Hande error scenarios involving target types and named arguments in n…

…ullable walker (#72635) * Recover from wrong collection expression target type in nullable walker * Test collection initializer * Catch error target typing scenarios sooner * Fix assert
dotnet · Mar 25, 2024 · ea0acb2 · ea0acb2
1 parent bd74319
commit ea0acb2
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Showing 2 changed files with 58 additions and 5 deletions.
diff --git a/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs b/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs
@@ -6718,7 +6718,13 @@ private ImmutableArray<VisitResult> VisitArguments(
                         (ParameterSymbol? parameter, TypeWithAnnotations parameterType, FlowAnalysisAnnotations parameterAnnotations, bool isExpandedParamsArgument) =
                             GetCorrespondingParameter(i, parametersOpt, argsToParamsOpt, expanded, ref paramsIterationType);
 
-                        if (parameter is null)
+                        if (// This is known to happen for certain error scenarios, because
+                            // the parameter matching logic above is not as flexible as the one we use in `Binder.BuildArgumentsForErrorRecovery`
+                            // so we may end up with a pending conversion completion for an argument apparently without a corresponding parameter.
+                            parameter is null ||
+                            // In error recovery with named arguments, target-typing cannot work as we can get a different parameter type
+                            // from our GetCorrespondingParameter logic than Binder.BuildArgumentsForErrorRecovery does.
+                            node is BoundCall { HasErrors: true, ArgumentNamesOpt.IsDefaultOrEmpty: false, ArgsToParamsOpt.IsDefault: true })
                         {
                             if (IsTargetTypedExpression(argumentNoConversion) && _targetTypedAnalysisCompletionOpt?.TryGetValue(argumentNoConversion, out var completion) is true)
                             {
@@ -6728,10 +6734,7 @@ private ImmutableArray<VisitResult> VisitArguments(
                                 completion(TypeWithAnnotations.Create(argument.Type));
                                 TargetTypedAnalysisCompletion.Remove(argumentNoConversion);
 
-                                // This is known to happen for certain error scenarios, because
-                                // the parameter matching logic above is not as flexible as the one we use in `Binder.BuildArgumentsForErrorRecovery`
-                                // so we may end up with a pending conversion completion for an argument apparently without a corresponding parameter.
-                                Debug.Assert(method is ErrorMethodSymbol);
+                                Debug.Assert(parameter is not null || method is ErrorMethodSymbol);
                             }
                             continue;
                         }

diff --git a/src/Compilers/CSharp/Test/Emit2/Semantics/CollectionExpressionTests.cs b/src/Compilers/CSharp/Test/Emit2/Semantics/CollectionExpressionTests.cs
@@ -13431,6 +13431,56 @@ private static void VerifyTypes(SemanticModel model, ExpressionSyntax expr, stri
             Assert.Equal(expectedConversionKind, conversion.Kind);
         }
 
+        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/72541")]
+        public void NamedArgumentConversion()
+        {
+            var source = """
+                #nullable enable
+                using System.Collections.Generic;
+
+                static class C
+                {
+                    static void Main()
+                    {
+                        C.M(y: [new D { }]);
+                    }
+                    static void M(string x, IReadOnlyList<D> y) { }
+                }
+
+                class D { }
+                """;
+            var comp = CreateCompilation(source);
+            comp.VerifyDiagnostics(
+                // (8,11): error CS7036: There is no argument given that corresponds to the required parameter 'x' of 'C.M(string, IReadOnlyList<D>)'
+                //         C.M(y: [new D { }]);
+                Diagnostic(ErrorCode.ERR_NoCorrespondingArgument, "M").WithArguments("x", "C.M(string, System.Collections.Generic.IReadOnlyList<D>)").WithLocation(8, 11));
+        }
+
+        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/72541")]
+        public void NamedArgumentConversion_CollectionInitializer()
+        {
+            var source = """
+                #nullable enable
+                using System.Collections.Generic;
+
+                static class C
+                {
+                    static void Main()
+                    {
+                        C.M(y: new() { new D() { } });
+                    }
+                    static void M(string x, List<D> y) { }
+                }
+
+                class D { }
+                """;
+            var comp = CreateCompilation(source);
+            comp.VerifyDiagnostics(
+                // (8,11): error CS7036: There is no argument given that corresponds to the required parameter 'x' of 'C.M(string, List<D>)'
+                //         C.M(y: new() { new D() { } });
+                Diagnostic(ErrorCode.ERR_NoCorrespondingArgument, "M").WithArguments("x", "C.M(string, System.Collections.Generic.List<D>)").WithLocation(8, 11));
+        }
+
         [CombinatorialData]
         [Theory]
         public void CollectionBuilder_01(bool useCompilationReference)