retronym

object test {

  case class L[A, B]() {
    def ToLub[AA >: A <: L, BB >: B <: L, L] = new { type LUB = L }
  }

  val intBoolLub = L[Int, Boolean].ToLub
                             
  (1: AnyVal) : intBoolLub.LUB
  1: intBoolLub.LUB