t5060.scala:2: error: covariant type T occurs in contravariant position in type => AnyRef{def contains(x: T): Unit} of value foo0
  val foo0 = {
      ^
t5060.scala:6: error: covariant type T occurs in contravariant position in type => AnyRef{def contains(x: T): Unit} of method foo1
  def foo1 = {
      ^
two errors found