OpenMP and UFS WM

[AlexanderRichert-NOAA]

In spack-stack, ip uses OpenMP, whereas sp does not. When using ip v5 to compile UFS WM, the OpenMP flags get propagated into the CMake, which causes some files that need to be compiled without '-qopenmp' (or equivalent) to fail building. I'm not sure what the best solution here is. We could have separate ip and sp targets with separate OpenMP settings. I may also be able to modify the UFS WM CMake config (specifically, FV3/ccpp/physics/CMakeLists.txt) to exclude the ip flags for those files if they're not actually used.

[AlexanderRichert-NOAA]

I think this can be resolved through the downstream applications, but I'll keep this open until the transition to ip@5 is complete.

[climbfuji]

@AlexanderRichert-NOAA Is the correct solution that IP declares its dependencies as private in the cmake target definitions? See also NCAR/ccpp-physics#1090 (comment) and comments below.

Tagging @DusanJovic-NOAA since he also ran into this problem, I believe.

[AlexanderRichert-NOAA]

I'm not sure. I know once upon a time I was able to resolve this by modifying FV3/ccpp/physics/CMakeLists.txt to explicitly add a flag to disable OpenMP as needed, though I don't know if it's the best solution. Unless you're already looking into it then I'll set up a test installation where the OpenMP dependency is PRIVATE and report back.

[climbfuji]

I am not working on this, just relaying the information.

[dustinswales]

@AlexanderRichert-NOAA Just seeing this issue now. I'm going to test Dom's suggestion of making the openMP a PRIVATE target def.