Merge pull request #293 from AArnott/fixReturnAsync

Fix VSTHRD110 to not report warnings on "return DoAsync()"
microsoft · Jun 7, 2018 · d0adeab · d0adeab
2 parents fd38f73 + fdc45a7
commit d0adeab
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Showing 2 changed files with 44 additions and 1 deletion.
diff --git a/...VisualStudio.Threading.Analyzers.Tests/VSTHRD110ObserveResultOfAsyncCallsAnalyzerTests.cs b/...VisualStudio.Threading.Analyzers.Tests/VSTHRD110ObserveResultOfAsyncCallsAnalyzerTests.cs
@@ -148,6 +148,49 @@ void OtherMethod(Task t) { }
             this.VerifyCSharpDiagnostic(test);
         }
 
+        [Fact]
+        public void ReturnStatement_ProducesNoDiagnostic()
+        {
+            var test = @"
+using System.Threading.Tasks;
+
+class Test {
+    Task Foo()
+    {
+        return BarAsync();
+    }
+
+    Task BarAsync() => null;
+
+    void OtherMethod(Task t) { }
+}
+";
+
+            this.VerifyCSharpDiagnostic(test);
+        }
+
+        [Fact]
+        public void ContinueWith_ProducesDiagnostic()
+        {
+            var test = @"
+using System.Threading.Tasks;
+
+class Test {
+    void Foo()
+    {
+        BarAsync().ContinueWith(_ => { }); // ContinueWith returns the dropped task
+    }
+
+    Task BarAsync() => null;
+
+    void OtherMethod(Task t) { }
+}
+";
+
+            this.expect = this.CreateDiagnostic(7, 20, 12);
+            this.VerifyCSharpDiagnostic(test, this.expect);
+        }
+
         [Fact]
         public void AsyncMethod_ProducesNoDiagnostic()
         {

diff --git a/src/Microsoft.VisualStudio.Threading.Analyzers/VSTHRD110ObserveResultOfAsyncCallsAnalyzer.cs b/src/Microsoft.VisualStudio.Threading.Analyzers/VSTHRD110ObserveResultOfAsyncCallsAnalyzer.cs
@@ -45,7 +45,7 @@ private void AnalyzeInvocation(SyntaxNodeAnalysisContext context)
 
             // Only consider invocations that are direct statements. Otherwise, we assume their
             // result is awaited, assigned, or otherwise consumed.
-            if (invocation.Parent is StatementSyntax)
+            if (invocation.Parent?.GetType().Equals(typeof(ExpressionStatementSyntax)) ?? false)
             {
                 var methodSymbol = context.SemanticModel.GetSymbolInfo(context.Node).Symbol as IMethodSymbol;
                 var returnedSymbol = methodSymbol?.ReturnType;