Write instances of Ordering[T] manually

T1.scala

sealed abstract class T1
object T1 {
  case class A(x: Int) extends T1
  case class B(x: Double) extends T1
  case class C(x: String) extends T1
  implicit val ordA: Ordering[A] = (a, b) => a.x compare b.x
  implicit val ordB: Ordering[B] = (a, b) => a.x compare b.x
  implicit val ordC: Ordering[C] = (a, b) => a.x compare b.x
}

T2.scala

sealed abstract class T2(val code: Int)
object T2 {
  case class A(x: Int) extends T2(0)
  case class B(x: Double) extends T2(1)
  case class C(x: String) extends T2(2)
  implicit def ordT2: Ordering[T2] = (t1, t2) => t1.code compare t2.code
}

T3.scala

sealed abstract class T3
object T3 {
  case class A(x: Int) extends T3
  case class B(x: Double) extends T3
  case class C(x: String) extends T3
  implicit val ordT3: Ordering[T3] = (a, b) => (a, b) match {
    case (a1@A(_), a2@A(_)) => ordA.compare(a1, a2)
    case (b1@B(_), b2@B(_)) => ordB.compare(b1, b2)
    case (c1@C(_), c2@C(_)) => ordC.compare(c1, c2)
  }
  implicit val ordA: Ordering[A] = (a, b) => a.x compare b.x
  implicit val ordB: Ordering[B] = (a, b) => a.x compare b.x
  implicit val ordC: Ordering[C] = (a, b) => a.x compare b.x
}