Fix analyzer RCS1174

ChangeLog.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix analyzer [RCS1229](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1229) ([PR](https://github.com/dotnet/roslynator/pull/1618))
+- Fix analyzer [RCS1174](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1174) ([PR](https://github.com/dotnet/roslynator/pull/1619))
 
 ### Added
 

src/Common/CSharp/Analysis/RemoveAsyncAwaitAnalysis.cs

@@ -372,7 +372,7 @@ private static bool VerifyTypes(
 
         foreach (AwaitExpressionSyntax awaitExpression in awaitExpressions)
         {
-            if (!VerifyAwaitType(awaitExpression, typeArgument, semanticModel, cancellationToken))
+            if (!VerifyAwaitType(awaitExpression, returnType, typeArgument, semanticModel, cancellationToken))
                 return false;
         }
 
@@ -400,10 +400,15 @@ private static bool VerifyTypes(
         if (typeArgument is null)
             return false;
 
-        return VerifyAwaitType(awaitExpression, typeArgument, semanticModel, cancellationToken);
+        return VerifyAwaitType(awaitExpression, returnType, typeArgument, semanticModel, cancellationToken);
     }
 
-    private static bool VerifyAwaitType(AwaitExpressionSyntax awaitExpression, ITypeSymbol typeArgument, SemanticModel semanticModel, CancellationToken cancellationToken)
+    private static bool VerifyAwaitType(
+        AwaitExpressionSyntax awaitExpression,
+        ITypeSymbol returnType,
+        ITypeSymbol typeArgument,
+        SemanticModel semanticModel,
+        CancellationToken cancellationToken)
     {
         if (!SymbolEqualityComparer.Default.Equals(typeArgument, semanticModel.GetTypeSymbol(awaitExpression, cancellationToken)))
             return false;
@@ -415,15 +420,13 @@ private static bool VerifyAwaitType(AwaitExpressionSyntax awaitExpression, IType
         if (expressionTypeSymbol is null)
             return false;
 
-        if (expressionTypeSymbol.OriginalDefinition.IsAwaitable(semanticModel, expression.SpanStart))
+        if (SymbolEqualityComparer.Default.Equals(returnType, expressionTypeSymbol))
             return true;
 
         SimpleMemberInvocationExpressionInfo invocationInfo = SyntaxInfo.SimpleMemberInvocationExpressionInfo(expression);
 
-        return invocationInfo.Success
-            && invocationInfo.Arguments.Count == 1
-            && invocationInfo.NameText == "ConfigureAwait"
-            && expressionTypeSymbol.OriginalDefinition.IsAwaitable(semanticModel, expression.SpanStart);
+        return invocationInfo is { Success: true, Arguments.Count: 1, NameText: "ConfigureAwait" }
+            && SymbolEqualityComparer.Default.Equals(returnType, semanticModel.GetTypeSymbol(invocationInfo.Expression, cancellationToken));
     }
 
     private static IMethodSymbol GetMethodSymbol(

src/Tests/Analyzers.Tests/RCS1174RemoveRedundantAsyncAwaitTests.cs

@@ -1066,6 +1066,38 @@ private Task<string> M2(FileStream stream)
         throw new NotImplementedException();
     }
 }
+""");
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.RemoveRedundantAsyncAwait)]
+    public async Task TestNoDiagnostic_Task_Vs_ValueTask()
+    {
+        await VerifyNoDiagnosticAsync("""
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+class C
+{
+    private async Task<bool> IsNotEmptyAsync(string text)
+    {
+        await Task.Delay(1);
+        return !string.IsNullOrEmpty(text);
+    }
+
+    private void Execute()
+    {
+        IAsyncEnumerable<string> texts = null!;
+        var notEmptyTexts = texts.WhereAwait(async t => await this.IsNotEmptyAsync(t));
+        Console.WriteLine(string.Join(", ", notEmptyTexts.ToEnumerable()));
+    }
+}
+
+public static class Extensions
+{
+    public static IAsyncEnumerable<TSource> WhereAwait<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate) => default;
+    public static IEnumerable<TSource> ToEnumerable<TSource>(this IAsyncEnumerable<TSource> source) => default;
+}
 """);
     }
 }