The primary improvements and enhancements that it includes are:
The Dotty Tasty Reader (https://github.com/scala/scala/pull/9109), which allows libraries compiled with Dotty to be consumed by 2.13.4+ (provided it utilises the subset of Scala 3 that Scalac 2.13 can understand)
Enabling range position by default, which is required by SemanticDB (and therefore Scalafix and Metals) - now they be enabled by default
Just a reminder that 2.13.4 is planned to go out this week, so please test it out if possible (particularly as I merged by pattern matching exhaustivity PR on Friday!)
We’ve had to push 2.13.4 out a bit again, as a handful of issues and PRs are still in flight, plus we’ll need to float an “RC” (a designated nightly) and run the community build. Current target date is Mon Nov 16
Scala.js 1.3.1 for Scala 2.13.4 is on its way to Maven Central.
I’ll try to back-publish earlier versions later today, but it’s not as easy because they don’t build out of the box with 2.13.4 due to the new warnings.