Handle nameof expressions in UnboundIdentifiersDiagnosticAnalyzerBase

Fixes #23667

src/EditorFeatures/CSharpTest/AddUsing/AddUsingTestsWithAddImportDiagnosticProvider.cs

@@ -283,6 +283,22 @@ class Program
     {
         public async Task<IReadOnlyCollection<ProjectConfiguration>>
     }
+}");
+        }
+
+        [WorkItem(23667, "https://github.com/dotnet/roslyn/issues/23667")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsAddImport)]
+        public async Task TestMissingDiagnosticForNameOf()
+        {
+            await TestDiagnosticMissingAsync(
+@"using System;
+
+class C
+{
+    Action action = () => {
+        var x = [|nameof|](System);
+#warning xxx
+    };
 }");
         }
     }

src/EditorFeatures/TestUtilities/Diagnostics/AbstractUserDiagnosticTest.cs

@@ -42,13 +42,7 @@ public abstract partial class AbstractUserDiagnosticTest : AbstractCodeActionOrU
 
         protected override async Task<ImmutableArray<Diagnostic>> GetDiagnosticsWorkerAsync(TestWorkspace workspace, TestParameters parameters)
         {
-            var diagnosticsAndCodeFixes = await GetDiagnosticAndFixAsync(workspace, parameters);
-            if (diagnosticsAndCodeFixes == null)
-            {
-                return ImmutableArray<Diagnostic>.Empty;
-            }
-
-            return ImmutableArray.Create(diagnosticsAndCodeFixes.Item1);
+            return (await GetDiagnosticsAsync(workspace, parameters)).AsImmutable();
         }
 
         internal async Task<Tuple<Diagnostic, CodeFixCollection>> GetDiagnosticAndFixAsync(

src/EditorFeatures/VisualBasicTest/Diagnostics/AddImport/AddImportTests.vb

@@ -2606,5 +2606,21 @@ Class C
         Dim s As Action = Sub()
                               Dim a = New Test()")
         End Function
+
+        <WorkItem(23667, "https://github.com/dotnet/roslyn/issues/23667")>
+        <Fact, Trait(Traits.Feature, Traits.Features.CodeActionsAddImport)>
+        Public Async Function TestMissingDiagnosticForNameOf() As Task
+            Await TestDiagnosticMissingAsync(
+"Imports System
+
+Class Class1
+    Sub M()
+        Dim a As Action = Sub()
+                            Dim x = [|NameOf|](System)
+                            Dim x2
+                          End Function
+    End Sub
+    Extension")
+        End Function
     End Class
 End Namespace

src/Features/CSharp/Portable/Diagnostics/Analyzers/CSharpUnboundIdentifiersDiagnosticAnalyzer.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System.Collections.Immutable;
+using Microsoft.CodeAnalysis.CSharp.Extensions;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Diagnostics.AddImport;
@@ -63,5 +64,7 @@ protected override bool ConstructorDoesNotExist(SyntaxNode node, SymbolInfo info
 
             return false;
         }
+
+        protected override bool IsNameOf(SyntaxNode node) => node.Parent is InvocationExpressionSyntax invocation && invocation.IsNameOfInvocation();
     }
 }

src/Features/Core/Portable/Diagnostics/Analyzers/UnboundIdentifiersDiagnosticAnalyzerBase.cs

@@ -18,6 +18,7 @@ internal abstract class UnboundIdentifiersDiagnosticAnalyzerBase<TLanguageKindEn
         protected abstract DiagnosticDescriptor DiagnosticDescriptor2 { get; }
         protected abstract ImmutableArray<TLanguageKindEnum> SyntaxKindsOfInterest { get; }
         protected abstract bool ConstructorDoesNotExist(SyntaxNode node, SymbolInfo info, SemanticModel semanticModel);
+        protected abstract bool IsNameOf(SyntaxNode node);
 
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(DiagnosticDescriptor, DiagnosticDescriptor2);
         public bool OpenFileOnly(Workspace workspace) => false;
@@ -73,6 +74,12 @@ private void ReportUnboundIdentifierNames(SyntaxNodeAnalysisContext context, Syn
                 var info = context.SemanticModel.GetSymbolInfo(typeName);
                 if (info.Symbol == null && info.CandidateSymbols.Length == 0)
                 {
+                    // GetSymbolInfo returns no symbols for "nameof" expression, so handle it specially.
+                    if (IsNameOf(typeName))
+                    {
+                        continue;
+                    }
+
                     context.ReportDiagnostic(Diagnostic.Create(DiagnosticDescriptor, typeName.GetLocation(), typeName.ToString()));
                 }
                 else if (ConstructorDoesNotExist(typeName, info, context.SemanticModel))

src/Features/VisualBasic/Portable/Diagnostics/Analyzers/VisualBasicUnboundIdentifiersDiagnosticAnalyzer.vb

@@ -71,5 +71,9 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Diagnostics
 
             Return False
         End Function
+
+        Protected Overrides Function IsNameOf(node As SyntaxNode) As Boolean
+            Return node.Kind() = SyntaxKind.NameOfKeyword
+        End Function
     End Class
 End Namespace