existential separate compilation bug

[scabug]

Two files:

  // Constraints.scala
  package server
  trait Constraints {
    class ConstraintEntry(constraint : List[_])
  }

and

  // Test.scala
  package server
  object Test extends Constraints

Clean compile no problem. Afterwards compile test (in a fresh compiler instance):

"object creation impossible, since type _$$1 in trait Constraints with bounds >: Nothing <: Any is not defined"

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-1086?orig=1
Reporter: @mcdirmid

[scabug]

@dubochet said:
I confirmed the issue in r15501.

[scabug]

@odersky said:
fixed in r15616