traits and self-type cause java.lang.AbstractMethodError

[dieu]

Hello,

I have a simple code which throws an error on 2.12.x+ but work perfectly fine on dotty.

abstract class Base[T] {
  type Type = T
  
  def methodOp(arg: Type): Unit = {
    this match {
      case m: Base[T] with Mark =>
        m.method(arg.asInstanceOf[m.Type]) throw java.lang.AbstractMethodError Apps$.method(Ljava/lang/Object;)V
      case _ =>
      
    }
  }
}

trait Mark { this: Base[_] => 
  def method(arg: Type): Unit
}

object Apps extends Base[Int] with Mark {
  override def method(arg: Apps.Type): Unit = {
    println(arg)
  }
}

https://scastie.scala-lang.org/ndlr1yZiSyiuORdjAvULmw

works with dotty:

https://scastie.scala-lang.org/nG7jh4zpRKWB9P20WuoXZw

Is it possible to work around this error?

[som-snytt]

I don't see any workaround on #8681

[eed3si9n]

Looks like we can close this. Also in general questions should be on Scala Users or Stackoverflow - https://www.scala-lang.org/community/

[dieu]

@som-snytt @eed3si9n

JFYI: We found a workaround to force the scala compiler to generated the bridge method.

def method[T <: Type](arg: T): Unit  

https://scastie.scala-lang.org/dih0xBjORWa65k901ekT6w