Analyzer fixes

src/Microsoft.VisualStudio.Threading.Analyzers.CSharp/VSTHRD103UseAsyncOptionAnalyzer.cs

@@ -171,22 +171,30 @@ private static bool IsInTaskReturningMethodOrDelegate(SyntaxNodeAnalysisContext
             // We want to scan invocations that occur inside Task and Task<T>-returning delegates or methods.
             // That is: methods that either are or could be made async.
             IMethodSymbol? methodSymbol = null;
-            AnonymousFunctionExpressionSyntax? anonymousFunc = context.Node.FirstAncestorOrSelf<AnonymousFunctionExpressionSyntax>();
-            if (anonymousFunc is object)
+            for (SyntaxNode? focusedNode = context.Node; focusedNode is not null; focusedNode = focusedNode.Parent)
             {
-                SymbolInfo symbolInfo = context.SemanticModel.GetSymbolInfo(anonymousFunc, context.CancellationToken);
-                methodSymbol = symbolInfo.Symbol as IMethodSymbol;
-            }
-            else
-            {
-                MethodDeclarationSyntax? methodDecl = context.Node.FirstAncestorOrSelf<MethodDeclarationSyntax>();
-                if (methodDecl is object)
+                switch (focusedNode)
                 {
-                    methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodDecl, context.CancellationToken);
+                    case AnonymousFunctionExpressionSyntax anonFunc:
+                        SymbolInfo symbolInfo = context.SemanticModel.GetSymbolInfo(anonFunc, context.CancellationToken);
+                        methodSymbol = symbolInfo.Symbol as IMethodSymbol;
+                        break;
+                    case LocalFunctionStatementSyntax localFunc:
+                        methodSymbol = context.SemanticModel.GetDeclaredSymbol(localFunc, context.CancellationToken) as IMethodSymbol;
+                        break;
+                    case MethodDeclarationSyntax methodDecl:
+                        methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodDecl, context.CancellationToken);
+                        break;
+                    default:
+                        // We want to continue iteration of the for loop.
+                        continue;
                 }
+
+                // We encountered one of our case statements, so whether or not we have a methodSymbol, we shouldn't look further.
+                break;
             }
 
-            return methodSymbol.HasAsyncCompatibleReturnType();
+            return methodSymbol?.HasAsyncCompatibleReturnType() is true;
         }
 
         private static bool InspectMemberAccess(SyntaxNodeAnalysisContext context, ExpressionSyntax memberName, IEnumerable<CommonInterest.SyncBlockingMethod> problematicMethods)

test/Microsoft.VisualStudio.Threading.Analyzers.Tests/VSTHRD103UseAsyncOptionAnalyzerTests.cs

@@ -1314,6 +1314,31 @@ Task MethodAsync()
         await CSVerify.VerifyAnalyzerAsync(test);
     }
 
+    [Fact]
+    public async Task DoNotRaiseInSyncLocalFunctionInsideAsyncMethod()
+    {
+        string test = """
+            using System.Threading.Tasks;
+
+            class SomeClass {
+                Task Foo()
+                {
+                    return Task.CompletedTask;
+
+                    void CompletionHandler()
+                    {
+                        this.Bar();
+                    }
+                }
+
+                void Bar() {}
+                Task BarAsync() => Task.CompletedTask;
+            }
+            """;
+
+        await CSVerify.VerifyAnalyzerAsync(test);
+    }
+
     private DiagnosticResult CreateDiagnostic(int line, int column, int length, string methodName)
         => CSVerify.Diagnostic(DescriptorNoAlternativeMethod).WithSpan(line, column, line, column + length).WithArguments(methodName);
 

test/Microsoft.VisualStudio.Threading.Analyzers.Tests/VSTHRD110ObserveResultOfAsyncCallsAnalyzerTests.cs

@@ -429,6 +429,21 @@ async Task Foo(Test? tester)
         await CSVerify.VerifyAnalyzerAsync(test);
     }
 
+    [Fact]
+    public async Task NullCoalescing_ProducesNoDiagnostic()
+    {
+        string test = """
+            using System.Threading.Tasks;
+
+            class Tree {
+                static Task ShakeTreeAsync(Tree? tree) => tree?.ShakeAsync() ?? Task.CompletedTask;
+                Task ShakeAsync() => Task.CompletedTask;
+            }
+            """;
+
+        await CSVerify.VerifyAnalyzerAsync(test);
+    }
+
     [Fact]
     public async Task TaskInFinalizer()
     {
@@ -470,7 +485,4 @@ class Class1
 
         await CSVerify.VerifyAnalyzerAsync(test);
     }
-
-    private DiagnosticResult CreateDiagnostic(int line, int column, int length)
-        => CSVerify.Diagnostic().WithSpan(line, column, line, column + length);
 }