It's possible, but I'd hate to write a problem that talks to two
libraries, one of which uses std::map and the other std::map2.

On Mon, 2025-06-09 at 15:06 +0200, Sebastian Wittmeier via Std-
Proposals wrote:
>
> Another option to correct it without ABI incompatibilities is to
> offer a std2 or a std::map2.
>
>
> > -----Ursprüngliche Nachricht-----
> > Von: Ville Voutilainen via Std-Proposals <std-
> > proposals_at_[hidden]>
> > Gesendet: Mo 09.06.2025 15:04
> > Betreff: Re: [std-proposals] ABI breaks
> > An: Avi Kivity <avi_at_[hidden]>;
> > CC: Ville Voutilainen <ville.voutilainen_at_[hidden]>; std-
> > proposals_at_[hidden];
> > 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?
> >
> > You can get the first part without such problems if you bite the
> > bullet and make it a separate type.
> >
> > But that might not work, of course, because the committee might not
> > want it.
> >
> > You could try the second part, but that's then not portable because
> > some vendors might not want it, and chances are that none of them
> > want
> > it,
> > so it's portable in the sense that no practical implementation
> > provides it.
> >
> > I'm not dismissing the idea, I love it; if I had a time machine,
> > I'd
> > travel back in time and incorporate such a "cheap to
> > default-construct, so do that instead
> > of constructing nothing" into optional's design. But it's quite a
> > different exercise to try to adapt it in afterwards.
> > --
> > Std-Proposals mailing list
> > Std-Proposals_at_[hidden]
> > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
> >