Synthesize delegate types for lambda expressions and method groups #55203
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| if (returnsVoid && returnRefKind != RefKind.None) | ||
| { | ||
| // Invalid return type. | ||
| return null; |
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Do we want to consider diagnostics for the cases we're returning null? It would be better to have specific error messages for those cases, I think. #Closed
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A specific error shouldn't be necessary. There are two cases where we return null: the case here of a ref void return type which will have been reported as a declaration error; and the case below where a parameter or return type cannot be used as a type argument. The second case should be resolved in #55217.
src/Compilers/CSharp/Portable/Symbols/AnonymousTypes/AnonymousTypeManager.Templates.cs
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src/Compilers/CSharp/Portable/Symbols/Synthesized/SynthesizedDelegateSymbol.cs
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| internal int Capacity => _bits.Capacity / 2; | ||
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| internal IEnumerable<ulong> Words() => _bits.Words(); |
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I'm surprised dynamic tests weren't affected by the change from BitVector to RefKindVector. MakeDynamicCallSiteDelegateName uses those "words" as part of the name for the synthesized delegate type.
Never mind, they were #Closed
| static bool isValidTypeArgument(TypeSymbol? type) | ||
| { | ||
| return type is { } && | ||
| !type.IsPointerOrFunctionPointer() && |
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nit: Consider including a test with an array of pointer types (that's an example to illustrate the difference between IsPointerOrFunctionPointer and IsUnsafe) #Closed
| var delegateType = ((INamedTypeSymbol)local.Type); | ||
| Assert.Equal(Accessibility.Internal, delegateType.DeclaredAccessibility); | ||
| Assert.Equal(expectedInvokeMethod, delegateType.DelegateInvokeMethod.ToTestDisplayString()); | ||
| } |
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Let's include a test with more types: dynamic, tuples with names, nint or reference types with nullability. #Resolved
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To add to the list, arrays of function pointer types where the parameters/return type of the function pointer have refkinds.
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I also think we should have public API verification, ie what are we returning from GetSymbolInfo or GetTypeInfo for these synthesized symbols.
| } | ||
| static void M2<T>(T t) where T : struct | ||
| { | ||
| var d = (ref T t) => t; |
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Consider varying parameter name here #Closed
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| int parameterCount = delegateSignature.Length - (returnsVoid ? 0 : 1); | ||
| Debug.Assert(_factory.CompilationState.ModuleBuilderOpt is { }); | ||
| int generation = _factory.CompilationState.ModuleBuilderOpt.CurrentGenerationOrdinal; | ||
| var synthesizedType = _factory.Compilation.AnonymousTypeManager.SynthesizeDelegate(parameterCount, byRefs, returnsVoid, generation); | ||
| return synthesizedType.Construct(delegateSignature); | ||
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| // The distinction between by-ref kinds is dropped. |
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Not sure, perhaps to allow greater sharing of delegate types. But I believe this preserves the original behavior.
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| public bool Equals(RefKindVector other) |
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Done review pass (commit 5) |
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Approved to merge |
Synthesize delegate types for lambda expressions and method groups with inferred type that cannot be represented with
System.Func<>orSystem.Action<>types.Uses the existing compiler infrastructure for delegates created at
dynamiccall-sites.The PR does not include support for parameter or return types that cannot be used as generic type arguments: pointer types,
ref structtypes, etc. (see #55217). Those cases will be addressed separately.Proposal: lambda-improvements.md
Test plan: #52192