Re: [PATCH] [11/12/13/14 Regression] ABI break in _Hash_node_value_base since GCC 11 [PR 111050]

[Jonathan Wakely <jwakely@redhat.com>]

On Wed, 27 Sept 2023 at 05:44, François Dumont <frs.dumont@gmail.com> wrote:
>
> Still no chance to get feedback from TC ? Maybe I can commit the below
> then ?

I've heard back from Tim now. Please use "Tim Song
<t.canens.cpp@gmail.com>" as the author.

You can change the commit again using git commit --amend --author "Tim
Song <t.canens.cpp@gmail.com>"

OK for trunk with that change - thanks for waiting.


>
> AFAICS on gcc mailing list several gcc releases were done recently, too
> late.

There have been no releases this month, so the delay hasn't caused any problems.


>
>
> On 14/09/2023 06:46, François Dumont wrote:
> > Author: TC <rs2740@gmail.com>
> > Date:   Wed Sep 6 19:31:55 2023 +0200
> >
> >     libstdc++: Force _Hash_node_value_base methods inline to fix abi
> > (PR111050)
> >
> > https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=1b6f0476837205932613ddb2b3429a55c26c409d
> >
> >     changed _Hash_node_value_base to no longer derive from
> > _Hash_node_base, which means
> >     that its member functions expect _M_storage to be at a different
> > offset. So explosions
> >     result if an out-of-line definition is emitted for any of the
> > member functions (say,
> >     in a non-optimized build) and the resulting object file is then
> > linked with code built
> >     using older version of GCC/libstdc++.
> >
> >     libstdc++-v3/ChangeLog:
> >
> >             PR libstdc++/111050
> >             * include/bits/hashtable_policy.h
> >             (_Hash_node_value_base<>::_M_valptr(),
> > _Hash_node_value_base<>::_M_v())
> >             Add [[__gnu__::__always_inline__]].
> >
> > Ok to commit ?
> >
> > On 12/09/2023 18:09, Jonathan Wakely wrote:
> >> On Mon, 11 Sept 2023 at 18:19, François Dumont <frs.dumont@gmail.com>
> >> wrote:
> >>>
> >>> On 11/09/2023 13:51, Jonathan Wakely wrote:
> >>>> On Sun, 10 Sept 2023 at 14:57, François Dumont via Libstdc++
> >>>> <libstdc++@gcc.gnu.org> wrote:
> >>>>> Following confirmation of the fix by TC here is the patch where I'm
> >>>>> simply adding a 'constexpr' on _M_next().
> >>>>>
> >>>>> Please let me know this ChangeLog entry is correct. I would prefer
> >>>>> this
> >>>>> patch to be assigned to 'TC' with me as co-author but I don't know
> >>>>> how
> >>>>> to do such a thing. Unless I need to change my user git identity
> >>>>> to do so ?
> >>>> Sam already explained that, but please check with Tim how he wants to
> >>>> be credited, if at all. He doesn't have a copyright assignment, and
> >>>> hasn't added a DCO sign-off to the patch, but it's small enough to not
> >>>> need it as this is the first contribution credited to him.
> >>>>
> >>>>
> >>>>>        libstdc++: Add constexpr qualification to
> >>>>> _Hash_node::_M_next()
> >>>> What has this constexpr addition got to do with the ABI change and the
> >>>> always_inline attributes?
> >>>>
> >>>> It certainly doesn't seem like it should be the summary line of the
> >>>> git commit message.
> >>> Oops, sorry, that's what I had started to do before Tim submitted
> >>> anything.
> >>>
> >>> Here is latest version:
> >> No patch attached, and the ChangeLog below still mentions the constexpr.
> >>
> >> I've pinged Tim via another channel to ask him about the author
> >> attribution.
> >>
> >>
> >>> Author: TC <rs2740@gmail.com>
> >>> Date:   Wed Sep 6 19:31:55 2023 +0200
> >>>
> >>>       libstdc++: Force inline on _Hash_node_value_base methods to
> >>> fix abi
> >>> (PR111050)
> >>>
> >>> https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=1b6f0476837205932613ddb2b3429a55c26c409d
> >>>
> >>>       changed _Hash_node_value_base to no longer derive from
> >>> _Hash_node_base, which means
> >>>       that its member functions expect _M_storage to be at a different
> >>> offset. So explosions
> >>>       result if an out-of-line definition is emitted for any of the
> >>> member functions (say,
> >>>       in a non-optimized build) and the resulting object file is then
> >>> linked with code built
> >>>       using older version of GCC/libstdc++.
> >>>
> >>>       libstdc++-v3/ChangeLog:
> >>>
> >>>               PR libstdc++/111050
> >>>               * include/bits/hashtable_policy.h
> >>>               (_Hash_node_value_base<>::_M_valptr(),
> >>> _Hash_node_value_base<>::_M_v())
> >>>               Add [[__gnu__::__always_inline__]].
> >>>               (_Hash_node<>::_M_next()): Add constexpr.
> >>>
> >>>       Co-authored-by: François Dumont <fdumont@gcc.gnu.org>
> >>>
> >>> Ok for you TC (Tim ?) ?
> >>>
> >>>
>