As usual for 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+ for compatibility with Scala 2.12.9. (#7375)
- Improved compiler performance. Benchmarks of compiler performance have improved by between 5% and 10% since 2.12.8, thanks to many performance 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)
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)
- Fix
-release N
flag on JDK 12+ (#7763) - Fix "cannot be represented as URI" on JDK 13 (#8210)
- Add JDK 9 constant types to the
ClassfileParser
to fix Scaladoc generation issue (#8289)
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
packedType
s deterministic in bytecode (#7751) - Add
-doc-canonical-base-url
to set a canonical URL in Scaladoc (#7998) - Backport fix for "illegal cyclic reference involving class" (#8161)
- Cache materialized
TypeTag
s (#8112) - Reduce the overhead of macro expansion (#8088)
For more details, check out all closed bugs and merged PRs.
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 26 contributors, according to git shortlog -sn --no-merges v2.12.8..2.12.x
. 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.
Thanks to Lightbend for their continued sponsorship of the Scala core team’s efforts. Lightbend offers commercial support for Scala.
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):
- Bump the
scalaVersion
setting in your sbt-based project - Download a distribution from scala-lang.org
- Obtain JARs via Maven Central
According to
there are three. We'd like to extend our gratitude to all three of them.