Re: fixing AC_OPENMP for Apple clang

"Andrew W. Nosenko" <[email protected]> Tue, 3 Mar 2026 00:45:48 +0200
Newsgroups gmane.comp.sysutils.autoconf.general
Message-ID <CALa-7vykPTgcefq=qkQUxv1xmieveR-5Tyy8Vc+tOe5dSs6pSw@mail.gmail.com>
On Tue, 3 Mar 2026 at 00:39, Andrew W. Nosenko <[email protected]>
wrote:

>
> On Mon, 2 Mar 2026 at 22:48, Dima Pasechnik <[email protected]> wrote:
>
>> On Mon, Mar 02, 2026 at 09:45:35PM +0200, Andrew W. Nosenko wrote:
>> >
>> > Does modern Xcode includes libomp =E2=80=9Cout of the box=E2=80=9D or =
it need to be
>> built
>> > separately from Homebrew/MacPorts/Git? (I have access to Catalina bot
>> not
>> > to more modern version, and on Catalina it doesn=E2=80=99t)
>> No, Xcode has no libomp. But Homebrew has a libomp package:
>> https://formulae.brew.sh/formula/libomp
>>
>> It's also provided by R Project:
>> https://mac.r-project.org/openmp/
>>
>> And, yes, naturally, one can build libomp as a part of the llvm
>> installation.
>>
>
>
> But then I=E2=80=99m confused again: if I need to build libomp separately=
 from
> LLVM sources, then why I would to prefer XCode=E2=80=99s Clang instead of=
 Clang
> from the same LLVM package, from which I=E2=80=99m going to build libomp =
anyway?
>

OpenMP is about compiler=E2=80=99s #pragmas plus runtime support library.  =
So I see
risks in de-synchronisation between frontend (compiler) and backend
(library).  But I see no benefits in using de-synchronised toolchain (Xcode
clang + non-Xcode llvm libomp).

>