Does C# 9 support the .NET Framework? [closed]

Question

Similar to Does C# 8 support the .NET Framework?

I know that it's officially unsupported, but what features in C# 9 are available when using the .Net Framework (4.8)?

Features from -- https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-version-history#c-version-9

• Records
• Init only setters
• Top-level statements
• Pattern matching enhancements
• Performance and interop
  • Native sized integers
  • Function pointers
  • Suppress emitting localsinit flag
• Fit and finish features
  • Target-typed new expressions
  • static anonymous functions
  • Target-typed conditional expressions
  • Covariant return types
  • Extension GetEnumerator support for foreach loops
  • Lambda discard parameters
  • Attributes on local functions
• Support for code generators
  • Module initializers
  • New features for partial methods

Answer 1

To the best of my knowledge this is what is done by the compiler, and what requires runtime support (i.e. will not run on .net framework, requires .net core)

C# 9

• Records (compiler only for .NET 4.0+, earlier versions would require additional work)
• init only setters (compiler, but needs class IsExternalInit)
• Top-level statements (compiler)
• Pattern matching enhancements (compiler)
• Native sized integers (eg nint and nuint, compiler)
• Function pointers (runtime I believe, wasn't able to verify)
• Suppress emitting localsinit flag (compiler, but needs class SkipLocalsInitAttribute)
• Target-typed new expressions (compiler)
• Static anonymous functions (compiler)
• Target-Typed Conditional Expression (compiler)
• Covariant return types (runtime)
• Extension GetEnumerator support for foreach loops (compiler, was already in VB)
• Lambda discard parameters (compiler)
• Attributes on local functions (compiler, can be used for debug only static functions)
• Support for code generators (compiler and ide)
• Module initializers (compiler, needs class ModuleInitializerAttribute)
• Extending Partial Methods (compiler)