Module alias/wrapper detection is broken/incomplete

[Flamefire]

Some modules have wrapper modules or aliases. E.g. Java/11 is not a real modules but implemented via a .modulerc.lua as module_version("Java/11.0.6-ppc64le", "11")

Similar thing exists for aliases: module_alias(...)

When EasyBuild checks for an existing module it runs module show <modname> and checks the output with a regexp ^\s*\S*/<modname>.*(\.lua)?:\s*$

This isn't exactly reliable. E.g. one might have a module Java/site-default-11 or so. Additionally not all possible modulerc locations are considered and aliases are completely unsupported. See https://lmod.readthedocs.io/en/latest/093_modulerc.html

The obvious solution would be to start parsing the modulerc files correctly.

But: Of course it isn't as this is what the modules tool can do way better.

Hence the better solution would be to check for _mlstatus = False and if that is found the module isn't available. Getting the filename isn't required for the correct return value of <ModulesTool>.exist so this can be greatly simplified.

Edit: This doesn't seem to work reliably for some reason. Sometimes lmod seems to return only _mlstatus = True even though the module isn't found. But only in EB, can't reproduce in shell. Seems to be that LMOD_QUIET=1 also suppresses the error code

In case we need the filename sometime later we should split the stdout/stderr and parse only stderr for a filename (LMod, not sure about EnvironmentModules)

[Flamefire]

I propose to remove the fallback via module_wrapper_exists as it would need to implement functionality of the module tool. Current state:

Fallback considers only:

• module_version command
• only module paths and 1 given directory

Fallback hence fails for:

• module_alias
• system MODULERC files
• ~/.modulerc.lua or ~/.modulerc