P2758 R5 Emitting messages at compile time

[wg21bot]

P2758R0 Emitting messages at compile time (Barry Revzin)

[tahonermann]

Since this paper has character encoding considerations, I'm going to schedule it for SG16 review.

[michaelbprice]

Relevant to https://isocpp.org/files/papers/P2758R0.html#improving-static_assert, see the previously discussed paper (which I authored) https://open-std.org/JTC1/SC22/WG21/docs/papers/2015/n4433.html and the corresponding EWG notes on the wiki from the Lenexa meeting.

Of note, it already contains potential wording, but was never reviewed by a Core expert and likely needs updating since we've done lots of character encoding work since then.

[erichkeane]

This was discussed in EWG during the February 8, 2023 afternoon session in Issaquah. The following polls were taken:

EWG would like to encourage more work on P2741R0 (static_assert-with-constexpr-message), solicit feedback from SG16, and see it again with core expert reviewed wording.

SF	F	N	A	SA
8	8	0	1	0

Result: Consensus

EWG would like to encourage more work on P2758 in the direction of constexpr_print_str/constexpr_error_str.

SF	F	N	A	SA
11	6	1	0	0

Result: Consensus

EWG ALSO would like to encourage more work on this topic that can print multiple errors per constant evaluation, but still result in a failed TU.

SF	F	N	A	SA
5	10	3	1	0

Result: Consensus

EWG would like to encourage more work on P2758 in the direction of a constexpr std::format.

SF	F	N	A	SA
13	4	1	0	0

Result: Consensus

[cor3ntin]

@tahonermann we can remove the SG16 tag from thar, right? SG16 guidance was given in #1434

[tahonermann]

@cor3ntin, the guidance provided in #1434 is clearly applicable, but I would prefer to see an updated paper that removes the duplication with P2741 and that has wording that implements that guidance first so that SG16 can definitively approve forwarding a specific revision.

[cor3ntin]

@tahonermann you are right, but i think we lost a needs-revision on this paper then.
@jfbastien you might want to ask barry whether he actually wants to present in Varna.