- Compiler performance has been improved significantly (related changes
- A new optimizer setting
-opt-inline-fromlimits the classes from which the inliner will copy code.
scalac -opt-inline-from:helpprovides detailed help.
- The presentation compiler has improved support for implicit macros, which should improve the experience with libraries based on Shapeless. It also has better support for code completion for dependently typed methods.
The REPL is undergoing renovations and features better positioning of errors and a cleaner internal implementation. multi-line editing and syntax highlighting.
Right associative methods with a by-name parameter no longer eagerly evaluate the operand.
Furthermore, all changes in the 2.12.3 will be part of 2.13.0-M2.
We are planning to make 2.13.x the default branch for pull requests after these releases to help us focus our collective attention on working towards 2.13.0. We’ll still target some changes to 2.12.x that are high reward and low risk, that fix important regressions.