Is this a bug? Interaction between `export` and pattern match

[ryanberckmans]

minimized code

Please see this issue ryanberckmans/noric-bot#1

Minimal repro https://scastie.scala-lang.org/MKy4rSaLSdKhSmuH7uALQA

Screenshot of this issue

expectation

No compile warning.

[liufengyun]

Thanks for reporting @ryanberckmans , it looks like to be a bug. It helps a lot if the code can be minimized to a small snippet.

[ryanberckmans]

I'll work on a minimal repro and update

[ryanberckmans]

@liufengyun minimal repro https://scastie.scala-lang.org/MKy4rSaLSdKhSmuH7uALQA

Please note the "Related Issue" in the Scastie snippet. I may have some confusion around the semantics of type X = Foo.X vs export Foo.X.

[liufengyun]

Thanks @ryanberckmans , it helps a lot.

It seems we miss some dealiasing in subtype checking (the same for the problem in your comment):

object Foo {
  enum MyEnum {
    case Red
    case Blue(msg: String)
  }
  export MyEnum._

  val a: Foo.MyEnum.Blue = ???
  a : Foo.Blue   // error:  Found: Foo.MyEnum.Blue(Foo.a), Required: Foo.Blue
}