On Mon, 16 Aug 2021 at 20:26, Jonathan Wakely via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> On Fri, 13 Aug 2021 at 18:10, François Dumont via Libstdc++
> <libstdc++@gcc.gnu.org> wrote:
> >
> > I just come back to this email and it sounds like the right moment to
> > commit it.
>
> Ah yes, thanks for the reminder!
>
> I'll push it tomorrow.
>
> >
> > On 27/02/20 2:06 pm, Jonathan Wakely wrote:
> > > These should wait for stage 1 but I'm posting them now for comment.
> > >
> > > With the change to __gnu_debug::__valid_range we now get a debug
> > > assertion for:
> > >
> > >   std::string s;
> > >   std::min_element(std::string::iterator{}, s.end());
> > >
> > > where previously it would just crash with undefined behaviour.

Actually, that change doesn't work. Some of our container iterators
use a value-initialized iterator as the past-the-end value, so the
check in the new __valid_range_aux function incorrectly rejects some
valid ranges. Maybe I can make it work for bidirectional iterators,
which must be attached to a container to be valid.

For now I've only pushed the second half of the patch, optimizing the
std::min/max/minmax overloads taking an initializer_list (as
attached).

Tested powerpc64le-linux, pushed to trunk.