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From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/112789] Missing clang __builtin_ctzs for short
Date: Sun, 03 Dec 2023 04:17:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112789

Xi Ruoyao <xry111 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xry111 at gcc dot gnu.org

--- Comment #13 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to gnzlbg from comment #8)
> Oh! Sorry! I see this was resolved as WONTFIX.
>=20
> Does that mean that GCC, in contrast with the LLVM community - which is
> always super helpful and friendly when it comes to trying to enable their
> toolchains to compile SW developed with GNU - intentionally does not want=
 to
> enable the GNU toolchains to compile SW developed with clang?=20

Because Clang developers actively claim to support GNU extensions, while GCC
never has such a policy to support other extensions.  When an extension is
considered useful we port it, but in this case we already have __builtin_ct=
zg
as all others have mentioned.

And Clang developers also reject GNU extensions if they consider the extens=
ion
"wrong", despite they make such a "compatibility" claim.

In the future (when C23 is widely adopted) people should just use
stdc_trailing_zerosus instead of directly invoking __builtin_ctz{g,s} of
whatever compiler.=