Sorry for the late reply, but I wasn't subscribed to this mailing list
and I wasn't aware there were proposed changes for fix the feature-test
macro conflicts introduced during the last plenary.
For libc++ combining the feature-test macros for these two papers isn't
P2508R1 "Expose std::basic-format-string<charT, Args...>"
P2419R2 "Clarify handling of encodings in localized formatting of chrono
P2508R1 is included in libc++15 which should ship this month. (The only
part I haven't implemented for that paper is the feature-test macro.)
I have started to work on the chrono formatters in libc++ but it will
take some time before it will be done. Especially since libc++ still
misses parts of C++20 chono: timezones, leapseconds, and some clocks.
So it will take some time before I have a look at P2419R2.
I propose to use two separate macros to resolve the conflicts between
these two papers:
P2508R1 __cpp_lib_format with the value 202207
P2419R2 __cpp_lib_format_chrono with the value 202207
Combining the two formatting ranges papers in __cpp_lib_format_ranges
sounds good to me.
But all the chrono formatting is already included in __cpp_lib_format (by way of P1361). If libc++ doesn't support that yet, you can't bump that macro anyway?