Pattern-match duplication error

[VladUreche]

Found while minimizing #181.

$ cat gh-bug-182.scala 
package miniboxing.tests.bug182
import annotation.tailrec

sealed abstract class ConsList[@miniboxed A] {
  import ConsList._

  def dropWhile(): ConsList[A] = this match {
    case Cons(h, t) => t
  }
}

object ConsList {
  class Cons[@miniboxed A](val head: A, val tail: ConsList[A]) extends ConsList[A]
  object Cons{ 
    def unapply[@miniboxed A](x: Cons[A]): Option[(A, miniboxing.tests.bug181.ConsList[A])] = 
      if (x == null)
        None
      else
        Some((x.head, x.tail))
  }
}

$ mb-scalac gh-bug-182.scala 
gh-bug-182.scala:8: error: type mismatch;
 found   : miniboxing.tests.bug181.ConsList[A(in method dropWhile)] where type A(in method dropWhile) >: A(in class ConsList) <: A(in class ConsList)
 required: miniboxing.tests.bug182.ConsList[A(in class ConsList)]
    case Cons(h, t) => t
                       ^
gh-bug-182.scala:19: error: type mismatch;
 found   : miniboxing.tests.bug182.ConsList[A]
 required: miniboxing.tests.bug181.ConsList[A]
        Some((x.head, x.tail))
                        ^
two errors found

[VladUreche]

Reopened, since this affects some version of the Scala compiler :/