The set of sharedlibs needed by a model should not be hardcoded

[jgfouca]

In build.py, we have the following code:

    if ufs_driver and ufs_driver == "nems" and not cpl_in_complist:
        libs = []
    elif case.get_value("MODEL") == "cesm":
	libs = ["gptl", "pio", "csm_share"]
    elif case.get_value("MODEL") == "e3sm":
        libs = ["gptl", "mct", "spio", "csm_share"]
    else:
        libs = ["gptl", "mct", "pio", "csm_share"]

I propose, instead of having this hardcoded in CIME's build system, this should be a config item in the host model. There's an entry in config_files.xml that is already pretty close:

  <entry id="BUILD_LIB_FILE">
    <type>char</type>
    <values>
      <value lib="kokkos">$SRCROOT/share/build/buildlib.kokkos</value>
      <value lib="gptl">$SRCROOT/share/build/buildlib.gptl</value>
      <value lib="pio">$CIMEROOT/CIME/build_scripts/buildlib.pio</value>
      <value lib="spio">$SRCROOT/share/build/buildlib.spio</value>
      <value lib="mct">$SRCROOT/share/build/buildlib.mct</value>
      <value lib="csm_share">$SRCROOT/share/build/buildlib.csm_share</value>
      <value lib="mpi-serial">$SRCROOT/share/build/buildlib.mpi-serial</value>
      <value lib="cprnc">$CIMEROOT/CIME/build_scripts/buildlib.cprnc</value>
      <value lib="ekat">$SRCROOT/share/build/buildlib.ekat</value>
    </values>

[jgfouca]

@jedwards4b had a good comment on this too:

No, it would be something like a new variable in the driver config_component.xml file, say
CASE_SUPPORT_LIBRARIES and this variable would be a list of strings naming support libraries to
be built with the case, so for example CASE_SUPPORT_LIBRARIES="gptl","pio2","csm_share","FMS","Kokkos"

[jedwards4b]

#4836

[bartgol]

Bonus points if we could make it so that, on top of the host model specifying sharedlibs that it knows are always needed (such as csm_share, or gptl), components can specify sharedlibs they need (e.g, kokkos). The goal being that, if a compset has, say, ATM active, CIME can ping the atm component to see what its sharedlibs needs are.

Right now, e.g. for kokkos, this logic is handled via the uses_kokkos function. But this forces the build system to be aware of the existence of kokkos. If we add a new lib (like ekat here, and who knows what next) we must update CIME to be aware of it. It'd be nice if CIME could do something like libs = case.get_shared_libs(), where the sharedlibs list is built during case.setup(), where each component adds to the list of sharedlibs based on its needs (perhaps, during buildnml, or maybe better via an xml var in config_component.xml, which can vary depending on compset specs).

Edit: sorry, I wrote this 1h ago (before seeing both of your posts) but forgot to hit enter.

[jedwards4b]

@bartgol good idea, I think that it would be easy to extend this implementation in that way.

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