t4440.scala:12: warning: The outer reference in this type test cannot be checked at run time.
    case _: b.Inner => println("b")
          ^
t4440.scala:13: warning: The outer reference in this type test cannot be checked at run time.
    case _: a.Inner => println("a") // this is the case we want
          ^
t4440.scala:16: warning: The outer reference in this type test cannot be checked at run time.
    case _: a.Inner => println("a")
          ^
t4440.scala:17: warning: The outer reference in this type test cannot be checked at run time.
    case _: b.Inner => println("b") // this is the case we want
          ^
error: No warnings can be incurred under -Xfatal-warnings.
four warnings found
one error found