I checked Fil-C out and it looks great. How is this different from Fil-C? Apart from the obvious LLVM stuff

Fil-C essentially lifts C onto a managed, garbage-collected runtime. This is a small header that adds some C++ features to C.

(These features are still essentially unsafe: the unique pointer implementation still permits UAF, for example, because nothing prevents another thread from holding the pointer and failing to observe that it has been freed.)