Difference in erasure between dotc and scalac

[Jasper-M]

sealed trait Foo
object Foo { type A }

Scalac erases the type Foo.A with Foo to Object. Dotc erases it to Foo.

I'm not sure if that would be considered a bug, but I was told differences in behavior between scala and dotty should be documented regardless.

[odersky]

I believe at some point scalac behaved like Dotty. Maybe @retronym can reconstruct why that got changed. It would be important to use the same algorithm for binary compatibility.

[smarter]

scalac algorithm: https://github.com/scala/scala/blob/cac6383e6658dc5956540b76b9b46c3b664774ac/src/reflect/scala/reflect/internal/transform/Erasure.scala#L290-L323
dotty algorithm: https://github.com/lampepfl/dotty/blob/1ab60276f5684ec7c80f3fed3c0f52ab491ecca6/compiler/src/dotty/tools/dotc/core/TypeErasure.scala#L285-L310

[smarter]

#4619 is a duplicate but has a bit more details so closing this one.