moves the lib list to the driver buildnml with backward compatibility

[jedwards4b]

Description

Proposed change to handle list of support libraries in the driver rather than in cime.

• Closes move support libraries to driver #4835

Checklist

• My code follows the style guidlines of this proejct (black formatting)
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have added tests that excerise my feature/fix and existing tests continue to pass
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding additions and changes to the documentation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.33%. Comparing base (256f24c) to head (48153cf).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4836      +/-   ##
==========================================
+ Coverage   55.28%   55.33%   +0.05%     
==========================================
  Files         266      266              
  Lines       38491    38493       +2     
  Branches     8323     8323              
==========================================
+ Hits        21279    21302      +23     
+ Misses      14856    14848       -8     
+ Partials     2356     2343      -13     

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[sjsprecious]

Thanks @jedwards4b for working on this PR. I could confirm that it builds and runs the Kokkos lib/kernels successfully in CAM, together with your other PR (ESCOMP/CMEPS#584).

[bartgol]

I think this line is pointless, no? It's already set before the if clause.

[jedwards4b]

Looks like a merge error, I'll clean it up - thanks.

[sjsprecious]

@bartgol if I understood your suggestion from #4837 correctly, the uses_kokkos function can be deprecated since the host model will define the shared libs in its config_component.xml?

[jedwards4b]

That's correct, this code is only still here for backward compatibility.

[bartgol]

Yeah, that was my idea. I don't want to inject knowledge about host model tpls into CIME. All CIME should care about is a list of libs names, and where to find their build scripts.

[jasonb5]

@jedwards4b Could you document this under Variables section of https://github.com/ESMCI/cime/blob/master/doc/source/ccs/model-configuration/config-files.rst. Lets add a Build section to put this under. Should probably include a snippet of how the host would populate this via buildnml.

Can we comment which sections are being kept for backwards compatibility.

[jedwards4b]

An issue that I think we still need to resolve is that some support libraries depend on others and
when all the libraries are defined in one place as is currently done it is easy to maintain an order so
that libraries are built in the correct order. How do we do this if several different buildnml scripts contribute
to the overall variable? One thought is that each buildnml include the dependencies specifying the order locally,
then in build.py in cime use libs = list(dict.fromkeys(libs)) to get an ordered list of unique libraries.

[bartgol]

An issue that I think we still need to resolve is that some support libraries depend on others and when all the libraries are defined in one place as is currently done it is easy to maintain an order so that libraries are built in the correct order. How do we do this if several different buildnml scripts contribute to the overall variable? One thought is that each buildnml include the dependencies specifying the order locally, then in build.py in cime use libs = list(dict.fromkeys(libs)) to get an ordered list of unique libraries.

Perhaps a non-trivial API change, but...what about asking that the buildlib.foo scripts also offer a command line option like --deps that return a list of libs names? So CIME can 1) get all lib names, 2) get build scripts for all libs, 3) call build.xyz --deps (perhaps with try/catch in case build script does not support this, in which case we assume "no deps", and host model already list them in "correct order") for all libs, to gather deps of each lib, 4) order libs so that if libA comes before libB, we can build B after A.

Alternatively, we can ask that buildnml (or config_compset.xml, depending on where this logic should be impl-ed) adds ALL libs (including deps) in the correct order. So, eg., if EAMxx in E3SM needs kokkos and for some reason kokkos depends on csm_share, it must add the libs "csm_share,kokkos" (and not just "kokkos"). CIME will concat all lists, and remove duplicates.

[jedwards4b]

@bargol your alternate solution is what I was suggesting and have implemented.

[jedwards4b]

@bartgol I have added ESCOMP/MOM_interface#276 to show what this looks like in a particular component and have tested this together with the CMEPS and cime changes.

[jedwards4b]

@jasonb5 I am ready to merge this with you're review.

[jasonb5]

LGTM
@jedwards4b Added some tests and a warning about using a deprecated method.