0.4.3 (2022-01-21)

We’re happy to announce the release of Scala Native v0.4.3, which brings support for Scala 3!

This release does also contain performance-critical bug fixes to performing operations on Strings, leading to significant improvement of regexes throughput. Furthermore it comes with improvements to the sbt plugin in the area of incremental compilation and implementation of some missing methods from Java standard library.

Breaking changes in release 0.4.3

The minimal version of Scala 3 supported by Scala Native is 3.1.0, due to fatal blockers in Scala 3.0.x. In the future, when improved backward compatibility support in Scala 3.2 would implemented, Scala Native might be backported to the older version of the compiler.

Changes to the main method resolving

In the previous versions of Scala Native main entry point was always resolved based on the companion object defining the main method. This behaviour however lead to multiple issues in situations when an actual main method was introduced via inheritance. Because of that issue, build tools needed to always add $ suffix to actual main class to make sure that entry method would be found. With the 0.4.3 release, Scala Native does generate static method forwarders in the same way as it is done in JVM and Scala.js. Build tools should make sure to no longer add $ to the discovered main class name.

Source compatibity of stackalloc[T] and alloc[T] methods

No-param methods scalanative.unsafe.stackalloc[T] and scalanative.unsafe.alloc[T] were removed from Scala 3 unsafe package. In Scala 2 these methods have been deprecated and it is recommended to use empty-param variants of these methods instead, eg. scalanative.unsafe.stackalloc[T](). This change was introduced due to changes of how does Scala 3 interpret source code as it could lead to dangerous, hard to debug, runtime errors. As an example call to stackalloc[Byte](10) in Scala 2 would result in allocating memory of size 10 * sizeof(Byte). In Scala 3 however, the given snippet would be interpreted as stackalloc[Byte].apply(10) which is still valid, but leads to allocating 1 * sizeof(Byte) chunk of memory and accessing its 10th element, which would lead to undefined behaviour. More information can be found in #2480

Known issues

Cannot create documentation using scaladoc in Scala Native sbt project

When trying to generate documentation using Scaladoc for projects using Scala Native compilation would fail with an exception. This issue is common for most of the compiler plugins and was already fixed in Scala 3.1.1 compiler. As a workaround in Scala 3.1.0 we would recomend adjusting sbt build, by filtering out all -Xplugin settings from Compile / doc / scalacOptions. Workaround can be find in this discussion

Commits since last release 65
Merged PRs 62
Contributors 7


Big thanks to everybody who contributed to this release or reported an issue!

$ git shortlog -sn --no-merges v0.4.2..v0.4.3
    54	Wojciech Mazur
     5	Eric K Richardson
     2	Jan Chyb
     1	Anton Sviridov
     1	Kamil Podsiadło
     1	Lorenzo Gabriele
     1	Ruslan Shevchenko

Merged PRs

v0.4.3 (2022-01-21)

Full Changelog

Merged pull requests:

Bug fixes

  • Initialize _String with _ Array[Char] #2449 (lolgab)
  • Fix ARM64 MacOS varargs #2448 (keynmol)
  • Fix certain absolute file paths being shown as relative on Windows #2471 (jchyb)
  • Make java.nio.MappedByteBuffer JDK9+ compliant #2453 (WojciechMazur)
  • Remove redundant coversion of CharSequence into Array in Character.codePoint{at, before} methods #2495 (WojciechMazur)

Native library

Standard Java library

Compiler plugin / NIR

sbt plugin