Is your feature request related to a problem? Please describe.

We recently switched our default version of modules from the ancient 3.2.6 to 5.3.1 on one of our clusters, and got an uncomfortable surprise when we discovered that our Temurin Java modules weren’t compatible with the new restrictions on naming made by the addition of module variants. Temurin versions are named as, for example, 21.0.2+13, and docs do state that the + character is no longer allowed in module names.

The way we discovered this, though, was that a module named java/temurin-17/17.0.2+8 would load on some partial matches, but not on a full match. This gives strange results like:

$ module path java/temurin-17
/shared/ucl/apps/modulefiles/development/java/temurin-17/17.0.2+8

$ module path java/temurin-17/17
/shared/ucl/apps/modulefiles/development/java/temurin-17/17.0.2+8

$ module path java/temurin-17/17.0
/shared/ucl/apps/modulefiles/development/java/temurin-17/17.0.2+8

$ module path java/temurin-17/17.0.2
ERROR: Unable to locate a modulefile for 'java/temurin-17/17.0.2'

$ module path java/temurin-17/17.0.2+8
ERROR: Unable to locate a modulefile for 'java/temurin-17/17.0.2+8'

$ module load /shared/ucl/apps/modulefiles/development/java/temurin-17/17.0.2+8
Loading /shared/ucl/apps/modulefiles/development/java/temurin-17/17.0.2+8{+8}
  ERROR: Unknown variant '8' specified
  ERROR: Unknown variant '8' specified

Describe the solution you'd like

I guess we’re just going to have to rename the modulefile on our end, but this seems like a bigger consistency problem that could use a fix, or at least a warning of some kind. I’m not sure what it should be, though, and I’m not really familiar with the module variant syntax itself. Clearly modulecmd is identifying and parsing the relevant file as a modulefile, but then has problems with the syntax on use, so perhaps as a first step it would make sense to print a warning or error when a modulefile containing illegal characters is parsed?

Describe alternatives you've considered

I'm happy to discuss alternative and additional ways to handle problems around this, but since the module variant syntax seems fully integrated into the module name handling, I'm not sure what to suggest.

I could imagine CLI options to, for example, force exact matching, or enable/disable variant parsing, but that doesn't solve the weirdness problem in the examples above.

TLDR

Because:

• partial matching + variant parsing seems to behave weirdly
• modulecmd parses modulefiles with illegal names
• modulecmd does not warn the user when it encounters illegal names
• upgrading from a version without variants to a version with variants can make existing module names unusable

It would be a good idea to:

• produce a message/error when encountering illegal names
• look into options to make partial matching + variant parsing behave less weirdly