Path to Scala 3

This is an issue for discussing and tracking necessary step to prepare for a Dotty/Scala3 cross-build.

Inspired by the awesome “Scala Love” conference, I attempted to cross-build util-core with Dotty 0.23.0-RC1. So far it went smoother than expected. In the end there were about 4 compile-errors that I couldn’t directly address.

In any case there’s some work that has to be done before a real cross-build can be achieved. So far I’ve identified the following but I will try and update this list as we learn more.

Preparations:

• Update sbt to recent version (e.g. 1.3.10; needed by sbt-dotty)
• Update Scalatest to 3.1.1 (which is cross-published for Dotty)
• Update twitter/util to Scalatest version available for latest Dotty (Dependency on Twitter codebase) | @mosesn
• Remove deprecated Config code | @mosesn
• Wait for Dotty to fix varargs override issue (see https://github.com/lampepfl/dotty/issues/9463)
• Wait for Scalatest 3.2.0 to be published for Dotty version which includes the varargs fix
• Refactor code which is not supported in Scala 3 (e.g. usage of Manifest/TypeTag reflection)

Resources for Dotty migration/cross-building:

• https://github.com/scalacenter/scala-3-migration-guide
• https://github.com/lampepfl/dotty-example-project#getting-your-project-to-compile-with-dotty

I hope you don’t mind this type of issue. This is not meant to push anyone, just as a place to discuss and organize things.

Cheers ~ Felix

[felixbr]

I’ve opened PRs #288 and #289 as preparation steps for a real Scala 3.0.0 cross-build. 🙂

[felixbr]

FYI: Scalatest has support for all Scala 3 releases so far:

• Scalatest 3.2.3 supports all Scala 3 milestone releases (3.0.0-M1, 3.0.0-M2, 3.0.0-M3)
• Scalatest 3.2.5 supports Scala 3.0.0-RC1
• Scalatest 3.2.7 supports Scala 3.0.0-RC2
• Scalatest 3.2.8 supports Scala 3.0.0-RC3
• Scalatest 3.2.9 supports Scala 3.0.0

https://mvnrepository.com/artifact/org.scalatest/scalatest

Just thought it might be good to know 🙂