Javac / Eclipse compiler discrepancy: who's correct?

Question

If you compile the following code using both javac and Eclipse 3.1, the results are different.
public class EclipseJavacDisagree
    public static <T> T method(Comparable<T> value)
        System.out.println("Method A");
        return null;
    public static <T extends Comparable<T>> T method(T value)
        System.out.println("Method B");
        return null;
    public static void main(String[] args)
        method("A Comparable String");
}The Eclipse output is "Method A" whilst javac's is "Method B".
Does anyone know which implementation is correct? I gather from JLS3 that both methods are applicable by subtyping, but I get lost in section 15.12.2.5 trying to figure out which of the two is most specific.
Thanks,
Alex.

Answer 1

I believe there is a typo in your post. Shouldn't the second definition be:
public static <T extends Comparable<T>> T method(T value)Should that even compile? I thought covariant return types were only for overloading. This is an example where the erased types method signatures are:
Object method(Comparable)
Comparable method(Comparable)
How does the compiler determine which one to use? Does it base it on what type the return value is cast to? What about the situation here where the return type is not used.
In any event, with Sun's compiler, I can't see how you can ever call the first method anyway. No matter whether you assigned the returned value in an Object or a String, it still calls version B. What does Eclispe do when the main method is:
    public static void main(String[] args)
        Object o = method("A Comparable String");
        String s = method("A Comparable String");
    }