Test: tzdata, tzdata-right, tzdata-posix 2024a-2 (TEST)

[Cygwin tzcode/tzdata Maintainer]

The following test packages have been uploaded to the Cygwin distribution:

* tzdata	2024a-2
* tzdata-right	2024a-2
* tzdata-posix	2024a-2

This Cygwin test release splits out the likely rarely used "right"
and "posix" subtrees from mandatory base /usr/share/zoneinfo into their
own optional packages tzdata-right and tzdata-posix.

Tests checking for missing or invalid representative zones in all parts
of the base, posix, and right subtrees has been added as part of the
package definition script.

Please test this base package and report any issues, and let us know if
you need to install and use the zones in the "right" or "posix" subtrees
in the optional tzdata-right and tzdata-posix packages, and whether this
change causes any issues for you.

If there are no reports of issues, all future tzdata updates will be
split into three packages, and only the base tzdata package installed by
default on all systems.

The space occupied by installed files, and downloaded from mirrors, is
shown below for each package, plus the current package with all zones.

install	  tar	tzdata
 721KB	172KB	base
 984KB	 78KB	right
 669KB	 74KB	posix
1367KB	444KB	source
3667KB	452KB	current


The Time Zone Database (often called tz, tzdb, or zoneinfo) contains
data that represents the history of local time for many locations around
the world, and supports conversion of UTC time to local time at those
locations to allow display of those local times. It is updated
periodically to reflect changes made by political bodies to summer
daylight saving time rules, UTC offsets, and time zone boundaries.

Three data packages are available: base 'tzdata' is always installed;
optional 'tzdata-right' provides TAI-10s time in the 'right' subtree;
and optional 'tzdata-posix' provides the same zones and times as base
data in the 'posix' subtree, as an explicit distinction from 'right'.

The tzcode package provides the tzselect, zdump, and zic utilities.

For more information, see the project home page:

	https://www.iana.org/time-zones

For more details on changes, see the announcement or below:

	https://mm.icann.org/pipermail/tz-announce/2024-February/000081.html


2024a	2024-02-01

Briefly:
- Kazakhstan unifies on UTC+5 beginning 2024-03-01.
- Palestine springs forward a week later after Ramadan.
- zic no longer pretends to support indefinite-past DST.
- localtime no longer mishandles Ciudad Juárez in 2422.

Changes to future timestamps

- Kazakhstan unifies on UTC+5. This affects Asia/Almaty and
  Asia/Qostanay which together represent the eastern portion of the
  country that will transition from UTC+6 on 2024-03-01 at 00:00 to join
  the western portion.

- Palestine springs forward a week later than previously predicted in
  2024 and 2025. Change spring-forward predictions to the second
  Saturday after Ramadan, not the first; this also affects other
  predictions starting in 2039.

Changes to past timestamps

- Asia/Ho_Chi_Minh's 1955-07-01 transition occurred at 01:00 not 00:00.

- From 1947 through 1949, Toronto's transitions occurred at 02:00 not
  00:00.

- In 1911 Miquelon adopted standard time on June 15, not May 15.

Changes to code

- The FROM and TO columns of Rule lines can no longer be "minimum" or an
  abbreviation of "minimum", because TZif files do not support DST rules
  that extend into the indefinite past - although these rules were
  supported when TZif files had only 32-bit data, this stopped working
  when 64-bit TZif files were introduced in 1995. This should not be a
  problem for realistic data, since DST was first used in the 20th
  century. As a transition aid, FROM columns like "minimum" are now
  diagnosed and then treated as if they were the year 1900; this should
  suffice for TZif files on old systems with only 32-bit time_t, and it
  is more compatible with bugs in 2023c-and-earlier localtime.c.

- localtime and related functions no longer mishandle some timestamps
  that occur about 400 years after a switch to a time zone with a DST
  schedule. In 2023d data this problem was visible for some timestamps
  in November 2422, November 2822, etc. in America/Ciudad_Juarez.

- strftime %s now uses tm_gmtoff if available.

Changes to build procedure

- The leap-seconds.list file is now copied from the IERS instead of from
  its downstream counterpart at NIST, as the IERS version is now in the
  public domain too and tends to be more up-to-date.

Changes to documentation

- The strftime man page documents which struct tm members affect which
  conversion specs, and that tzset is called.