[Bug sanitizer/64717] -fsanitize=vptr leads to warning:=?UTF-8?Q?=20=E2=80=98?=<anonymous>=?UTF-8?Q?=E2=80=99=20may=20be=20used=20uninitialized=20in=20this=20function=20?=[-Wmaybe-uninitialized]

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64717

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-01-29
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 34619
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34619&action=edit
gcc5-pr64717.patch

Untested fix.  The SAVE_EXPR in there was needed in earlier versions of =vptr
support, where it emitted the __ubsan_* calls early, but right now it is used
just once, and the SAVE_EXPR causes problems when the same dtor call is used
shared in multiple locations (finally and cleanup).  There is still a possible
SAVE_EXPR if the address of the object has side-effects, but I hope dtors are
never called that way if they'd could appear in cleanups.