t6011.scala:4: warning: unreachable code
    case 'a' | 'c' => 1 // unreachable
                      ^
t6011.scala:10: warning: unreachable code
    case 'b' | 'a'  => 1 // unreachable
                       ^
t6011.scala:8: warning: could not emit switch for @switch annotated match
  def f2(ch: Char): Any = (ch: @annotation.switch) match {
                                ^
error: No warnings can be incurred under -Xfatal-warnings.
three warnings found
one error found