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Subject: Re: [isocpp-core] Updated draft revision: D2029R2 (Proposed resolution for core issues 411, 1656, and 2333; numeric and universal character escapes in character and string literals)
From: Tom Honermann (tom_at_[hidden])
Date: 2020-07-13 23:02:51


On 7/8/20 1:54 PM, Tom Honermann wrote:
> On 7/8/20 6:43 AM, Alisdair Meredith wrote:
>> Minor nit: I dislike normatively stating that a null character is
>> appended after string concatenation in two places. I do like
>> the addition of this directly to the phase 6 wording, so suggest
>> that the original in [lex.string]p12 with its extra flowery language
>> be demoted to a note.
> That seems reasonable to me, I'll do so.

After looking at this again, I elected to go in a different direction.

[lex.phases] describes at a high level what is to be done in each phase
and more-or-less defers to other sections for elaboration. From this
lens, changing the normative text in [lex.string] into a note felt like
the wrong direction.  Instead, I chose to update the wording in
[lex.string] to read a little nicer and to omit the flowery language.  I
then updated [lex.phases] to be less precise and to explicitly direct
the reader to [lex.string] for details. I hope this acceptably satisfies
the (very reasonable) concern about the previous normative duplication.

This paper has now been submitted for the upcoming mailing and can be
found at https://isocpp.org/files/papers/P2029R2.html. The previous
links to the draft will no longer work.

Tom.

>> In the normative text, AFAICT, in C++20 wide multi character
>> literals must be supported, with an implementation-defined value,
>> but after this paper they will be conditionally supported. I don’t
>> see that design change addressed in the front matter. Same
>> applies to non-encodable wide characters .
>
> That is addressed in the "Proposed resolution overview" section.  I
> can add a statement about this to the introduction if you like.
>
> I've been under the impression that the lack of
> conditionally-supported for these is an oversight.  My understanding
> (and someone please correct me if I'm mistaken; I don't recall where I
> was informed of this) is that, in the C standard,
> implementation-defined includes an allowance for rejecting the code as
> ill-formed, but in the C++ standard, implementation-defined implies
> well-formed; hence the addition of conditionally-supported.  If that
> understanding is correct, then the updated wording corrects alignment
> with the intent of the C standard.
>
>> (I thought this also applied to ordinary multi character literals,
>> but it turns out they are already conditionally supported.)
>
> Yup, in [lex.ccon]p1 <http://eel.is/c++draft/lex.ccon#1.sentence-4>.
>
> Tom.
>
>> AlisdairM
>>
>>> On Jul 7, 2020, at 16:33, Tom Honermann via Core<core_at_[hidden]> wrote:
>>>
>>> An update of D2029R2 (Proposed resolution for core issues 411, 1656, and 2333; numeric and universal character escapes in character and string literals) is now available athttps://rawgit.com/sg16-unicode/sg16/master/papers/d2029r2.html. This addresses the feedback provided on the core mailing list in the thread starting athttps://lists.isocpp.org/core/2020/06/9455.php.
>>>
>>> Wording review feedback prior to the next Core issues processing teleconference would be much appreciated!
>>>
>>> Tom.
>>>
>>> _______________________________________________
>>> Core mailing list
>>> Core_at_[hidden]
>>> Subscription:https://lists.isocpp.org/mailman/listinfo.cgi/core
>>> Link to this post:http://lists.isocpp.org/core/2020/07/9545.php
>
>



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