exhausting.scala:20: error: match is not exhaustive!
missing combination              *           Nil

  def fail1[T](xs: List[T]) = xs match {
                              ^
exhausting.scala:24: error: match is not exhaustive!
missing combination            Nil

  def fail2[T](xs: List[T]) = xs match {
                              ^
exhausting.scala:27: error: match is not exhaustive!
missing combination           Bar3

  def fail3[T](x: Foo[T]) = x match {
                            ^
exhausting.scala:31: error: match is not exhaustive!
missing combination           Bar2          Bar2

  def fail4[T <: AnyRef](xx: (Foo[T], Foo[T])) = xx match {
                                                 ^
exhausting.scala:36: error: match is not exhaustive!
missing combination           Bar1          Bar2
missing combination           Bar1          Bar3
missing combination           Bar2          Bar1
missing combination           Bar2          Bar2

  def fail5[T](xx: (Foo[T], Foo[T])) = xx match {
                                       ^
5 errors found