[PATCH v2] libstdc++: add default template parameters to algorithms

[Jonathan Wakely]

On Fri, 13 Sept 2024 at 18:36, Patrick Palka <ppalka@redhat.com> wrote:
>
> On Fri, 13 Sep 2024, Patrick Palka wrote:
> >
> > Ah, we very recently implemented P2609R3 which has the following note
> > about projected_value_t: https://wg21.link/p2609r3#proposal
> >
> > Do we want to honor this note here and define projected_value_t as
> > remove_cvref_t<__indirect_value_t<_Iter>> then?  It seems the working
> > draft doesn't define it that way despite having merged both these
> > papers.
>
> Oops, that seems wrong, it seems the correct definition in terms
> of indirect_value_t should be
>
>   remove_cvref_t<indirect_value_t<projected<I, Proj>>>
>
> as mentioned in P2248R8/5.9.1.

That predates the note in p2609r3, because P2248R8 refers to P2609R0.
In P2609R3 indirect_value_t became the exposition-only
indirect-value-t which is our __detail::indirect_value_t.

I think the working draft should be changed as those two papers
suggest, but I'm not sure if there's any advantage to us making that
change proactively.