This release is a HUGE milestone for us, for Dotty, for Scala 3, for our community. Since that initial commit on the 6th December of 2012 when the only feature was the basic structure of a compiler based on the DOT calculus, we have come a long way.
7 years and 20k commits later we are happy to announce that we are now feature-complete for Scala 3.
This means that with this release we stop adding new features and we focus on the stability of the language, performance and eduction.
Other than that, this release brings some novelties to the language, such as explicit nulls, new syntax for conditional givens, new match syntax and pattern matching on quotes. You can read more about these in our blog post: https://dotty.epfl.ch/blog/2019/12/20/21th-dotty-milestone-release.html
Notable Changes
- Dotty with explicit nulls (and flow typing) #7546
- Add SemanticDB extractor #7379
- Add quoted.util.ExprMap #7570
- Improve performance of tuple operations #7689
- Change extension method syntax #7557
- Independent tasty-core library #7616
Contributors
Thank you to all the contributors who made this release possible 
According to git shortlog -sn --no-merges 0.20.0-RC1..0.21.0-RC1 these are:
176 Martin Odersky
171 Bryan Abate
88 Nicolas Stucki
81 Jamie Thompson
44 noti0na1
29 Anatolii
28 bishabosha
23 Antoine Brunner
19 Guillaume Martres
10 Aleksander Boruch-Gruszecki
8 Guillaume Raffin
6 Olafur Pall Geirsson
5 SΓ©bastien Doeraene
4 Aggelos Biboudis
4 Liu Fengyun
4 Paolo G. Giarrusso
3 Andrea Mocci
3 Martijn Hoekstra
2 Ben Elliott
2 Patrik Mada
2 Rafal Piotrowski
2 odersky
1 Markus Kahl
1 Richard Beddington
1 Vlastimil Dort
1 Anatolii Kmetiuk
1 Raphael Jolly
1 Lucas
1 Nikita Eshkeev
1 Brian Wignall
1 Olivier Blanvillain
1 εΌ εΏθ±ͺ
Reporting Bugs
If you encounter a bug, please open an issue! 