Extensions: adjust SpecialName on implementation methods (#79068)

Author: Julien Couvreur

src/Compilers/CSharp/Portable/Symbols/ErrorMethodSymbol.cs

@@ -83,6 +83,8 @@ internal sealed override ObsoleteAttributeData ObsoleteAttributeData
 
         internal sealed override UnmanagedCallersOnlyAttributeData GetUnmanagedCallersOnlyAttributeData(bool forceComplete) => null;
 
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
+
         public override Accessibility DeclaredAccessibility
         {
             get { return Accessibility.Public; }

src/Compilers/CSharp/Portable/Symbols/Extensions/RewrittenMethodSymbol.cs

@@ -76,6 +76,8 @@ internal sealed override int CalculateLocalSyntaxOffset(int localPosition, Synta
         internal sealed override UnmanagedCallersOnlyAttributeData? GetUnmanagedCallersOnlyAttributeData(bool forceComplete)
             => _originalMethod.GetUnmanagedCallersOnlyAttributeData(forceComplete);
 
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
+
         public sealed override ImmutableArray<CustomModifier> RefCustomModifiers
         {
             get { return _typeMap.SubstituteCustomModifiers(_originalMethod.RefCustomModifiers); }

src/Compilers/CSharp/Portable/Symbols/Extensions/SourceExtensionImplementationMethodSymbol.cs

@@ -35,7 +35,7 @@ public SourceExtensionImplementationMethodSymbol(MethodSymbol sourceMethod)
         public override MethodKind MethodKind => MethodKind.Ordinary;
         public override bool IsImplicitlyDeclared => true;
 
-        internal override bool HasSpecialName => false;
+        internal override bool HasSpecialName => _originalMethod.HasSpecialNameAttribute;
 
         internal override int ParameterCount
         {

src/Compilers/CSharp/Portable/Symbols/FunctionPointers/FunctionPointerMethodSymbol.cs

@@ -848,6 +848,7 @@ public override bool IsVararg
         internal override bool IsMetadataNewSlot(bool ignoreInterfaceImplementationChanges = false) => false;
         internal override bool IsMetadataVirtual(IsMetadataVirtualOption option = IsMetadataVirtualOption.None) => false;
         internal sealed override UnmanagedCallersOnlyAttributeData? GetUnmanagedCallersOnlyAttributeData(bool forceComplete) => null;
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
 
         internal override bool GenerateDebugInfo => throw ExceptionUtilities.Unreachable();
         internal override ObsoleteAttributeData? ObsoleteAttributeData => throw ExceptionUtilities.Unreachable();

src/Compilers/CSharp/Portable/Symbols/Metadata/PE/PEMethodSymbol.cs

@@ -1682,6 +1682,8 @@ internal override ObsoleteAttributeData ObsoleteAttributeData
 
             return _uncommonFields?._lazyUnmanagedCallersOnlyAttributeData;
         }
+
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
 #nullable disable
 
         internal override bool GenerateDebugInfo => false;

src/Compilers/CSharp/Portable/Symbols/MethodSymbol.cs

@@ -96,6 +96,8 @@ public virtual bool IsGenericMethod
         /// </summary>
         internal virtual bool IsDirectlyExcludedFromCodeCoverage { get => false; }
 
+        internal abstract bool HasSpecialNameAttribute { get; }
+
         /// <summary>
         /// If a method is annotated with `[MemberNotNull(...)]` attributes, returns the list of members
         /// listed in those attributes.

src/Compilers/CSharp/Portable/Symbols/NativeIntegerTypeSymbol.cs

@@ -374,6 +374,8 @@ public override ImmutableArray<ParameterSymbol> Parameters
 
         internal override UnmanagedCallersOnlyAttributeData? GetUnmanagedCallersOnlyAttributeData(bool forceComplete) => UnderlyingMethod.GetUnmanagedCallersOnlyAttributeData(forceComplete);
 
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
+
         public override Symbol? AssociatedSymbol => _associatedSymbol;
 
         internal override int CalculateLocalSyntaxOffset(int localPosition, SyntaxTree localTree)

src/Compilers/CSharp/Portable/Symbols/ReducedExtensionMethodSymbol.cs

@@ -444,6 +444,8 @@ internal sealed override ObsoleteAttributeData ObsoleteAttributeData
         internal sealed override UnmanagedCallersOnlyAttributeData GetUnmanagedCallersOnlyAttributeData(bool forceComplete)
             => _reducedFrom.GetUnmanagedCallersOnlyAttributeData(forceComplete);
 
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
+
         public override Accessibility DeclaredAccessibility
         {
             get { return _reducedFrom.DeclaredAccessibility; }

src/Compilers/CSharp/Portable/Symbols/Retargeting/RetargetingMethodSymbol.cs

@@ -256,6 +256,8 @@ public override ImmutableArray<CSharpAttributeData> GetReturnTypeAttributes()
             return _lazyUnmanagedAttributeData;
         }
 
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
+
         internal override bool TryGetThisParameter(out ParameterSymbol? thisParameter)
         {
             if (!_underlyingMethod.TryGetThisParameter(out var underlyingParameter))

src/Compilers/CSharp/Portable/Symbols/SignatureOnlyMethodSymbol.cs

@@ -124,6 +124,8 @@ internal sealed override bool HasAsyncMethodBuilderAttribute(out TypeSymbol buil
 
         internal sealed override UnmanagedCallersOnlyAttributeData GetUnmanagedCallersOnlyAttributeData(bool forceComplete) => throw ExceptionUtilities.Unreachable();
 
+        internal sealed override bool HasSpecialNameAttribute => throw ExceptionUtilities.Unreachable();
+
         internal override ImmutableArray<string> GetAppliedConditionalSymbols() { throw ExceptionUtilities.Unreachable(); }
 
         public override ImmutableArray<TypeWithAnnotations> TypeArgumentsWithAnnotations { get { throw ExceptionUtilities.Unreachable(); } }