daylight ¶POSIX specification:
https://pubs.opengroup.org/onlinepubs/9799919799/functions/daylight.html
Gnulib module: —
Portability problems fixed by Gnulib:
Portability problems not fixed by Gnulib:
TZ setting like TZ="America/Los_Angeles".
_daylight on some platforms:
mingw with -DNO_OLDNAMES, MSVC.
tzset.
This variable is vestigial: it is not needed and does not suffice in general.
It is planned to be removed from a future version of POSIX.
A more portable way of getting the UTC offset is to use
strftime with the %z format. See strftime.