I don't see real-time semantic highlighting using an embedded compiler there. Maybe I missed it.

My bad, I assumed it included highlighting, but it appears it is just auto-complete from Clang.

https://github.com/brianjcj/auto-complete-clang

That being said, if the core infrastructure is there, the hard part (Clang backend) is there, how much more can semantic highlighting be?

(I duck because I write amateurish code and do not do C/C++ yet, but would hopefully learn to do something awesome like that one day.)