t5954.scala:36: warning: class D should be placed directly in package A instead of package object A. Under some circumstances companion objects and case classes in package objects can fail to recompile. See https://issues.scala-lang.org/browse/SI-5954.
  case class D()
             ^
t5954.scala:35: warning: object C should be placed directly in package A instead of package object A. Under some circumstances companion objects and case classes in package objects can fail to recompile. See https://issues.scala-lang.org/browse/SI-5954.
  object C
         ^
t5954.scala:34: warning: trait C should be placed directly in package A instead of package object A. Under some circumstances companion objects and case classes in package objects can fail to recompile. See https://issues.scala-lang.org/browse/SI-5954.
  trait C
        ^
t5954.scala:33: warning: object B should be placed directly in package A instead of package object A. Under some circumstances companion objects and case classes in package objects can fail to recompile. See https://issues.scala-lang.org/browse/SI-5954.
  object B
         ^
t5954.scala:32: warning: class B should be placed directly in package A instead of package object A. Under some circumstances companion objects and case classes in package objects can fail to recompile. See https://issues.scala-lang.org/browse/SI-5954.
  class B
        ^
error: No warnings can be incurred under -Xfatal-warnings.
5 warnings found
one error found