You're technically correct in regards to Mach, but in the context of Mac OS X a very large percentage of the kernel is composed of BSD-derived code.
Unfortunately, none of this is particularly relevant to clang, as the kernel design (in respect to Mach or BSD) really has little bearing on its compiliability.
[Edit]
I'm very surprised that this was downvoted to 0. The discussion was in context of Mac OS X, and the technical veracity is easily confirmed:
Unfortunately, none of this is particularly relevant to clang, as the kernel design (in respect to Mach or BSD) really has little bearing on its compiliability.
[Edit]
I'm very surprised that this was downvoted to 0. The discussion was in context of Mac OS X, and the technical veracity is easily confirmed:
http://en.wikipedia.org/wiki/Xnu http://fxr.watson.org/fxr/source/bsd/?v=xnu-1228