Generate class? if the constraint has a type annotation

dotnet · Oct 4, 2019 · 21584df · 21584df
1 parent aa7faa1
commit 21584df
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Showing 3 changed files with 11 additions and 2 deletions.
diff --git a/src/EditorFeatures/CSharpTest/Diagnostics/GenerateMethod/GenerateMethodTests.cs b/src/EditorFeatures/CSharpTest/Diagnostics/GenerateMethod/GenerateMethodTests.cs
@@ -4686,6 +4686,7 @@ internal static void Test(global::Outer.Inner inner)
 
         [Theory]
         [InlineData("class")]
+        [InlineData("class?")]
         [InlineData("struct")]
         [InlineData("new()")]
         [InlineData("unmanaged")]

diff --git a/src/Workspaces/CSharp/Portable/Extensions/ITypeParameterSymbolExtensions.cs b/src/Workspaces/CSharp/Portable/Extensions/ITypeParameterSymbolExtensions.cs
@@ -42,7 +42,11 @@ internal static class ITypeParameterSymbolExtensions
 
             if (typeParameter.HasReferenceTypeConstraint)
             {
-                constraints.Add(SyntaxFactory.ClassOrStructConstraint(SyntaxKind.ClassConstraint));
+                var questionMarkToken = typeParameter.ReferenceTypeConstraintNullableAnnotation == NullableAnnotation.Annotated
+                                        ? SyntaxFactory.Token(SyntaxKind.QuestionToken)
+                                        : default;
+
+                constraints.Add(SyntaxFactory.ClassOrStructConstraint(SyntaxKind.ClassConstraint, SyntaxFactory.Token(SyntaxKind.ClassKeyword), questionMarkToken));
             }
             else if (typeParameter.HasUnmanagedTypeConstraint)
             {

diff --git a/...Workspaces/CSharp/Portable/Extensions/ITypeSymbolExtensions.TypeSyntaxGeneratorVisitor.cs b/...Workspaces/CSharp/Portable/Extensions/ITypeSymbolExtensions.TypeSyntaxGeneratorVisitor.cs
@@ -308,7 +308,11 @@ public override TypeSyntax VisitTypeParameter(ITypeParameterSymbol symbol)
             {
                 TypeSyntax typeSyntax =  AddInformationTo(symbol.Name.ToIdentifierName(), symbol);
 
-                if (symbol.GetNullability() == NullableAnnotation.Annotated)
+                // Add a ? if the type parameter is annotated as nullable, and the constraints allow it. It's possible to end up with
+                // a T? where T is constrained to class? if we combined a type parameter with some flow state -- we'll ignore the ? here
+                // at this stage. We should consider moving that check earlier when we actually wrap the symbol.
+                if (symbol.GetNullability() == NullableAnnotation.Annotated &&
+                    !(symbol.HasReferenceTypeConstraint && symbol.ReferenceTypeConstraintNullableAnnotation == NullableAnnotation.Annotated))
                 {
                     typeSyntax = AddInformationTo(SyntaxFactory.NullableType(typeSyntax), symbol);
                 }