Scala 2.12.5 is here!

Major highlights:

• When compiling on Java 9 or higher, the new-release N flag changes the compilation classpath to match the JDK version N. This works for the JDK itself and for multi-release JARs on the classpath.
• With the new -Ybackend-parallelism N compiler flag, the backend can now run bytecode serialization, classfile writing, and method-local optimizations (-opt:l:method) in parallel on N threads.
• The raw"" and s"" string interpolators are now intercepted by the compiler to produce more efficient bytecode.
• The -Ycache-plugin-class-loader and -Ycache-macro-class-loader flags enable caching of classloaders for compiler plugins and macro definitions. This can lead to significant performance improvements.

Other features include:

• The apply method on the PartialFunction companion object is now deprecated.
• Scala JARs (library, reflect, compiler) now have an Automatic-Module-Name attribute in their manifests.
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• Enabling unused warnings now lead to fewer false positives.
• Explicit eta-expansion (foo _) of a nullary method no longer gives a deprecation warning.

Scala releases are available through a variety of channels, including:

• Bump the scalaVersion setting in your sbt-based project
• Download a distribution from scala-lang.org
• Obtain JARs via Maven Central

However, there is regression since 2.12.4 when compiling code on Java 9 or 10 that uses macros. Users must either compile on Java 8 or wait for 2.12.6.

You can check out all closed bugs and merged PRs for further details.