FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Server VM (build 1.6.0-b105, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux XXX 2.6.17-10-generic #2 SMP Fri Oct 13 18:45:35 UTC 2006 i686 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
The code snippet given below does not compile

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the given code

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
It should compile
ACTUAL -
It does not

ERROR MESSAGES/STACK TRACES THAT OCCUR :
X.java:5: inconvertible types
found   : java.lang.Enum<capture#262 of ?>
required: E
      if (o instanceof E) {
          ^
1 error


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
enum E { }

class X {
    void f(Enum<?> o) {
      if (o instanceof E) {
        return;
      }
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
use E.class.isInstance(o)