In VS 2013 with Roslyn but without ReSharper, the code compiles fine and I don't see any errors or squigglies.
This is the expected behavior, since this proposed C# 6.0 feature is supported in the current Roslyn preview.
If I enable ReSharper, I start seeing the squigglies, but there are no errors in the Error List window and the code still compiles fine.
This is also the expected behavior, because the current version of R# doesn't have any support for C# 6.0 features (why would it?).
So, you see the squigglies from R#, but VS can work with the code just fine.
If you want to try out the proposed C# 6.0 features, I suggest you temporarily disable R#.