On Mon, 2025-06-09 at 22:21 +0300, Avi Kivity wrote:
> On Mon, 2025-06-09 at 16:04 +0300, Ville Voutilainen wrote:
> > On Mon, 9 Jun 2025 at 14:17, Avi Kivity <avi_at_[hidden]> wrote:
> > > The Standard should not make decisions that cannot be
> > > implemented. But it also should not refrain from making decisions
> > > that cannot be implemented optimally on every platform, and
> > > instead leave it to the platform to make a choice.
> >
> > Well, that leads to this question: would you like it to be portably
> > reliable that destroying a
> > vector<optional<vector<optional<string>>>>
> > is fast, or would you like
> > it to be theoretically but not practically fast?
> >
>
>
> That's a good question.
>

Actually, there's no problem. Eliding the branch in std::optional's
destructor doesn't trigger all downstream destructors, just the next
one down the line. So instead of the branch in std::optional you'd see
the branch in std::vector (or rather, operator delete) but you're still
ahead in terms of branch predictor resource consumption.