In which way terrible? Error messages for C++ were at times unhelpful, but I can't remember being dissatisfied with those for C. Outside the Desktop environment, is there much C++ code in the FreeBSD system?
devd is C++, and it is not alone. Unfortunately, the dynamically-linkable C++ runtime library is in the wrong place, and not in the same place as the C runtime library, so things like devd have to be statically linked.
But the clang switch was not motivated by its C++ error messages, to my knowledge.
