Notable Changes

Language

• Add @experimental annotation #12102
• A simpler implementation of init checker #12495
• Allow _ as a type lambda placeholder in -Ykind-projector:underscores compatiblity mode #12378
• Support variance annotations in -Ykind-projector mode #12341
• Better error message for errors arising from implicit completions #12002
• Explain match type reduction failures in error messages #12053

Metaprogramming

• Cache quote unpickling #12242
• Add Expr.valueOrAbort and reflect.report.errorAndAbort #12056
• Avoid pickled tasty for some captured quote reference #12248
• Improve quote matcher performance #12418
• Port scala.quoted.runtime.impl.QuoteMatcher #12402
• Check transparent inline type argument bounds #12334
• Improve constant folding logic #12080
• Support inline val references in top level splices #12235

Scaladoc

• Snippet compiler #11582
• Update user manual for scaladoc #12083

Bug fixes

• IArray.toArray: Deprecate broken method #12598
• Fix comparison of dependent function types #12214
• Make translucentSuperType handle match types #12153
• Harden Type Inference #12560
• Reject references to self in super constructor calls #12567
• Provide mirror support after inlining #12062
• Allow export paths to see imports #12134
• Streamline given syntax #12107
• Export constructor proxies #12311
• Identify package and nested package object in isSubPrefix #12297
• Treat Refinements more like AndTypes #12317
• Fix #9871: use toNestedPairs in provablyDisjoint #10560
• Fix TypeTest exhaustivity check #12059

Other

• record end markers in trees and semanticdb, exclude top level def wrappers #12541
• Use stringOf from REPL to avoid trimming #11562

Contributors

Thank you to all the contributors who made this release possible 🎉

According to git shortlog -sn --no-merges 3.0.0-RC2..3.0.1-RC1 these are†:

   121  Martin Odersky
   111  Liu Fengyun
    98  Nicolas Stucki
    29  Guillaume Martres
    24  Phil
    20  Olivier Blanvillain
    14  Tom Grigg
    14  Adrien Piquerez
    13  Natsu Kagami
    12  Andrzej Ratajczak
    10  odersky
    10  Aleksander Boruch-Gruszecki
     9  Anatolii Kmetiuk
     8  Jamie Thompson
     6  Maxime Kjaer
     5  Som Snytt
     3  Filip Zybała
     3  Krzysztof Romanowski
     3  Kai
     3  Fengyun Liu
     3  noti0na1
     3  Phil Walker
     2  Johannes Rudolph
     2  soronpo
     2  tanishiking
     2  Adam Warski
     2  Kacper Korban
     2  Raphael Jolly
     2  Sébastien Doeraene
     1  xuwei-k
     1  Alexander Ioffe
     1  David Barri
     1  Devon Stewart
     1  Dmitrii Naumenko
     1  Ivan Kurchenko
     1  Jakub Kozłowski
     1  Jonas Ackermann
     1  Kevin Lee
     1  Martin
     1  Michał Pałka
     1  Miles Sabin
     1  Oron Port
     1  Paweł Marks
     1  Ruslan Shevchenko
     1  Seth Tisue
     1  Vadim Chelyshov
     1  nogurenn
     1  nurekata

†: Note that we measure against 3.0.0-RC2 and not 3.0.0 because we stabilized on 3.0.0-RC2. Only critical bug fixes found their way into 3.0.0-RC3 and further, while the majority of changes ended up in 3.0.1-RC1.

Reporting Bugs

If you encounter a bug, please open an issue! 🙏