Scala 2.12.21 release planning

Announcements
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This thread is for updates and discussions about the eventual Scala 2.12.21 release.

As of yet, we don’t know anything about the release’s likely timing or contents (except that we’ll likely need to upgrade ASM for the optimizer to support JDK 24).

We can use this thread to ask, propose, discuss.

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There is now some pressure to release Scala 2.12.21 in order to ship the ASM upgrade that allows the optimizer to work on JDK 24. (This upgrade is already available in our nightly builds.)

Is anyone aware of anything else that ought to go in the release? If so, please speak up this week.

Nothing else of interest to end users has been merged since 2.12.20.

Work is in progress on adding JDK 24 to our testing matrix; see JDK 24 · Issue #897 · scala/scala-dev · GitHub

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I just opened two PRs:

Thanks!

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Thank you for bringing this to our attention. Yes, looks like waiting for this makes sense.

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JDK 25 is GA now. We don’t yet have a planned date for a 2.12.21 release, but JDK 25 support has been merged on our 2.12.x branch, so users may consider using a nightly build.

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Will this also be released with the 2.13.x version that supports JDK25 byte code? Are we expecting weeks or more than a month or two?

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We haven’t set a date yet. As far as I can know

  • code compiled with 2.12.20 runs fine on JDK 25
  • the 2.12.20 compiler also works fine on Java 25, except when using the optimizer

If someone is blocked, let us know!

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That’s true, failed when optimizer is enabled

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I am not sure I am blocked but I would like to run Java 25 in CI https://github.com/ekrich/sconfig but I have a scalafix setup with scalafix tests and it does not work on on Scala 2.12.20. Scalafix/scalameta has now been updated to 0.14.4 so it works on Scala 2.13.17 and 3.3.6. To confirm you can clone and just run +test while using Java 25.

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Now that 2.13.18 is out, it’s time to also go ahead with 2.12.21 to fully support Java 25.

Proposed timeline:

  • Thu Nov 27: announce a “release candidate” (nightly build version)
  • Mon Dec 8: build and publish the release
  • A couple of days later: announcement
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The release candidate is version 2.12.21-bin-b7cc68a, the community build is green.

Release notes draft.

As announced recently there is a new resolver that can be used to access Scala 2 and Scala 3 nightly / mergely builds:

  • https://repo.scala-lang.org/artifactory/maven-nightlies
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Successfully tested Scala.js 1.20.1 with 2.12.21-bin-b7cc68a.

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Scala 2.12.21 is now on Maven Central (macro paradise 2.1.1 as well). We will announce it in a couple of days.

Tools and compiler plugins can now be published!

Release notes draft: scala-dev#922

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Scala.js 1.20.1 support for 2.12.21 is on Maven Central.

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Scala Native 0.5.9 and 0.4.17 artifacts for Scala 2.12.21 are now available

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The release is now announced, the release notes are on GitHub.

Thanks everyone for the quick tooling releases!

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