sbt metabuild support

[rarkins]

Discussed in #29083

^{Originally posted by ArtyomGabeev May 15, 2024}

What would you like help with?

I think I found a bug

How are you running Renovate?

Self-hosted

If you're self-hosting Renovate, tell us which platform (GitHub, GitLab, etc) and which version of Renovate.

Bitbucket

Please tell us more about your question or problem

sbt has an idea of meta-builds. One of primary usage is to organize dependency management in one place, as documented here:
https://www.scala-sbt.org/1.x/docs/Organizing-Build.html#Tracking+dependencies+in+one+place

The issue comes with scalaVersion resolution.
scalaVersion can be defined only in build.sbt file, e.g.:

ThisBuild / scalaVersion := "3.4.1"

But when there are scala dependencies in Dependencies.scala file from meta-build project directory, there is no information about scala version. We need somehow to propagate this information.

Options considered:

1. Create some anchor (e.g. via renovate comment) which can be used to specify scala version at top of Dependencies.scala file - the issue is that we will have several places with scalaVersion defined
2. Pass scala version as sbt manager parameter - same problem, several places with scalaVersion needs to be synced by developers
3. Parse build.sbt and extract scalaVersion from root file, pass scalaVersion when parsing other files - this is ideal solution, but I'm not sure about implementation feasibility.

Notes:
I'm looking for advice how to proceed and can contribute the fix.

Logs (if relevant)

Logs

Replace this text with your logs, between the starting and ending triple backticks

[rarkins]

The sbt manager already uses extractAllPackageFiles(), which means it processes every file at the same time and can apply "shared" values before returning them. For example there's already a loop where Renovate iterates over each detected file and applies registryUrls settings:

renovate/lib/modules/manager/sbt/extract.ts

Line 396 in f951139

for (const pkg of packages) {

We could perhaps reuse that loop to apply scala version settings for meta builds

[ArtyomGabeev]

Hi, @rarkins

I've opened PR some time ago, but no reviewers are assigned.
May I ask for a review?

Thanks.