------- Comment #5 from dodji at gcc dot gnu dot org 2010-02-26 12:58 ------- Created an attachment (id=19968) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19968&action=view) Candidate patch
Here is what I think is happening, at least on gcc 4.5. A/ The deleting dtor's DIE *is* being generated but: 1/ not as a member of struct A's DIE 2/ no DW_AT_vtable_elem_location was being generated for it. But there is (and I believe, rightfully so) a DW_AT_abstract_origin attribute pointing back to the abstract dtor that is part of the struct A's DIE members. B/ The complete destructor was not being generated. That was because the complete dtor is not only a clone of the abstract destructor, but also an *alias* (i.e it shares the same body) of the base dtor (the not-in charge one). Note that the base dtor is not part of the vtable, but the complete dtor is. So the complete dtor is an alias. But for a reason, cgraph forgets to emit debug info for aliases. It emits debug info only for the *target* of an alias. Independently of this, and after chatting with Tom Tromey and Jason Merrill, it looks like we ought to generate debug info for all variants of destructors, even if only the abstract dtor is part of the members DIEs of the struct. The most natural way of doing this would be to stay compatible with what's done already and fix issues A.1/ and B/ described above. The debugger would be able to tell that a given function is a destructor variant if it has a DW_AT_abstract_origin pointing back to the abstract destructor of the type. Now a problem remains which is how to let the debugger know that a given destructor is either a base, complete or deleting one. It looks like a new attribute (GNU extension) would address that issue. The attached patch fixes A.1/ and B/ but doesn't add the new attribute yet. I wanted to have your input before. I am cc-ing Jason too, as I notice he is not in the CC list. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37237
