On Thu, Sep 19, 2024 at 10:21:15AM -0400, Jason Merrill wrote:
> On 9/19/24 7:57 AM, Richard Biener wrote:
> > On Wed, Sep 18, 2024 at 6:22 PM Jason Merrill <ja...@redhat.com> wrote:
> > >
> > > Tested x86_64-pc-linux-gnu with 5.5.0 bootstrap compiler. Thoughts?
> >
> > I'm fine with this in general - do we have needs of bumping the requirement
> > for
> > GCC 15 though? IMO we should bump once we are requiring actual C++14
> > in some place.
>
> Jakub's dwarf2asm patch yesterday uses C++14 if available, and I remember
And libcpp too.
> seeing a couple of other patches that would have been simpler with C++14
> available.
It was just a few lines and if I removed the now never true
HAVE_DESIGNATED_INITIALIZERS cases, it wouldn't even add any new lines, just
change some to others. Both of those patches were just minor optimizations,
it is fine if they don't happen during stage1.
We also have some spots with
#if __cpp_inline_variables < 201606L
#else
#endif
conditionals but that doesn't mean we need to bump to C++17.
Sure, bumping the required C++ version means we can remove the corresponding
conditionals, and more importantly stop worrying about working around GCC
4.8.x/4.9 bugs (I think that is actually more important).
The price is stopping to use some of the cfarm machines for testing or
using IBM Advanced Toolchain or hand-built GCC 14 there as the system
compiler there.
At some point we certainly want to do that, the question is if the benefits
right now overweight the pain.
> > As of the version requirement as you say only some minor versions of the
> > GCC 5
> > series are OK I would suggest to say we recommend using GCC 6 or later
> > but GCC 5.5 should also work?
>
> Aren't we already specifying a minor revision with 4.8.3 for C++11?
>
> Another possibility would be to just say GCC 5, and adjust that upward if we
> run into problems.
I think for the oldest supported version we need some CFarm machines around
with that compiler so that all people can actually test issues with it.
Dunno which distros shipped GCC 5 in long term support versions if any and
at which minor those are.
Jakub
