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Build ID: I20070209-1006 Steps To Reproduce: 1. compile the following code public class EclipseBug1 { public static <E extends Enum<E>> void f() { } public static void main(String[] args) { f(); } } More information: The error message is weird: "Bound mismatch: The generic method f() of type EclipseBug1 is not applicable for the arguments (). The inferred type Enum<Enum<E>> is not a valid substitute for the bounded parameter <E extends Enum<E>>" The inferred type can't be Enum<Enum<E>> because we don't provide any E. Futhermore javac infers java.lang.Object and i think it is closer to that the JLS says. Rémi
javac (1.5, 6, 7) says: EclipseBug1.java:6: incompatible types; inferred type argument(s) java.lang.Object do not conform to bounds of type variable(s) E found : <E>void required: void f(); ^ 1 error While I agree that the bound we publish looks quite mysterious, I believe that the second part of our message is better (since it gives more information about the type parameter expected by f). Except if we can find cases where greater damages are caused by the said odd bound (aka if we find instances in which the error message is outrightly misleading, or even the code fails whereas it should not or the other way round) or Philippe says otherwise, I would suggest a WONTFIX here. Philippe, what do you think?
(In reply to comment #1) > javac (1.5, 6, 7) says: > EclipseBug1.java:6: incompatible types; inferred type argument(s) > java.lang.Object do not conform to bounds of type variable(s) E > found : <E>void > required: void > f(); > ^ > 1 error > > While I agree that the bound we publish looks quite mysterious, I believe that > the second part of our message is better (since it gives more information about > the type parameter expected by f). i agree that your message is more explicit but your bound is not correct. perhaps the problem is not the error message but how the argument type is processed. thus i believe the second part of the message should be : "The inferred type Object is not a valid substitute for the bounded parameter <E extends Enum<E>>" > > Except if we can find cases where greater damages are caused by the said odd > bound (aka if we find instances in which the error message is outrightly > misleading, or even the code fails whereas it should not or the other way > round) the way an implicit argument of a parameter type is infered is specified by the JLS, and in that example the inference fails so the infered type should be Object and not Enum<Enum<E>>. > or Philippe says otherwise, I would suggest a WONTFIX here. > > Philippe, what do you think? >
I believe that the issue comes from ParameterizedGenericMethodBinding (round line 421), that fails to recognize self-referencing types early enough. Moving to Philippe for comments.
Will look, indeed it feels that the message is not appropriate; though the code is correctly rejected.
Also see bug 121369. I do not think it should reflect Object in the end, according to JLS15.12.2.8. It would yield Enum<E> for E, which still contains reference to unbound E. This is part of a larger problem, will wait until spec is being clarified.
*** This bug has been marked as a duplicate of bug 121369 ***
Added GenericTypeTest#test1380
