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

["François Dumont" <frs.dumont@gmail.com>]

Still no chance to get feedback from TC ? Maybe I can commit the below 
then ?

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


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 ?) ?
>>>
>>>