Fix not offering to remove unnecessary nullable pragmas (#79356)

Author: CyrusNajmabadi

src/Analyzers/CSharp/Analyzers/RemoveUnnecessaryNullableDirective/CSharpRemoveUnnecessaryNullableDirectiveDiagnosticAnalyzer.cs

@@ -19,26 +19,19 @@
 namespace Microsoft.CodeAnalysis.RemoveUnnecessaryNullableDirective;
 
 [DiagnosticAnalyzer(LanguageNames.CSharp)]
-internal sealed class CSharpRemoveUnnecessaryNullableDirectiveDiagnosticAnalyzer
-    : AbstractBuiltInUnnecessaryCodeStyleDiagnosticAnalyzer
+internal sealed class CSharpRemoveUnnecessaryNullableDirectiveDiagnosticAnalyzer()
+    : AbstractBuiltInUnnecessaryCodeStyleDiagnosticAnalyzer(IDEDiagnosticIds.RemoveUnnecessaryNullableDirectiveDiagnosticId,
+        EnforceOnBuildValues.RemoveUnnecessaryNullableDirective,
+        option: null,
+        fadingOption: null,
+        new LocalizableResourceString(nameof(CSharpAnalyzersResources.Remove_unnecessary_nullable_directive), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)),
+        new LocalizableResourceString(nameof(CSharpAnalyzersResources.Nullable_directive_is_unnecessary), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)))
 {
-    public CSharpRemoveUnnecessaryNullableDirectiveDiagnosticAnalyzer()
-        : base(IDEDiagnosticIds.RemoveUnnecessaryNullableDirectiveDiagnosticId,
-               EnforceOnBuildValues.RemoveUnnecessaryNullableDirective,
-               option: null,
-               fadingOption: null,
-               new LocalizableResourceString(nameof(CSharpAnalyzersResources.Remove_unnecessary_nullable_directive), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)),
-               new LocalizableResourceString(nameof(CSharpAnalyzersResources.Nullable_directive_is_unnecessary), CSharpAnalyzersResources.ResourceManager, typeof(CSharpAnalyzersResources)))
-    {
-    }
-
     public override DiagnosticAnalyzerCategory GetAnalyzerCategory()
         => DiagnosticAnalyzerCategory.SemanticDocumentAnalysis;
 
     protected override void InitializeWorker(AnalysisContext context)
-    {
-        context.RegisterCompilationStartAction(AnalyzeCompilation);
-    }
+        => context.RegisterCompilationStartAction(AnalyzeCompilation);
 
     private void AnalyzeCompilation(CompilationStartAnalysisContext context)
     {

src/Analyzers/CSharp/Analyzers/RemoveUnnecessaryNullableDirective/NullableImpactingSpanWalker.cs

@@ -97,6 +97,10 @@ private static bool IsLanguageRestrictedToNonNullForm(TypeSyntax node)
             return true;
         }
 
+        // An attribute name cannot itself be nullable.  `[CLSCompliant?]` is not a thing.
+        if (node.IsParentKind(SyntaxKind.Attribute))
+            return true;
+
         return false;
 
         // If this is Y in X.Y, walk up to X.Y

src/Analyzers/CSharp/Tests/RemoveUnnecessaryNullableDirective/CSharpRemoveUnnecessaryNullableDirectiveTests.cs

@@ -8,6 +8,7 @@
 using Microsoft.CodeAnalysis.RemoveUnnecessaryNullableDirective;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Test.Utilities;
+using Roslyn.Test.Utilities;
 using Xunit;
 
 namespace Microsoft.CodeAnalysis.CSharp.Analyzers.UnitTests.RemoveUnnecessaryNullableDirective;
@@ -62,6 +63,32 @@ enum EnumName
             }
             """);
 
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/65401")]
+    public Task TestUnnecessaryDisableEnumDeclaration_WithAttribute()
+        => VerifyCodeFixAsync(
+            NullableContextOptions.Enable,
+            """
+            [|#nullable disable|]
+            using System;
+
+            [CLSCompliant(false)]
+            enum EnumName
+            {
+                First,
+                Second,
+            }
+            """,
+            """
+            using System;
+
+            [CLSCompliant(false)]
+            enum EnumName
+            {
+                First,
+                Second,
+            }
+            """);
+
     [Fact]
     public Task TestUnnecessaryDisableEnumDeclarationWithFileHeader()
         => VerifyCodeFixAsync(