Better support type-heavy pattern matches#12549

Merged

dwijnand merged 9 commits intoscala:masterfrom

dotty-staging:fix-12475

Jun 3, 2021

Commits on May 26, 2021

Fix #12602: Only generate sum mirrors for sealed trait or sealed abstract class
liufengyun
committed

Commits on Jun 2, 2021

Fix #12681: Approximate `ThisType` in child instantiation
liufengyun
committed