On Sunday 21 July 2024 08:51:22 GMT-7 Hans via Std-Proposals wrote:
> I want to be able to mark some datastructures as guaranteed-stable, and
> for the rest of the datastructures to have no stability guarantee.

Good. Please explain why this needs to be anything beyond documentation in
your library.

> I hope that this will improve interface design in C++ in general (for
> all libraries), and over time also free the standard library from its
> current ABI concerns.

Please explain how that will improve the interface design in C++ in general
above and beyond what we already have. There must be a problem that prevents
its current design that makes interfaces currently designed sub-optimal and
your proposal thus makes easier to achieve and/or maintain.

As for freeing the Standard Library from its current ABI restrictions, have
you asked the vendors if they want this? There are only three major
implementations, so it should be easy to contact the maintainers for all three
and ask if this has been an impediment to their development. Moreover, you
should gauge the responses on whether their users would accept breakages: I
suspect the answer of all three will be "doesn't matter if the Standard
allows us to break, we can't do it and we will oppose any Standard change that
would require us to break".

As one such user, I vehemently oppose breaking the ABI of the current standard
libraries. And as maintainer of QtCore, my voice is not exactly your average
one.

> And for good measure: I do not want to break the ABI of existing
> standard library classes either.

Good.

But why is then your goal to allow the implementations to do that?

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Principal Engineer - Intel DCAI Platform & System Engineering