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.

Tom.

AlisdairM

On Jul 7, 2020, at 16:33, Tom Honermann via Core <core@lists.isocpp.org> 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 at https://rawgit.com/sg16-unicode/sg16/master/papers/d2029r2.html. This addresses the feedback provided on the core mailing list in the thread starting at https://lists.isocpp.org/core/2020/06/9455.php.

Wording review feedback prior to the next Core issues processing teleconference would be much appreciated!

Tom.

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