1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
import annotation.unchecked
class Test {
trait Two[A, B]
type One[A] = Two[A,A]
class View extends One[Any]
def checkAny(x: Some[One[Any]]) = x match { // okay
case Some(_: View) => true
case _ => false
}
def checkAbstract[A](x: Some[One[A]]) = x match { // okay
case Some(_: View) => true
case _ => false
}
def checkExistential(x: Some[One[_]]) = x match {
case Some(_: View) => true // compiler crash
case _ => false
}
}
object Test {
def main(args: Array[String]): Unit = {
val t1 = new Test
val t2 = new Test
assert(t1.checkAny(Some(new t1.View)))
assert(t1.checkAbstract(Some(new t1.View)))
assert(t1.checkExistential(Some(new t1.View)))
}
}
|
