My rough notes for this meeting are available on the WG21 wiki here. The P3681 GH issue has been updated with the SG16 poll results and tagged with the needs-revision label to request a revision with wording for the SG16 consensus for deprecation for use of user-defined types that model CharTraits with standard library classes that have a Traits template parameter. Once a new revision materializes with wording, we'll review again and then poll forwarding to LEWG.

Tom.

On 9/9/25 3:50 PM, Tom Honermann via SG16 wrote:

SG16 will hold a meeting tomorrow, Wednesday, September 10th, at 19:30 UTC (timezone conversion).

If you need a .ics file to import into your calendar, you can download it here.

The agenda is:

P3681R0 is Corentin's attempt to dissuade the continued appearance of std::char_traits in new standard library features and comes to us following discussions of P3655 (std::zstring_view). SG16 discussed P3655R0 during the 2025-04-23 SG16 meeting where we took the following poll.

Poll 1: P3655R0: No objection to use of std::char_traits for consistency and compatibility with std::string_view.

Corentin was not present for that meeting, so this paper does not represent a change of opinion from him, but rather a request to reconsider that poll and to perhaps establish a policy related to std::char_traits for future work. The paper explicitly addresses the possibility of custom char trait types and how such existing use with std::basic_string would impact convertibility to std::zstring_view.

P3672R0 is an opinion paper that discusses encoding expectations on different platforms, the consequences of command line arguments and file paths that are not well-formed text, the degree to which we should care about such content, and the impact such complexity can, and should, have on standard library features and interfaces. Thoughts on these issues has implications for P3474R0 (std::arguments); a paper we last discussed during the 2025-04-09 SG16 meeting and which is currently awaiting a new revision.

Tom.