Modernize FindZeroMQ.cmake and fix some ZeroMQ related compile bugs

[SunBlack]

Supersedes #5089 and fixes #5088.

Since the discussion in #5089 showed that pkg conf is necessary, and therefore a separate find script is still required, I tested this locally with vcpkg and ran into several other issues with ZeroMQ, so it’s probably worth creating a separate PR after all.

Changes:

• Modernized CMake script to use always imported targets (and therefore get also retrieve maybe necessary compiler flags and other indirect dependencies)
• Didn't raised minimum required version to 4.2.2 - didn't checked whether 4.1 exports pkg files
• To prevent recursive calls, added MODULE and CONFIG to the find_package calls
• Removed alternative operator representations, as they caused compile issues with MSVC 2026 (and are deprecated anyway)

Notes:

• Didn't verified the pkg path
• Is it okay to add pkgconf to scripts/ci/images/Dockerfile.ci-spack-ubuntu22.04-base or is there really a another legacy path necessary?

[vicentebolea]

find_dependency will avoid having to explicitly forward these flags.

[SunBlack]

True, always forgetting this command :-/

[vicentebolea]

Let's move the CONFIG find this to the detect options, in that manner it remains consistent with the other deps. There if it fails you can invoke this MODULE find.

[vicentebolea]

Thanks for the changes, what I meant is to move the CONFIG find to the DetectOptions.cmake

[SunBlack]

Not sure whether this is a good idea, as there are always more duplication in the DetectOptions.cmake due to the AUTO/ON paths:

if(ADIOS2_USE_ZeroMQ STREQUAL AUTO)
    find_package(ZeroMQ 4.1 CONFIG)
    if (NOT ZeroMQ_FOUND)
      find_package(ZeroMQ 4.1 MODULE)
	endif()
elseif(ADIOS2_USE_ZeroMQ)
    find_package(ZeroMQ 4.1 CONFIG REQUIRED)
    if (NOT ZeroMQ_FOUND)
      find_package(ZeroMQ 4.1 MODULE REQUIRED)
	endif()
endif()

Another downside: The (3) examples could not use the Config code or need also the duplicated paths there

[vicentebolea]

The reason to have this in detectoptions.cmake is keep that file consistent, the dance of find_package is common there.

Another downside: The (3) examples could not use the Config code or need also the duplicated paths there

Can you develop this point?

Thanks!

[SunBlack]

I do think it's poor design to move it to DetectOptions, since that means anyone looking for ZeroMQ has to implement both variants instead of having a central location, but if that's what you want...

The examples don't actually need ZeroMQ, since the target is only linked privately.

[vicentebolea]

The examples don't actually need ZeroMQ, since the target is only linked privately.

This is true since we find_dependency(zeroMq) in the adios2-config.cmake.

[vicentebolea]

lets just use libzmq thru adios2? Looking at libzmq source code it seems that they do not namespace their targets in the config cmake file.

[vicentebolea]

No need for the rename, you can use find_package(... MODULE)

[SunBlack]

I know. I put that there on purpose to make it clear that it's only intended for the pkg variant. If the module is ever exported and someone runs find_package(ZeroMQ), they might not realize that it's only meant for that one variant.

[vicentebolea]

This add extra complexity, please keep it simple using the module is more succinct.