CMake zstd (and friends) compression options

Coming from [1] there seems to be an error with parsing the zstd library version (or does it explicitly need the static zstd library?). I'd like to request having toggles (like -DHEPMC3_COMPRESS_{ZLIB,...}) for enabling/disabling the different compression algorithms since automagic dependencies are a pain (see [2]). Or do such options exist and I just did not find them?

-- Found zstd: /usr/lib/libzstd.so (Required is at least version "1.4.0")
-- Could NOT find zstd (missing: zstd_STATIC_LIBRARY) (found suitable version "1.5.6", minimum required is "1.4.0")

[1] https://bugs.gentoo.org/937356

[2] https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Automagic_dependencies

changed title from CMake zstd compression options to CMake zstd (and friends) compression options

changed the description

Hi @aneuwirt, but the compression is used only in tests. Those are not dependencies at all. There is HEPMC3_TEST_PACKAGES_LIST to disable/enable the needed tests. Hopefully this helps.

Best regards,

Andrii

The FindZSTD.cmake, however, should be improved, I think.

I think it is a dependency, but maybe I am wrong. For example here https://gitlab.cern.ch/hepmc/HepMC3/-/blob/master/include/HepMC3/ReaderFactory.h?ref_type=heads#L38.

If I compile it on system1 where libz is installed (=> HEPMC3_USE_COMPRESSION is defined) and then try to use the shared object library on system2 which does not have libz installed it would fail, because on system1 it was dynamically linked to libz.

The other way round: Compiling on system2 without libz works (=> HEPMC3_USE_COMPRESSION is not defined) and it can be also used on system1 with libz installed (but it can't read a like file.hepmc.gz by deduce_reader).

EDIT: I think the linked gentoo bug is actually due to MUSL.

Hi @aneuwirt,

indeed the line is blurred, but all the functionality related to compression is designed to be a kind of "header only". So one cannot "compile" that header. But if one compiles an application with that header then yes, the app will have libz as a dependency. This was done on purpose to satisfy "no dependencies" requirement for hepmc. Hopefully this helps.

Best regards,

Andrii

I see and for example rivet has:

include/Rivet/Tools/RivetHepMC.hh:#define HEPMC3_USE_COMPRESSION 1

before including HEPMC. So then I just depend on them for the tests and examples.

Thanks, APN.

closed

Hi @aneuwirt,

So then I just depend on them

indeed. But that is a downstream software, we cannot do much.

Andrii