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Re: [SG16] Revised and repaired P1949R2 - C++ Identifier Syntax using Unicode Standard Annex 31

From: Steve Downey <sdowney_at_[hidden]>
Date: Mon, 24 Feb 2020 13:23:31 -0500
Excellent. I'll make sure the requested changes and discussion are
reflected in the body of the paper in an update in the pre-Varna mailing.
The post-Prague mailing will have the cleaned up paper, with no
substantive changes. I'm planning on being in Varna, and in NY in the fall.

On Mon, Feb 24, 2020 at 12:50 PM JF Bastien via SG16 <sg16_at_[hidden]>
wrote:

>
>
> On Mon, Feb 24, 2020 at 8:08 AM Hubert Tong via SG16 <
> sg16_at_[hidden]> wrote:
>
>> - Was EWG informed that the proposal can be understood as introducing new
>>> core language undefined behaviour for existing programs with identifiers in
>>> NFC form where the concatenation is not in NFC form ([cpp.concat])? I note
>>> that R1 of the paper was not clear on that point and R2 does not identify
>>> it as a consideration.
>>>
>>> I don't recall discussing this in EWG, but I believe it was discussed at
>>> some point and the conclusion was that an identifier not in NFC form
>>> resulting from such concatenation was ill-formed. Can you elaborate as to
>>> how the UB manifests?
>>>
>> The typical manifestation of the UB in cpp.concat that does not produce a
>> diagnostic for the case in question is that the concatenation may instead
>> leave the operand tokens behind. That is, the ill-formed result is not
>> required to manifest.
>>
>
> Per our new process with SG12, we need to document and add rationale to
> any new UB. Let's make sure that's in the proposal.
>
>
> Given the amount of (small but important) feedback so far, I'm not going
> to forward the paper directly to Core under our "tentative ready" process.
> We'll re-discuss in EWG, so please make sure all changes and discussions
> since last meeting are documented in the paper.
> --
> SG16 mailing list
> SG16_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/sg16
>

Received on 2020-02-24 12:26:24