i4.8
  IL_0017:  add
  IL_0018:  ldc.i4.0
  IL_0019:  stind.i1
  IL_001a:  ldc.i4.s   10
  IL_001c:  add
  IL_001d:  ldc.i4.1
  IL_001e:  stind.i1
  IL_001f:  ldc.i4.0
  IL_0020:  conv.u
  IL_0021:  stloc.0
  IL_0022:  ret
}");
        }

        [Fact]
        public void FixedBufferUsageWith_this()
        {
            var text = @"
using System;

unsafe struct s
    {
        private fixed ushort _e_res[4]; 
        void Error_UsingFixedBuffersWithThis()
        {
            fixed (ushort* abc = this._e_res)
            {
                abc[2] = 1;
            }
        }
        
    }
";
            CompileAndVerify(text, options: TestOptions.UnsafeReleaseDll, verify: Verification.Fails);
        }

        [Fact]
        [WorkItem(547074, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547074")]
        public void FixedBufferWithNoSize()
        {
            var text = @"
unsafe struct S
{
    fixed[
}
";
            var s = CreateCompilation(text).GlobalNamespace.GetMember<TypeSymbol>("S");
            foreach (var member in s.GetMembers())
            {
                var field = member as FieldSymbol;
                if (field != null)
                {
                    Assert.Equal(0, field.FixedSize);
                    Assert.True(field.Type.IsPointerType());
                    Assert.True(field.HasPointerType);
                }
            }
        }

        [Fact()]
        [WorkItem(547030, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547030")]
        public void FixedBufferUsageDifferentAssemblies()
        {
            // Ensure fixed buffers work as expected when fixed buffer is created in different assembly to where it is consumed.
            var s1 =
@"using System;

namespace ClassLibrary1
{

    public unsafe struct FixedBufferExampleForSizes
    {
        public fixed bool _buffer[5]; // This is a fixed buffer.
    }
}";
            var s2 =
@"using System; using ClassLibrary1;

namespace ConsoleApplication30
{
    class Program
    {
        static FixedBufferExampleForSizes _fixedBufferExample = new FixedBufferExampleForSizes();

        static void Main()
        {
            // Store values in the fixed buffer.
            // ... The load the values from the fixed buffer.
            Store();
            Load();
        }

        unsafe static void Store()
        {
            // Put the fixed buffer in unmovable memory.
            // ... Then assign some elements.
            fixed (bool* buffer = _fixedBufferExample._buffer)
            {
                buffer[0] = true;
                buffer[10] = false;
            }
        }

        unsafe static void Load()
        {
            // Put in unmovable memory.
            // ... Then load some values from the memory.
            fixed (bool* buffer = _fixedBufferExample._buffer)
            {
                Console.Write(buffer[0]);
                Console.Write(buffer[10]);
            }
        }

    }
}";
            var comp1 = CompileAndVerify(s1, options: TestOptions.UnsafeReleaseDll, verify: Verification.Passes).Compilation;

            var comp2 = CompileAndVerify(s2,
                options: TestOptions.UnsafeReleaseExe, verify: Verification.Fails,
                references: new MetadataReference[] { MetadataReference.CreateFromImage(comp1.EmitToArray()) },
                expectedOutput: "TrueFalse").Compilation;

            var s3 =
@"using System; using ClassLibrary1;

namespace ConsoleApplication30
{
    class Program
    {
        static FixedBufferExampleForSizes _fixedBufferExample = new FixedBufferExampleForSizes();

        static void Main()
        {
            // Store values in the fixed buffer.
            // ... The load the values from the fixed buffer.
            Store();
            Load();
        }

        unsafe static void Store()
        {
            // Put the fixed buffer in unmovable memory.
            // ... Then assign some elements.
            fixed (bool* buffer = _fixedBufferExample._buffer)
            {
                buffer[0] = true;
                buffer[10] = false;
                buffer[1024] = true;  //Intentionally outside range
            }
        }

        unsafe static void Load()
        {
            // Put in unmovable memory.
            // ... Then load some values from the memory.
            fixed (bool* buffer = _fixedBufferExample._buffer)
            {
                Console.Write(buffer[0]);
                Console.Write(buffer[10]);
                Console.Write(buffer[1024]);
            }
        }

    }
}";

            // Only compile this as its intentionally writing outside of fixed buffer boundaries and 
            // this doesn't warn but causes flakiness when executed.
            var comp3 = CompileAndVerify(s3,
                options: TestOptions.UnsafeReleaseDll, verify: Verification.Fails,
                references: new MetadataReference[] { MetadataReference.CreateFromImage(comp1.EmitToArray()) }).Compilation;
        }

        [Fact]
        public void FixedBufferUsageSizeCheckChar()
        {
            //Determine the Correct size based upon expansion for different no of elements

            var text = @"using System;

unsafe struct FixedBufferExampleForSizes1
{
    public fixed char _buffer[1]; // This is a fixed buffer.
}
unsafe struct FixedBufferExampleForSizes2
{
    public fixed char _buffer[2]; // This is a fixed buffer.
}

unsafe struct FixedBufferExampleForSizes3
{
    public fixed char _buffer[3]; // This is a fixed buffer.
}

class Program
{
    // Reference to struct containing a fixed buffer
    static FixedBufferExampleForSizes1 _fixedBufferExample1 = new FixedBufferExampleForSizes1();
    static FixedBufferExampleForSizes2 _fixedBufferExample2 = new FixedBufferExampleForSizes2();
    static FixedBufferExampleForSizes3 _fixedBufferExample3 = new FixedBufferExampleForSizes3();  

    static unsafe void Main()
    {                      
        int x = System.Runtime.InteropServices.Marshal.SizeOf(_fixedBufferExample1);          
        Console.Write(x.ToString());
        
        x = System.Runtime.InteropServices.Marshal.SizeOf(_fixedBufferExample2);
        Console.Write(x.ToString());

        x = System.Runtime.InteropServices.Marshal.SizeOf(_fixedBufferExample3);
        Console.Write(x.ToString());
    }   
}
";
            CompileAndVerify(text, options: TestOptions.UnsafeReleaseExe, expectedOutput: @"246");
        }

        [Fact]
        public void FixedBufferUsageSizeCheckInt()
        {
            //Determine the Correct size based upon expansion for different no of elements

            var text = @"using System;

unsafe struct FixedBufferExampleForSizes1
{
    public fixed int _buffer[1]; // This is a fixed buffer.
}
unsafe struct FixedBufferExampleForSizes2
{
    public fixed int _buffer[2]; // This is a fixed buffer.
}

unsafe struct FixedBufferExampleForSizes3
{
    public fixed int _buffer[3]; // This is a fixed buffer.
}

class Program
{
    // Reference to struct containing a fixed buffer
    static FixedBufferExampleForSizes1 _fixedBufferExample1 = new FixedBufferExampleForSizes1();
    static FixedBufferExampleForSizes2 _fixedBufferExample2 = new FixedBufferExampleForSizes2();
    static FixedBufferExampleForSizes3 _fixedBufferExample3 = new FixedBufferExampleForSizes3();  

    static unsafe void Main()
    {                      
        int x = System.Runtime.InteropServices.Marshal.SizeOf(_fixedBufferExample1);          
        Console.Write(x.ToString());
        
        x = System.Runtime.InteropServices.Marshal.SizeOf(_fixedBufferExample2);
        Console.Write(x.ToString());

        x = System.Runtime.InteropServices.Marshal.SizeOf(_fixedBufferExample3);
        Console.Write(x.ToString());
    }   
}
";
            CompileAndVerify(text, options: TestOptions.UnsafeReleaseExe, expectedOutput: @"4812");
        }

        [Fact]
        public void CannotTakeAddressOfRefReadOnlyParameter()
        {
            CreateCompilation(@"
public class Test
{
    unsafe void M(in int p)
    {
        int* pointer = &p;
    }
}", options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (6,24): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         int* pointer = &p;
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&p").WithLocation(6, 24)
                );
        }

        #endregion

        [Fact]
        public void AddressOfFixedSizeBuffer()
        {
            CreateCompilation(@"
unsafe struct S
{
    public fixed int Buf[1];
}

unsafe class C
{
    static S s_f;
    void M(S s)
    {
        fixed (int* a = &s.Buf) {}
        fixed (int* b = &s_f.Buf) {}
        int* c = &s.Buf;
        int* d = &s_f.Buf;
    }
}", options: TestOptions.UnsafeDebugDll).VerifyDiagnostics(
                // (12,25): error CS0213: You cannot use the fixed statement to take the address of an already fixed expression
                //         fixed (int* a = &s.Buf) {}
                Diagnostic(ErrorCode.ERR_FixedNotNeeded, "&s.Buf").WithLocation(12, 25),
                // (13,26): error CS1666: You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement.
                //         fixed (int* b = &s_f.Buf) {}
                Diagnostic(ErrorCode.ERR_FixedBufferNotFixed, "s_f.Buf").WithLocation(13, 26),
                // (14,18): error CS0266: Cannot implicitly convert type 'int**' to 'int*'. An explicit conversion exists (are you missing a cast?)
                //         int* c = &s.Buf;
                Diagnostic(ErrorCode.ERR_NoImplicitConvCast, "&s.Buf").WithArguments("int**", "int*").WithLocation(14, 18),
                // (15,19): error CS1666: You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement.
                //         int* d = &s_f.Buf;
                Diagnostic(ErrorCode.ERR_FixedBufferNotFixed, "s_f.Buf").WithLocation(15, 19));
        }

        [Fact]
        public void FixedFixedSizeBuffer()
        {
            CreateCompilation(@"
unsafe struct S
{
    public fixed int Buf[1];
}

unsafe class C
{
    static S s_f;
    void M(S s)
    {
        fixed (int* a = s.Buf) {}
        fixed (int* b = s_f.Buf) {}
        int* c = s.Buf;
        int* d = s_f.Buf;
    }
}", options: TestOptions.UnsafeDebugDll).VerifyDiagnostics(
                // (12,25): error CS0213: You cannot use the fixed statement to take the address of an already fixed expression
                //         fixed (int* a = s.Buf) {}
                Diagnostic(ErrorCode.ERR_FixedNotNeeded, "s.Buf").WithLocation(12, 25),
                // (15,18): error CS1666: You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement.
                //         int* d = s_f.Buf;
                Diagnostic(ErrorCode.ERR_FixedBufferNotFixed, "s_f.Buf").WithLocation(15, 18));
        }

        [Fact]
        public void NoPointerDerefMoveableFixedSizeBuffer()
        {
            CreateCompilation(@"
unsafe struct S
{
    public fixed int Buf[1];
}

unsafe class C
{
    static S s_f;
    void M(S s)
    {
        int x = *s.Buf;
        int y = *s_f.Buf;
    }
}", options: TestOptions.UnsafeDebugDll).VerifyDiagnostics(
                // (13,18): error CS1666: You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement.
                //         int y = *s_f.Buf;
                Diagnostic(ErrorCode.ERR_FixedBufferNotFixed, "s_f.Buf").WithLocation(13, 18));
        }

        [Fact]
        public void AddressOfElementAccessFixedSizeBuffer()
        {
            CreateCompilation(@"
unsafe struct S
{
    public fixed int Buf[1];
}

unsafe class C
{
    static S s_f;
    void M(S s)
    {
        fixed (int* a = &s.Buf[0]) { }
        fixed (int* b = &s_f.Buf[0]) { }
        int* c = &s.Buf[0];
        int* d = &s_f.Buf[0];
        int* e = &(s.Buf[0]);
        int* f = &(s_f.Buf[0]);
    }
}", options: TestOptions.UnsafeDebugDll).VerifyDiagnostics(
                // (12,25): error CS0213: You cannot use the fixed statement to take the address of an already fixed expression
                //         fixed (int* a = &s.Buf[0]) { }
                Diagnostic(ErrorCode.ERR_FixedNotNeeded, "&s.Buf[0]").WithLocation(12, 25),
                // (15,18): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         int* d = &s_f.Buf[0];
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&s_f.Buf[0]").WithLocation(15, 18),
                // (17,18): error CS0212: You can only take the address of an unfixed expression inside of a fixed statement initializer
                //         int* f = &(s_f.Buf[0]);
                Diagnostic(ErrorCode.ERR_FixedNeeded, "&(s_f.Buf[0])").WithLocation(17, 18));
        }

        [Fact, WorkItem(34693, "https://github.com/dotnet/roslyn/issues/34693")]
        public void Repro_34693()
        {
            var csharp = @"
namespace Interop
{
    public unsafe struct PROPVARIANT
    {
        public CAPROPVARIANT ca;
    }

    public unsafe struct CAPROPVARIANT
    {
        public uint cElems;
        public PROPVARIANT* pElems;
    }
}";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAliasWithCompilationOptionOff1()
        {
            var csharp = @"
using unsafe X = int*;

class C
{
}
";
            var expectedDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int*;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int*;").WithLocation(2, 1),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = int*;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7),
            };
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void TestUnsafeAliasWithCompilationOptionOff2()
        {
            var csharp = @"
using unsafe X = int;

class C
{
}
";
            var expectedDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int;").WithLocation(2, 1),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = int;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7),
            };
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void TestUnsafeAliasCSharp11_1()
        {
            var csharp = @"
using unsafe X = int*;
";
            var comp = CreateCompilation(csharp, options: TestOptions.DebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int*;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int*;").WithLocation(2, 1),
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int*;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = int*;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7));
        }

        [Fact]
        public void TestUnsafeAliasCSharp11_2()
        {
            var csharp = @"
using unsafe X = int;
";
            var comp = CreateCompilation(csharp, options: TestOptions.DebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int;").WithLocation(2, 1),
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = int;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7));
        }

        [Fact]
        public void TestUnsafeAliasCSharp11_3()
        {
            var csharp = @"
using unsafe X = int*;
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int*;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int*;").WithLocation(2, 1),
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int*;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7));
        }

        [Fact]
        public void TestUnsafeAliasCSharp11_4()
        {
            var csharp = @"
using unsafe X = int;
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int;").WithLocation(2, 1),
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7));
        }

        [Fact]
        public void TestUnsafeAliasCSharp11_5()
        {
            var csharp = @"
using unsafe X = System.String;
";
            var comp = CreateCompilation(csharp, options: TestOptions.DebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = System.String;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = System.String;").WithLocation(2, 1),
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = System.String;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = System.String;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7));
        }

        [Fact]
        public void TestUnsafeAliasCSharp11_6()
        {
            var csharp = @"
using unsafe X = System.String;
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = System.String;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = System.String;").WithLocation(2, 1),
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = System.String;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7));
        }

        [Fact]
        public void TestUnsafeAlias1()
        {
            var csharp = @"
using unsafe X = int*;
using Y = int*;

class C
{
    void M1(X x) { }
    unsafe void M2(X x) { }

    void N1(Y y) { }
    unsafe void N2(Y y) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (3,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using Y = int*;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 11),
                // (7,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X x) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(7, 13),
                // (10,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void N1(Y y) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "Y").WithLocation(10, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias2()
        {
            var csharp = @"
using unsafe X = int*;
namespace N
{
    using Y = X;
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (5,5): hidden CS8019: Unnecessary using directive.
                //     using Y = X;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using Y = X;").WithLocation(5, 5),
                // (5,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     using Y = X;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(5, 15));

            var expectedPreviewDiagnostics = new[]
            {
                // (5,5): hidden CS8019: Unnecessary using directive.
                //     using Y = X;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using Y = X;").WithLocation(5, 5),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias3()
        {
            var csharp = @"
using unsafe X = int*;
namespace N
{
    using unsafe Y = X;
}
";
            var expectedDiagnostics = new[]
            {
                // (5,5): hidden CS8019: Unnecessary using directive.
                //     using unsafe Y = X;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe Y = X;").WithLocation(5, 5),
            };
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias5()
        {
            var csharp = @"
using X = int*;

class C
{
    void M(int* x) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = int*;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = int*;").WithLocation(2, 1),
                // (2,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = int*;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 11),
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(int* x) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 12));

            var expectedPreviewDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = int*;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = int*;").WithLocation(2, 1),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias6()
        {
            var csharp = @"
using unsafe X = int*;

class C
{
    unsafe void M((X x1, X x2) t) { }
}
";
            var expectedDiagnostics = new[]
            {
                // (6,32): error CS0306: The type 'int*' may not be used as a type argument
                //     unsafe void M((X x1, X x2) t) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "t").WithArguments("int*").WithLocation(6, 32),
                // (6,32): error CS0306: The type 'int*' may not be used as a type argument
                //     unsafe void M((X x1, X x2) t) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "t").WithArguments("int*").WithLocation(6, 32),
            };
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias7()
        {
            var csharp = @"
using unsafe X = int*;

class C
{
    unsafe void M(X[] t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias8()
        {
            var csharp = @"
using unsafe X = int*;

class C
{
    void M(X[] t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(X[] t) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 12));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias9()
        {
            var csharp = @"
using unsafe X = int*[];
";
            var expectedDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = int*[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = int*[];").WithLocation(2, 1),
            };
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias10()
        {
            var csharp = @"
using X = int*[];
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = int*[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = int*[];").WithLocation(2, 1),
                // (2,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = int*[];
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 11));

            var expectedPreviewDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = int*[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = int*[];").WithLocation(2, 1),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias11()
        {
            var csharp = @"
using unsafe X = int*[];

class C
{
    void M1(X t) { }
    unsafe void M2(X t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X t) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias13()
        {
            var csharp = @"
using unsafe X = int*[][];

class C
{
    void M1(X t) { }
    unsafe void M2(X t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X t) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias14_A()
        {
            var csharp = @"
using unsafe X = int;

class C
{
    void ThisMethodIsNotUnsafe(X x) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias14_B()
        {
            var csharp = @"
using unsafe X = int;

class C
{
    void ThisMethodIsNotUnsafe(X x) { }
}
";
            var expectedDiagnostics = new[]
            {
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = int;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7),
            };
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.DebugDll);
            comp.VerifyDiagnostics(expectedDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias1_FP()
        {
            var csharp = @"
using unsafe X = delegate*<int,int>;

class C
{
    void M1(X x) { }
    unsafe void M2(X x) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X x) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias3_FP()
        {
            var csharp = @"
using X = delegate*<int,int>;

class C
{
    void M1(X x) { }
    unsafe void M2(X x) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (2,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = delegate*<int,int>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "delegate*").WithLocation(2, 11),
                // (6,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X x) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias5_FP()
        {
            var csharp = @"
using X = delegate*<int,int>;

class C
{
    void M(int* x) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = delegate*<int,int>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = delegate*<int,int>;").WithLocation(2, 1),
                // (2,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = delegate*<int,int>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "delegate*").WithLocation(2, 11),
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(int* x) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(6, 12));

            var expectedPreviewDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = delegate*<int,int>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = delegate*<int,int>;").WithLocation(2, 1),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias6_FP()
        {
            var csharp = @"
using unsafe X = delegate*<int,int>;

class C
{
    unsafe void M1((X x1, X x2) t) { }
    unsafe void M2(X[] t) { }
    void M3(X[] t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,33): error CS0306: The type 'delegate*<int, int>' may not be used as a type argument
                //     unsafe void M1((X x1, X x2) t) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "t").WithArguments("delegate*<int, int>").WithLocation(6, 33),
                // (6,33): error CS0306: The type 'delegate*<int, int>' may not be used as a type argument
                //     unsafe void M1((X x1, X x2) t) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "t").WithArguments("delegate*<int, int>").WithLocation(6, 33),
                // (8,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M3(X[] t) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(8, 13));

            var expectedPreviewDiagnostics = new[]
            {
                // (6,33): error CS0306: The type 'delegate*<int, int>' may not be used as a type argument
                //     unsafe void M1((X x1, X x2) t) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "t").WithArguments("delegate*<int, int>").WithLocation(6, 33),
                // (6,33): error CS0306: The type 'delegate*<int, int>' may not be used as a type argument
                //     unsafe void M1((X x1, X x2) t) { }
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "t").WithArguments("delegate*<int, int>").WithLocation(6, 33),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias9_FP()
        {
            var csharp = @"
using unsafe X = delegate*<int,int>[];
using Y = delegate*<int,int>[];
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = delegate*<int,int>[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = delegate*<int,int>[];").WithLocation(2, 1),
                // (3,1): hidden CS8019: Unnecessary using directive.
                // using Y = delegate*<int,int>[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using Y = delegate*<int,int>[];").WithLocation(3, 1),
                // (3,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using Y = delegate*<int,int>[];
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "delegate*").WithLocation(3, 11));

            var expectedPreviewDiagnostics = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = delegate*<int,int>[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = delegate*<int,int>[];").WithLocation(2, 1),
                // (3,1): hidden CS8019: Unnecessary using directive.
                // using Y = delegate*<int,int>[];
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using Y = delegate*<int,int>[];").WithLocation(3, 1),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact]
        public void TestUnsafeAlias11_FP()
        {
            var csharp = @"
using unsafe X = delegate*<int,int>[];

class C
{
    void M1(X t) { }
    unsafe void M2(X t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X t) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void TestUnsafeAlias13_FP()
        {
            var csharp = @"
using unsafe X = delegate*<int,int>[][];

class C
{
    void M1(X t) { }
    unsafe void M2(X t) { }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,13): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M1(X t) { }
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 13));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void UsingAlias_Multiple()
        {
            var src1 = """
                #pragma warning disable CS8019 // unnecessary using
                using unsafe X = System.Collections.Generic.List<int*[]>;
                using Y = System.Collections.Generic.List<long*[]>;
                """;
            CreateCompilation(src1,
                parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using Y = System.Collections.Generic.List<long*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*").WithLocation(3, 43));

            CreateCompilation(src1, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(src1, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();

            var src2 = """
                #pragma warning disable CS8019 // unnecessary using
                using X = System.Collections.Generic.List<int*[]>;
                using unsafe Y = System.Collections.Generic.List<long*[]>;
                """;
            CreateCompilation(src2,
                parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43));

            CreateCompilation(src2, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(src2, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/82426")]
        public void UsingStatic_Multiple()
        {
            var src1 = """
                #pragma warning disable CS8019 // unnecessary using
                using static unsafe System.Collections.Generic.List<int*[]>;
                using static System.Collections.Generic.List<long*[]>;
                """;
            CreateCompilation(src1,
                parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,46): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using static System.Collections.Generic.List<long*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "long*").WithLocation(3, 46));

            CreateCompilation(src1, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(src1, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();

            var src2 = """
                #pragma warning disable CS8019 // unnecessary using
                using static System.Collections.Generic.List<int*[]>;
                using static unsafe System.Collections.Generic.List<long*[]>;
                """;
            CreateCompilation(src2,
                parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (2,46): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using static System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 46));

            CreateCompilation(src2, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
            CreateCompilation(src2, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
        }

        [Fact]
        public void TestStructWithReferenceToItselfThroughAliasPointer1()
        {
            var csharp = @"
using unsafe X = S*;

unsafe struct S
{
    X x;
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,7): warning CS0169: The field 'S.x' is never used
                //     X x;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "x").WithArguments("S.x").WithLocation(6, 7));

            Assert.Equal(ManagedKind.Unmanaged, comp.GlobalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);

            // Try again with a fresh compilation, without having done anything to pull on this type.
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            Assert.Equal(ManagedKind.Unmanaged, comp.GlobalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            Assert.Equal(ManagedKind.Unmanaged, comp.GlobalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);
        }

        [Fact]
        public void TestStructWithReferenceToItselfThroughAliasPointer2()
        {
            var csharp = @"
using unsafe X = S*;

unsafe struct S
{
    X x;
}

class C
{
    void M(S s)
    {
        N<S>(s);
    }

    void N<T>(T t) where T : unmanaged { }
}

";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyDiagnostics(
                // (6,7): warning CS0169: The field 'S.x' is never used
                //     X x;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "x").WithArguments("S.x").WithLocation(6, 7));

            Assert.Equal(ManagedKind.Unmanaged, comp.GlobalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);

            // Try again with a fresh compilation, without having done anything to pull on this type.
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            Assert.Equal(ManagedKind.Unmanaged, comp.GlobalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            Assert.Equal(ManagedKind.Unmanaged, comp.GlobalNamespace.GetMember<NamedTypeSymbol>("S").ManagedKindNoUseSiteDiagnostics);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void AliasToGenericOfPointers()
        {
            var csharp = @"
using X = System.Collections.Generic.List<int*>;
";
            var expectedCSharp11 = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = System.Collections.Generic.List<int*>;").WithLocation(2, 1),
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7)
            };

            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(expectedCSharp11);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(expectedCSharp11);

            var expected = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = System.Collections.Generic.List<int*>;").WithLocation(2, 1),
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43)
            };

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(expected);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void AliasToGenericOfPointers_UseSiteWithoutUnsafeContext()
        {
            var csharp = @"
using X = System.Collections.Generic.List<int*>;

class C
{
    void M(X x)
    {
    }
}
";
            var expectedCSharp11 = new[]
            {
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 12),
                // (6,14): error CS0306: The type 'int*' may not be used as a type argument
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "x").WithArguments("int*").WithLocation(6, 14)
            };

            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(expectedCSharp11);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(expectedCSharp11);

            var expected = new[]
            {
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43),
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 12),
                // (6,14): error CS0306: The type 'int*' may not be used as a type argument
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "x").WithArguments("int*").WithLocation(6, 14)
            };

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(expected);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void AliasToGenericOfPointers_UseSiteWithUnsafeContext()
        {
            var csharp = @"
using X = System.Collections.Generic.List<int*>;

class C
{
    unsafe void M(X x)
    {
    }
}
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (6,21): error CS0306: The type 'int*' may not be used as a type argument
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "x").WithArguments("int*").WithLocation(6, 21));

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (6,17): error CS0227: Unsafe code may only appear if compiling with /unsafe
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "M").WithLocation(6, 17),
                // (6,21): error CS0306: The type 'int*' may not be used as a type argument
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "x").WithArguments("int*").WithLocation(6, 21));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43),
                // (6,21): error CS0306: The type 'int*' may not be used as a type argument
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "x").WithArguments("int*").WithLocation(6, 21));

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(
                // (2,7): error CS0306: The type 'int*' may not be used as a type argument
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "X").WithArguments("int*").WithLocation(2, 7),
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43),
                // (6,17): error CS0227: Unsafe code may only appear if compiling with /unsafe
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "M").WithLocation(6, 17),
                // (6,21): error CS0306: The type 'int*' may not be used as a type argument
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_BadTypeArgument, "x").WithArguments("int*").WithLocation(6, 21));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void AliasToGenericOfArrayOfPointers()
        {
            // legal in C# 11 for back compat reasons.
            var csharp = @"
using X = System.Collections.Generic.List<int*[]>;
";
            var expectedCSharp11 = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = System.Collections.Generic.List<int*[]>;").WithLocation(2, 1)
            };
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(expectedCSharp11);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(expectedCSharp11);

            var expected = new[]
            {
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using X = System.Collections.Generic.List<int*[]>;").WithLocation(2, 1),
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43)
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics(expectedCSharp11);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics(expectedCSharp11);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics(expectedCSharp11);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics(expectedCSharp11);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void AliasToGenericOfArrayOfPointers_UseSiteWithoutUnsafeContext()
        {
            var csharp = @"
using X = System.Collections.Generic.List<int*[]>;

class C
{
    void M(X x)
    {
    }
}
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 12));

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 12));

            var expected = new[]
            {
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43),
                // (6,12): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void M(X x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 12)
            };

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics();
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void AliasToGenericOfArrayOfPointers_UseSiteInUnsafeContext()
        {
            var csharp = @"
using X = System.Collections.Generic.List<int*[]>;

class C
{
    unsafe void M(X x)
    {
    }
}
";
            var illegalUnsafe = new[]
            {
                // (6,17): error CS0227: Unsafe code may only appear if compiling with /unsafe
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "M").WithLocation(6, 17),
            };
            var unsafeNeeded = new[]
            {
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43),
            };

            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(illegalUnsafe);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(unsafeNeeded);

            comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(
                // (2,43): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                // using X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(2, 43),
                // (6,17): error CS0227: Unsafe code may only appear if compiling with /unsafe
                //     unsafe void M(X x)
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "M").WithLocation(6, 17));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics(illegalUnsafe);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics(illegalUnsafe);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void UnsafeAliasToGenericOfArrayOfPointers()
        {
            var csharp = @"
using unsafe X = System.Collections.Generic.List<int*[]>;
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = System.Collections.Generic.List<int*[]>;").WithLocation(2, 1));

            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics(
                // (2,1): hidden CS8019: Unnecessary using directive.
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using unsafe X = System.Collections.Generic.List<int*[]>;").WithLocation(2, 1),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void UnsafeAliasToGenericOfArrayOfPointers_UseSiteWithoutUnsafeContext()
        {
            var csharp = @"
using unsafe X = System.Collections.Generic.List<int*[]>;

class C
{
    X M(X x) => throw null; // 1
    void M2()
    {
        X x = null; // 2
        x.ToString();
        var y = X (X x) => throw null; // 3
        y = delegate { throw null; }; // 4
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7),
                // (6,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 5),
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 9),
                // (9,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         X x = null; // 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(9, 9),
                // (11,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 17),
                // (11,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 20),
                // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(11, 22),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y").WithLocation(12, 9),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y = delegate { throw null; }").WithLocation(12, 9));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (6,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 5),
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 9),
                // (9,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         X x = null; // 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(9, 9),
                // (11,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 17),
                // (11,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 20),
                // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(11, 22),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y").WithLocation(12, 9),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y = delegate { throw null; }").WithLocation(12, 9));

            var expected = new[]
            {
                // (6,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 5),
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 9),
                // (9,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         X x = null; // 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(9, 9),
                // (11,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 17),
                // (11,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 20),
                // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(11, 22),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y").WithLocation(12, 9),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y = delegate { throw null; }").WithLocation(12, 9)
            };

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics();
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void UnsafeAliasToGenericOfArrayOfPointers_UseSiteWithoutUnsafeContext_ArrayOfPointers()
        {
            var csharp = @"
using unsafe X = int*[];

class C
{
    X M(X x) => throw null; // 1
    void M2()
    {
        X x = null; // 2
        x.ToString();
        var y = X (X x) => throw null; // 3
        y = delegate { throw null; }; // 4
        var z = int*[] (int*[] x) => throw null; // 5
    }
}
";

            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int*[];
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = int*[];
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7),
                // (6,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 5),
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 9),
                // (9,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         X x = null; // 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(9, 9),
                // (11,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 17),
                // (11,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 20),
                // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(11, 22),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y").WithLocation(12, 9),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y = delegate { throw null; }").WithLocation(12, 9),
                // (13,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 17),
                // (13,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 25),
                // (13,32): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(13, 32));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int*[];
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (6,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 5),
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 9),
                // (9,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         X x = null; // 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(9, 9),
                // (11,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 17),
                // (11,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 20),
                // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(11, 22),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y").WithLocation(12, 9),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y = delegate { throw null; }").WithLocation(12, 9),
                // (13,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 17),
                // (13,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 25),
                // (13,32): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(13, 32));

            var expected = new[]
            {
                // (6,5): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 5),
                // (6,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     X M(X x) => throw null; // 1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(6, 9),
                // (9,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         X x = null; // 2
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(9, 9),
                // (11,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 17),
                // (11,20): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "X").WithLocation(11, 20),
                // (11,22): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var y = X (X x) => throw null; // 3
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(11, 22),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y").WithLocation(12, 9),
                // (12,9): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         y = delegate { throw null; }; // 4
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "y = delegate { throw null; }").WithLocation(12, 9),
                // (13,17): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 17),
                // (13,25): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(13, 25),
                // (13,32): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //         var z = int*[] (int*[] x) => throw null; // 5
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "x").WithLocation(13, 32)
            };

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular14);
            comp.VerifyDiagnostics(expected);

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularNext);
            comp.VerifyDiagnostics();
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void UnsafeAliasToGenericOfArrayOfPointers_UseSiteWithUnsafeContext()
        {
            var csharp = @"
using unsafe X = System.Collections.Generic.List<int*[]>;

unsafe class C
{
    X M(X x) => throw null;
    void M2()
    {
        X x = null;
        x.ToString();
        var y = X (X x) => throw null; // 4, 5
        y = delegate { throw null; };
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7),
                // (2,7): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "unsafe").WithLocation(2, 7),
                // (4,14): error CS0227: Unsafe code may only appear if compiling with /unsafe
                // unsafe class C
                Diagnostic(ErrorCode.ERR_IllegalUnsafe, "C").WithLocation(4, 14));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = System.Collections.Generic.List<int*[]>;
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7));

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/67281")]
        public void UnsafeAliasToGenericOfArrayOfPointers_UseSiteWithUnsafeContext_ArrayOfPointers()
        {
            var csharp = @"
using unsafe X = int*[];

unsafe class C
{
    X M(X x) => throw null;
    void M2()
    {
        X x = null;
        x.ToString();
        var y = X (X x) => throw null;
        y = delegate { throw null; };
        var z = int*[] (int*[] x) => throw null;
    }
}
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular11);
            comp.VerifyDiagnostics(
                // (2,7): error CS9058: Feature 'using type alias' is not available in C# 11.0. Please use language version 12.0 or greater.
                // using unsafe X = int*[];
                Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion11, "unsafe").WithArguments("using type alias", "12.0").WithLocation(2, 7)
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.Regular12);
            comp.VerifyDiagnostics();

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, parseOptions: TestOptions.RegularPreview);
            comp.VerifyDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_01()
        {
            var csharp = @"
interface ITest<T>
{
    void Method();
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    unsafe void ITest<void*[]>.Method()
    {

    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_02()
        {
            var csharp = @"
interface ITest<T>
{
    int P1 {get;}
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    unsafe int ITest<void*[]>.P1
    {
        get;
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_03()
        {
            var csharp = @"
interface ITest<T>
{
    int this[int i] {get;}
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    unsafe int ITest<void*[]>.this[int i]
    {
        get => 0;
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_04()
        {
            var csharp = @"
interface ITest<T>
{
    event System.Action E1;
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    unsafe event System.Action ITest<void*[]>.E1
    {
        add{}
        remove{}    
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_05()
        {
            var csharp = @"
interface ITest<T>
{
    abstract static ITest<T> operator-(ITest<T> x);
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    static unsafe ITest<void*[]> ITest<void*[]>.operator-(ITest<void*[]> x)
    {
        return null;
    }
}
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_06()
        {
            var csharp = @"
interface ITest<T>
{
    abstract static implicit operator int(ITest<T> x);
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    static unsafe implicit ITest<void*[]>.operator int(ITest<void*[]> x)
    {
        return 0;
    }
}
";
            var comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics(
                // (4,39): error CS0552: 'ITest<T>.implicit operator int(ITest<T>)': user-defined conversions to or from an interface are not allowed
                //     abstract static implicit operator int(ITest<T> x);
                Diagnostic(ErrorCode.ERR_ConversionWithInterface, "int").WithArguments("ITest<T>.implicit operator int(ITest<T>)").WithLocation(4, 39)
                );
        }

        [Fact]
        public void ExplicitImplementation_07()
        {
            var csharp = @"
interface ITest<T>
{
    void Method();
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    void ITest<void*[]>.Method()
    {

    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                // (14,16): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     void ITest<void*[]>.Method()
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 16)
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_08()
        {
            var csharp = @"
interface ITest<T>
{
    int P1 {get;}
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    int ITest<void*[]>.P1
    {
        get;
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                // (14,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     int ITest<void*[]>.P1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 15)
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_09()
        {
            var csharp = @"
interface ITest<T>
{
    int this[int i] {get;}
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    int ITest<void*[]>.this[int i]
    {
        get => 0;
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                // (14,15): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     int ITest<void*[]>.this[int i]
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 15)
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_10()
        {
            var csharp = @"
interface ITest<T>
{
    event System.Action E1;
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    event System.Action ITest<void*[]>.E1
    {
        add{}
        remove{}    
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics(
                // (14,31): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     event System.Action ITest<void*[]>.E1
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 31)
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_11()
        {
            var csharp = @"
interface ITest<T>
{
    abstract static ITest<T> operator-(ITest<T> x);
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    static ITest<void*[]> ITest<void*[]>.operator-(ITest<void*[]> x)
    {
        return null;
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics(
                // (14,18): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     static ITest<void*[]> ITest<void*[]>.operator-(ITest<void*[]> x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 18),
                // (14,33): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     static ITest<void*[]> ITest<void*[]>.operator-(ITest<void*[]> x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 33),
                // (14,58): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     static ITest<void*[]> ITest<void*[]>.operator-(ITest<void*[]> x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 58)
                );

            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics();
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics();
        }

        [Fact]
        public void ExplicitImplementation_12()
        {
            var csharp = @"
interface ITest<T>
{
    abstract static implicit operator int(ITest<T> x);
}

unsafe interface IPointerTest : ITest<void*[]>
{

}

class PointerImpl : IPointerTest
{
    static implicit ITest<void*[]>.operator int(ITest<void*[]> x)
    {
        return 0;
    }
}
";
            var comp = CreateCompilation(csharp, parseOptions: TestOptions.Regular14, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics(
                // (4,39): error CS0552: 'ITest<T>.implicit operator int(ITest<T>)': user-defined conversions to or from an interface are not allowed
                //     abstract static implicit operator int(ITest<T> x);
                Diagnostic(ErrorCode.ERR_ConversionWithInterface, "int").WithArguments("ITest<T>.implicit operator int(ITest<T>)").WithLocation(4, 39),
                // (14,27): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     static implicit ITest<void*[]>.operator int(ITest<void*[]> x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 27),
                // (14,55): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                //     static implicit ITest<void*[]>.operator int(ITest<void*[]> x)
                Diagnostic(ErrorCode.ERR_UnsafeNeeded, "void*").WithLocation(14, 55)
                );

            var expectedPreviewDiagnostics = new[]
            {
                // (4,39): error CS0552: 'ITest<T>.implicit operator int(ITest<T>)': user-defined conversions to or from an interface are not allowed
                //     abstract static implicit operator int(ITest<T> x);
                Diagnostic(ErrorCode.ERR_ConversionWithInterface, "int").WithArguments("ITest<T>.implicit operator int(ITest<T>)").WithLocation(4, 39),
            };
            comp = CreateCompilation(csharp, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics(expectedPreviewDiagnostics);
            comp = CreateCompilation(csharp, parseOptions: TestOptions.RegularNext, options: TestOptions.UnsafeDebugDll, targetFramework: TargetFramework.NetCoreApp);
            comp.VerifyEmitDiagnostics(expectedPreviewDiagnostics);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
        public void PointerToNonExistentType_NoSuperfluousError()
        {
            var source = """
                class Program
                {
                    static unsafe void Method(Type* type)
                    {
                    }
                }
                """;
            CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,31): error CS0246: The type or namespace name 'Type' could not be found (are you missing a using directive or an assembly reference?)
                //     static unsafe void Method(Type* type)
                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type").WithArguments("Type").WithLocation(3, 31));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
        public void PointerToInaccessibleType()
        {
            var source = """
                class X { class Y { } }

                class Program
                {
                    static unsafe void Method(X.Y* y)
                    {
                    }
                }
                """;
            CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,33): error CS0122: 'X.Y' is inaccessible due to its protection level
                //     static unsafe void Method(X.Y* y)
                Diagnostic(ErrorCode.ERR_BadAccess, "Y").WithArguments("X.Y").WithLocation(5, 33),
                // (5,36): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('X.Y')
                //     static unsafe void Method(X.Y* y)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "y").WithArguments("X.Y").WithLocation(5, 36));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
        public void PointerToWrongArity()
        {
            var source = """
                class X { }

                class Program
                {
                    static unsafe void Method(X<int>* y)
                    {
                    }
                }
                """;
            CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,31): error CS0308: The non-generic type 'X' cannot be used with type arguments
                //     static unsafe void Method(X<int>* y)
                Diagnostic(ErrorCode.ERR_HasNoTypeVars, "X<int>").WithArguments("X", "type").WithLocation(5, 31),
                // (5,39): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('X<int>')
                //     static unsafe void Method(X<int>* y)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "y").WithArguments("X<int>").WithLocation(5, 39));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
        public void PointerToNonExistentType_MultiplePointers()
        {
            var source = """
                class Program
                {
                    static unsafe void Method(Type1* p1, Type2** p2)
                    {
                    }
                }
                """;
            CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,31): error CS0246: The type or namespace name 'Type1' could not be found (are you missing a using directive or an assembly reference?)
                //     static unsafe void Method(Type1* p1, Type2** p2)
                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type1").WithArguments("Type1").WithLocation(3, 31),
                // (3,42): error CS0246: The type or namespace name 'Type2' could not be found (are you missing a using directive or an assembly reference?)
                //     static unsafe void Method(Type1* p1, Type2** p2)
                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type2").WithArguments("Type2").WithLocation(3, 42));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/36877")]
        public void PointerToNonExistentType_LocalVariable()
        {
            var source = """
                unsafe class Program
                {
                    static void Method()
                    {
                        Type* local;
                    }
                }
                """;
            CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,9): error CS0246: The type or namespace name 'Type' could not be found (are you missing a using directive or an assembly reference?)
                //         Type* local;
                Diagnostic(ErrorCode.ERR_SingleTypeNameNotFound, "Type").WithArguments("Type").WithLocation(5, 9),
                // (5,15): warning CS0168: The variable 'local' is declared but never used
                //         Type* local;
                Diagnostic(ErrorCode.WRN_UnreferencedVar, "local").WithArguments("local").WithLocation(5, 15));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/38378")]
        public void PointerToExistingManagedType_StillReportsError()
        {
            var source = """
                unsafe class Program
                {
                    static void Method(string* str)
                    {
                    }
                }
                """;
            CreateCompilation(source, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,32): warning CS8500: This takes the address of, gets the size of, or declares a pointer to a managed type ('string')
                //     static void Method(string* str)
                Diagnostic(ErrorCode.WRN_ManagedAddr, "str").WithArguments("string").WithLocation(3, 32));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/44088")]
        public void PointerTypeInTypeParameter_Field_RequiresUnsafeContext()
        {
            var code = """
                class C<T>
                {
                    C<int*[]> field;
                }
                """;

            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll,
                [
                    // (3,7): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //     C<int*[]> field;
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(3, 7),
                    // (3,15): warning CS0169: The field 'C<T>.field' is never used
                    //     C<int*[]> field;
                    Diagnostic(ErrorCode.WRN_UnreferencedField, "field").WithArguments("C<T>.field").WithLocation(3, 15)
                ]);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/44088")]
        public void PointerTypeInTypeParameter_Field_UnsafeModifierRemovesUnsafeNeededError()
        {
            var code = """
                unsafe class C<T>
                {
                    C<int*[]> field;
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (3,15): warning CS0169: The field 'C<T>.field' is never used
                //     C<int*[]> field;
                Diagnostic(ErrorCode.WRN_UnreferencedField, "field").WithArguments("C<T>.field").WithLocation(3, 15));
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/44088")]
        public void PointerTypeInTypeParameter_Variable_RequiresUnsafeContext()
        {
            var code = """
                class C<T>
                {
                    void M()
                    {
                        C<int*[]> c = null;
                    }
                }
                """;

            VerifyUnsafeContextDiagnostics(code, TestOptions.UnsafeReleaseDll,
                [
                    // (5,11): error CS0214: Pointers and fixed size buffers may only be used in an unsafe context
                    //         C<int*[]> c = null;
                    Diagnostic(ErrorCode.ERR_UnsafeNeeded, "int*").WithLocation(5, 11),
                    // (5,19): warning CS0219: The variable 'c' is assigned but its value is never used
                    //         C<int*[]> c = null;
                    Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "c").WithArguments("c").WithLocation(5, 19)
                ]);
        }

        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/44088")]
        public void PointerTypeInTypeParameter_Variable_UnsafeModifierRemovesUnsafeNeededError()
        {
            var code = """
                unsafe class C<T>
                {
                    void M()
                    {
                        C<int*[]> c = null;
                    }
                }
                """;

            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                // (5,19): warning CS0219: The variable 'c' is assigned but its value is never used
                //         C<int*[]> c = null;
                Diagnostic(ErrorCode.WRN_UnreferencedVarAssg, "c").WithArguments("c").WithLocation(5, 19));
        }
    }
}
