Support Scala 2.13

[jdegoes]

Any plans to cross-build for Scala 2.13?

[olafurpg]

Thanks for reporting! I’ve been planning to add Scala 2.13 support once the RC is out. I think I have publish rights for most of our transitive dependencies excluding ScalaTest so I don’t expect to encounter major blockers in the upgrade.

[jdegoes]

@olafurpg Awesome! Thank you for looking into this.

More context here

[olafurpg]

The traditional way to use the mdoc plugin is only enable it for a single “docs” project in the build that is not published. I’m not sure how microsite uses mdoc but I’m surprised if lack of 2.13 support should be a blocker for 2.13 crossbuilt libraries. The docs are usually only compiled against one Scala versions.

[jdegoes]

@olafurpg

More information:

• skip in publish := true is set in the microsite project
• microsite is the only project using the plug-in
• Despite the above and also trying to exclude scalameta mdoc from transitive dependencies, publishLocal still fails due to non-existence of 2.13

My sbt-fu is weak though. I may be missing something obvious.

[olafurpg]

What is the value of “crossScalaVersions”?

[jdegoes]

crossScalaVersions := Seq("2.12.8", "2.13.0-M5")

[olafurpg]

Does publishLocal work if you set crossScalaVersions := Seq("2.12.8") in the docs project?

If that works, then we  improve the error message in sbt-mdoc to give actionable feedback on how to fix the resolution error for unsupported Scala versions.

[jdegoes]

@olafurpg Will try and report back.

[gabro]

For the record, cross building for 2.13.0 is currently blocked by the lack of 2.13.0 binaries for:

• monadic-html (Scala 2.13 support OlivierBlanvillain/monadic-html#109)
• metaconfig (https://github.com/olafurpg/metaconfig/issues/71)

Here's a WIP PR #173

[gabro]

Actually, monadic-html is only used in the documentation, so it should be fine. We're currently only blocked by metaconfig (working on it!)

[olafurpg]

Fixed in #184, waiting for CI to release 1.3.2 https://travis-ci.org/scalameta/mdoc/builds/576584631