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// scalac fails for test2/3
// dotc fails for all three
object test1 {
class Tree[-T >: Null]
def f(x: Any): Tree[Null] = x match {
case y: Tree[_] => y
}
}
object test2 {
class Tree[T >: Null]
def f(x: Any): Tree[Null] = x match {
case y: Tree[_] => y
}
}
object test3 {
class Tree[+T >: Null]
def f(x: Any): Tree[Null] = x match {
case y: Tree[_] => y
}
}
// Example contributed by Jason. I believe this should not typecheck,
// even though scalac does typecheck it.
object test4 {
class Base {
type N
class Tree[-S, -T >: Option[S]]
def g(x: Any): Tree[_, _ <: Option[N]] = x match {
case y: Tree[_, _] => y
}
}
}
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