https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114645
--- Comment #16 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Harald van Dijk from comment #14) > (In reply to Jonathan Wakely from comment #8) > > None of libstdc++, LLVM libc++, MSVC STL or the > > date/tz.h reference implementation uses $TZ for chrono::current_zone, > > This does not appear to be accurate. > > libc++ appears to always uses $TZ on POSIX-like platforms if it is set: > https://github.com/llvm/llvm-project/blob/ > 788be0d9fc6aeca548c90bac5ebe6990dd3c66ec/libcxx/src/tzdb.cpp#L708 ... incorrectly though? I would expect TZ=:Europe/London to work according to POSIX, but it seems they don't remove the ':' before the lookup. So it only works for a string like "MST7MDT" which means only the following entries in the IANA database can be matched by a value in $TZ: Z CET 1 c CE%sT Z CST6CDT -6 u C%sT Z EET 2 E EE%sT Z EST -5 - EST Z EST5EDT -5 u E%sT Z Factory 0 - -00 Z HST -10 - HST Z MET 1 c ME%sT Z MST -7 - MST Z MST7MDT -7 u M%sT Z PST8PDT -8 u P%sT Z WET 0 E WE%sT That doesn't seem very well thought out or tested.
