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Re: GCC version bikeshedding
- From: pinskia at gmail dot com
- To: Marek Polacek <polacek at redhat dot com>
- Cc: Richard Biener <richard dot guenther at gmail dot com>, Jakub Jelinek <jakub at redhat dot com>, Eric Botcazou <ebotcazou at libertysurf dot fr>, Ian Lance Taylor <iant at google dot com>, GCC Development <gcc at gcc dot gnu dot org>, Jason Merrill <jason at redhat dot com>
- Date: Wed, 6 Aug 2014 02:16:25 -0700
- Subject: Re: GCC version bikeshedding
- Authentication-results: sourceware.org; auth=none
- References: <20140720165506 dot GT3003 at laptop dot redhat dot com> <201407291845 dot 14107 dot ebotcazou at libertysurf dot fr> <CAKOQZ8whj_m9yjYVdX_p24ocV25VRZwwmTf=VvGjEoxNeHbxSg at mail dot gmail dot com> <201408060925 dot 48414 dot ebotcazou at libertysurf dot fr> <20140806074223 dot GY7393 at tucnak dot redhat dot com> <CAFiYyc1+LTfbPF=nT3O4pA4ST6Z2X5FJ0ywMxL9bk3UsqwnV2w at mail dot gmail dot com> <20140806084803 dot GB7393 at tucnak dot redhat dot com> <CAFiYyc0+YgrRA-CheSFx5not6XadTWOa-mr_LWpX4sZ_gQMgdg at mail dot gmail dot com> <20140806091021 dot GL24292 at redhat dot com>
> On Aug 6, 2014, at 2:10 AM, Marek Polacek <polacek@redhat.com> wrote:
>
>> On Wed, Aug 06, 2014 at 11:04:14AM +0200, Richard Biener wrote:
>>> On Wed, Aug 6, 2014 at 10:48 AM, Jakub Jelinek <jakub@redhat.com> wrote:
>>> - libstdc++ ABI changes (it is a significant user visible change,
>>> if you rebuild everything, no extra effort is needed, but otherwise
>>> if you want some C++ code built with older compilers work together
>>> with code built with newer compilers, it might require source code
>>> changes (the abi_tag attribute additions where needed and warning
>>> suggest to put those at), at least that is my current understanding
>>> of the plans
>>
>> But that's only with -std=c++11? Which had no compatibility
>> guarantees before?
>>
>>> - likely libgfortran ABI changes (different array descriptors)
>>
>> Let's wait and see ...
>>
>> We'll find a good reason to bump the major with every release.
>> Like for 4.9 LTO defaults to slim-objects, or C++ rejecting even more
>> invalid code, or libstdc++ header re-orgs, or defaulting to dwarf4+
>> (or even support for it), or VTA, or ...
>>
>> Where do we set the barrier? GCC isn't a C++ (or Fortran) compiler
>> only.
>>
>> So if we change to 5.1 (please not .0) then let's switch the default
>> optimization level to -O2! _That's_ a user-visible change across
>> the board.
>
> I'm planning to move the default C standard from gnu90 to gnu11
> (Currently it's blocked on the -Wc90-c99-compat warning).
> That's a pretty big user-visible change as well, I suppose.
I don't think this is a good move due to extern inline and a lot of code is still k&r c and not even c90.
Thanks,
Andrew
>
> Marek