Consider the following code:
---
enum Test {
    enum Inner { }
}
---

Compiling this produces the following errors:
---
E.java:2: error: as of release 5, 'enum' is a keyword, and may not be used as an identifier
    enum Inner { }
    ^
  (use -source 1.4 or lower to use 'enum' as an identifier)
E.java:2: error: ',', '}', or ';' expected
    enum Inner { }
         ^
E.java:2: error: '}' expected
    enum Inner { }
              ^
3 errors
---

It would be nice if the parser could handle situations like this better.