Improve MA0155 to report async void local functions

src/Meziantou.Analyzer/Rules/DoNotUseAsyncVoidAnalyzer.cs

@@ -1,6 +1,8 @@
-using System.Collections.Immutable;
+using System;
+using System.Collections.Immutable;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
 
 namespace Meziantou.Analyzer.Rules;
 
@@ -25,6 +27,16 @@ public override void Initialize(AnalysisContext context)
         context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
 
         context.RegisterSymbolAction(AnalyzeSymbol, SymbolKind.Method);
+        context.RegisterOperationAction(AnalyzeLocalFunction, OperationKind.LocalFunction);
+    }
+
+    private void AnalyzeLocalFunction(OperationAnalysisContext context)
+    {
+        var operation = (ILocalFunctionOperation)context.Operation;
+        if (operation.Symbol is { ReturnsVoid: true, IsAsync: true })
+        {
+            context.ReportDiagnostic(Rule, operation);
+        }
     }
 
     private static void AnalyzeSymbol(SymbolAnalysisContext context)

tests/Meziantou.Analyzer.Test/Rules/DoNotUseAsyncVoidAnalyzerTests.cs

@@ -52,4 +52,52 @@ class Sample
               .ValidateAsync();
     }
 
+    [Fact]
+    public async Task LocalFunction_Void()
+    {
+        await CreateProjectBuilder()
+              .WithSourceCode("""
+                  class Sample
+                  {
+                      void A()
+                      {
+                        void Local() => throw null;
+                      }
+                  }
+                  """)
+              .ValidateAsync();
+    }
+
+    [Fact]
+    public async Task LocalFunction_AsyncVoid()
+    {
+        await CreateProjectBuilder()
+              .WithSourceCode("""
+                  class Sample
+                  {
+                      void A()
+                      {
+                        [|async void Local() => throw null;|]
+                      }
+                  }
+                  """)
+              .ValidateAsync();
+    }
+
+    [Fact]
+    public async Task LocalFunction_AsyncTask()
+    {
+        await CreateProjectBuilder()
+              .WithSourceCode("""
+                  class Sample
+                  {
+                      void A()
+                      {
+                        async System.Threading.Tasks.Task Local() => throw null;
+                      }
+                  }
+                  """)
+              .ValidateAsync();
+    }
+
 }