object Unchecked {
  def nowarn[T] = (null: Any) match { case _: Some[T]      => } 

  def warn1[T]  = (null: Any) match { case _: T            => }
  def warn2     = (null: Any) match { case _: Some[String] => } 
}

    /** Is this type a subtype of that type in a pattern context?
     *  Dummy type arguments on the right hand side are replaced with
     *  fresh existentials, except for Arrays.
     *
     *  See bug1434.scala for an example of code which would fail
     *  if only a <:< test were applied.
     */
    def matchesPattern(that: Type): Boolean = (this <:< that) || (that match {
      case ArrayTypeRef(elem2) if elem2.typeConstructor.isHigherKinded =>
        this match {
          case ArrayTypeRef(elem1) => elem1 matchesPattern elem2
          case _                   => false
        }
      case TypeRef(_, sym, args) =>
        val that1 = existentialAbstraction(args map (_.typeSymbol), that)
        (that ne that1) && (this <:< that1) && {
          debuglog(s"$this.matchesPattern($that) depended on discarding args and testing <:< $that1")
          true
        }
      case _ =>
        false
    })