GCC selftest improvements

[Nicholas Krause]

On 11/23/19 11:33 AM, Jeff Law wrote:
> 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
CCing myself to the conversation as the original idea contributor
for adding support for C++11.

Thanks,
Nick
>