[aspectj-dev] Declare parents extends quirk ? Comments?

[Andrew Clement <CLEMAS@xxxxxxxxxx>]

Here is a simple set of types I have
in a source file:

=========================
class X { }

class SubX extends X { }

aspect A {
 declare parents: X+ extends java.util.Observable;
}
=========================

(Note the inclusion of the + on the
type pattern).

if I compile it, it succeeds and X now
extends Observable (SubX does not because X does)

Now, if I switch it to this (order of
types switched):

=========================
class SubX extends X { }

class X { }

aspect A {
 declare parents: X+ extends java.util.Observable;
}
=========================

And compile it, I get:

============
C:\ajbugs\p\A.java:6 error can only
insert a class into hierarchy, but java.util.Observable is not a  subtype
of X
declare parents: X+ extends java.util.Observable;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1 error
============

It is because this time the compiler
encountered 'SubX' first, which matched 'X+' - it then barfed because we
could not insert Observable into the hierarchy, as Observable does not
extend X.  

This made me think that specifying a
'+' on the type pattern in the case of 'extends <class>' should be
regarded as an error ?  Is there any case when it would actually make
sense?

Andy.