On Sat, 6 Jan 2024, 19:03 Tom Honermann, <tom_at_[hidden]> wrote:

> On 1/5/24 11:26 AM, Jonathan Wakely via SG16 wrote:
>
> -
> - *Poll 4: [FR-010-133][FR-021-013]: SG16 recommends resolving
> these comments by restricting all references to the Unicode Standard to the
> version that corresponds to the referenced version of ISO/IEC 10646.*
> Attendees: 9 (1 abstention)
> SF
> F
> N
> A
> SA
> 2
> 3
> 0
> 3
> 0
> No consensus.
> A: It doesn't benefit the community to reference a Unicode version
> that is outdated by the time the standard is published.
>
>
Except that it provides a baseline of what's supported as valid syntax. The
set of valid code points that can be named by a universal character name in
C++23 is unclear. According to the standard, the day that a new unicode
standard is published, it should be possible to use any new code points in
a C++23 program. Even if one implementation supports that, it creates a
portability trap because other "C++23" implementations might not know those
character names yet. (But maybe I'm missing some context here, and the
relevant parts of the unicode standard that we depend on are stable between
versions? That doesn't seem to be true for UAX #29.)

Something like recommended practice to use "at least version 15.0.0" would
give users a baseline they can rely on, and caution them that relying on
anything newer might not be portable.

Another way to look at this is just to say that there is no real
portability or strict conformance in practice, and you can only ever rely
on what your implementations happen to support. So this unstable normative
reference isn't a problem. But that seems more fitting for a living
standard like the HTML spec, rather than an ISO standard with fixed
editions.