Merge pull request #16989 from CyrusNajmabadi/generateTypeValueTupleSingleArity

Properly generate type syntax for tuples with less than arity-2.
Fixes #16793

src/EditorFeatures/CSharpTest/ImplementInterface/ImplementInterfaceTests.cs

@@ -141,6 +141,35 @@ class Class : IInterface
 }");
         }
 
+        [WorkItem(16793, "https://github.com/dotnet/roslyn/issues/16793")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsImplementInterface)]
+        public async Task TestMethodWithValueTupleArity1()
+        {
+            await TestWithAllCodeStyleOptionsOffAsync(
+@"
+using System;
+interface I
+{
+    ValueTuple<object> F();
+}
+class C : [|I|]
+{
+}",
+@"
+using System;
+interface I
+{
+    ValueTuple<object> F();
+}
+class C : I
+{
+    public ValueTuple<object> F()
+    {
+        throw new NotImplementedException();
+    }
+}");
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsImplementInterface)]
         public async Task TestExpressionBodiedMethod1()
         {

src/EditorFeatures/VisualBasicTest/ImplementInterface/ImplementInterfaceTests.vb

@@ -4514,5 +4514,40 @@ Public MustInherit Class C
 End Class",
 index:=1)
         End Function
+
+        <WorkItem(16793, "https://github.com/dotnet/roslyn/issues/16793")>
+        <Fact, Trait(Traits.Feature, Traits.Features.CodeActionsImplementInterface)>
+        Public Async Function TestMethodWithValueTupleArity1() As Task
+            Await TestAsync(
+"
+Imports System
+interface I
+    Function F() As ValueTuple(Of Object)
+end interface
+class C
+    Implements [|I|]
+
+end class
+Namespace System
+    Structure ValueTuple(Of T1)
+    End Structure
+End Namespace",
+"
+Imports System
+interface I
+    Function F() As ValueTuple(Of Object)
+end interface
+class C 
+    Implements I
+
+Public Function F() As ValueTuple(Of Object) Implements I.F
+        Throw New NotImplementedException()
+    End Function
+end class
+Namespace System
+    Structure ValueTuple(Of T1)
+    End Structure
+End Namespace")
+        End Function
     End Class
 End Namespace
\ No newline at end of file

src/Workspaces/CSharp/Portable/Extensions/ITypeSymbolExtensions.TypeSyntaxGeneratorVisitor.cs

@@ -100,6 +100,11 @@ public TypeSyntax CreateSimpleTypeSyntax(INamedTypeSymbol symbol)
                     }
                 }
 
+                if (symbol.IsTupleType && symbol.TupleUnderlyingType != null && !symbol.Equals(symbol.TupleUnderlyingType))
+                {
+                    return CreateSimpleTypeSyntax(symbol.TupleUnderlyingType);
+                }
+
                 if (symbol.Name == string.Empty || symbol.IsAnonymousType)
                 {
                     return CreateSystemObject();
@@ -145,7 +150,7 @@ private TypeSyntax TryCreateSpecializedNamedTypeSyntax(INamedTypeSymbol symbol)
                     return SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.VoidKeyword));
                 }
 
-                if (symbol.IsTupleType)
+                if (symbol.IsTupleType && symbol.TupleElements.Length >= 2)
                 {
                     return CreateTupleTypeSyntax(symbol);
                 }

src/Workspaces/VisualBasic/Portable/Extensions/INamespaceOrTypeSymbolExtensions.vb

 ' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
-Imports System.Collections.Generic
 Imports System.Runtime.CompilerServices
 Imports Microsoft.CodeAnalysis
 Imports Microsoft.CodeAnalysis.Simplification
-Imports Microsoft.CodeAnalysis.Text
-Imports Microsoft.CodeAnalysis.VisualBasic
-Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.Extensions

src/Workspaces/VisualBasic/Portable/Extensions/TypeSyntaxGeneratorVisitor.vb

@@ -67,6 +67,35 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Extensions
         End Function
 
         Public Function CreateSimpleTypeSyntax(symbol As INamedTypeSymbol) As TypeSyntax
+            Dim syntax = TryCreateSpecializedNamedTypeSyntax(symbol)
+            If syntax IsNot Nothing Then
+                Return syntax
+            End If
+
+            If symbol.IsTupleType AndAlso
+               symbol.TupleUnderlyingType IsNot Nothing AndAlso
+               Not symbol.Equals(symbol.TupleUnderlyingType) Then
+                Return CreateSimpleTypeSyntax(symbol.TupleUnderlyingType)
+            End If
+
+            If symbol.Name = String.Empty OrElse symbol.IsAnonymousType Then
+                Return SyntaxFactory.QualifiedName(SyntaxFactory.IdentifierName("System"), SyntaxFactory.IdentifierName("Object"))
+            End If
+
+            If symbol.OriginalDefinition.SpecialType = SpecialType.System_Nullable_T Then
+                Return AddInformationTo(SyntaxFactory.NullableType(symbol.TypeArguments.First().Accept(Me)), symbol)
+            End If
+
+            If symbol.TypeParameters.Length = 0 Then
+                Return symbol.Name.ToIdentifierName
+            End If
+
+            Return SyntaxFactory.GenericName(
+                symbol.Name.ToIdentifierToken,
+                SyntaxFactory.TypeArgumentList(SyntaxFactory.SeparatedList(symbol.TypeArguments.[Select](Function(t) t.Accept(Me)))))
+        End Function
+
+        Private Function TryCreateSpecializedNamedTypeSyntax(symbol As INamedTypeSymbol) As TypeSyntax
             Select Case symbol.SpecialType
                 Case SpecialType.System_Object
                     Return SyntaxFactory.QualifiedName(SyntaxFactory.IdentifierName("System"), SyntaxFactory.IdentifierName("Object"))
@@ -102,25 +131,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Extensions
                     Return SyntaxFactory.QualifiedName(SyntaxFactory.IdentifierName("System"), SyntaxFactory.IdentifierName("DateTime"))
             End Select
 
-            If symbol.IsTupleType Then
+            If symbol.IsTupleType AndAlso symbol.TupleElements.Length >= 2 Then
                 Return CreateTupleTypeSyntax(symbol)
             End If
 
-            If symbol.Name = String.Empty OrElse symbol.IsAnonymousType Then
-                Return SyntaxFactory.QualifiedName(SyntaxFactory.IdentifierName("System"), SyntaxFactory.IdentifierName("Object"))
-            End If
-
-            If symbol.OriginalDefinition.SpecialType = SpecialType.System_Nullable_T Then
-                Return AddInformationTo(SyntaxFactory.NullableType(symbol.TypeArguments.First().Accept(Me)), symbol)
-            End If
-
-            If symbol.TypeParameters.Length = 0 Then
-                Return symbol.Name.ToIdentifierName
-            End If
-
-            Return SyntaxFactory.GenericName(
-                symbol.Name.ToIdentifierToken,
-                SyntaxFactory.TypeArgumentList(SyntaxFactory.SeparatedList(symbol.TypeArguments.[Select](Function(t) t.Accept(Me)))))
+            Return Nothing
         End Function
 
         Private Shared Function CreateTupleTypeSyntax(symbol As INamedTypeSymbol) As TypeSyntax