Checks for found and target in singularity-eosConfig.cmake

[mauneyc-LANL]

PR Summary

The exported configuration checked for Eigen3_FOUND and passed, but the concurrent processing wasn't able to find the interface target Eigen3::Eigen. This updates the configuration check to check both.

PR Checklist

• Adds a test for any bugs fixed. Adds tests for new features.
• Format your changes by using the make format command after configuring with cmake.
• Document any new features, update documentation for changes made.
• Make sure the copyright notice on any files you modified is up to date.
• After creating a pull request, note it in the CHANGELOG.md file

[Yurlungur]

I don't understand these changes or their impact. But I'll trust you that they're correct. I'll approve once the boxes are all checked.

[mauneyc-LANL]

I don't understand these changes or their impact. But I'll trust you that they're correct. I'll approve once the boxes are all checked.

In the singularity-eosConfig.cmake file, what was happening was

if(NOT Eigen3_FOUND)
        find_package(Eigen3  REQUIRED)
endif()

What was happening when building downstream was Eigen3_FOUND was set by an earlier part of the build, but for some reason the target Eigen3::Eigen was not finding it's was down to singularity-eos. That is our target singularity-eos::singlarity-eos had an link dependency on Eigen3::Eigen, but at the end of the configuration step, CMake was complaining that singularity-eos depends on target Eigen3::Eigen, but that target was not found.

This is a bit brutish, but now singularity-eosConfig.cmake will have

if(NOT Eigen3_FOUND OR NOT TARGET Eigen3::Eigen)
        find_package(Eigen3  REQUIRED)
endif()

So that, if Eigen3::Eigen isn't a defined target, CMake will engage the find_package() tools to explicitly make it.

[dholladay00]

If I am understanding correctly, this change will be in effect for all dependencies @mauneyc-LANL? It seems like a good addition if we want to maintain in-tree and externally built capabilities for our dependencies.

[mauneyc-LANL]

If I am understanding correctly, this change will be in effect for all dependencies @mauneyc-LANL? It seems like a good addition if we want to maintain in-tree and externally built capabilities for our dependencies.

This effects any dependencies that define an interface target that we adhere to, e.g. Eigen3::Eigen, ports-of-call; and, this is a fix for downstream codes that use find_package(singularity-eos), so any codes that manually add within a source-tree are not effected.

A counter-example is when we import HDF5, we no longer rely on an interface target and add the paths explicitly to the export config. This is b/c HDF5 doesn't have a consistent interface target for a range of cmake & hdf5 installs - that is, HDF5::HDF5 could resolve to different configurations downstream (or not be defined at all), and I threw my hands up and just rely on exporting explicit paths.

I should stress that this is a sloppy attempt to fix an issue I haven't figured out - specifically, when I was importing singularity-eos into a host code, that Eigen3_FOUND was set, but CMake was complaining that Eigen3::Eigen was not a defined target. This is likely due to some conflict in how a separate dependency was importing Eigen, but I didn't try and track that down. This change will ensure that the target Eigen3::Eigen is set by find_package(), regardless of what prior configuration has done.