This is needed for version-3 tz-format files; it supports time
stamps past 2037 for America/Godthab (the only entry in the tz
database for which this change is relevant).
* manual/time.texi (TZ Variable): Document transition times
from -167:59:59 through -00:00:01.
* time/tzset.c (tz_rule): Time of day is now signed.
(__tzset_parse_tz): Parse negative time of day.
Resolves#14888.
This only really manifests itself when there are no spaces between
format specifiers, which is not allowed by POSIX, but is allowed by
the glibc implementation.
Fixes#15346.
The POSIX description of getdate allows for extra spaces in the
getdate input string. __getdate_r uses strptime internally, which
works fine with extra spaces between format strings (and hence within
an input string) but not with leading and trailing spaces. So we trim
off the leading and trailing spaces before we pass it on to strptime.
* time/mktime.c (isdst_differ): New static function.
(__mktime_internal): No need to normalize tm_isdst now.
(__mktime_internal, not_equal_tm): Use isdst_differ to compare
tm_isdst values.
* time/mktime.c (TYPE_ONES_COMPLEMENT, TYPE_SIGNED_MAGNITUDE): Remove.
The code didn't really work on such machines anyway.
(TYPE_MINIMUM): Assume two's complement.
(twos_complement_arithmetic): Verify that long_int and time_t
are two's complement (or unsigned, in the latter case).
* time/mktime.c (verify): Move decl up.
(long_int): New type.
(leapyear, ydhms_diff, guess_time_tm, __mktime_internal): Use it,
to remove assumption in the code that 'long' is wide enough to
store year values. This assumption is not true on x32 and on
some non-glibc platforms.
* time/mktime.c (WRAPV): New macro.
(time_t_avg, time_t_add_ok, time_t_int_add_ok): New static functions.
(guess_time_tm, __mktime_internal): Do not assume that signed
integer overflow wraps around; modern compilers generate code
where this assumption is no longer valid.
