Test Plan for Overload Resolution Priority

[333fred]

Championed issue: dotnet/csharplang#7706
Speclet: https://github.com/dotnet/csharplang/blob/main/proposals/csharp-13.0/overload-resolution-priority.md

C# Compiler

• spec: confirm LangVer behavior
• spec: confirm for local functions,
• effect in invocation
  • higher values win, lower values lose, default value is zero, same values remain ambiguous
  • pruning happens on applicable candidates
  • applies to extensions
  • in source and metadata (changes in overrides in metadata have no effect)
  • LangVer doesn't affect overload resolution
• effect in object creation and attributes
• effect in delegate conversion
• effect on properties
  • indexers
  • indexed properties
• effect in unary and binary operators
• no effect in function type (var x = A.B; with multiple B candidates)
• attribute application
  • LangVer
  • error on overrides (even those restating priority) and explicit interface implementations
  • error on accessors
  • cycles
  • applied twice
  • applied on partial method or indexer
  • nothing on local functions,
  • spec: error on lambdas, destructors, conversion operators, static constructors
• public API? (not planned yet)
• BCL types (added)
• notify other teams/languages
• expression tree. Expression<> x = (a) => A.B(a); // priority should be honored, silent source break like params? can yield an error identify and document known scenario, notify BCL team (apply with care)
• interpolation handlers
• query syntax

VB Compiler

• TBD (we'll plan and implement in .NET 9)

Productivity

No IDE impact

[jaredpar]

@333fred make sure to create an issue label we can use for this feature and attach it to this issue