Bug#1006682: /usr/lib/cmake/mathgl2/MathGL2Config.cmake: Could NOT find OpenMP_CXX

[Sylvain Joubert]

Ok, I just figured out why you probably can't reproduce the issue: you need
to use clang as a compiler.
If you use `CXX=clang++-14 cmake [...]` as a configure command line you'll
likely trigger the error.

And the required package providing OpenMP for clang must match the clang
version used: if I install libomp-13-dev while using clang++-14 for example
I'll still get the error.

With this additional info I get that the issue is triggered with a
non-default setup, so I'm not sure how or even if it can be fixed
correctly. Especially given that the proper dependency is heavily dependent
on the clang version used/installed.
Given that understanding I'd be fine with leaving things as is. And maybe
it's the upstream MathGL2Config.cmake that needs a rework to deal more
easily with various setups.

Anyway, thanks for taking a look.

Le mer. 31 août 2022 à 10:03, Sylvain Joubert <joubert.sy at gmail.com> a
écrit :

> Hi,
> Here is the minimal CMakeLists.txt that reproduces the issue:
>
> cmake_minimum_required(VERSION 3.22.0)
> project(mgl_test LANGUAGES CXX)
> find_package(MathGL2 REQUIRED)
>
> If the packages libomp-dev and libomp-XX-dev that it drags (libomp-11-dev
> on stable, libomp-14-dev on my testing setup) are not installed I get the
> initial reported error.
>
>
> Le mar. 30 août 2022 à 22:03, Rafael Laboissière <rafael at debian.org> a
> écrit :
>
>> Control: tags -1 moreinfo
>>
>> * Sylvain Joubert <joubert.sy at gmail.com> [2022-03-02 11:17]:
>>
>> >  Package: libmgl-dev
>> >  Version: 8.0.1-1
>> >  Severity: normal
>> >
>> > Dear Maintainer,
>> >
>> > Trying to use libmgl-dev through find_package(MathGL2) in CMake I'm
>> facing the
>> > following error:
>> >
>> >  CMake Error at
>> /usr/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:230
>> >  (message): Could NOT find OpenMP_CXX (missing: OpenMP_CXX_FLAGS
>> OpenMP_CXX_LIB_NAMES)
>> >  Call Stack (most recent call first):
>> >  /usr/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:594
>> >  (_FPHSA_FAILURE_MESSAGE)
>> >   /usr/share/cmake-3.22/Modules/FindOpenMP.cmake:544
>> >  (find_package_handle_standard_args)
>> >   /usr/share/cmake-3.22/Modules/CMakeFindDependencyMacro.cmake:47
>> >  (find_package)
>> >   /usr/lib/cmake/mathgl2/MathGL2Config.cmake:22 (find_dependency)
>> >  [...]
>> >
>> > It appears the libmgl-dev package is missing a dependency on an OpenMP
>> > related package. Installing libomp-dev fixes the issue though I'm not
>> > sure this is the correct package to depend on.
>>
>> Thank you for the bug report.
>>
>> Could you please provide an example that trigger the bug? For
>> inspiration, look at Bug #1004218 [1] or #1004219 [2].
>>
>> Best,
>>
>> Rafael Laboissière
>>
>>   [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1004218
>>   [2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1004219
>>
>
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