overloading resolution

object C {

  def join(in: Seq[List[_]]): Int = error("TODO")

  def join[S](in: Seq[List[S]]): String = error("TODO")

  join(Seq[List[Int]]())

  // 

  // ./a.scala:13: error: ambiguous reference to overloaded definition,

  // both method join in object C of type [S](in: Seq[List[S]])String

  // and  method join in object C of type (in: Seq[List[_]])Int

  // match argument types (Seq[List[Int]])

  //   join(Seq[List[Int]]())

  //   ^

  // one error found

}