I think we can do the same without the symbol alias feature. It's even 
simpler cause do not require any maintenance when version symbol bump.

Here is what I'm testing, at least exported symbol is fine.

François


On 08/10/2023 16:06, Iain Sandoe wrote:
> Hi François,
>
>> On 21 Sep 2023, at 05:41, François Dumont <frs.dumont@gmail.com> wrote:
>>
>> Tests were successful, ok to commit ?
>>
>> On 20/09/2023 19:51, François Dumont wrote:
>>> libstdc++: [_GLIBCXX_INLINE_VERSION] Add handle_contract_violation symbol alias
>>>
>>> libstdc++-v3/ChangeLog:
>>>
>>>      * src/experimental/contract.cc
>>>      [_GLIBCXX_INLINE_VERSION](handle_contract_violation): Provide symbol alias
>>>      without version namespace decoration for gcc.
> This does not work in the source on targets without support for symbol aliases (Darwin is one)
> “../experimental/contract.cc:79:8: warning: alias definitions not supported in Mach-O; ignored”
>
> - there might be a way to do it at link-time (for one symbol not too bad); I will have to poke at
>    it a bit.
> Iain
>
>>> Here is what I'm testing eventually, ok to commit if successful ?
>>>
>>> François
>>>
>>> On 20/09/2023 11:32, Jonathan Wakely wrote:
>>>> On Wed, 20 Sept 2023 at 05:51, François Dumont via Libstdc++
>>>> <libstdc++@gcc.gnu.org> wrote:
>>>>> libstdc++: Remove std::constract_violation from versioned namespace
>>>> Spelling mistake in contract_violation, and it's not
>>>> std::contract_violation, it's std::experimental::contract_violation
>>>>
>>>>> GCC expects this type to be in std namespace directly.
>>>> Again, it's in std::experimental not in std directly.
>>>>
>>>> Will this change cause problems when including another experimental
>>>> header, which does put experimental below std::__8?
>>>>
>>>> I think std::__8::experimental and std::experimental will become ambiguous.
>>>>
>>>> Maybe we do want to remove the inline __8 namespace from all
>>>> experimental headers. That needs a bit more thought though.
>>>>
>>>>> libstdc++-v3/ChangeLog:
>>>>>
>>>>>        * include/experimental/contract:
>>>>>        Remove _GLIBCXX_BEGIN_NAMESPACE_VERSION/_GLIBCXX_END_NAMESPACE_VERSION.
>>>> This line is too long for the changelog.
>>>>
>>>>> It does fix 29 g++.dg/contracts in gcc testsuite.
>>>>>
>>>>> Ok to commit ?
>>>>>
>>>>> François