It doesn't have anything to do with the compiler warning messages -- the problem is much simpler than that. The implementation of Element.__copy__ is wrong for Expression objects; namely, it doesn't set the _gobj attribute. To fix it, we just add a proper implementation of copy:
def __copy__(self): return new_Expression_from_GEx(self._parent, self._gobj) --Mike -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org