Merge pull request dotnet#54142 from AlekseyTs/StaticAbstractMembersI…

…nInterfaces_32 Merge 'features/StaticAbstractMembersInInterfaces' into 'main'
sharwell · Jun 16, 2021 · 6920e1e · 6920e1e
2 parents 4fb8c42 + 07e319e
commit 6920e1e
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diff --git a/docs/features/StaticAbstractMembersInInterfaces.md b/docs/features/StaticAbstractMembersInInterfaces.md
@@ -0,0 +1,14 @@
+Static Abstract Members In Interfaces
+=====================================
+
+An interface is allowed to specify abstract static members that implementing classes and structs are then
+required to provide an explicit or implicit implementation of. The members can be accessed off of type
+parameters that are constrained by the interface.
+
+Proposal: 
+- https://github.com/dotnet/csharplang/issues/4436
+- https://github.com/dotnet/csharplang/blob/main/proposals/static-abstracts-in-interfaces.md
+
+Feature branch: https://github.com/dotnet/roslyn/tree/features/StaticAbstractMembersInInterfaces
+
+Test plan: https://github.com/dotnet/roslyn/issues/52221
diff --git a/src/Compilers/CSharp/Portable/Binder/Binder.ValueChecks.cs b/src/Compilers/CSharp/Portable/Binder/Binder.ValueChecks.cs
@@ -1133,7 +1133,7 @@ private bool CheckPropertyValueKind(SyntaxNode node, BoundExpression expr, BindV
                         return false;
                     }
 
-                    CheckRuntimeSupportForSymbolAccess(node, receiver, setMethod, diagnostics);
+                    CheckReceiverAndRuntimeSupportForSymbolAccess(node, receiver, setMethod, diagnostics);
                 }
             }
 
@@ -1177,7 +1177,7 @@ private bool CheckPropertyValueKind(SyntaxNode node, BoundExpression expr, BindV
                         return false;
                     }
 
-                    CheckRuntimeSupportForSymbolAccess(node, receiver, getMethod, diagnostics);
+                    CheckReceiverAndRuntimeSupportForSymbolAccess(node, receiver, getMethod, diagnostics);
                 }
             }
 

diff --git a/src/Compilers/CSharp/Portable/Binder/BinderFactory.BinderFactoryVisitor.cs b/src/Compilers/CSharp/Portable/Binder/BinderFactory.BinderFactoryVisitor.cs
@@ -448,11 +448,11 @@ private static string GetMethodName(BaseMethodDeclarationSyntax baseMethodDeclar
                     case SyntaxKind.DestructorDeclaration:
                         return WellKnownMemberNames.DestructorName;
                     case SyntaxKind.OperatorDeclaration:
-                        return OperatorFacts.OperatorNameFromDeclaration((OperatorDeclarationSyntax)baseMethodDeclarationSyntax);
+                        var operatorDeclaration = (OperatorDeclarationSyntax)baseMethodDeclarationSyntax;
+                        return ExplicitInterfaceHelpers.GetMemberName(outerBinder, operatorDeclaration.ExplicitInterfaceSpecifier, OperatorFacts.OperatorNameFromDeclaration(operatorDeclaration));
                     case SyntaxKind.ConversionOperatorDeclaration:
-                        return ((ConversionOperatorDeclarationSyntax)baseMethodDeclarationSyntax).ImplicitOrExplicitKeyword.Kind() == SyntaxKind.ImplicitKeyword
-                            ? WellKnownMemberNames.ImplicitConversionName
-                            : WellKnownMemberNames.ExplicitConversionName;
+                        var conversionDeclaration = (ConversionOperatorDeclarationSyntax)baseMethodDeclarationSyntax;
+                        return ExplicitInterfaceHelpers.GetMemberName(outerBinder, conversionDeclaration.ExplicitInterfaceSpecifier, OperatorFacts.OperatorNameFromDeclaration(conversionDeclaration));
                     case SyntaxKind.MethodDeclaration:
                         MethodDeclarationSyntax methodDeclSyntax = (MethodDeclarationSyntax)baseMethodDeclarationSyntax;
                         return ExplicitInterfaceHelpers.GetMemberName(outerBinder, methodDeclSyntax.ExplicitInterfaceSpecifier, methodDeclSyntax.Identifier.ValueText);

diff --git a/src/Compilers/CSharp/Portable/Binder/Binder_Conversions.cs b/src/Compilers/CSharp/Portable/Binder/Binder_Conversions.cs
@@ -90,6 +90,7 @@ protected BoundExpression CreateConversion(
 
             // Obsolete diagnostics for method group are reported as part of creating the method group conversion.
             ReportDiagnosticsIfObsolete(diagnostics, conversion, syntax, hasBaseReceiver: false);
+            CheckConstraintLanguageVersionAndRuntimeSupportForConversion(syntax, conversion, diagnostics);
 
             if (conversion.IsAnonymousFunction && source.Kind == BoundKind.UnboundLambda)
             {
@@ -214,6 +215,25 @@ protected BoundExpression CreateConversion(
             { WasCompilerGenerated = wasCompilerGenerated };
         }
 
+        internal void CheckConstraintLanguageVersionAndRuntimeSupportForConversion(SyntaxNodeOrToken syntax, Conversion conversion, BindingDiagnosticBag diagnostics)
+        {
+            if (conversion.IsUserDefined && conversion.Method is MethodSymbol method && method.IsStatic && method.IsAbstract)
+            {
+                Debug.Assert(conversion.ConstrainedToTypeOpt is TypeParameterSymbol);
+
+                if (Compilation.SourceModule != method.ContainingModule)
+                {
+                    Debug.Assert(syntax.SyntaxTree is object);
+                    CheckFeatureAvailability(syntax.SyntaxTree, MessageID.IDS_FeatureStaticAbstractMembersInInterfaces, diagnostics, syntax.GetLocation()!);
+
+                    if (!Compilation.Assembly.RuntimeSupportsStaticAbstractMembersInInterfaces)
+                    {
+                        Error(diagnostics, ErrorCode.ERR_RuntimeDoesNotSupportStaticAbstractMembersInInterfaces, syntax);
+                    }
+                }
+            }
+        }
+
         private BoundExpression ConvertObjectCreationExpression(SyntaxNode syntax, BoundUnconvertedObjectCreationExpression node, bool isCast, TypeSymbol destination, BindingDiagnosticBag diagnostics)
         {
             var arguments = AnalyzedArguments.GetInstance(node.Arguments, node.ArgumentRefKindsOpt, node.ArgumentNamesOpt);
@@ -346,6 +366,7 @@ private BoundExpression CreateUserDefinedConversion(
             bool hasErrors)
         {
             Debug.Assert(conversionGroup != null);
+            Debug.Assert(conversion.IsUserDefined);
 
             if (!conversion.IsValid)
             {
@@ -788,7 +809,7 @@ private bool MemberGroupFinalValidation(BoundExpression? receiverOpt, MethodSymb
         {
             if (!IsBadBaseAccess(node, receiverOpt, methodSymbol, diagnostics))
             {
-                CheckRuntimeSupportForSymbolAccess(node, receiverOpt, methodSymbol, diagnostics);
+                CheckReceiverAndRuntimeSupportForSymbolAccess(node, receiverOpt, methodSymbol, diagnostics);
             }
 
             if (MemberGroupFinalValidationAccessibilityChecks(receiverOpt, methodSymbol, node, diagnostics, invokedAsExtensionMethod))

diff --git a/src/Compilers/CSharp/Portable/Binder/Binder_Crefs.cs b/src/Compilers/CSharp/Portable/Binder/Binder_Crefs.cs
@@ -757,6 +757,7 @@ private static ImmutableArray<Symbol> PerformCrefOverloadResolution(ArrayBuilder
                                 name: null,
                                 refKind: RefKind.None,
                                 isInitOnly: false,
+                                isStatic: false,
                                 returnType: default,
                                 refCustomModifiers: ImmutableArray<CustomModifier>.Empty,
                                 explicitInterfaceImplementations: ImmutableArray<MethodSymbol>.Empty);