hazards of lower-case first-letters in `case object` names in scala

puzzler.scala

{
  sealed trait obj
  case object one extends obj
  case object two extends obj

  def bad(o: obj) =
    o match {
      case one ⇒ 1
      case two ⇒ 2
    }
  bad(one) // 1
  bad(two) // 1 !!!!!

  def ok(o: obj) =
    o match {
      case _: one.type ⇒ 1
      case _: two.type ⇒ 2
    }
  
  ok(one) // 1
  ok(two) // 2
}
{
  sealed trait obj
  case class one() extends obj
  case class two() extends obj
  def ok(o: obj) =
    o match {
      case one() ⇒ 1
      case two() ⇒ 2
    }
  
  ok(one) // 1
  ok(two) // 2
}
{
  sealed trait obj
  case object One extends obj
  case object Two extends obj
  def ok(o: obj) =
    o match {
      case One ⇒ 1
      case Two ⇒ 2
    }
  
  ok(one) // 1
  ok(two) // 2
}
{
  sealed trait obj
  case object `one` extends obj
  case object `two` extends obj
  def ok(o: obj) =
    o match {
      case `one` ⇒ 1
      case `two` ⇒ 2
    }
  
  ok(one) // 1
  ok(two) // 2
}