Bug#963991: libmkl-rt: libomp-dev dependency too strict

[Marc Glisse]

Package: libmkl-rt
Version: 2020.1.217-2
Severity: normal

Dear Maintainer,

I would like to install libomp-11-dev on this computer, but libmkl-rt
has a dependency on libomp-dev | libomp-7-dev | libomp-8-dev, and the
versions of libomp conflict with each other. As far as I know, llvm aims
to keep a compatible ABI on this library. Would it be possible to extend
the list of alternatives to more recent libomp-*-dev? You could even
preventively add libomp-12-dev so you don't have to add it later. I
don't know if it would be ok to depend on the virtual libomp-x.y-dev.

Or maybe the dependency could be downgraded to a recommendation, since
when it cannot find libiomp5.so it seems to fall back to sequential
mode?  With MKL_THREADING_LAYER=GNU and a suitable LD_LIBRARY_PATH
(gcc's libgomp.so is a bit hidden), it even seems possible to use a
threaded mkl without libomp, although that may be asking a bit much from
users. I only did some extremely basic testing, I may be completely
wrong about things actually "working".

(I could probably work around this by rebuilding libomp-dev to depend on
the libomp-*-dev I want, or creating fake packages)

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing-debug
  APT policy: (500, 'testing-debug'), (500, 'stable-debug'), (500, 'testing'), (400, 'stable'), (50, 'unstable-debug'), (50, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, arm64, ppc64el, mips64el

Kernel: Linux 5.6.0-2-amd64 (SMP w/16 CPU cores)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_FIRMWARE_WORKAROUND, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libmkl-rt depends on:
ii  debconf [debconf-2.0]                  1.5.74
ii  libatlas3-base [liblapack.so.3]        3.10.3-10
ii  libblas3 [libblas.so.3]                3.9.0-2
ii  libc6                                  2.30-8
ii  libgcc-5-dev                           5.5.0-12
ii  libgcc-6-dev                           6.5.0-2
ii  libgcc-8-dev                           8.4.0-4
ii  liblapack3 [liblapack.so.3]            3.9.0-2
ii  libmkl-locale                          2020.1.217-2
ii  libmkl-meta-computational              2020.1.217-2
ii  libmkl-meta-interface                  2020.1.217-2
ii  libmkl-meta-threading                  2020.1.217-2
ii  libomp-dev                             1:9.0-49.1
ii  libopenblas0-pthread [liblapack.so.3]  0.3.9+ds-3
ii  libtbb-dev                             2020.2-2

libmkl-rt recommends no packages.

libmkl-rt suggests no packages.

-- debconf information:
* libmkl-rt/use-as-default-blas-lapack: true
  libmkl-rt/title:
* libmkl-rt/exact-so-3-selections: libblas.so.3, liblapack.so.3