[Bug lto/84044] Spurious -Wodr warning with -flto

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84044

--- Comment #7 from rguenther at suse dot de <rguenther at suse dot de> ---
On Fri, 26 Jan 2018, marxin at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84044
> 
> --- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
> (In reply to Richard Biener from comment #4)
> > (In reply to Martin Liška from comment #3)
> > > Fixed on trunk by Richi's r256685. Is it intentional Richi that the revision
> > > should fix such situations?
> > 
> > Not really.  It means that the following hunk removes too many TYPE_BINFOs
> > I guess?
> > 
> > @@ -5150,15 +5145,9 @@ free_lang_data_in_type (tree type)
> >         {
> >           free_lang_data_in_binfo (TYPE_BINFO (type));
> >           /* We need to preserve link to bases and virtual table for all
> > -            polymorphic types to make devirtualization machinery working.
> > -            Debug output cares only about bases, but output also
> > -            virtual table pointers so merging of -fdevirtualize and
> > -            -fno-devirtualize units is easier.  */
> > -         if ((!BINFO_VTABLE (TYPE_BINFO (type))
> > -              || !flag_devirtualize)
> > -             && ((!BINFO_N_BASE_BINFOS (TYPE_BINFO (type))
> > -                  && !BINFO_VTABLE (TYPE_BINFO (type)))
> > -                 || debug_info_level != DINFO_LEVEL_NONE))
> > +            polymorphic types to make devirtualization machinery working. 
> > */
> > +         if (!BINFO_VTABLE (TYPE_BINFO (type))
> > +             || !flag_devirtualize)
> >             TYPE_BINFO (type) = NULL;
> >         }
> >      }
> 
> Reverting this hunk makes the warning visible again.

Interesting.  This means that with -g it didn't warn before either?
Which means that maybe unconditionally

  && !BINFO_N_BASE_BINFOS (TYPE_BINFO (type))

was intented?  Honza?