LWG3565: Handling of encodings in localized formatting of chrono types is underspecified

[jwakely]

SG16 needs to clarify the intended design for https://cplusplus.github.io/LWG/issue3565

[tahonermann]

SG16 will do so at its 2021-06-23 telecon.

[tahonermann]

SG16 did not get to this at its 2021-06-23 telecon; it is now the first item on the agenda for our 2021-07-14 telecon.

[tahonermann]

SG16 did not get to this at its 2021-07-14 telecon (the agenda was changed to allow progress on other issues). This is now the first item on the agenda for our 2021-07-28 telecon (and it will remain there).

[cor3ntin]

This is resolved by #1093

[tahonermann]

For historical reference, SG16 discussed this issue during its July 28th, 2021 telecon. The following polls were taken.

Poll 1: Require implementations to make std::chrono substitutions with std::format as if transcoded to UTF-8 when the literal ecoding E associated with the format string is UTF-8, for an implementation-defined set of locales.

• Attendance: 9

• SF	F	N	A	SA
  1	6	2	0	0

• Consensus in favor.

Poll 2: Permit such substitutions when the encoding E is any Unicode encoding form.

• Attendance: 9

• SF	F	N	A	SA
  0	7	2	0	0

• Consensus in favor.

Poll 3: Prohibit such substitutions otherwise.

• Attendance: 9

• SF	F	N	A	SA
  1	3	3	1	1

• No consensus.
• SA: This is an over constraint; should permit implementations to do best effort work.

Removing the SG16 label. This issue is now tracked by P2419 (#1093).