Since VS2013 some useful and popular C99 language features are supported. And then there's Clang/C2 but it can't be used via command-line yet.
Their standard library (besides being intentionally not fully compliant) is missing some C11 features though. I guess we have to wait at least for C++17:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p006...