// NOTE: the companion inherits a public apply method from Function1!
case class NeedsCompanion private (x: Int)

object ClashNoSig { // ok
  private def apply(x: Int) = if (x > 0) new ClashNoSig(x) else ???
}
case class ClashNoSig private (x: Int)


object Clash {
  private def apply(x: Int) = if (x > 0) new Clash(x) else ???
}
case class Clash private (x: Int)

object ClashSig {
  private def apply(x: Int): ClashSig = if (x > 0) new ClashSig(x) else ???
}
case class ClashSig private (x: Int)

object ClashOverload {
  private def apply(x: Int): ClashOverload = if (x > 0) new ClashOverload(x) else apply("")
  def apply(x: String): ClashOverload = ???
}
case class ClashOverload private (x: Int)

object NoClashSig {
  private def apply(x: Boolean): NoClashSig = if (x) NoClashSig(1) else ???
}
case class NoClashSig private (x: Int)

object NoClashOverload {
  // needs full sig
  private def apply(x: Boolean): NoClashOverload = if (x) NoClashOverload(1) else apply("")
  def apply(x: String): NoClashOverload = ???
}
case class NoClashOverload private (x: Int)



class BaseNCP[T] {
  // error: overloaded method apply needs result type
  def apply(x: T): NoClashPoly = if (???) NoClashPoly(1) else ???
}

object NoClashPoly extends BaseNCP[Boolean]
case class NoClashPoly private(x: Int)


class BaseCP[T] {
  // error: overloaded method apply needs result type
  def apply(x: T): ClashPoly = if (???) ClashPoly(1) else ???
}
object ClashPoly extends BaseCP[Int]
case class ClashPoly private(x: Int)