FULL PRODUCT VERSION :
6.0_06, 1.6.0_10-beta-b14 and 1.7.0-ea-b25


A DESCRIPTION OF THE PROBLEM :
Code fails to compile when casting from a generic class with unbounded wildcard to a subclass.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
class A<X extends Comparable<X>> {}

class B extends A<String> {}

public class Teste {
    public static void main(String[] args) {
        B x = new B();
        A<?> y = x;
        B z = (B) y;
    }
}

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
It should compile (and run) nicely.
ACTUAL -
Code fails to compile.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
class A<X extends Comparable<X>> {}

class B extends A<String> {}

public class Teste {
    public static void main(String[] args) {
        B x = new B();
        A<?> y = x;
        B z = B.class.cast(y); // <-- Workaround here. Using the cast method.
    }
}