Comment # 14 on bug 1119186 from Wolfgang Bauer

(In reply to Krzysztof Kurek from comment #13)
> Ah, I've made an oversight. I had clang7 installed, not clang.
> Indeed it works with just clang, and doesn't require clang-devel.

Yes, as the version is part of the include path, you need the same version
installed that it is built against. (i.e. clang7-devel wouldn't have helped
either)
Unless you explicitly set $KDEV_CLANG_BUILTIN_DIR yourself...
(there is some autodetection on runtime, but only on Windows so far:
https://cgit.kde.org/kdevelop.git/commit/?h=5.3&id=ec5477f351b6c4b25b7f6533314628ebdd7c2945
)

That also means that we should probably better use "%requires_eq clang" to
force the "correct" version.