// 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.

using System;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Microsoft.CodeAnalysis.CSharp.Symbols;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.CSharp
{
    internal sealed partial class LocalRewriter
    {
        /// <summary>
        /// This rewriter lowers pre-/post- increment/decrement operations (initially represented as
        /// unary operators). We use BoundSequenceExpressions because we need to capture the RHS of the
        /// assignment in a temp variable.
        /// </summary>
        /// <remarks>
        /// This rewriter assumes that it will be run before decimal rewriting (so that it does not have
        /// to lower decimal constants and operations) and call rewriting (so that it does not have to
        /// lower property accesses).
        /// </remarks>
        public override BoundNode VisitUnaryOperator(BoundUnaryOperator node)
        {
            switch (node.OperatorKind.Operator())
            {
                case UnaryOperatorKind.PrefixDecrement:
                case UnaryOperatorKind.PrefixIncrement:
                case UnaryOperatorKind.PostfixDecrement:
                case UnaryOperatorKind.PostfixIncrement:
                    Debug.Assert(false); // these should have been represented as a BoundIncrementOperator
                    return base.VisitUnaryOperator(node);
            }

            // TODO(tomat): We need to pass a parent operator kind into binary operator visitor.
            // We circumvent logic in VisitExpression. The extra logic doesn't apply under these conditions so we are ok. 
            // This is a bit fragile however. Consider refactoring VisitExpression.

            if (node.Operand.Kind == BoundKind.BinaryOperator)
            {
                // Optimization:
                // Binary operator lowering combines the binary operator with IsTrue/IsFalse more efficiently than we can do here.

                var binaryOperator = (BoundBinaryOperator)node.Operand;
                if (node.OperatorKind == UnaryOperatorKind.DynamicTrue && binaryOperator.OperatorKind == BinaryOperatorKind.DynamicLogicalOr ||
                    node.OperatorKind == UnaryOperatorKind.DynamicFalse && binaryOperator.OperatorKind == BinaryOperatorKind.DynamicLogicalAnd)
                {
                    return VisitBinaryOperator(binaryOperator, applyParentUnaryOperator: node);
                }
            }

            BoundExpression loweredOperand = VisitExpression(node.Operand);
            return MakeUnaryOperator(node, node.OperatorKind, node.Syntax, node.MethodOpt, node.ConstrainedToTypeOpt, loweredOperand, node.Type);
        }

        private BoundExpression MakeUnaryOperator(
            UnaryOperatorKind kind,
            SyntaxNode syntax,
            MethodSymbol? method,
            TypeSymbol? constrainedToTypeOpt,
            BoundExpression loweredOperand,
            TypeSymbol type)
        {
            return MakeUnaryOperator(null, kind, syntax, method, constrainedToTypeOpt, loweredOperand, type);
        }

        private BoundExpression MakeUnaryOperator(
            BoundUnaryOperator? oldNode,
            UnaryOperatorKind kind,
            SyntaxNode syntax,
            MethodSymbol? method,
            TypeSymbol? constrainedToTypeOpt,
            BoundExpression loweredOperand,
            TypeSymbol type)
        {
            if (kind.IsDynamic())
            {
                Debug.Assert((kind == UnaryOperatorKind.DynamicTrue || kind == UnaryOperatorKind.DynamicFalse) && type.SpecialType == SpecialType.System_Boolean
                    || type.IsDynamic());
                Debug.Assert(method is null);

                // Logical operators on boxed Boolean constants:
                var constant = UnboxConstant(loweredOperand);
                if (constant == ConstantValue.True || constant == ConstantValue.False)
                {
                    switch (kind)
                    {
                        case UnaryOperatorKind.DynamicTrue:
                            return _factory.Literal(constant.BooleanValue);
                        case UnaryOperatorKind.DynamicLogicalNegation:
                            return MakeConversionNode(_factory.Literal(!constant.BooleanValue), type, @checked: false);
                    }
                }

                return _dynamicFactory.MakeDynamicUnaryOperator(kind, loweredOperand, type).ToExpression();
            }
            else if (kind.IsLifted())
            {
                if (!_inExpressionLambda)
                {
                    return LowerLiftedUnaryOperator(kind, syntax, method, constrainedToTypeOpt, loweredOperand, type);
                }
            }
            else if (kind.IsUserDefined())
            {
                Debug.Assert(method is { });
                Debug.Assert(TypeSymbol.Equals(type, method.ReturnType, TypeCompareKind.ConsiderEverything2));
                if (!_inExpressionLambda || kind == UnaryOperatorKind.UserDefinedTrue || kind == UnaryOperatorKind.UserDefinedFalse)
                {
                    return BoundCall.Synthesized(
                        syntax,
                        receiverOpt: constrainedToTypeOpt is null ? null : new BoundTypeExpression(syntax, aliasOpt: null, constrainedToTypeOpt),
                        initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown,
                        method,
                        loweredOperand);
                }
            }
            else if (kind.Operator() == UnaryOperatorKind.UnaryPlus)
            {
                // We do not call the operator even for decimal; we simply optimize it away entirely.
                return loweredOperand;
            }

            if (kind == UnaryOperatorKind.EnumBitwiseComplement)
            {
                var underlyingType = loweredOperand.Type.GetEnumUnderlyingType();
                Debug.Assert(underlyingType is { });
                var upconvertSpecialType = Binder.GetEnumPromotedType(underlyingType.SpecialType);
                var upconvertType = upconvertSpecialType == underlyingType.SpecialType ?
                    underlyingType :
                    _compilation.GetSpecialType(upconvertSpecialType);

                var newOperand = MakeConversionNode(loweredOperand, upconvertType, false);
                UnaryOperatorKind newKind = kind.Operator().WithType(upconvertSpecialType);

                var newNode = (oldNode != null) ?
                    oldNode.Update(
                        newKind,
                        newOperand,
                        oldNode.ConstantValueOpt,
                        methodOpt: method,
                        constrainedToTypeOpt: constrainedToTypeOpt,
                        newOperand.ResultKind,
                        upconvertType) :
                    new BoundUnaryOperator(
                        syntax,
                        newKind,
                        newOperand,
                        null,
                        methodOpt: method,
                        constrainedToTypeOpt: constrainedToTypeOpt,
                        LookupResultKind.Viable,
                        upconvertType);

                return MakeConversionNode(newNode.Syntax, newNode, Conversion.ExplicitEnumeration, type, @checked: false);
            }

            if (kind == UnaryOperatorKind.DecimalUnaryMinus)
            {
                method = (MethodSymbol)_compilation.Assembly.GetSpecialTypeMember(SpecialMember.System_Decimal__op_UnaryNegation);
                if (!_inExpressionLambda)
                {
                    return BoundCall.Synthesized(syntax, receiverOpt: null, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, method, loweredOperand);
                }
            }

            return (oldNode != null) ?
                oldNode.Update(kind, loweredOperand, oldNode.ConstantValueOpt, methodOpt: method, constrainedToTypeOpt: constrainedToTypeOpt, oldNode.ResultKind, type) :
                new BoundUnaryOperator(syntax, kind, loweredOperand, null, methodOpt: method, constrainedToTypeOpt: constrainedToTypeOpt, LookupResultKind.Viable, type);
        }

        private BoundExpression LowerLiftedUnaryOperator(
            UnaryOperatorKind kind,
            SyntaxNode syntax,
            MethodSymbol? method,
            TypeSymbol? constrainedToTypeOpt,
            BoundExpression loweredOperand,
            TypeSymbol type)
        {
            // First, an optimization. If we know that the operand is always null then
            // we can simply lower to the alternative.

            BoundExpression? optimized = OptimizeLiftedUnaryOperator(kind, syntax, method, constrainedToTypeOpt, loweredOperand, type);
            if (optimized != null)
            {
                return optimized;
            }

            // We do not know whether the operand is null or non-null, so we generate:
            //
            // S? temp = operand;
            // R? r = temp.HasValue ? 
            //        new R?(OP(temp.GetValueOrDefault())) :
            //        default(R?);

            BoundAssignmentOperator tempAssignment;
            BoundLocal boundTemp = _factory.StoreToTemp(loweredOperand, out tempAssignment);
            MethodSymbol getValueOrDefault = UnsafeGetNullableMethod(syntax, boundTemp.Type, SpecialMember.System_Nullable_T_GetValueOrDefault);

            // temp.HasValue
            BoundExpression condition = _factory.MakeNullableHasValue(syntax, boundTemp);

            // temp.GetValueOrDefault()
            BoundExpression call_GetValueOrDefault = BoundCall.Synthesized(syntax, boundTemp, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, getValueOrDefault);

            // new R?(temp.GetValueOrDefault())
            BoundExpression consequence = GetLiftedUnaryOperatorConsequence(kind, syntax, method, constrainedToTypeOpt, type, call_GetValueOrDefault);

            // default(R?)
            BoundExpression alternative = new BoundDefaultExpression(syntax, type);

            // temp.HasValue ? 
            //          new R?(OP(temp.GetValueOrDefault())) : 
            //          default(R?);
            BoundExpression conditionalExpression = RewriteConditionalOperator(
                syntax: syntax,
                rewrittenCondition: condition,
                rewrittenConsequence: consequence,
                rewrittenAlternative: alternative,
                constantValueOpt: null,
                rewrittenType: type,
                isRef: false);

            // temp = operand; 
            // temp.HasValue ? 
            //          new R?(OP(temp.GetValueOrDefault())) : 
            //          default(R?);
            return new BoundSequence(
                syntax: syntax,
                locals: ImmutableArray.Create<LocalSymbol>(boundTemp.LocalSymbol),
                sideEffects: ImmutableArray.Create<BoundExpression>(tempAssignment),
                value: conditionalExpression,
                type: type);
        }

        private BoundExpression? OptimizeLiftedUnaryOperator(
            UnaryOperatorKind operatorKind,
            SyntaxNode syntax,
            MethodSymbol? method,
            TypeSymbol? constrainedToTypeOpt,
            BoundExpression loweredOperand,
            TypeSymbol type)
        {
            if (NullableNeverHasValue(loweredOperand))
            {
                return new BoundDefaultExpression(syntax, type);
            }

            // Second, another simple optimization. If we know that the operand is never null
            // then we can obtain the non-null value and skip generating the temporary. That is,
            // "~(new int?(M()))" is the same as "new int?(~M())".

            BoundExpression? neverNull = NullableAlwaysHasValue(loweredOperand);
            if (neverNull != null)
            {
                return GetLiftedUnaryOperatorConsequence(operatorKind, syntax, method, constrainedToTypeOpt, type, neverNull);
            }

            var conditionalLeft = loweredOperand as BoundLoweredConditionalAccess;

            // NOTE: we could in theory handle side-effecting loweredRight here too
            //       by including it as a part of whenNull, but there is a concern 
            //       that it can lead to code duplication
            var optimize = conditionalLeft != null &&
                (conditionalLeft.WhenNullOpt == null || conditionalLeft.WhenNullOpt.IsDefaultValue());

            if (optimize)
            {
                var result = LowerLiftedUnaryOperator(operatorKind, syntax, method, constrainedToTypeOpt, conditionalLeft!.WhenNotNull, type);
                Debug.Assert(result.Type is { });

                return conditionalLeft.Update(
                    conditionalLeft.Receiver,
                    conditionalLeft.HasValueMethodOpt,
                    whenNotNull: result,
                    whenNullOpt: null,
                    id: conditionalLeft.Id,
                    forceCopyOfNullableValueType: conditionalLeft.ForceCopyOfNullableValueType,
                    type: result.Type
                );
            }

            // This optimization is analogous to DistributeLiftedConversionIntoLiftedOperand.

            // Suppose we have a lifted unary conversion whose operand is itself a lifted operation.
            // That is, we have something like:
            //
            // int? r = - (M() + N());
            // 
            // where M() and N() return nullable ints. We would simply codegen this as first
            // creating the nullable int result of M() + N(), then checking it for nullity,
            // and then doing the unary minus. That is:
            //
            // int? m = M();
            // int? n = N();
            // int? t = m.HasValue && n.HasValue ? new int?(m.Value + n.Value) : new int?();
            // int? r = t.HasValue ? new int?(-t.Value) : new int?();
            //
            // However, we also observe that we can distribute the unary minus into both branches of
            // the conditional:
            //
            // int? m = M();
            // int? n = N();
            // int? r = m.HasValue && n.HasValue ? - (new int?(m.Value + n.Value))) : - new int?();
            //
            // And we already optimize those! So we could reduce this to:
            //
            // int? m = M();
            // int? n = N();
            // int? r = m.HasValue && n.HasValue ? new int?(- (m.Value + n.Value)) : new int?());
            //
            // which avoids entirely the creation of the unnecessary nullable int and the unnecessary
            // extra null check.

            if (loweredOperand.Kind == BoundKind.Sequence)
            {
                BoundSequence seq = (BoundSequence)loweredOperand;
                if (seq.Value.Kind == BoundKind.ConditionalOperator)
                {
                    BoundConditionalOperator conditional = (BoundConditionalOperator)seq.Value;
                    Debug.Assert(TypeSymbol.Equals(seq.Type, conditional.Type, TypeCompareKind.ConsiderEverything2));
                    Debug.Assert(TypeSymbol.Equals(conditional.Type, conditional.Consequence.Type, TypeCompareKind.ConsiderEverything2));
                    Debug.Assert(TypeSymbol.Equals(conditional.Type, conditional.Alternative.Type, TypeCompareKind.ConsiderEverything2));

                    if (NullableAlwaysHasValue(conditional.Consequence) != null && NullableNeverHasValue(conditional.Alternative))
                    {
                        return new BoundSequence(
                            syntax,
                            seq.Locals,
                            seq.SideEffects,
                            RewriteConditionalOperator(
                                syntax,
                                conditional.Condition,
                                MakeUnaryOperator(operatorKind, syntax, method, constrainedToTypeOpt, conditional.Consequence, type),
                                MakeUnaryOperator(operatorKind, syntax, method, constrainedToTypeOpt, conditional.Alternative, type),
                                ConstantValue.NotAvailable,
                                type,
                                isRef: false),
                            type);
                    }
                }
            }

            return null;
        }

        private BoundExpression GetLiftedUnaryOperatorConsequence(UnaryOperatorKind kind, SyntaxNode syntax, MethodSymbol? method, TypeSymbol? constrainedToTypeOpt, TypeSymbol type, BoundExpression nonNullOperand)
        {
            MethodSymbol ctor = UnsafeGetNullableMethod(syntax, type, SpecialMember.System_Nullable_T__ctor);

            // OP(temp.GetValueOrDefault())
            BoundExpression unliftedOp = MakeUnaryOperator(
                oldNode: null,
                kind: kind.Unlifted(),
                syntax: syntax,
                method: method,
                constrainedToTypeOpt: constrainedToTypeOpt,
                loweredOperand: nonNullOperand,
                type: type.GetNullableUnderlyingType());

            // new R?(OP(temp.GetValueOrDefault()))
            BoundExpression consequence = new BoundObjectCreationExpression(
                    syntax,
                    ctor,
                    unliftedOp);
            return consequence;
        }

        private static bool IsIncrement(BoundIncrementOperator node)
        {
            var op = node.OperatorKind.Operator();
            return op == UnaryOperatorKind.PostfixIncrement || op == UnaryOperatorKind.PrefixIncrement;
        }

        private static bool IsPrefix(BoundIncrementOperator node)
        {
            var op = node.OperatorKind.Operator();
            return op == UnaryOperatorKind.PrefixIncrement || op == UnaryOperatorKind.PrefixDecrement;
        }

        public override BoundNode VisitIncrementOperator(BoundIncrementOperator node)
        {
            return VisitIncrementOperator(node, used: true);
        }

        private BoundExpression VisitIncrementOperator(BoundIncrementOperator node, bool used)
        {
            if (node.MethodOpt?.IsStatic == false)
            {
                return VisitInstanceIncrementOperator(node, used);
            }
            else
            {
                return VisitBuiltInOrStaticIncrementOperator(node);
            }
        }

        private BoundExpression VisitInstanceIncrementOperator(BoundIncrementOperator node, bool used)
        {
            Debug.Assert(node.MethodOpt is { });
            Debug.Assert(node.OperandConversion is null || (node.Operand.Type!.IsReferenceType && node.MethodOpt.IsExtensionBlockMember()));

            SyntaxNode syntax = node.Syntax;

            if (!used)
            {
                Debug.Assert(node.Type.IsVoidType());
                return BoundCall.Synthesized(syntax,
                                             ApplyConversionIfNotIdentity(node.OperandConversion, node.OperandPlaceholder, VisitExpression(node.Operand)),
                                             initialBindingReceiverIsSubjectToCloning: ThreeState.False,
                                             node.MethodOpt);
            }

            TypeSymbol? operandType = node.Operand.Type; //type of the variable being incremented
            Debug.Assert(operandType is { });
            Debug.Assert(TypeSymbol.Equals(operandType, node.Type, TypeCompareKind.AllIgnoreOptions));

            if (!IsPrefix(node))
            {
                throw ExceptionUtilities.Unreachable();
            }

            if (operandType.IsReferenceType)
            {
                BoundAssignmentOperator tempAssignment;
                BoundLocal boundTemp;

                boundTemp = _factory.StoreToTemp(VisitExpression(node.Operand), out tempAssignment);
                return new BoundSequence(
                    syntax: syntax,
                    locals: [boundTemp.LocalSymbol],
                    sideEffects:
                        [
                            tempAssignment,
                            BoundCall.Synthesized(syntax,
                                                  ApplyConversionIfNotIdentity(node.OperandConversion, node.OperandPlaceholder, boundTemp),
                                                  initialBindingReceiverIsSubjectToCloning: ThreeState.False,
                                                  node.MethodOpt)
                        ],
                    value: boundTemp,
                    type: operandType);
            }

            Debug.Assert(node.OperandConversion is null);

            return MakeInstanceCompoundAssignmentOperatorResult(node.Syntax, node.Operand, rightOpt: null, node.MethodOpt, node.OperatorKind.IsChecked(), AssignmentKind.IncrementDecrement);
        }

        private BoundExpression MakeInstanceCompoundAssignmentOperatorResult(SyntaxNode syntax, BoundExpression left, BoundExpression? rightOpt, MethodSymbol operatorMethod, bool isChecked, AssignmentKind assignmentKind)
        {
            TypeSymbol? operandType = left.Type; //type of the variable being incremented
            Debug.Assert(operandType is { });

            ArrayBuilder<LocalSymbol> tempSymbols = ArrayBuilder<LocalSymbol>.GetInstance();
            ArrayBuilder<BoundExpression> tempInitializers = ArrayBuilder<BoundExpression>.GetInstance();

            // This will be filled in with the LHS that uses temporaries to prevent
            // double-evaluation of side effects.
            BoundExpression transformedLHS = TransformCompoundAssignmentLHS(left, tempInitializers, tempSymbols, isDynamicAssignment: false);
            Debug.Assert(TypeSymbol.Equals(operandType, transformedLHS.Type, TypeCompareKind.AllIgnoreOptions));

            BoundAssignmentOperator tempAssignment;
            BoundLocal boundTemp;

            boundTemp = _factory.StoreToTemp(transformedLHS, out tempAssignment);
            tempSymbols.Add(boundTemp.LocalSymbol);

            tempInitializers.Add(tempAssignment);

            rightOpt = VisitExpression(rightOpt);

            if (operandType.IsValueType)
            {
                BoundCall increment = makeIncrementCall(syntax, boundTemp, rightOpt, operatorMethod);
                BoundExpression assignBack = makeAssignmentBack(syntax, transformedLHS, boundTemp, isChecked, assignmentKind);

                tempInitializers.Add(increment);
                tempInitializers.Add(assignBack);
            }
            else
            {
                if (rightOpt is not null)
                {
                    BoundLocal capturedRight = _factory.StoreToTemp(rightOpt, out tempAssignment);
                    tempSymbols.Add(capturedRight.LocalSymbol);
                    tempInitializers.Add(tempAssignment);
                    rightOpt = capturedRight;
                }

                BoundCall increment = makeIncrementCall(syntax, boundTemp, rightOpt, operatorMethod);
                BoundExpression assignBack = makeAssignmentBack(syntax, transformedLHS, boundTemp, isChecked, assignmentKind);

                //  (object)default(T) != null
                var isNotClass = _factory.IsNotNullReference(_factory.Default(operandType));
                tempInitializers.Add(
                    _factory.Conditional(
                        isNotClass,
                        new BoundSequence(
                            syntax: syntax,
                            locals: [],
                            sideEffects: [increment, assignBack],
                            value: boundTemp,
                            type: operandType),
                        increment,
                        operandType,
                        isRef: false));
            }

            return new BoundSequence(
                syntax: syntax,
                locals: tempSymbols.ToImmutableAndFree(),
                sideEffects: tempInitializers.ToImmutableAndFree(),
                value: boundTemp,
                type: operandType);

            static BoundCall makeIncrementCall(SyntaxNode syntax, BoundLocal boundTemp, BoundExpression? rightOpt, MethodSymbol operatorMethod)
            {
                return BoundCall.Synthesized(syntax, boundTemp, initialBindingReceiverIsSubjectToCloning: ThreeState.False, operatorMethod, rightOpt is null ? [] : [rightOpt]);
            }

            BoundExpression makeAssignmentBack(SyntaxNode syntax, BoundExpression transformedLHS, BoundLocal boundTemp, bool isChecked, AssignmentKind assignmentKind)
            {
                // Note: the receiver is known to be captured because of TransformCompoundAssignmentLHS
                return MakeAssignmentOperator(syntax, transformedLHS, boundTemp, used: false, isChecked: isChecked, assignmentKind, receiverIsKnownToBeCaptured: true);
            }
        }

        /// <summary>
        /// The rewrites are as follows: suppose the operand x is a variable of type X. The
        /// chosen increment/decrement operator is modelled as a static method on a type T,
        /// which takes a value of type T and returns the result of incrementing or decrementing
        /// that value.
        /// 
        /// x++
        ///     X temp = x
        ///     x = (X)(T.Increment((T)temp))
        ///     return temp
        /// x--
        ///     X temp = x
        ///     x = (X)(T.Decrement((T)temp))
        ///     return temp
        /// ++x
        ///     X temp = (X)(T.Increment((T)x))
        ///     x = temp
        ///     return temp
        /// --x
        ///     X temp = (X)(T.Decrement((T)x))
        ///     x = temp
        ///     return temp
        /// 
        /// Note: 
        /// Dev11 implements dynamic prefix operators incorrectly.
        /// 
        ///   result = ++x.P  is emitted as  result = SetMember{"P"}(t, UnaryOperation{Inc}(GetMember{"P"}(x)))
        /// 
        /// The difference is that Dev11 relies on SetMember returning the same value as it was given as an argument.
        /// Failing to do so changes the semantics of ++/-- operator which is undesirable. We emit the same pattern for
        /// both dynamic and static operators.
        ///    
        /// For example, we might have a class X with user-defined implicit conversions
        /// to and from short, but no user-defined increment or decrement operators. We
        /// would bind x++ as "X temp = x; x = (X)(short)((int)(short)temp + 1); return temp;"
        /// </summary>
        /// <param name="node">The unary operator expression representing the increment/decrement.</param>
        /// <returns>A bound sequence that uses a temp to achieve the correct side effects and return value.</returns>
        public BoundExpression VisitBuiltInOrStaticIncrementOperator(BoundIncrementOperator node)
        {
            bool isPrefix = IsPrefix(node);
            bool isDynamic = node.OperatorKind.IsDynamic();
            bool isChecked = node.OperatorKind.IsChecked();

            ArrayBuilder<LocalSymbol> tempSymbols = ArrayBuilder<LocalSymbol>.GetInstance();
            ArrayBuilder<BoundExpression> tempInitializers = ArrayBuilder<BoundExpression>.GetInstance();

            SyntaxNode syntax = node.Syntax;

            // This will be filled in with the LHS that uses temporaries to prevent
            // double-evaluation of side effects.
            BoundExpression transformedLHS = TransformCompoundAssignmentLHS(node.Operand, tempInitializers, tempSymbols, isDynamic);
            TypeSymbol? operandType = transformedLHS.Type; //type of the variable being incremented
            Debug.Assert(operandType is { });
            Debug.Assert(TypeSymbol.Equals(operandType, node.Type, TypeCompareKind.ConsiderEverything2));

            LocalSymbol tempSymbol = _factory.SynthesizedLocal(operandType);
            tempSymbols.Add(tempSymbol);
            // Not adding an entry to tempInitializers because the initial value depends on the case.

            BoundExpression boundTemp = new BoundLocal(
                syntax: syntax,
                localSymbol: tempSymbol,
                constantValueOpt: null,
                type: operandType);

            // prefix:  (X)(T.Increment((T)operand)))
            // postfix: (X)(T.Increment((T)temp)))
            var newValue = makeBuiltInOrStaticIncrementOperator(node, rewrittenValueToIncrement: (isPrefix ? MakeRValue(transformedLHS) : boundTemp));

            // there are two strategies for completing the rewrite.
            // The reason is that indirect assignments read the target of the assignment before evaluating 
            // of the assignment value and that may cause reads of operand and boundTemp to cross which 
            // in turn would require one of them to be a real temp (not a stack local)
            //
            // To avoid this issue, in a case of ByRef operand, we perform a "nested sequence" rewrite.
            //
            // Ex: 
            //    Seq{..., operand = Seq{temp = operand + 1, temp}, ...}       
            //  instead of 
            //    Seq{.... temp = operand + 1, operand = temp, ...}              
            //
            // Such rewrite will nest reads of boundTemp relative to reads of operand so both 
            // operand and boundTemp could be optimizable (subject to all other conditions of course).
            //
            // In a case of the non-byref operand we use a single-sequence strategy as it results in shorter 
            // overall life time of temps and as such more appropriate. (problem of crossed reads does not affect that case)
            //
            if (isIndirectOrInstanceField(transformedLHS))
            {
                Debug.Assert(transformedLHS is not BoundPropertyAccess);
                return rewriteWithRefOperand(isPrefix, isChecked, tempSymbols, tempInitializers, syntax, transformedLHS, boundTemp, newValue);
            }
            else
            {
                return rewriteWithNotRefOperand(isPrefix, isChecked, tempSymbols, tempInitializers, syntax, transformedLHS, boundTemp, newValue);
            }

            static bool isIndirectOrInstanceField(BoundExpression expression)
            {
                switch (expression.Kind)
                {
                    case BoundKind.Local:
                        return ((BoundLocal)expression).LocalSymbol.RefKind != RefKind.None;

                    case BoundKind.Parameter:
                        Debug.Assert(!IsCapturedPrimaryConstructorParameter(expression));
                        return ((BoundParameter)expression).ParameterSymbol.RefKind != RefKind.None;

                    case BoundKind.FieldAccess:
                        return !((BoundFieldAccess)expression).FieldSymbol.IsStatic;
                }

                return false;
            }

            BoundExpression rewriteWithNotRefOperand(
                bool isPrefix,
                bool isChecked,
                ArrayBuilder<LocalSymbol> tempSymbols,
                ArrayBuilder<BoundExpression> tempInitializers,
                SyntaxNode syntax,
                BoundExpression transformedLHS,
                BoundExpression boundTemp,
                BoundExpression newValue)
            {
                Debug.Assert(boundTemp.Type is not null);

                // prefix:  temp = (X)(T.Increment((T)operand)));  operand = temp; 
                // postfix: temp = operand;                        operand = (X)(T.Increment((T)temp)));
                tempInitializers.Add(MakeAssignmentOperator(syntax, boundTemp, isPrefix ? newValue : MakeRValue(transformedLHS), used: false, isChecked: isChecked, AssignmentKind.SimpleAssignment, receiverIsKnownToBeCaptured: true));

                // Note: the receiver in transformedLHS is known to be captured because of TransformCompoundAssignmentLHS
                if (!isPrefix && IsExtensionBlockMemberAccessWithByValPossiblyStructReceiver(transformedLHS))
                {
                    // We need to create a tree that ensures that receiver of 'set' is evaluated after the increment operation
                    BoundLocal incrementResult = _factory.StoreToTemp(newValue, out BoundAssignmentOperator assignmentToTemp, refKind: RefKind.None);
                    tempSymbols.Add(incrementResult.LocalSymbol);
                    tempInitializers.Add(assignmentToTemp);
                    tempInitializers.Add(MakeAssignmentOperator(syntax, transformedLHS, incrementResult, used: false, isChecked: isChecked, AssignmentKind.IncrementDecrement, receiverIsKnownToBeCaptured: true));
                }
                else
                {
                    tempInitializers.Add(MakeAssignmentOperator(syntax, transformedLHS, isPrefix ? boundTemp : newValue, used: false, isChecked: isChecked, AssignmentKind.IncrementDecrement, receiverIsKnownToBeCaptured: true));
                }

                // prefix:  Seq( operand initializers; temp = (T)(operand + 1); operand = temp;          result: temp)
                // postfix: Seq( operand initializers; temp = operand;          operand = (T)(temp + 1); result: temp)
                return new BoundSequence(
                    syntax: syntax,
                    locals: tempSymbols.ToImmutableAndFree(),
                    sideEffects: tempInitializers.ToImmutableAndFree(),
                    value: boundTemp,
                    type: boundTemp.Type);
            }

            BoundExpression rewriteWithRefOperand(
                bool isPrefix,
                bool isChecked,
                ArrayBuilder<LocalSymbol> tempSymbols,
                ArrayBuilder<BoundExpression> tempInitializers,
                SyntaxNode syntax,
                BoundExpression operand,
                BoundExpression boundTemp,
                BoundExpression newValue)
            {
                Debug.Assert(boundTemp.Type is not null);

                var tempValue = isPrefix ? newValue : MakeRValue(operand);
                Debug.Assert(tempValue.Type is { });
                var tempAssignment = MakeAssignmentOperator(syntax, boundTemp, tempValue, used: false, isChecked: isChecked, AssignmentKind.SimpleAssignment, receiverIsKnownToBeCaptured: true);

                var operandValue = isPrefix ? boundTemp : newValue;
                var tempAssignedAndOperandValue = new BoundSequence(
                        syntax,
                        ImmutableArray<LocalSymbol>.Empty,
                        ImmutableArray.Create<BoundExpression>(tempAssignment),
                        operandValue,
                        tempValue.Type);

                // prefix:  operand = Seq{temp = (T)(operand + 1);  temp;}
                // postfix: operand = Seq{temp = operand;        ;  (T)(temp + 1);}
                BoundExpression operandAssignment = MakeAssignmentOperator(syntax, operand, tempAssignedAndOperandValue, used: false, isChecked: isChecked, AssignmentKind.IncrementDecrement, receiverIsKnownToBeCaptured: true);

                // prefix:  Seq{operand initializers; operand = Seq{temp = (T)(operand + 1);  temp;}          result: temp}
                // postfix: Seq{operand initializers; operand = Seq{temp = operand;        ;  (T)(temp + 1);} result: temp}
                tempInitializers.Add(operandAssignment);
                return new BoundSequence(
                    syntax: syntax,
                    locals: tempSymbols.ToImmutableAndFree(),
                    sideEffects: tempInitializers.ToImmutableAndFree(),
                    value: boundTemp,
                    type: boundTemp.Type);
            }

            BoundExpression makeBuiltInOrStaticIncrementOperator(BoundIncrementOperator node, BoundExpression rewrittenValueToIncrement)
            {
                if (node.OperatorKind.IsDynamic())
                {
                    return _dynamicFactory.MakeDynamicUnaryOperator(node.OperatorKind, rewrittenValueToIncrement, node.Type).ToExpression();
                }

                BoundExpression result;
                if (node.OperatorKind.OperandTypes() == UnaryOperatorKind.UserDefined)
                {
                    result = MakeUserDefinedStaticIncrementOperator(node, rewrittenValueToIncrement);
                }
                else
                {
                    result = MakeBuiltInIncrementOperator(node, rewrittenValueToIncrement);
                }

                // Generate the conversion back to the type of the original expression.

                // (X)(short)((int)(short)x + 1)
                result = ApplyConversionIfNotIdentity(node.ResultConversion, node.ResultPlaceholder, result);

                return result;
            }
        }

        private BoundExpression ApplyConversionIfNotIdentity(BoundExpression? conversion, BoundValuePlaceholder? placeholder, BoundExpression replacement)
        {
            if (hasNonIdentityConversion(conversion))
            {
                Debug.Assert(placeholder is not null);

                return ApplyConversion(conversion, placeholder, replacement);
            }

            return replacement;

            static bool hasNonIdentityConversion([NotNullWhen(true)] BoundExpression? expression)
            {
                while (expression is BoundConversion conversion)
                {
                    if (!conversion.Conversion.IsIdentity)
                    {
                        return true;
                    }

                    expression = conversion.Operand;
                }

                return false;
            }
        }

        private BoundExpression ApplyConversion(BoundExpression conversion, BoundValuePlaceholder placeholder, BoundExpression replacement)
        {
            AddPlaceholderReplacement(placeholder, replacement);
            replacement = VisitExpression(conversion);
            RemovePlaceholderReplacement(placeholder);
            return replacement;
        }

        private BoundExpression MakeUserDefinedStaticIncrementOperator(BoundIncrementOperator node, BoundExpression rewrittenValueToIncrement)
        {
            Debug.Assert(node.MethodOpt is { });
            Debug.Assert(node.MethodOpt.ParameterCount == 1);

            bool isLifted = node.OperatorKind.IsLifted();
            bool @checked = node.OperatorKind.IsChecked();

            SyntaxNode syntax = node.Syntax;

            TypeSymbol type = node.MethodOpt.GetParameterType(0);
            if (isLifted)
            {
                type = _compilation.GetSpecialType(SpecialType.System_Nullable_T).Construct(type);
                Debug.Assert(TypeSymbol.Equals(node.MethodOpt.GetParameterType(0), node.MethodOpt.ReturnType, TypeCompareKind.ConsiderEverything2));
            }

            BoundExpression rewrittenArgument = ApplyConversionIfNotIdentity(node.OperandConversion, node.OperandPlaceholder, rewrittenValueToIncrement);

            if (!isLifted)
            {
                return BoundCall.Synthesized(
                    syntax,
                    receiverOpt: node.ConstrainedToTypeOpt is null ? null : new BoundTypeExpression(syntax, aliasOpt: null, node.ConstrainedToTypeOpt),
                    initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown,
                    node.MethodOpt,
                    rewrittenArgument);
            }

            // S? temp = operand;
            // S? r = temp.HasValue ? 
            //        new S?(op_Increment(temp.GetValueOrDefault())) :
            //        default(S?);

            // Unlike the other unary operators, we do not attempt to optimize nullable user-defined 
            // increment or decrement. The operand is a variable (or property), and so we do not know if
            // it is always null/never null.

            BoundAssignmentOperator tempAssignment;
            BoundLocal boundTemp = _factory.StoreToTemp(rewrittenArgument, out tempAssignment);

            MethodSymbol getValueOrDefault = UnsafeGetNullableMethod(syntax, type, SpecialMember.System_Nullable_T_GetValueOrDefault);
            MethodSymbol ctor = UnsafeGetNullableMethod(syntax, type, SpecialMember.System_Nullable_T__ctor);

            // temp.HasValue
            BoundExpression condition = _factory.MakeNullableHasValue(node.Syntax, boundTemp);

            // temp.GetValueOrDefault()
            BoundExpression call_GetValueOrDefault = BoundCall.Synthesized(syntax, boundTemp, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, getValueOrDefault);

            // op_Increment(temp.GetValueOrDefault())
            BoundExpression userDefinedCall = BoundCall.Synthesized(
                syntax,
                receiverOpt: node.ConstrainedToTypeOpt is null ? null : new BoundTypeExpression(syntax, aliasOpt: null, node.ConstrainedToTypeOpt),
                initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown,
                node.MethodOpt,
                call_GetValueOrDefault);

            // new S?(op_Increment(temp.GetValueOrDefault()))
            BoundExpression consequence = new BoundObjectCreationExpression(syntax, ctor, userDefinedCall);

            // default(S?)
            BoundExpression alternative = new BoundDefaultExpression(syntax, type);

            // temp.HasValue ? 
            //          new S?(op_Increment(temp.GetValueOrDefault())) : 
            //          default(S?);
            BoundExpression conditionalExpression = RewriteConditionalOperator(
                syntax: syntax,
                rewrittenCondition: condition,
                rewrittenConsequence: consequence,
                rewrittenAlternative: alternative,
                constantValueOpt: null,
                rewrittenType: type,
                isRef: false);

            // temp = operand; 
            // temp.HasValue ? 
            //          new S?(op_Increment(temp.GetValueOrDefault())) : 
            //          default(S?);
            return new BoundSequence(
                syntax: syntax,
                locals: ImmutableArray.Create<LocalSymbol>(boundTemp.LocalSymbol),
                sideEffects: ImmutableArray.Create<BoundExpression>(tempAssignment),
                value: conditionalExpression,
                type: type);
        }

        private BoundExpression MakeBuiltInIncrementOperator(BoundIncrementOperator node, BoundExpression rewrittenValueToIncrement)
        {
            BoundExpression result;
            // If we have a built-in increment or decrement then things get a bit trickier. Suppose for example we have
            // a user-defined conversion from X to short and from short to X, but no user-defined increment operator on
            // X.  The increment portion of "++x" is then: (X)(short)((int)(short)x + 1). That is, first x must be
            // converted to short via an implicit user- defined conversion, then to int via an implicit numeric
            // conversion, then the addition is performed in integers. The resulting integer is converted back to short,
            // and then the short is converted to X.

            // This is the input and output type of the unary increment operator we're going to call.
            // That is, "short" in the example above.
            TypeSymbol unaryOperandType = GetUnaryOperatorType(node);

            // This is the kind of binary operator that we're going to realize the unary operator
            // as. That is, "int + int --> int" in the example above.
            BinaryOperatorKind binaryOperatorKind = GetCorrespondingBinaryOperator(node);
            binaryOperatorKind |= IsIncrement(node) ? BinaryOperatorKind.Addition : BinaryOperatorKind.Subtraction;

            // The input/output type of the binary operand. "int" in the example. 
            // The "1" in the example above.
            (TypeSymbol binaryOperandType, ConstantValue constantOne) = GetConstantOneForIncrement(_compilation, binaryOperatorKind);

            Debug.Assert(constantOne != null);
            Debug.Assert(constantOne.SpecialType != SpecialType.None);
            Debug.Assert(binaryOperandType.SpecialType != SpecialType.None);
            Debug.Assert(binaryOperatorKind.OperandTypes() != 0);

            // 1
            BoundExpression boundOne = MakeLiteral(
                syntax: node.Syntax,
                constantValue: constantOne,
                type: binaryOperandType);

            if (binaryOperatorKind.IsLifted())
            {
                binaryOperandType = _compilation.GetOrCreateNullableType(binaryOperandType);
                MethodSymbol ctor = UnsafeGetNullableMethod(node.Syntax, binaryOperandType, SpecialMember.System_Nullable_T__ctor);
                boundOne = new BoundObjectCreationExpression(node.Syntax, ctor, boundOne);
            }

            // Now we construct the other operand to the binary addition. We start with just plain "x".
            BoundExpression binaryOperand = rewrittenValueToIncrement;

            bool @checked = node.OperatorKind.IsChecked();

            // If we need to make a conversion from the original operand type to the operand type of the
            // underlying increment operation, do it now.
            binaryOperand = ApplyConversionIfNotIdentity(node.OperandConversion, node.OperandPlaceholder, binaryOperand);

            // Early-out for pointer increment - we don't need to convert the operands to a common type.
            if (node.OperatorKind.OperandTypes() == UnaryOperatorKind.Pointer)
            {
                Debug.Assert(binaryOperatorKind.OperandTypes() == BinaryOperatorKind.PointerAndInt);
                Debug.Assert(binaryOperand.Type is { TypeKind: TypeKind.Pointer });
                Debug.Assert(boundOne.Type is { SpecialType: SpecialType.System_Int32 });
                return MakeBinaryOperator(node.Syntax, binaryOperatorKind, binaryOperand, boundOne, binaryOperand.Type, method: null, constrainedToTypeOpt: null);
            }

            // If we need to make a conversion from the unary operator type to the binary operator type,
            // do it now.

            // (int)(short)x
            binaryOperand = MakeConversionNode(binaryOperand, binaryOperandType, @checked, markAsChecked: true);

            // Perform the addition.

            // (int)(short)x + 1            
            BoundExpression binOp;
            if (unaryOperandType.SpecialType == SpecialType.System_Decimal)
            {
                binOp = MakeDecimalIncDecOperator(node.Syntax, binaryOperatorKind, binaryOperand);
            }
            else if (unaryOperandType.IsNullableType() && unaryOperandType.GetNullableUnderlyingType().SpecialType == SpecialType.System_Decimal)
            {
                binOp = MakeLiftedDecimalIncDecOperator(node.Syntax, binaryOperatorKind, binaryOperand);
            }
            else
            {
                binOp = MakeBinaryOperator(node.Syntax, binaryOperatorKind, binaryOperand, boundOne, binaryOperandType, method: null, constrainedToTypeOpt: null);
            }

            // Generate the conversion back to the type of the unary operator.

            // (short)((int)(short)x + 1)
            result = MakeConversionNode(binOp, unaryOperandType, @checked, markAsChecked: true);
            return result;
        }

        private MethodSymbol GetDecimalIncDecOperator(BinaryOperatorKind oper)
        {
            SpecialMember member;
            switch (oper.Operator())
            {
                case BinaryOperatorKind.Addition: member = SpecialMember.System_Decimal__op_Increment; break;
                case BinaryOperatorKind.Subtraction: member = SpecialMember.System_Decimal__op_Decrement; break;
                default:
                    throw ExceptionUtilities.UnexpectedValue(oper.Operator());
            }

            var method = (MethodSymbol)_compilation.Assembly.GetSpecialTypeMember(member);
            Debug.Assert((object)method != null); // Should have been checked during Warnings pass
            return method;
        }

        // Build Decimal.op_Increment((Decimal)operand) or Decimal.op_Decrement((Decimal)operand)
        private BoundExpression MakeDecimalIncDecOperator(SyntaxNode syntax, BinaryOperatorKind oper, BoundExpression operand)
        {
            Debug.Assert(operand.Type is { SpecialType: SpecialType.System_Decimal });
            MethodSymbol method = GetDecimalIncDecOperator(oper);
            return BoundCall.Synthesized(syntax, receiverOpt: null, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, method, operand);
        }

        private BoundExpression MakeLiftedDecimalIncDecOperator(SyntaxNode syntax, BinaryOperatorKind oper, BoundExpression operand)
        {
            Debug.Assert(operand.Type is { } && operand.Type.IsNullableType() && operand.Type.GetNullableUnderlyingType().SpecialType == SpecialType.System_Decimal);

            // This method assumes that operand is already a temporary and so there is no need to copy it again.
            MethodSymbol method = GetDecimalIncDecOperator(oper);
            MethodSymbol getValueOrDefault = UnsafeGetNullableMethod(syntax, operand.Type, SpecialMember.System_Nullable_T_GetValueOrDefault);
            MethodSymbol ctor = UnsafeGetNullableMethod(syntax, operand.Type, SpecialMember.System_Nullable_T__ctor);

            // x.HasValue
            BoundExpression condition = _factory.MakeNullableHasValue(syntax, operand);
            // x.GetValueOrDefault()
            BoundExpression getValueCall = BoundCall.Synthesized(syntax, operand, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, getValueOrDefault);
            // op_Inc(x.GetValueOrDefault())
            BoundExpression methodCall = BoundCall.Synthesized(syntax, receiverOpt: null, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, method, getValueCall);
            // new decimal?(op_Inc(x.GetValueOrDefault()))
            BoundExpression consequence = new BoundObjectCreationExpression(syntax, ctor, methodCall);
            // default(decimal?)
            BoundExpression alternative = new BoundDefaultExpression(syntax, operand.Type);

            // x.HasValue ? new decimal?(op_Inc(x.GetValueOrDefault())) : default(decimal?)
            return RewriteConditionalOperator(syntax, condition, consequence, alternative, ConstantValue.NotAvailable, operand.Type, isRef: false);
        }

        /// <summary>
        /// Transform an expression from a form suitable as an lvalue to a form suitable as an rvalue.
        /// </summary>
        /// <param name="transformedExpression">The children of this node must already be lowered.</param>
        /// <returns>Fully lowered node.</returns>
        private BoundExpression MakeRValue(BoundExpression transformedExpression)
        {
            switch (transformedExpression.Kind)
            {
                case BoundKind.PropertyAccess:
                    var propertyAccess = (BoundPropertyAccess)transformedExpression;
                    return MakePropertyGetAccess(transformedExpression.Syntax, propertyAccess.ReceiverOpt, propertyAccess.PropertySymbol, propertyAccess);

                case BoundKind.DynamicMemberAccess:
                    var dynamicMemberAccess = (BoundDynamicMemberAccess)transformedExpression;
                    return _dynamicFactory.MakeDynamicGetMember(dynamicMemberAccess.Receiver, dynamicMemberAccess.Name, resultIndexed: false).ToExpression();

                case BoundKind.IndexerAccess:
                    var indexerAccess = (BoundIndexerAccess)transformedExpression;
                    return MakePropertyGetAccess(transformedExpression.Syntax, indexerAccess.ReceiverOpt, indexerAccess.Indexer, indexerAccess.Arguments, indexerAccess.ArgumentRefKindsOpt);

                case BoundKind.DynamicIndexerAccess:
                    var dynamicIndexerAccess = (BoundDynamicIndexerAccess)transformedExpression;
                    return MakeDynamicGetIndex(
                        dynamicIndexerAccess,
                        dynamicIndexerAccess.Receiver,
                        dynamicIndexerAccess.Arguments,
                        dynamicIndexerAccess.ArgumentNamesOpt,
                        dynamicIndexerAccess.ArgumentRefKindsOpt);

                default:
                    return transformedExpression;
            }
        }

        // There are ++ and -- operators defined on sbyte, byte, short, ushort, int,
        // uint, long, ulong, char, float, double, decimal and any enum type.
        // Given a built-in increment operator, get the associated type.  Note
        // that this need not be the result type or the operand type of the node!
        // We could have a user-defined conversion from the type of the operand
        // to short, and a user-defined conversion from short to the result
        // type.
        private TypeSymbol GetUnaryOperatorType(BoundIncrementOperator node)
        {
            UnaryOperatorKind kind = node.OperatorKind.OperandTypes();

            // If overload resolution chose an enum operator then the operand
            // type and the return type really are an enum; we are not in a user-
            // defined conversion scenario. 
            if (kind == UnaryOperatorKind.Enum)
            {
                return node.Type;
            }

            SpecialType specialType;

            switch (kind)
            {
                case UnaryOperatorKind.Int:
                    specialType = SpecialType.System_Int32;
                    break;
                case UnaryOperatorKind.SByte:
                    specialType = SpecialType.System_SByte;
                    break;
                case UnaryOperatorKind.Short:
                    specialType = SpecialType.System_Int16;
                    break;
                case UnaryOperatorKind.Byte:
                    specialType = SpecialType.System_Byte;
                    break;
                case UnaryOperatorKind.UShort:
                    specialType = SpecialType.System_UInt16;
                    break;
                case UnaryOperatorKind.Char:
                    specialType = SpecialType.System_Char;
                    break;
                case UnaryOperatorKind.UInt:
                    specialType = SpecialType.System_UInt32;
                    break;
                case UnaryOperatorKind.Long:
                    specialType = SpecialType.System_Int64;
                    break;
                case UnaryOperatorKind.ULong:
                    specialType = SpecialType.System_UInt64;
                    break;
                case UnaryOperatorKind.NInt:
                    specialType = SpecialType.System_IntPtr;
                    break;
                case UnaryOperatorKind.NUInt:
                    specialType = SpecialType.System_UIntPtr;
                    break;
                case UnaryOperatorKind.Float:
                    specialType = SpecialType.System_Single;
                    break;
                case UnaryOperatorKind.Double:
                    specialType = SpecialType.System_Double;
                    break;
                case UnaryOperatorKind.Decimal:
                    specialType = SpecialType.System_Decimal;
                    break;
                case UnaryOperatorKind.Pointer:
                    return node.Type;
                case UnaryOperatorKind.UserDefined:
                case UnaryOperatorKind.Bool:
                default:
                    throw ExceptionUtilities.UnexpectedValue(kind);
            }

            NamedTypeSymbol type = _compilation.GetSpecialType(specialType);
            if (node.OperatorKind.IsLifted())
            {
                type = _compilation.GetSpecialType(SpecialType.System_Nullable_T).Construct(type);
            }

            return type;
        }

        private static BinaryOperatorKind GetCorrespondingBinaryOperator(BoundIncrementOperator node)
        {
            // We need to create expressions that have the semantics of incrementing or decrementing:
            // sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal and
            // any enum.  However, the binary addition operators we have at our disposal are just
            // int, uint, long, ulong, float, double and decimal.

            UnaryOperatorKind unaryOperatorKind = node.OperatorKind;
            BinaryOperatorKind result;

            switch (unaryOperatorKind.OperandTypes())
            {
                case UnaryOperatorKind.Int:
                case UnaryOperatorKind.SByte:
                case UnaryOperatorKind.Short:
                    result = BinaryOperatorKind.Int;
                    break;
                case UnaryOperatorKind.Byte:
                case UnaryOperatorKind.UShort:
                case UnaryOperatorKind.Char:
                case UnaryOperatorKind.UInt:
                    result = BinaryOperatorKind.UInt;
                    break;
                case UnaryOperatorKind.Long:
                    result = BinaryOperatorKind.Long;
                    break;
                case UnaryOperatorKind.ULong:
                    result = BinaryOperatorKind.ULong;
                    break;
                case UnaryOperatorKind.NInt:
                    result = BinaryOperatorKind.NInt;
                    break;
                case UnaryOperatorKind.NUInt:
                    result = BinaryOperatorKind.NUInt;
                    break;
                case UnaryOperatorKind.Float:
                    result = BinaryOperatorKind.Float;
                    break;
                case UnaryOperatorKind.Double:
                    result = BinaryOperatorKind.Double;
                    break;
                case UnaryOperatorKind.Decimal: //Dev10 special cased this, but we'll let DecimalRewriter handle it
                    result = BinaryOperatorKind.Decimal;
                    break;
                case UnaryOperatorKind.Enum:
                    {
                        TypeSymbol? underlyingType = node.Type;
                        Debug.Assert(underlyingType is { });
                        if (underlyingType.IsNullableType())
                        {
                            underlyingType = underlyingType.GetNullableUnderlyingType();
                        }
                        Debug.Assert(underlyingType.IsEnumType());
                        underlyingType = underlyingType.GetEnumUnderlyingType();
                        Debug.Assert(underlyingType is { });

                        // Operator overload resolution will not have chosen the enumerated type
                        // unless the operand actually is of the enumerated type (or nullable enum type.)

                        switch (underlyingType.SpecialType)
                        {
                            case SpecialType.System_SByte:
                            case SpecialType.System_Int16:
                            case SpecialType.System_Int32:
                                result = BinaryOperatorKind.Int;
                                break;
                            case SpecialType.System_Byte:
                            case SpecialType.System_UInt16:
                            case SpecialType.System_UInt32:
                                result = BinaryOperatorKind.UInt;
                                break;
                            case SpecialType.System_Int64:
                                result = BinaryOperatorKind.Long;
                                break;
                            case SpecialType.System_UInt64:
                                result = BinaryOperatorKind.ULong;
                                break;
                            default:
                                throw ExceptionUtilities.UnexpectedValue(underlyingType.SpecialType);
                        }
                    }
                    break;
                case UnaryOperatorKind.Pointer:
                    result = BinaryOperatorKind.PointerAndInt;
                    break;
                case UnaryOperatorKind.UserDefined:
                case UnaryOperatorKind.Bool:
                default:
                    throw ExceptionUtilities.UnexpectedValue(unaryOperatorKind.OperandTypes());
            }

            switch (result)
            {
                case BinaryOperatorKind.UInt:
                case BinaryOperatorKind.Int:
                case BinaryOperatorKind.ULong:
                case BinaryOperatorKind.Long:
                case BinaryOperatorKind.NUInt:
                case BinaryOperatorKind.NInt:
                case BinaryOperatorKind.PointerAndInt:
                    result |= (BinaryOperatorKind)unaryOperatorKind.OverflowChecks();
                    break;
            }

            if (unaryOperatorKind.IsLifted())
            {
                result |= BinaryOperatorKind.Lifted;
            }

            return result;
        }

        private static (TypeSymbol, ConstantValue) GetConstantOneForIncrement(
            CSharpCompilation compilation,
            BinaryOperatorKind binaryOperatorKind)
        {
            ConstantValue constantOne;
            switch (binaryOperatorKind.OperandTypes())
            {
                case BinaryOperatorKind.PointerAndInt:
                case BinaryOperatorKind.Int:
                    constantOne = ConstantValue.Create(1);
                    break;
                case BinaryOperatorKind.UInt:
                    constantOne = ConstantValue.Create(1U);
                    break;
                case BinaryOperatorKind.Long:
                    constantOne = ConstantValue.Create(1L);
                    break;
                case BinaryOperatorKind.ULong:
                    constantOne = ConstantValue.Create(1LU);
                    break;
                case BinaryOperatorKind.NInt:
                    constantOne = ConstantValue.Create(1);
                    return (compilation.CreateNativeIntegerTypeSymbol(signed: true), constantOne);
                case BinaryOperatorKind.NUInt:
                    constantOne = ConstantValue.Create(1U);
                    return (compilation.CreateNativeIntegerTypeSymbol(signed: false), constantOne);
                case BinaryOperatorKind.Float:
                    constantOne = ConstantValue.Create(1f);
                    break;
                case BinaryOperatorKind.Double:
                    constantOne = ConstantValue.Create(1.0);
                    break;
                case BinaryOperatorKind.Decimal:
                    constantOne = ConstantValue.Create(1m);
                    break;
                default:
                    throw ExceptionUtilities.UnexpectedValue(binaryOperatorKind.OperandTypes());
            }
            return (compilation.GetSpecialType(constantOne.SpecialType), constantOne);
        }
    }
}
