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object Magic {
abstract class A[T1,T2]() {
trait C { type T; }
trait C1 extends C { type T = T1; }
trait C2 extends C { type T <: T2; }
type CX >: Null;
val c: CX with C2 = null;
def castA(x: c.T): T2 = x;
}
class B[T1,T2] extends A[T1,T2]() {
type CX = C1;
def castB(x: T1): T2 = castA(x);
}
def cast[T1,T2](v: T1): T2 =
new B[T1,T2]().castB(v)
}
object Test {
def main(args: Array[String]): Unit = {
Magic.cast[String,Exception]("xyz").printStackTrace();
}
}
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