FR: Gazelle Kotlin Support

[rob-pomelo]

Hi is there any thought / interest in adding kotlin support to the gazelle extension?

Have briefly started to look at the changes required and curious if its on others radar.

Thanks!

[illicitonion]

Would gladly review some PRs (with tests) to enable this!

[MorganR]

I've put up a (very messy, don't use it) PR up (#313 ) for discussion on this

[shs96c]

Thank you for the PR. I'm pinging @restingbull, as he might be interested in this being part of rules_kotlin. We can work together to find the best place for this :)

[MorganR]

I'd also be curious what @alexeagle thinks about merging Kotlin support in with the Java plugin, given his experience from the independent Kotlin plugin.

[restingbull]

Hm. We are generally trying to keep our maintenance footprint small, and adding Go to the dependencies is a bit non-ideal for us.

@Bencodes @nkoroste -- Thoughts?

[MorganR]

@shs96c, I understand why it seems like rules_kotlin would be a good spot for this, but I actually think that if someone is using Kotlin specifically with the JVM, then the best place for handling those rules is in the same plugin that handles the Java rules. I put more thoughts about why this is the case in the draft PR I linked above.

The only new dependency it adds to rules_jvm is one new Maven dependency on the "kotlin" package for parsing the Kotlin files.

[shs96c]

I am quite persuaded by the argument that kotlin and java source is often co-mingled in a way that other JVM-based languages don't seem to do.

[alexeagle]

FWIW We already have a Kotlin gazelle extension over here: https://github.com/aspect-build/aspect-cli/tree/main/gazelle/kotlin written by @jbedard

There are no great options for where to place Gazelle extensions since they're always compiled from source and introduce new toolchain dependencies (e.g. you'd want to use Tree-Sitter and that needs a C++ toolchain) IMO bazel-contrib/bazel-gazelle#938 is needed, so that Gazelle binary can load extensions that rulesets ship as pre-built binaries on their releases page.