Scala 3.9.0-RC5 release procedure

[WojciechMazur]

Release procedure for unstable version 3.9.0-RC5

• Publish artifacts to Maven via CI

  • Ensure scala-steward is blocking automatic upgrades for 3.9.0
  • On release-3.9.0 branch:
    • Create changelog file in changelogs/3.9.0-RC5.md
    • In project/Build.scala: Set baseVersion = "3.9.0-RC5"
    • In tasty/src/dotty/tools/tasty/TastyFormat.scala ensure MinorVersion is set to 9
    • In tasty/src/dotty/tools/tasty/TastyFormat.scala ensure ExperimentalVersion is set to experimental (1 or higher)
    • Tag the branch as 3.9.0-RC5
    • Wait for CI to publish artifacts https://github.com/scala/scala3/actions/runs/31369241416
    • Audit and release artifacts on https://central.sonatype.com/

• On main branch:

  • In project/Build.scala: Set referenceVersion to 3.9.0-RC5 [chore] Set reference compiler version to 3.9.0-RC5 #26767
  • Check and update project/MiMaFilters.scala

• Wait for releases/confirmation from tooling:

  • Scala CLI - test: Bump Scala 3 Next RC to 3.9.0-RC5 VirtusLab/scala-cli#4419
  • Scala Native - publish compiler plugin
  • Scastie - update available versions
  • Scalameta Parser - test and update dialects to include new features on a new minor
  • Metals - update tests and make sure new features are supported
  • Mdoc - update tests
  • Open Community Build

• Announce the release

  • Publish release on GitHub Releases (as pre-release)
  • Update tracking thread on https://contributors.scala-lang.org