Ville, FWIW, I think we're in agreement here (at least to some extent) --
see my reply to your previous email.

Louis

On Tue, Oct 14, 2025 at 5:10 PM Ville Voutilainen via SG21 <
sg21_at_[hidden]> wrote:

> On Wed, 15 Oct 2025 at 00:07, Tom Honermann <tom_at_[hidden]> wrote:
> >
> > On 10/14/25 4:49 PM, Ville Voutilainen via SG15 wrote:
> > > On Tue, 14 Oct 2025 at 23:39, Tom Honermann <tom_at_[hidden]> wrote:
> > >
> > >> I would be very unhappy if any implementation made observe the
> default.
> > >> But I find observe useful and see no reason to prohibit
> implementations
> > >> from offering it.
> > > Right. I do see such a reason, because the whole reason some of the
> > > hardened implementations
> > > were written to begin with is to guarantee that stdlib calls that
> > > violate the hardened preconditions
> > > aren't UB, ever.
> >
> > Sure, and implementors are free to not offer an observe semantic for
> > hardened preconditions. I don't see a problem.
>
> Right, and I do, because "are free not to offer an observe semantic"
> is not a guarantee,
> whereas existing practice is to offer a guarantee. I see it quite a
> problem that WG21 is suggesting
> to introduce UB where there was none before.
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