[Bug c++/112789] Missing clang __builtin_ctzs for short

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112789

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to gnzlbg from comment #6)
> Thanks for all the quick feedback!
> 
> > Also clang does not even document __builtin_ctzs anywhere ...
> 
> This builtin is documented in the list of clang bultins. You can find it by
> using CTRL+F for the builtin, in that list,
> https://clang.llvm.org/docs/LanguageExtensions.html, which is the first link
> that Google reveals when searching for this exact builtin. Hope that helps.

Look at that part where __builtin_ctzs  is mentioned there.
It just says it is valid inside a constexpr and nothing else about the builtin.

>There is an HPC QCD app that was developed mostly using clang, and for which we can't apply source code modifications, that we'd like to compile which GCC as is, but currently doesn't due to this issue. 

Sounds like that HPC QCD app is broken. You should report it to the developers.
Also since __builtin_ctzg is added, adding __builtin_ctzs really does not make
any sense since it would just done as `#define __builtin_ctzs
__builtin_ctzg((unsigned short)a)` in the source.