We should now cite CLDR as primary reference for the zone name mapping. Discussion: https://postgr.es/m/3266414.1633045628@sss.pgh.pa.us
There's no functional change at all here, but I'm curious to see whether this change successfully shuts up Coverity's warning about a useless strcmp(), which appeared with the previous update. Discussion: http://mm.icann.org/pipermail/tz/2020-October/029370.html
This changes zic's default output format from "-b fat" to "-b slim". We were already using "slim" in v13/HEAD, so those branches drop the explicit -b switch in the Makefiles. Instead, add an explicit "-b fat" in v12 and before, so that we don't change the output file format in those branches. (This is perhaps excessively conservative, but we decided not to do so in a12079109, and I'll stick with that.) Other non-cosmetic changes are to drop support for zic's long-obsolete "-y" switch, and to ensure that strftime() does not change errno unless it fails. As usual with tzcode changes, back-patch to all supported branches.
The IANA tzcode library has a feature to read a time zone file named "posixrules" and apply the daylight-savings transition dates and times therein, when it is given a POSIX-style time zone specification that lacks an explicit transition rule. However, there's a problem with that code: it doesn't work for dates past the Y2038 time_t rollover. (Effectively, all times beyond that point are treated as standard time.) The IANA crew regard this feature as legacy, so their plan is to remove it not fix it. The time frame in which that will happen is unclear, but presumably it'll happen well before 2038. Moreover, effective with the next IANA data update (probably this fall), the recommended default will be to not install a "posixrules" file in the first place. The time frame in which tzdata packagers might adopt that suggestion is likewise unclear, but at least some platforms will probably do it in the next year or so. While we could ignore that recommendation so far as PG-supplied tzdata trees are concerned, builds using --with-system-tzdata will be subject to whatever the platform's tzdata packager decides to do. Thus, whether or not we do anything, some increasing fraction of Postgres users will be exposed to the behavior observed when there is no "posixrules" file; and if we do nothing, we'll have essentially no control over the timing of that change. The best thing to do to ameliorate the uncertainty seems to be to proactively remove the posixrules-reading feature. If we do that in a scheduled release then at least we can release-note the behavioral change, rather than having users be surprised by it after a routine tzdata update. The change in question is fairly minor anyway: to be affected, you have to be using a POSIX-style timezone spec, it has to not have an explicit rule, and it has to not be one of the four traditional continental-USA zone names (EST5EDT, CST6CDT, MST7MDT, or PST8PDT), as those are special-cased. Since the default "posixrules" file provides USA DST rules, the number of people who are likely to find such a zone spec useful is probably quite small. Moreover, the fallback behavior with no explicit rule and no "posixrules" file is to apply current USA rules, so the only thing that really breaks is the DST transitions in years before 2007 (and you get the countervailing fix that transitions after 2038 will be applied). Now, some installations might have replaced the "posixrules" file, allowing e.g. EU rules to be applied to a POSIX-style timezone spec. That won't work anymore. But it's not exactly clear why this solution would be preferable to using a regular named zone. In any case, given the Y2038 issue, we need to be pushing users to stop depending on this. Back-patch into v13; it hasn't been released yet, so it seems OK to change its behavior. (Personally I think we ought to back-patch further, but I've been outvoted.) Discussion: https://postgr.es/m/1390.1562258309@sss.pgh.pa.us Discussion: https://postgr.es/m/20200621211855.6211-1-eggert@cs.ucla.edu
This absorbs a leap-second-related bug fix in localtime.c, and teaches zic to handle an expiration marker in the leapseconds file. Neither are of any interest to us (for the foreseeable future anyway), but we need to stay more or less in sync with upstream. Also adjust some over-eager changes in the README from commit 957338418. I have no intention of making changes that require C99 in this code, until such time as all the live back branches require C99. Otherwise back-patching will get too exciting. For the same reason, absorb assorted whitespace and other cosmetic changes from HEAD into the back branches; mostly this reflects use of improved versions of pgindent. All in all then, quite a boring update. But I figured I'd get it done while I was looking at this code.
stdint.h belongs to the compiler (as opposed to inttypes.h), so by requiring a C99 compiler we can also require stdint.h unconditionally. Remove configure checks and other workarounds for it. This also removes a few steps in the required portability adjustments to the imported time zone code, which can be applied on the next import. When using GCC on a platform that is otherwise pre-C99, this will now require at least GCC 4.5, which is the first release that supplied a standard-conforming stdint.h if the native platform didn't have it. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://www.postgresql.org/message-id/flat/5d398bbb-262a-5fed-d839-d0e5cff3c0d7%402ndquadrant.com
A large fraction of this diff is just due to upstream's somewhat random decision to rename a bunch of internal variables and struct fields. However, there is an interesting new feature in zic: it's grown a "-b slim" option that emits zone files without 32-bit data and other backwards-compatibility hacks. We should consider whether we wish to enable that.
Missed an inttypes.h dependency in previous patch. Per buildfarm.
This corrects a small bug in zic that caused it to output an incorrect year-2440 transition in the Africa/Casablanca zone. More interestingly, zic has grown a "-r" option that limits the range of zone transitions that it will put into the output files. That might be useful to people who don't like the weird GMT offsets that tzdb likes to use for very old dates. It appears that for dates before the cutoff time specified with -r, zic will use the zone's standard-time offset as of the cutoff time. So for example one might do make install ZIC_OPTIONS='-r @-1893456000' to cause all dates before 1910-01-01 to be treated as though 1910 standard time prevailed indefinitely far back. (Don't blame me for the unfriendly way of specifying the cutoff time --- it's seconds since or before the Unix epoch. You can use extract(epoch ...) to calculate it.) As usual, back-patch to all supported branches.
This patch absorbs an upstream fix to "zic" for a recently-introduced bug that made it output data that some 32-bit clients couldn't read. Given the current source data, the bug only manifests in zones with leap seconds, which we don't generate, so that there's no actual change in our installed timezone data files from this. Still, in case somebody uses our copy of "zic" to do something else, it seems best to apply the fix promptly. Also, update the README's notes about converting upstream code to our conventions.