Annotation element as '_' gives compiler error instead of a warning

Sample test case:
//Annotation with _ as one of the elements
@interface MyAnno {
    int _() default 0;
}
// Element Value pair
@MyAnno(_=2)
class test{}


Compilation output:
test.java:3: warning: '_' used as an identifier
    int _() default 0;
        ^
  (use of '_' as an identifier might not be supported in future releases)
test.java:6: warning: '_' used as an identifier
  @MyAnno(_=2)
          ^
  (use of '_' as an identifier might not be supported in future releases)
test.java:6: error: ')' expected
  @MyAnno(_=2)
           ^
test.java:6: error: class, interface, or enum expected
  @MyAnno(_=2)
            ^
test.java:6: error: class, interface, or enum expected
  @MyAnno(_=2)
             ^
3 errors
2 warnings

Errors in the above output are unexpected.

JLS rule in section 9.6 states the following:
AnnotationTypeElementDeclaration:
AbstractMethodModifiersopt Type Identifier ( ) DefaultValueopt ;