Notes from LEWG discussion.
https://wiki.edg.com/bin/view/Wg21telecons2021/P2432#Library-Evolution-2021-09-09

Due to the breaking changes proposed here LWG will process this prior to the completion of electronic polls

As mentioned, R0 was seen by LEWG on 2021-09-09 and forwarded as a DR to C++20

Polls

POLL: Forward P2432 to electronic polling for C++23 as a B2 item and apply it as a DR for C++20

__Attendance:__21

__# of Authors:__1

__Author Position:__SF

Outcome: Consensus in favor

Summary

The paper was approved as a C++23 B2 item (in terms of P0592, see Prioritization for more details), and a C++20 DR.

LWG reviewed and approved for C++20 DR and C++23 pending approval by LEWG polling.

https://wiki.edg.com/bin/view/Wg21telecons2021/P2432-20210924

poll: put P2432r1 into C++23 as a DR against C++20 assuming LEWG approval

2021 September Library Evolution Polls

P2451: 2021 September Library Evolution Poll Outcomes

Poll 3: Send P2432R0 (Fix istream_view) to Library Working Group for C++23, classified as an improvement of an existing feature (P0592R4 bucket 2 item), with the recommendation that implementations retroactively apply it to C++20.

Outcome: Weak consensus in favor.

Selected Comments

This is an annoying and preventable inconsistency, and we should use the chance to fix this while we still can.

— Strongly Favor

It's unfortunate to do that post-fact, and it should have been fixed years ago, but better have some (controlled) pain now as opposed to ongoing pain over the next decade or so.

— Strongly Favor

I really strongly encourage consistency. This problem will not impact large amount of users, and by the same reasoning, change that late is not breaking a lot of code.

— Weakly Favor

I'm all for fixing C++20 now, before it gets used by lots an lots of people. Adoption is always slow, we can continue to fix things.

— Weakly Favor

SF for adding views::istream. WA on changing istream_view (once we have views::istream, nobody should be using istream_view; it seems unnecessarily breaking all things considered). WF overall.

— Weakly Favor

Consistency by itself is a poor reason to change something in C++20, but given that there are numerous other retroactive changes being made, this change is a reasonable candidate for that set.

— Neutral

Consistency in the standard library would be nice, but [my users] don't care about binary compatibility and will use whatever API is available at the time we need the feature.

— Neutral

These are not things that need to be applied as a DR. We add functions to classes regularly. We add concepts. We even subtly change the results of things like "begin".

In addition, this proposal needs more bake time, particularly since it has substantial chance of breaking things.

— Weakly Against

Changed from Weakly Favor [at the telecon] to Strongly against here. I think the best option is for us to deprecate std::ranges::istream_view and add std::views::istream in its place.

— Strongly Against

P2432R1 Fix istream_view, Rev 1 (Nicolai Josuttis)

Adopted 2021-10.