t7007.scala:5: error: Implementation restriction: <$anon: A => B> requires premature access to class Crash.
  def this(a: Seq[A]) = this(a.collect{ case b: B => b}, a.collect{ case b: B => b})
                                      ^
t7007.scala:5: error: Implementation restriction: <$anon: A => B> requires premature access to class Crash.
  def this(a: Seq[A]) = this(a.collect{ case b: B => b}, a.collect{ case b: B => b})
                                                                  ^
two errors found