TryCastWithoutUsingAsNotNull with anonymous type kungfu introduces a compilation error when renaming symbols

[Vannevelj]

There is one scenario in which TryCastWithoutUsingAsNotNull breaks:

TryCastWithoutUsingAsNotNull_AnonymousTypeRenaming

The scenario as layed out in AnonymousTypeRenaming is not yet supported by Renamer.RenameAsync. We could do it ourselves manually but that would probably be rather expensive. It is a niche scenario though so it's not too horrible to leave unsupported for now.

I'm making this issue to keep track of it but it's not something I consider a must-fix until Roslyn supports it themselves.

For reference, the full test:

        public void TryCastWithoutUsingAsNotNull_AnonymousTypeRenaming()
        {
            var original = @"
using System;
using System.Text;

namespace ConsoleApplication1
{
    class MyClass
    {
        void Method()
        {
            object o = 5;
            if (o is int)
            {
                var x = (int) o;
                var y = new { x };
                var z = y.x;
            }
        }
    }
}";

            var expected = @"
using System;
using System.Text;

namespace ConsoleApplication1
{
    class MyClass
    {
        void Method()
        {
            object o = 5;
            var oAsInt32 = o as int?;
            if (oAsInt32 != null)
            {
                var y = new { oAsInt32 };
                var z = y.oAsInt32;
            }
        }
    }
}";

            VerifyDiagnostic(original, string.Format(TryCastWithoutUsingAsNotNullAnalyzer.Rule.MessageFormat.ToString(), "o"));
            VerifyFix(original, expected);
        }

This currently fails on the line var z = y.oAsInt32; which, in reality, is var z = y.x;

Related PR: dotnet/roslyn#5786