Add support for bzlmod

[Vertexwahn]

Add support for bzlmod

[Wito-1]

Hello @Vertexwahn, this is a great repository.

I've taken this repo made some modifications to do a few things:

1. upgrade to bzlmod
2. download the qt libs using aqt
3. modified the QtToolchainInfo / gen_* rules to be able to run in a sandbox environment (no local tags)

Are you accepting contributions?

[Vertexwahn]

@Wito-1
Yes, I definitely accept contributions!
What you describe sounds perfect!
For me, it is also not so important to keep the old traditional WORKSPACE approach - if this does not work anymore - no problem - we can delete it. Maybe I can do a last release that people can reference for using those rules without Bzlmod, before we delete this approach.

[Sayter99]

Hi @Vertexwahn, I came across this issue and started trying to migrate rules_qt6 to use bzlmod (my attempt). However, I found a weird thing that the compilation time increased a lot after migration.

Here's a test repository. By building //qwt with bzlmod, it takes ~3 mins, but only ~1 min using WORKSPACE approach.

Noted that it only happens on Windows, (linux behaves the same), so I guess long paths might play a role here, but have no idea how to confirm this assumption. Any thoughts/ideas?

[Vertexwahn]

@Sayter99 I have no clue. Maybe you repost this in the bzlmod channel of Bazel on Slack

[Sayter99]

good idea, I've posted one https://bazelbuild.slack.com/archives/C014RARENH0/p1717470840590809, FYI.