virtpatmat_exhaust_compound.scala:14: warning: match may not be exhaustive.
It would fail on the following inputs: O1, O2, O4
  a match {
  ^
virtpatmat_exhaust_compound.scala:18: warning: match may not be exhaustive.
It would fail on the following input: O4
  def t1(a: Product with Base with Base2) = a match {
                                            ^
virtpatmat_exhaust_compound.scala:22: warning: match may not be exhaustive.
It would fail on the following input: O2
  def t2(a: Product with Base { def foo: Int }) = a match {
                                                  ^
error: No warnings can be incurred under -Xfatal-warnings.
three warnings found
one error found