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Subject: Re: SG16 meeting summary for March 24th, 2021
From: Corentin Jabot (corentinjabot_at_[hidden])
Date: 2021-03-28 14:06:46


On Sun, Mar 28, 2021 at 8:56 PM Alisdair Meredith via SG16 <
sg16_at_[hidden]> wrote:

> This paper touches, incidentally, wording that is of concern to SG12
> regarding UB.
> To ease communication/concerns, it might be worth pointing out the that UB
> wording
> added to [lex.concat] is not new UB, but merely moving where we document
> the
> existing UB in [lex.phases]p4.
>
> As part of this cleanup, is the UB in [lex.phases]p2 still possible, or
> does the raw
> remaining string reversion no longer have the ability to accidentally form
> a UCN as
> all we are reverting is line-splicing, which implies there must be a
> new-line character
> emdedded in any reversion, which would not enable forming a UCN?
>

There is still UB. While we don't replace unicode by UCNs in phase 1
anymore, there still may be UCNs spelled in the source.

Removing the UB in lexing is on my radar.
I think there is consensus that the UB should not be there - and that its
purpose (dealing with the observability of different models chosen by C and
C++) is no longer relevant,
although ideally we would have the same behavior in C and we can confer to
SG22.

>
> AlisdairM
>
> On Mar 28, 2021, at 2:15 PM, Tom Honermann via SG16 <sg16_at_[hidden]>
> wrote:
>
> The summary for the SG16 meeting held March 24th, 2021 is now available.
> For those that attended, please review and suggest corrections:
>
> - https://github.com/sg16-unicode/sg16-meetings#march-24th-2021
>
> A decision was made to forward Jens' D2314R2: Character sets and encodings
> <https://wiki.edg.com/pub/Wg21telecons2021/SG16/d2314r2.html> to EWG at
> this meeting. Per SG16 operating procedures
> <https://github.com/sg16-unicode/sg16/blob/master/OperatingProcedures.md>,
> this decision has tentative consensus as of now and will become the SG16
> consensus one week from now pending new dissenting perspectives or other
> new information. Given that the decision was unanimous (though there were
> abstentions), EWG has already been informed and has tentatively scheduled
> this paper for discussion on May 6th.
>
> *Poll: Forward D2314R2 as presented on 2021-03-24 to EWG for inclusion in
> C++23.*
>
> -
>
> Attendance: 9
> SF F N A SA
> 3 5 0 0 0
> -
>
> Consensus is in favor.
>
> Tom.
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>
>
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