Incremental compilation is something that no major compiler for any ahead-of-time compiled language anywhere does. It's one of the most advanced features in any compiler, and as such it's taking time to implement. No C++ compiler I know of is even thinking of it.

As the first post here in this thread mentions, going down the C++ road of header files might have gotten us some short term wins, but ultimately it hits a brick wall. Incremental compilation is inescapable.