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trait Contravariant[-X]
trait Invariant[X]
trait Covariant[+X]
abstract class M {
type H
type L <: H
type T >: L <: H
def h1(x: Contravariant[H]) = {
/* nowarn */ println(x.isInstanceOf[Contravariant[H]])
/* nowarn */ println(x.isInstanceOf[Contravariant[T]])
/* nowarn */ println(x.isInstanceOf[Contravariant[L]])
}
def h2(x: Contravariant[T]) = {
/* warn */ println(x.isInstanceOf[Contravariant[H]])
/* nowarn */ println(x.isInstanceOf[Contravariant[T]])
/* nowarn */ println(x.isInstanceOf[Contravariant[L]])
}
def h3(x: Contravariant[L]) = {
/* warn */ println(x.isInstanceOf[Contravariant[H]])
/* warn */ println(x.isInstanceOf[Contravariant[T]])
/* nowarn */ println(x.isInstanceOf[Contravariant[L]])
}
def h4(x: Invariant[H]) = {
/* nowarn */ println(x.isInstanceOf[Invariant[H]])
/* warn */ println(x.isInstanceOf[Invariant[T]])
/* warn */ println(x.isInstanceOf[Invariant[L]])
}
def h5(x: Invariant[T]) = {
/* warn */ println(x.isInstanceOf[Invariant[H]])
/* nowarn */ println(x.isInstanceOf[Invariant[T]])
/* warn */ println(x.isInstanceOf[Invariant[L]])
}
def h6(x: Invariant[L]) = {
/* warn */ println(x.isInstanceOf[Invariant[H]])
/* warn */ println(x.isInstanceOf[Invariant[T]])
/* nowarn */ println(x.isInstanceOf[Invariant[L]])
}
def h7(x: Covariant[H]) = {
/* nowarn */ println(x.isInstanceOf[Covariant[H]])
/* warn */ println(x.isInstanceOf[Covariant[T]])
/* warn */ println(x.isInstanceOf[Covariant[L]])
}
def h8(x: Covariant[T]) = {
/* nowarn */ println(x.isInstanceOf[Covariant[H]])
/* nowarn */ println(x.isInstanceOf[Covariant[T]])
/* warn */ println(x.isInstanceOf[Covariant[L]])
}
def h9(x: Covariant[L]) = {
/* nowarn */ println(x.isInstanceOf[Covariant[H]])
/* nowarn */ println(x.isInstanceOf[Covariant[T]])
/* nowarn */ println(x.isInstanceOf[Covariant[L]])
}
}
object Test extends M {
type H = Any
type T = Int
type L = Nothing
val conh = new Contravariant[H] { }
val cont = new Contravariant[T] { }
val conl = new Contravariant[L] { }
val invh = new Invariant[H] { }
val invt = new Invariant[T] { }
val invl = new Invariant[L] { }
val covh = new Covariant[H] { }
val covt = new Covariant[T] { }
val covl = new Covariant[L] { }
def main(args: Array[String]): Unit = {
h1(conh)
h2(conh)
h2(cont)
h3(conh)
h3(cont)
h3(conl)
h4(invh)
h5(invt)
h6(invl)
h7(covh)
h7(covt)
h7(covl)
h8(covt)
h8(covl)
h9(covl)
}
}
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