correct extrapolation for existential in contravariant position

[scabug]

class O {
  class Y
  class U extends Y
  class A[-T] {def x(x: T) = 1}
  def foo[T >: U]: A[Y] forSome {type Y >: T} = new A[T]
  val g = foo
  g.x(new U)
  g.x(new Y) // <-- compiler error: found: O.this.Y required: T
}

Error requires some type T, however in this context there is no such type, so anyway this is a bug in description (but I think not only in description).

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-4880?orig=1
Reporter: @Alefas
Affected Versions: 2.9.0-1

[scabug]

@paulp said:
T should be some existential or other, yes? Over to you, moors.

[scabug]

@adriaanm said:

class Test {
  class A[-T]
  def foo[T]: A[Y] forSome {type Y >: T} = new A[T]
  val tmp/*: A[T] <-- ERRONEOUS INFERENCE*/ = foo
}