Type inference and lambda binding failure when one method in the group and wrong number of arguments

[gafter]

The following test (which currently would fail) illustrates that we fail to infer a good target type for a lambda expression argument when there is exactly one method in the method group.

        [Fact]
        [WorkItem(11901, "https://github.com/dotnet/roslyn/issues/11901")]
        public void TestLambdaWithError15()
        {
            // These tests ensure we attempt to perform type inference and bind a lambda expression
            // argument even when there are too many or too few arguments to an invocation, in the
            // case when there is exactly one method in the method group.
            var source =
@"using System;

class Program
{
    static void Main(string[] args)
    {
        Thing<string> t = null;
        t.X1(x => x, 1); // too many args
        t.X2(x => x);    // too few args
        t.M2(string.Empty, x => x, 1); // too many args
        t.M3(string.Empty, x => x); // too few args
    }
}
public class Thing<T>
{
    public void M2<T>(T x, Func<T, T> func) {}
    public void M3<T>(T x, Func<T, T> func, T y) {}
}
public static class XThing
{
    public static Thing<T> X1<T>(this Thing<T> self, Func<T, T> func) => null;
    public static Thing<T> X2<T>(this Thing<T> self, Func<T, T> func, int i) => null;
}
";
            var compilation = CreateCompilationWithMscorlibAndSystemCore(source);
            var tree = compilation.SyntaxTrees[0];
            var sm = compilation.GetSemanticModel(tree);
            foreach (var lambda in tree.GetRoot().DescendantNodes().OfType<LambdaExpressionSyntax>())
            {
                var reference = lambda.Body.DescendantNodesAndSelf().OfType<IdentifierNameSyntax>().First();
                Assert.Equal("x", reference.ToString());
                var typeInfo = sm.GetTypeInfo(reference);
                Assert.Equal(TypeKind.Class, typeInfo.Type.TypeKind);
                Assert.Equal("String", typeInfo.Type.Name);
                Assert.NotEmpty(typeInfo.Type.GetMembers("Replace"));
            }
        }
    }

[gafter]

Fixed in 7abdbb5