- Faster compiler: 5–10% faster since 2.12.8, thanks to many optimizations (mostly by Jason Zaugg and Diego E. Alonso-Blas: kudos!)
- Improved compatibility with JDK 11, 12, and 13 (see below)
- Experimental support for build pipelining and outline type checking (see below)
As usual for our minor releases, Scala 2.12.9 is binary compatible with the whole Scala 2.12 series.
Scala.js users must update to 0.6.28+ or 1.0.0-M8+ to use Scala 2.12.9. (#7375)
Compatibility with JDK 11, 12, and 13
Scala 2.12.9 contains various fixes to improve compatibility with JDK 11, 12, and 13.
- Backport upgrade to ASM 7 for JDK 12 compatibility (#7780)
-release Nflag on JDK 12+ (#7763)
- Fix "cannot be represented as URI" on JDK 13 (#8210)
- Add JDK 9 constant types to the
ClassfileParserto fix Scaladoc generation issue (#8289)
Build pipelining and outline type checking
Scala 2.12.9 adds experimental infrastructure intended to support "build pipelining". Once build tools add support, compilation of downstream subprojects could begin once upstream code has been type-checked. See scala-dev#643.
- Fix large string interpolation causing compile-time StackOverflowError (#7995, #7996)
- Un-deprecate eta-expansion of 0-ary methods (#7740)
- Fix Java signature for value classes appearing in type arguments (#8127)
- Backport fix for interop between Java and generic inner Scala classes (#7977)
- Make the inferred
packedTypes deterministic in bytecode (#7751)
-doc-canonical-base-urlto set a canonical URL in Scaladoc (#7998)
- Backport fix for "illegal cyclic reference involving class" (#8161)
- Cache materialized
- Reduce the overhead of macro expansion (#8088)
A big thank you to everyone who's helped improve Scala by reporting bugs, improving our documentation,
spreading kindness in discussions around Scala, and submitting and reviewing pull requests! You are all magnificent.
This release was brought to you by 24 contributors, according to
git shortlog -sn --no-merges v2.12.8..v2.12.9. Thank you Jason Zaugg, Diego E. Alonso-Blas, Seth Tisue, Harrison Houghton, Adriaan Moors, Lukas Rytz, Aaron S. Hawley, Eugene Yokota, Michael Pollmeier, ta.tanaka, Enno Runne, A. P. Marki, Georgi Krastev, Kenji Yoshida, Stefan Zeiger, exoego, Benjamin Kurczyk, Anselm von Wangenheim, Alex Vayda, Sunil Mishra, Sébastien Doeraene, tgodzik, Dale Wijnand, Ryo Fukumuro.
Scala 2.12 notes
The release notes for Scala 2.12.0 have important information applicable to the whole 2.12 series.
Scala releases are available through a variety of channels, including (but not limited to):