Do not report MA0152 when the inner await suppresses the exceptions

docs/Rules/MA0152.md

@@ -1,4 +1,4 @@
-# MA0152 - Use Unwrap instead of using await twice
+# MA0152 - Use Unwrap instead of using await twice
 <!-- sources -->
 Sources: [UseTaskUnwrapAnalyzer.cs](https://github.com/meziantou/Meziantou.Analyzer/blob/main/src/Meziantou.Analyzer/Rules/UseTaskUnwrapAnalyzer.cs), [UseTaskUnwrapFixer.cs](https://github.com/meziantou/Meziantou.Analyzer/blob/main/src/Meziantou.Analyzer.CodeFixers/Rules/UseTaskUnwrapFixer.cs)
 <!-- sources -->
@@ -11,3 +11,15 @@ await await t; // non-compliant
 
 await t.Unwrap(); // compliant
 ````
+
+The rule is not reported when the inner task is awaited with `ConfigureAwaitOptions.SuppressThrowing`, as `Unwrap()` would also suppress the exceptions of the outer task:
+
+````c#
+Task<Task> t;
+
+// The exceptions of t are propagated, only the ones of the inner task are suppressed
+await (await t).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
+
+// The exceptions of t are suppressed too
+await t.Unwrap().ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
+````

src/Meziantou.Analyzer/Rules/UseTaskUnwrapAnalyzer.cs

@@ -40,6 +40,9 @@ public AnalyzerContext(Compilation compilation)
             ConfiguredTaskAwaitableSymbol = compilation.GetBestTypeByMetadataName("System.Runtime.CompilerServices.ConfiguredTaskAwaitable");
             ConfiguredTaskAwaitableOfTSymbol = compilation.GetBestTypeByMetadataName("System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1");
 
+            ConfigureAwaitOptionsSymbol = compilation.GetBestTypeByMetadataName("System.Threading.Tasks.ConfigureAwaitOptions");
+            SuppressThrowingValue = ConfigureAwaitOptionsSymbol?.GetMembers("SuppressThrowing").OfType<IFieldSymbol>().FirstOrDefault()?.ConstantValue as int?;
+
             if (TaskSymbol is not null && TaskOfTSymbol is not null)
             {
                 TaskOfTaskSymbol = TaskOfTSymbol.Construct(TaskSymbol);
@@ -55,6 +58,9 @@ public AnalyzerContext(Compilation compilation)
         public INamedTypeSymbol? ConfiguredTaskAwaitableSymbol { get; }
         public INamedTypeSymbol? ConfiguredTaskAwaitableOfTSymbol { get; }
 
+        public INamedTypeSymbol? ConfigureAwaitOptionsSymbol { get; }
+        public int? SuppressThrowingValue { get; }
+
         public bool IsValid => TaskOfTaskSymbol is not null || TaskOfTaskOfTSymbol is not null;
 
         public void AnalyzeAwait(OperationAnalysisContext context)
@@ -77,8 +83,13 @@ public void AnalyzeAwait(OperationAnalysisContext context)
                     context.ReportDiagnostic(Rule, operation);
                 }
             }
-            else if (operation.Operation is IInvocationOperation { Instance: IAwaitOperation { Operation.Type: INamedTypeSymbol childAwaitOperationType }, Type: var invocationType } && invocationType.IsEqualToAny(ConfiguredTaskAwaitableSymbol, ConfiguredTaskAwaitableOfTSymbol))
+            else if (operation.Operation is IInvocationOperation { Instance: IAwaitOperation { Operation.Type: INamedTypeSymbol childAwaitOperationType } } invocation && invocation.Type.IsEqualToAny(ConfiguredTaskAwaitableSymbol, ConfiguredTaskAwaitableOfTSymbol))
             {
+                // The inner task is the only one configured with SuppressThrowing, whereas Unwrap() would also
+                // suppress the exceptions of the outer task, which the outer await currently propagates
+                if (MaySuppressThrowing(invocation))
+                    return;
+
                 // Task<Task>
                 if (childAwaitOperationType.IsEqualTo(TaskOfTaskSymbol))
                 {
@@ -91,5 +102,22 @@ public void AnalyzeAwait(OperationAnalysisContext context)
                 }
             }
         }
+
+        private bool MaySuppressThrowing(IInvocationOperation operation)
+        {
+            if (SuppressThrowingValue is not { } suppressThrowing)
+                return false;
+
+            foreach (var argument in operation.Arguments)
+            {
+                if (!argument.Parameter!.Type.IsEqualTo(ConfigureAwaitOptionsSymbol))
+                    continue;
+
+                // The options are only known not to suppress the exceptions when they are a constant
+                return argument.Value.ConstantValue is not { HasValue: true, Value: int options } || (options & suppressThrowing) is not 0;
+            }
+
+            return false;
+        }
     }
 }

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

@@ -1,4 +1,4 @@
-using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Testing;
 using CodeFixTest = Meziantou.Analyzer.Test.Harness.CSharpCodeFixTest<
     Meziantou.Analyzer.Rules.UseTaskUnwrapAnalyzer,
@@ -158,6 +158,70 @@ public Task TaskOfTask_ConfigureAwait_Root_WithoutUsingDirective()
         return test.RunAsync();
     }
 
+    [Fact]
+    public Task TaskOfTask_ConfigureAwaitOptions_Root()
+    {
+        var test = CreateTest();
+        test.TestCode = """
+            using System.Threading.Tasks;
+
+            Task<Task> a = null;
+            {|MA0152:await (await a).ConfigureAwait(ConfigureAwaitOptions.ForceYielding | ConfigureAwaitOptions.ContinueOnCapturedContext)|};
+            """;
+        test.FixedCode = """
+            using System.Threading.Tasks;
+
+            Task<Task> a = null;
+            await a.Unwrap().ConfigureAwait(ConfigureAwaitOptions.ForceYielding | ConfigureAwaitOptions.ContinueOnCapturedContext);
+            """;
+
+        return test.RunAsync();
+    }
+
+    [Fact]
+    public Task TaskOfTask_ConfigureAwaitOptions_SuppressThrowing_Root()
+    {
+        // Unwrap() would also suppress the exceptions of the outer task
+        var test = CreateTest();
+        test.TestCode = """
+            using System.Threading.Tasks;
+
+            Task<Task> a = null;
+            await (await a).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
+            """;
+
+        return test.RunAsync();
+    }
+
+    [Fact]
+    public Task TaskOfTask_ConfigureAwaitOptions_SuppressThrowing_Combined_Root()
+    {
+        var test = CreateTest();
+        test.TestCode = """
+            using System.Threading.Tasks;
+
+            Task<Task> a = null;
+            await (await a).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing | ConfigureAwaitOptions.ForceYielding);
+            """;
+
+        return test.RunAsync();
+    }
+
+    [Fact]
+    public Task TaskOfTask_ConfigureAwaitOptions_NotConstant_Root()
+    {
+        var test = CreateTest();
+        test.TestCode = """
+            using System.Threading.Tasks;
+
+            Task<Task> a = null;
+            ConfigureAwaitOptions options = default;
+            await (await a).ConfigureAwait(options);
+            """;
+
+        return test.RunAsync();
+    }
+
     [Fact]
     public Task TaskOfTask_Unwrap_ConfigureAwait_Root()
     {