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Re: GCC selftest improvements
- From: Jeff Law <law at redhat dot com>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>, Jakub Jelinek <jakub at redhat dot com>
- Cc: Andrew Dean <Andrew dot Dean at microsoft dot com>, Richard Biener <richard dot guenther at gmail dot com>, Gabriel Dos Reis <gdr at microsoft dot com>, David Malcolm <dmalcolm at redhat dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, "ro at CeBiTec dot Uni-Bielefeld dot DE" <ro at cebitec dot uni-bielefeld dot de>, "mikestump at comcast dot net" <mikestump at comcast dot net>, "jason at redhat dot com" <jason at redhat dot com>, Jonathan Wakely <cxx at kayari dot org>
- Date: Sat, 23 Nov 2019 09:33:12 -0700
- Subject: Re: GCC selftest improvements
- References: <BN3PR00MB0116141705F4EA4B22045A19EA650@BN3PR00MB0116.namprd00.prod.outlook.com> <BL0PR2101MB10099E3DB7EB62603AFE4F21B0640@BL0PR2101MB1009.namprd21.prod.outlook.com> <acbd13b7-8869-3b52-1590-27ec4dc894cb@redhat.com> <20191028202713.GF28442@gate.crashing.org> <00dcb1c4-793c-c44f-da1b-eabe067c7e1e@redhat.com> <20191028221203.GG28442@gate.crashing.org> <CAFiYyc1ebisLwK18VxLrTa3MMTm1H1yifOLJ-cdFg7b-Ed+LRQ@mail.gmail.com> <SN2PR00MB0127006BC6445225EBC29646EA490@SN2PR00MB0127.namprd00.prod.outlook.com> <20191122220143.GH9491@gate.crashing.org> <20191122223618.GF2466@tucnak> <20191122234144.GJ9491@gate.crashing.org>
On 11/22/19 4:41 PM, Segher Boessenkool wrote:
> On Fri, Nov 22, 2019 at 11:36:18PM +0100, Jakub Jelinek wrote:
>> On Fri, Nov 22, 2019 at 04:01:43PM -0600, Segher Boessenkool wrote:
>>> On Fri, Nov 22, 2019 at 09:02:05PM +0000, Andrew Dean wrote:
>>>>>> Many systems do not have a system compiler newer than this *four years
>>>>>> old* one. GCC 4.8 is the first GCC version that supports all of
>>>>>> C++11, which is the only reason it would be even near acceptable to
>>>>>> require something this *new*.
>>>>>
>>>>> Agreed. Note we're even shipping new service packs for SLE12 which has that
>>>>> "ancient" compiler version (OTOH there _is_ a fully supported GCC 9 available
>>>>> for SLE12 as well).
>>>>>
>>>>> So, if we want C++11 then fine. But requiring GCC 9+ isn't going to fly. IIRC
>>>>> GCC 6 is first having -std=c++14 by default, but unless there's a compelling
>>>>> reason to use C++14 in GCC I'd rather not do it at this point.
>>>>>
>>>>> Removing all the workarounds in the tree we have for GCC 4.[12].x would of
>>>>> course be nice.
>>>>>
>>>>> But I have to update the testers that still use GCC 4.1.x as host compiler :P
>>>
>>>> Richard/Segher: Are we in agreement that we can move forward with updating to c++11 as the minimum version? I have made the simple change locally to modify the flag and verified that I got the exact same test results with/without the change. I can look into the work to add a configuration warning if the compiler doesn't support c++11, but wanted to make sure we are on the same page before doing so.
>>>
>>> If GCC 4.8.5 works as bootstrap compiler, it is fine with me, and good
>>> progress too. (Which means 4.8.5 has to work for at least all primary
>>> targets.)
>>
>> What would be the advantage of bumping the requirement now as opposed to at
>> the start of next stage 1 though? We should be fixing bugs now, not
>> introduce new features nor do code refactoring.
>
> Oh, I meant for GCC 11, of course. I thought we all agreed on that.
Yea, I don't see that stepping forward for gcc-10 really brings us
anything. We're past stage1 and thus Andrew's work would naturally
target gcc-11.
So the advice I'd give Andrew is go ahead with using C++11 as needed.
However, also try to be sensible in terms of what features you use :-)
jeff