CA1024: Do not report on tasks return types

Author: Evangelink

src/NetAnalyzers/Core/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/UsePropertiesWhereAppropriate.cs

@@ -42,47 +42,63 @@ public override void Initialize(AnalysisContext analysisContext)
             analysisContext.EnableConcurrentExecution();
             analysisContext.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
 
-            analysisContext.RegisterOperationBlockStartAction(context =>
+            analysisContext.RegisterCompilationStartAction(context =>
             {
+                var taskTypesBuilder = ImmutableHashSet.CreateBuilder<ITypeSymbol>();
 
-                if (!(context.OwningSymbol is IMethodSymbol methodSymbol) ||
-                    methodSymbol.ReturnsVoid ||
-                    methodSymbol.ReturnType.Kind == SymbolKind.ArrayType ||
-                    !methodSymbol.Parameters.IsEmpty ||
-                    !methodSymbol.MatchesConfiguredVisibility(context.Options, Rule, context.Compilation, context.CancellationToken) ||
-                    methodSymbol.IsAccessorMethod() ||
-                    !IsPropertyLikeName(methodSymbol.Name))
-                {
-                    return;
-                }
+                taskTypesBuilder.AddIfNotNull(
+                    context.Compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemThreadingTasksTask));
+                taskTypesBuilder.AddIfNotNull(
+                    context.Compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemThreadingTasksTask1));
+                taskTypesBuilder.AddIfNotNull(
+                    context.Compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemThreadingTasksValueTask));
+                taskTypesBuilder.AddIfNotNull(
+                    context.Compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemThreadingTasksValueTask1));
 
-                // A few additional checks to reduce the noise for this diagnostic:
-                // Ensure that the method is non-generic, non-virtual/override, has no overloads and doesn't have special names: 'GetHashCode' or 'GetEnumerator'.
-                // Also avoid generating this diagnostic if the method body has any invocation expressions.
-                // Also avoid implicit interface implementation (explicit are handled through the member accessibility)
-                if (methodSymbol.IsGenericMethod ||
-                    methodSymbol.IsVirtual ||
-                    methodSymbol.IsOverride ||
-                    methodSymbol.ContainingType.GetMembers(methodSymbol.Name).Length > 1 ||
-                    methodSymbol.Name == GetHashCodeName ||
-                    methodSymbol.Name == GetEnumeratorName ||
-                    methodSymbol.IsImplementationOfAnyImplicitInterfaceMember())
-                {
-                    return;
-                }
+                var taskTypes = taskTypesBuilder.ToImmutable();
 
-                bool hasInvocations = false;
-                context.RegisterOperationAction(operationContext =>
+                context.RegisterOperationBlockStartAction(context =>
                 {
-                    hasInvocations = true;
-                }, OperationKind.Invocation);
+                    if (!(context.OwningSymbol is IMethodSymbol methodSymbol) ||
+                        methodSymbol.ReturnsVoid ||
+                        methodSymbol.ReturnType.Kind == SymbolKind.ArrayType ||
+                        !methodSymbol.Parameters.IsEmpty ||
+                        !methodSymbol.MatchesConfiguredVisibility(context.Options, Rule, context.Compilation, context.CancellationToken) ||
+                        methodSymbol.IsAccessorMethod() ||
+                        !IsPropertyLikeName(methodSymbol.Name))
+                    {
+                        return;
+                    }
 
-                context.RegisterOperationBlockEndAction(endContext =>
-                {
-                    if (!hasInvocations)
+                    // A few additional checks to reduce the noise for this diagnostic:
+                    // Ensure that the method is non-generic, non-virtual/override, has no overloads and doesn't have special names: 'GetHashCode' or 'GetEnumerator'.
+                    // Also avoid generating this diagnostic if the method body has any invocation expressions.
+                    // Also avoid implicit interface implementation (explicit are handled through the member accessibility)
+                    if (methodSymbol.IsGenericMethod ||
+                        methodSymbol.IsVirtual ||
+                        methodSymbol.IsOverride ||
+                        methodSymbol.Name == GetHashCodeName ||
+                        methodSymbol.Name == GetEnumeratorName ||
+                        methodSymbol.ContainingType.GetMembers(methodSymbol.Name).Length > 1 ||
+                        taskTypes.Contains(methodSymbol.ReturnType.OriginalDefinition) ||
+                        methodSymbol.IsImplementationOfAnyImplicitInterfaceMember())
                     {
-                        endContext.ReportDiagnostic(endContext.OwningSymbol.CreateDiagnostic(Rule));
+                        return;
                     }
+
+                    bool hasInvocations = false;
+                    context.RegisterOperationAction(operationContext =>
+                    {
+                        hasInvocations = true;
+                    }, OperationKind.Invocation);
+
+                    context.RegisterOperationBlockEndAction(endContext =>
+                    {
+                        if (!hasInvocations)
+                        {
+                            endContext.ReportDiagnostic(endContext.OwningSymbol.CreateDiagnostic(Rule));
+                        }
+                    });
                 });
             });
         }

src/NetAnalyzers/UnitTests/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/UsePropertiesWhereAppropriateTests.cs

@@ -439,6 +439,45 @@ public object GetContent()
 ");
         }
 
+        [Fact, WorkItem(3877, "https://github.com/dotnet/roslyn-analyzers/issues/3877")]
+        public async Task CA1024_ReturnsTask_NoDiagnostic()
+        {
+            await VerifyCS.VerifyAnalyzerAsync(@"
+using System.Threading.Tasks;
+
+public class Something
+{
+    public Task GetTask() => default(Task);
+    public Task<int> GetGenericTask() => default(Task<int>);
+
+    public ValueTask GetValueTask() => default(ValueTask);
+    public ValueTask<int> GetGenericValueTask() => default(ValueTask<int>);
+}
+");
+
+            await VerifyVB.VerifyAnalyzerAsync(@"
+Imports System.Threading.Tasks
+
+Public Class Something
+    Public Function GetTask() As Task
+        Return Nothing
+    End Function
+
+    Public Function GetGenericTask() As Task(Of Integer)
+        Return Nothing
+    End Function
+
+    Public Function GetValueTask() As ValueTask
+        Return Nothing
+    End Function
+
+    Public Function GetGenericValueTask() As ValueTask(Of Integer)
+        Return Nothing
+    End Function
+End Class
+");
+        }
+
         private static DiagnosticResult GetCA1024CSharpResultAt(int line, int column, string methodName)
             => VerifyCS.Diagnostic()
                 .WithLocation(line, column)