## C# Language Design Notes for 2025

### Wed December 17, 2025

[C# Language Design Meeting for December 17th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-12-17.md)

- Collection expression arguments parsing question
- Null-conditionals evaluating to a pointer type
- Triage
    - Top-Level Members
    - Using local declaration improvements

### Wed Dec 10, 2025

[C# Language Design Meeting for December 10th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-12-10.md)

- Collection expression arguments

### Wed Nov 12, 2025

[C# Language Design Meeting for November 12th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-11-12.md)

- Unsafe evolution

### Wed Nov 5, 2025

[C# Language Design Meeting for November 5th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-11-05.md)

- Unsafe evolution

### Wed Oct 29, 2025

[C# Language Design Meeting for October 29th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-10-29.md)

- Unsafe evolution

### Mon Oct 13, 2025

[C# Language Design Meeting for October 13th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-10-13.md)

- Collection expression safe-context bug fix
- Immediately-enumerated collection expressions

### Wed Oct 1, 2025

[C# Language Design Meeting for October 1st, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-10-01.md)

- Closed enums
- Closed Hierarchies

### Mon Sep 29, 2025

[C# Language Design Meeting for September 29th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-09-29.md)

- Union Syntax Thunderdome Part 2
- Enums vs Unions

### Wed Sep 24, 2025

[C# Language Design Meeting for September 24th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-09-24.md)

- Union Syntax Thunderdome Part 1

### Wed Sep 17, 2025

[C# Language Design Meeting for September 17th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-09-17.md)

- Unsafe evolution

### Wed Sep 10, 2025

[C# Language Design Meeting for September 10th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-09-10.md)

- Unions overview

### Wed Aug 27, 2025

[C# Language Design Meeting for August 27th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-08-27.md)

- Type inference in patterns
- Type value conversion
- Union syntax

### Wed Aug 20, 2025

[C# Language Design Meeting for August 20th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-08-20.md)

- Union interfaces
- Target-type inference improvements

### Mon Aug 18, 2025

[C# Language Design Meeting for August 18th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-08-18.md)

- C# 15 Kickoff and Themes
    - Unions
    - Extensions
    - Dictionary expressions
    - Type inference
    - Continuing the null monad
    - Object initialization
    - Top-level methods
    - Caller type name
    - Switch statement/expression improvements

### Wed Aug 13, 2025

[C# Language Design Meeting for August 13th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-08-13.md)

- Unions

### Wed Jul 30, 2025

[C# Language Design Meeting for July 30th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-07-30.md)

- '/main' and top-level statements
- Union proposals overview
- Add type parameter restriction to closed hierarchies
- Standard unions
- Union interfaces
- Custom unions
- Non-boxing access pattern

### Mon Jun 30, 2025

[C# Language Design Meeting for June 30th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-30.md)

- Type parameter inference from constraints
- Target-typed static member lookup

### Wed Jun 25, 2025

[C# Language Design Meeting for June 25th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-25.md)

- Unions
    - Stand-alone issues
    - Mutually exclusive issues

### Mon Jun 23, 2025

[C# Language Design Meeting for June 23rd, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-23.md)

- Extensions
    - Use of extension operators in LINQ expression trees
    - `ref` encoding and conflict checks
    - Extern support
    - Lookup

### Wed Jun 18, 2025

[C# Language Design Meeting for June 18th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-18.md)

- Iterators in lambdas
- Extensions

### Wed Jun 11, 2025

[C# Language Design Meeting for June 11th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-11.md)

- Extensions
    - Dynamic resolution of operator `true`/`false`
    - Extension operators in LINQ expression trees
    - Built-in operator protection rules
    - Extension module initializers
    - Extension methods as entry points
    - Langversion behavior for new extensions
    - `nameof`

### Mon Jun 9, 2025

[C# Language Design Meeting for June 9th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-09.md)

- Extensions - crefs

### Wed Jun 4, 2025

[C# Language Design Meeting for June 4th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-06-04.md)

- Extensions
    - Should extension operators on nullable of extended type be disallowed
    - Applicability of bitwise operators during evaluation of user-defined conditional logical operators
    - Extension user-defined conditional logical operators
    - Extension compound assignment operators
    - Delegate returning properties
    - Extension declaration validation
    - Cref references

### Wed May 28, 2025

[C# Language Design Meeting for May 28th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-05-28.md)

- Nominal type unions

### Mon May 12, 2025

[C# Language Design Meeting for May 12th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-05-12.md)

- Collection expression arguments
    - Empty argument lists
    - Constructor binding behavior
    - Syntax
- Dictionary expressions

### Wed May 7, 2025

[C# Language Design Meeting for May 7th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-05-07.md)

- Collection Expression Arguments
    - Interface target type
    - Constructor binding behavior
    - Syntax

### Mon May 5, 2025

[C# Language Design Meeting for May 5th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-05-05.md)

- Extensions
    - XML Docs
    - Participation in pattern-based constructs
    - Skeleton type metadata
    - Single-phase consequences

### Wed, Apr 23, 2025

[C# Language Design Meeting for April 23rd, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-04-23.md)

- Extensions
    - Extension operators
    - Overload resolution priority
- Dictionary Expressions

### Wed Apr 16, 2025

[C# Language Design Meeting for April 16th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-04-16.md)

- Extensions

### Mon Apr 14, 2025

[C# Language Design Meeting for April 14th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-04-14.md)

- Dictionary expressions
- Collection expression arguments

### Wed Apr 9, 2025

[C# Language Design Meeting for April 9th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-04-09.md)

- Dictionary expressions
- Collection expression arguments

### Mon Apr 7, 2025 

[C# Language Design Meeting for April 7th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-04-07.md)

- Breaking change discussion: making partial members in interfaces virtual and/or public
- Interpolated string handler argument values

### April 2, 2025

[C# Language Design Meeting for April 2nd, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-04-02.md)

- User Defined Compound Assignment Operators
    - Should readonly modifier be allowed in structures?
    - Should shadowing be allowed
    - Should we have any consistency enforcement between declared += and + operators?
- Readonly setters
    - Expansions

### Mon Mar 24, 2025

[C# Language Design Meeting for March 24th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-24.md)

- Dictionary Expressions
    - Support dictionary types as `params` type
    - Type inference for `KeyValuePair<K, V>` collections
    - Overload resolution for `KeyValuePair<K, V>` collections
- Extensions
    - Signature conflict rules
    - `extension` vs `extensions`

### Wed Mar 19, 2025

[C# Language Design Meeting for March 19th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-19.md)

- Readonly setters on non-variables

### Mon Mar 17, 2025

[C# Language Design Meeting for March 17th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-17.md)

- Collection expression arguments
    - `with` breaking change
    - Collection expression arguments and conversions
- Dictionary expressions
- Extensions
    - Accessibility
    - Static factory scenarios

### Mon Mar 12, 2025

[C# Language Design Meeting for March 12th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-12.md)

- Optional and named parameters in expression trees
- Collection builder method parameter order
- Ignored directives

### Mon Mar 10, 2025

[C# Language Design Meeting for March 10th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-10.md)

- Extensions
    - Property method calling
    - Scoping and Shadowing
    - Type parameter inferrability
    - Accessibility

### Wed Mar 5, 2025

[C# Language Design Meeting for March 5th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-05.md)

- Dictionary expressions
- Target-typed static member lookup

### Mon Mar 3, 2025

[C# Language Design Meeting for March 3rd, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-03.md)

- Extensions

### Wed Feb 26, 2025

[C# Language Design Meeting for February 26th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-02-26.md)

- Extensions

### Mon Feb 24, 2025

[C# Language Design Meeting for February 24th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-02-24.md)

- Extensions
- Interpolated string handler method names

### Wed Feb 19, 2025

[C# Language Design Meeting for February 19th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-02-19.md)

- Extensions

### Wed Feb 12, 2025

[C# Language Design Meeting for February 12th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-02-12.md)

- User-defined instance-based operators
- Left-right join in query expressions

### Wed Jan 22, 2025

[C# Language Design Meeting for January 22nd, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-01-22.md)

- Partial events and constructors
- Collection expression arguments
- Extensions disambiguation syntax

### Wed Jan 15, 2025

[C# Language Design Meeting for January 15th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-01-15.md)

- `fieldof`
- Simple lambda parameters
- Interpolated string handler method names

### Mon Jan 13th, 2025

[C# Language Design Meeting for January 13th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-01-13.md)

- Discriminated Unions

### Mon Jan 6, 2025

[C# Language Design Meeting for January 6th, 2025](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-01-06.md)

- Ignoring `ref struct`s in `Expression`s
- Extensions
