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Re: [tz] tz Digest, Vol 136, Issue 11
by nadir altinbas Jan. 8, 2023

Jan. 8, 2023

There are 195 countries in the world today.As mentioned in ( https://www.worldometers.info/geography/how-many-countries-are-there-in-the…) About Today's Topics:. T?rkiye (Jonathan Leffler); My own comment is to be written as" Republic of Turkiye (Turkiye) " Thank Nadir Altinbas e:nadiraltinbas@yahoo.com n.altinbas On Sunday, January 8, 2023 at 03:00:07 PM GMT+3, tz-request(a)iana.org <tz-request(a)iana.org> wrote: Send tz mailing list submissions to tz(a)iana.org To subscribe or unsubscribe via the World Wide Web, visit https://mm.icann.org/mailman/listinfo/tz or, via email, send a message with subject or body 'help' to tz-request(a)iana.org You can reach the person managing the list at tz-owner(a)iana.org When replying, please edit your Subject line so it is more specific than "Re: Contents of tz digest..." Today's Topics: 1. T?rkiye (Jonathan Leffler) ---------------------------------------------------------------------- Message: 1 Date: Sat, 7 Jan 2023 21:47:15 -0700 From: Jonathan Leffler <jonathan.leffler(a)gmail.com> To: Time Zone Mailing List <tz(a)iana.org> Subject: [tz] T?rkiye Message-ID: <CAH+RLGEKNgZK4c9e4rdO6nmU-tMHnZ3+cXMV9=6LVaJ7VvDAJg(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" >From the Los Angeles Times, 2023-01-05 (summary from an email dated 2023-01-06): Ceding to a longstanding Turkish demand, the State Department on Thursday > agreed to begin spelling the country?s name in Turkish > <https://click.email.latimes.com/?qs=fff6b852d8f4b17927eabd337816fdb1705edee…> in > its official documents. Turkey will now be referred to as ?T?rkiye,? > Wilkinson reported. https://www.latimes.com/politics/story/2023-01-05/state-department-will-now… -- Jonathan Leffler <jonathan.leffler(a)gmail.com> #include <disclaimer.h> Guardian of DBD::Informix - v2018.1031 - http://dbi.perl.org "Blessed are we who can laugh at ourselves, for we shall never cease to be amused."

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Türkiye
by Jonathan Leffler Jan. 8, 2023

Jan. 8, 2023

>From the Los Angeles Times, 2023-01-05 (summary from an email dated 2023-01-06): Ceding to a longstanding Turkish demand, the State Department on Thursday > agreed to begin spelling the country’s name in Turkish > <https://click.email.latimes.com/?qs=fff6b852d8f4b17927eabd337816fdb1705edee…> in > its official documents. Turkey will now be referred to as “Türkiye,” > Wilkinson reported. https://www.latimes.com/politics/story/2023-01-05/state-department-will-now… -- Jonathan Leffler <jonathan.leffler(a)gmail.com> #include <disclaimer.h> Guardian of DBD::Informix - v2018.1031 - http://dbi.perl.org "Blessed are we who can laugh at ourselves, for we shall never cease to be amused."

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Re: [tz] ptrdiff_t changes in tzcode
by Paul Eggert Jan. 7, 2023

Jan. 7, 2023

On 2022-12-12 08:12, Christos Zoulas wrote: > How about changing it then to be: > > sum <= (ptrdiff_t)min(PTRDIFF_MAX, SIZE_MAX) > > This does the check explicitly and avoids the signed/unsigned warning? It is also what the #else part of the code does... This pattern > lives in many places, so we could put the RHS of the expression to a #define? Sure, we can do that. The attached proposed patch (installed in the development repository) uses a new macro INDEX_MAX to capture this notion. This shouldn't change behavior (or even generated code) but can help clarify things. (Although I'm not a fan of casts I don't see how to avoid it here.) >>> There are also a bunch of places now where you get sign comparison warnings (where ptrdiff_t is compared to size_t, like sizeof() or >>> the result of strlen(3). That's OK, they're false alarms: GCC and Clang go overboard in this department. To pacify the compilers you can compile with -Wno-sign-compare as suggested in Makefile's GCC_DEBUG_FLAGS macro. > I think that the ptrdiff_t changes make things more complicated... Yes, it's a tradeoff between complexity now, and simplicity/safety in the long run. Once we can assume C23 (say, 30 years from now!) we can get rid of the trickier code that ports to C17 and earlier. In the meantime as C23 becomes more popular we can start using the simpler code. (I did resist the temptation in the tricky code to write "itemsize**nitems_alloc", which though correct doesn't mean what it looks like....) >> By the way, I'd been meaning to try to sync tzdb localtime.c with NetBSD's at some point. Shouldn't be that hard, I'd think, and might help get bugs fixed faster (in both directions). > > That would be great! OK, thanks, I'll add that to my list of things to do.

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Split America into North America and South America
by Benjamin Drung Jan. 7, 2023

Jan. 7, 2023

Hi, debconf [1] for the tzdata Debian/Ubuntu package ask for the geographic area (e.g. Europe, Asia, etc) and then for the city inside this area. The resulting timezone is $area/$city. While working on the debconf template, I noticed that the America directory is the biggest with 157 cities. Having to find the correct city in that big list can take some time. The second biggest area is Asia with 90 countries. The timezones are split by continent/ocean. The Afro-Eurasia continent is split into Africa, Asia, Europe, but America is not split into North America and South America. For consistency I suggest to split America into North America and South America to have all seven continents present [2]. The git repository already separate northamerica and southamerica files. [1] https://en.wikipedia.org/wiki/Debian_configuration_system [2] https://en.wikipedia.org/wiki/Continent -- Benjamin Drung Debian & Ubuntu Developer

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Re: [tz] Split America into North America and South America
by dpatte Jan. 6, 2023

Jan. 6, 2023

Personally, I'd like to at least see 'America' renamed 'Americas', to both differentiate from the nickname for the USA, and to show there two continents (by traditional naming). ----- Original Message ----- From: Clive D.W. Feather via tz [mailto:tz@iana.org] To: "Wolfgang Keller" <wolfgangkeller(a)gmail.com> Cc: tz(a)iana.org Sent: Fri, 6 Jan 2023 21:46:47 +0000 Subject: Re: [tz] Split America into North America and South America Wolfgang Keller via tz said: > Hi, > let us consider what conventions for the number and separations of > continents exist. According to > > https://en.wikipedia.org/w/index.php?title=Continent&oldid=1131827063#N… > there exist (at least) five common conventions for the number and > separation of continents: > > a) 4 continents (Afro-Eurasia (Old World), America (New World), > Australia, Antarctica > b) 5 continents (Africa, Eurasia, America, Antarctica, Australia) > c) 6 continents, combined-Eurasia (Africa, Eurasia, North America, > South America, Antarctica, Australia) > d) 6 continents, combined-America (Africa, Asia, Europe, America, > Antarctica, Australia) > e) 7 continents (Africa, Asia, Europe, North America, South America, > Antarctica, Australia) You've forgotten Zealandia, which some consider to be a continent. > For the prevalence of these separations (prevalence of c)-e) taken > from the linked section of the Wikipedia article) > a) is to my knowledge motivated by geology > c) is is mostly used in Russia and some parts of Eastern Europe. > d) is taught in some countries where Romance languages are spoken and in Greece > e) is the model taught in most English-speaking countries > > So the central question that the problem reduces to is: which > separation of continents should tzdata implicitly endorse by its data > structures? If I were to ask, I would immediately say a) because this > is the only convention of this list that is motivated by science > (geology) and not by politics or history, I disagree. e is justifiable by geography: a continent doesn't have to be the largest contiguous landmass; it can be bordered by an isthmus or mountain range just as much as a puddle. But I don't see the need for this split. The division was made for the few humans who work with the raw data, not for the general public and certainly not for geologists. It works, so don't break it. -- Clive D.W. Feather | If you lie to the compiler, Email: clive(a)davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646

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Request for Russian Antarctic stations
by Benjamin Drung Jan. 6, 2023

Jan. 6, 2023

Hi, Ubuntu bug https://launchpad.net/bugs/1457285 requests to add Russian Antarctic research stations to tzdata. They are: AQ -6212-05858 Antarctica/Bellingshausen Bellingshausen Station, Vaterloo Island, GMT-4 AQ -7046+01149 Antarctica/Novolasarevskaya Novolasarevskaya Station, GMT AQ -6739+04530 Antarctica/Molodezhnaya Molodezhnaya Station, GMT+3 AQ -6633+09300 Antarctica/Mirniy Mirniy Station, GMT+7 AQ -6930+15923 Antarctica/Leningradskaya Leningradskaya Station, GMT+10 AQ -7445-13648 Antarctica/Russkaya Russkaya Station, GMT-6 AQ -6922+07623 Antarctica/Progress Progress Station, GMT+5 AQ -6944+07342 Antarctica/Druzhnaya Druzhnaya Station, GMT+5 Please mean that GMT data given are POSIX inversed. -- Benjamin Drung Debian & Ubuntu Developer

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[PROPOSED] A couple more ptrdiff_t overflow safety checks
by Paul Eggert Jan. 4, 2023

Jan. 4, 2023

* private.h (TYPE_BIT): Now returns a signed value. * zdump.c (sumsize, xmalloc): Now takes signed args, like the result. (xstrsize): New function. (tzalloc, saveabbr): Use xstrsize to properly catch strings so long that their sizes do not fit into ptrdiff_t. Although quite implausible in real-life uses, it is possible according to the C standard. --- private.h | 2 +- zdump.c | 28 ++++++++++++++++++++-------- 2 files changed, 21 insertions(+), 9 deletions(-) diff --git a/private.h b/private.h index 03ee4d10..b638e9e4 100644 --- a/private.h +++ b/private.h @@ -805,7 +805,7 @@ ATTRIBUTE_REPRODUCIBLE time_t time2posix_z(timezone_t, time_t); ** Finally, some convenience items. */ -#define TYPE_BIT(type) (sizeof(type) * CHAR_BIT) +#define TYPE_BIT(type) (CHAR_BIT * (ptrdiff_t) sizeof(type)) #define TYPE_SIGNED(type) (((type) -1) < 0) #define TWOS_COMPLEMENT(t) ((t) ~ (t) 0 < 0) diff --git a/zdump.c b/zdump.c index 98537f4e..b93910ed 100644 --- a/zdump.c +++ b/zdump.c @@ -133,9 +133,9 @@ size_overflow(void) } /* Return A + B, exiting if the result would overflow either ptrdiff_t - or size_t. */ + or size_t. A and B are both nonnegative. */ ATTRIBUTE_REPRODUCIBLE static ptrdiff_t -sumsize(size_t a, size_t b) +sumsize(ptrdiff_t a, ptrdiff_t b) { #ifdef ckd_add ptrdiff_t sum; @@ -148,10 +148,22 @@ sumsize(size_t a, size_t b) size_overflow(); } +/* Return the size of of the string STR, including its trailing NUL. + Report an error and exit if this would exceed INDEX_MAX which means + pointer subtraction wouldn't work. */ +static ptrdiff_t +xstrsize(char const *str) +{ + size_t len = strlen(str); + if (len < INDEX_MAX) + return len + 1; + size_overflow(); +} + /* Return a pointer to a newly allocated buffer of size SIZE, exiting - on failure. SIZE should be nonzero. */ + on failure. SIZE should be positive. */ ATTRIBUTE_MALLOC static void * -xmalloc(size_t size) +xmalloc(ptrdiff_t size) { void *p = malloc(size); if (!p) { @@ -253,7 +265,7 @@ tzalloc(char const *val) static ptrdiff_t fakeenv0size; void *freeable = NULL; char **env = fakeenv, **initial_environ; - size_t valsize = strlen(val) + 1; + ptrdiff_t valsize = xstrsize(val); if (fakeenv0size < valsize) { char **e = environ, **to; ptrdiff_t initial_nenvptrs = 1; /* Counting the trailing NULL pointer. */ @@ -410,13 +422,13 @@ saveabbr(char **buf, ptrdiff_t *bufalloc, struct tm const *tmp) if (HAVE_LOCALTIME_RZ) return ab; else { - size_t ablen = strlen(ab); - if (*bufalloc <= ablen) { + ptrdiff_t absize = xstrsize(ab); + if (*bufalloc < absize) { free(*buf); /* Make the new buffer at least twice as long as the old, to avoid O(N**2) behavior on repeated calls. */ - *bufalloc = sumsize(*bufalloc, ablen + 1); + *bufalloc = sumsize(*bufalloc, absize); *buf = xmalloc(*bufalloc); } -- 2.37.2

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Questions on tzname and tm_zone
by Patrik Lantto Dec. 31, 2022

Dec. 31, 2022

Dear all, I have a few questions regarding how the tzdb code handles tzname and tm_zone: * The define HAVE_TZNAME have three different "settings"; 0 if tzname is not supported, 1 to support tzname defined by the system library and 2 to support and define tzname. In the code though, when defining tzname it also adds the value of TZ_TIME_T which reduces the options. Basically, if time_tz is defined to another datatype that time_t, tzname cannot be defined by the system library since setting HAVE_TZNAME to 1 would still define tzname (around line 195 of localtime.c). Is there a reason for this behaviour (which is also similar for USG_COMPAT)? In my platform we define a new 64 bit datatype, but would still need tzname as defined by the system library. * In case of an invalid timezone, the behaviour of tzname and tm_zone behaves differently; tzname would be set to WILDABBR (which is possible to define), but if localtime is called tm_zone will be set to "UTC" while if gmtime is called, tm_zone is set to "-00" and if offtime is called (with a non-0 offset) tm_zone is WILDABBR. It seems somewhat inconsistent, so is this by design? * The way tzname is updated (in settzname) in settzname is that it first set tzname[0] and tzname[1] to either WILDABBR or UTC, and then possibly update with the correct names. While tzname is not considered thread safe, this way writing to tzname twice means that even call to tzset with the same timezone could affect other threads reading tzname. Not a huge risk, but still possible. Is this something to consider in the implementation? * Since tzname is not thread safe, and due to the way tm_zone is handled it is somewhat hard to detect if a TZ string is valid or not. Is there a recommended way to detect an invalid string? Best regards, Patrik Lantto -- Patrik Lantto - patrik.lantto(a)wisi.se - +46 13 210918

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[PROPOSED] Support leap-seconds.list tombstone
by Paul Eggert Dec. 23, 2022

Dec. 23, 2022

From: Paul Eggert <eggert@trombone> This change looks forward to the possibility of leap seconds being discontinued by 2035. If and when that happens, the expiration date on the leap-seconds.list file is likely to stop being maintained, as there will be no need to issue new versions of leap-seconds.list every six months. Although the details have not been decided, for now assume that the last edition of leap-seconds.list will simply lack an expiration-date line. * leapseconds.awk: If the input lacks an expiration line like ‘#@ 3896899200’, do not treat it as if ‘#@ 0’ were present, as that would mean an expiration date of 1900-01-01. Instead, do not output an expiration date; just output a comment saying that there is no expiration date. Similarly for update dates and input lacking lines like ’#$ 3676924800’. --- NEWS | 3 +++ leapseconds.awk | 50 ++++++++++++++++++++++++++++++------------------- 2 files changed, 34 insertions(+), 19 deletions(-) diff --git a/NEWS b/NEWS index 9ac3367..5510823 100644 --- a/NEWS +++ b/NEWS @@ -42,6 +42,9 @@ Unreleased, experimental changes 'restrict' keyword consistently with their documentation. This may allow future optimizations. + leapseconds.awk can now process a leap seconds file that never + expires; this might be useful if leap seconds are discontinued. + Changes to commentary Note that leap seconds are planned to be discontinued by 2035. diff --git a/leapseconds.awk b/leapseconds.awk index b6c48bc..7d2556b 100644 --- a/leapseconds.awk +++ b/leapseconds.awk @@ -104,18 +104,23 @@ BEGIN { } END { - sstamp_to_ymdhMs(expires, ss_NTP) - print "" - print "# UTC timestamp when this leap second list expires." - print "# Any additional leap seconds will come after this." - if (! EXPIRES_LINE) { - print "# This Expires line is commented out for now," - print "# so that pre-2020a zic implementations do not reject this file." + + if (expires) { + sstamp_to_ymdhMs(expires, ss_NTP) + + print "# UTC timestamp when this leap second list expires." + print "# Any additional leap seconds will come after this." + if (! EXPIRES_LINE) { + print "# This Expires line is commented out for now," + print "# so that pre-2020a zic implementations do not reject this file." + } + printf "%sExpires %.4d\t%s\t%.2d\t%.2d:%.2d:%.2d\n", \ + EXPIRES_LINE ? "" : "#", \ + ss_year, monthabbr[ss_month], ss_mday, ss_hour, ss_min, ss_sec + } else { + print "# (No Expires line, since the expires time is unknown.)" } - printf "%sExpires %.4d\t%s\t%.2d\t%.2d:%.2d:%.2d\n", \ - EXPIRES_LINE ? "" : "#", \ - ss_year, monthabbr[ss_month], ss_mday, ss_hour, ss_min, ss_sec # The difference between the NTP and POSIX epochs is 70 years # (including 17 leap days), each 24 hours of 60 minutes of 60 @@ -124,15 +129,22 @@ END { print "" print "# POSIX timestamps for the data in this file:" - sstamp_to_ymdhMs(updated, ss_NTP) - printf "#updated %d (%.4d-%.2d-%.2d %.2d:%.2d:%.2d UTC)\n", \ - updated - epoch_minus_NTP, \ - ss_year, ss_month, ss_mday, ss_hour, ss_min, ss_sec - sstamp_to_ymdhMs(expires, ss_NTP) - printf "#expires %d (%.4d-%.2d-%.2d %.2d:%.2d:%.2d UTC)\n", \ - expires - epoch_minus_NTP, \ - ss_year, ss_month, ss_mday, ss_hour, ss_min, ss_sec - + if (updated) { + sstamp_to_ymdhMs(updated, ss_NTP) + printf "#updated %d (%.4d-%.2d-%.2d %.2d:%.2d:%.2d UTC)\n", \ + updated - epoch_minus_NTP, \ + ss_year, ss_month, ss_mday, ss_hour, ss_min, ss_sec + } else { + print "#(updated time unknown)" + } + if (expires) { + sstamp_to_ymdhMs(expires, ss_NTP) + printf "#expires %d (%.4d-%.2d-%.2d %.2d:%.2d:%.2d UTC)\n", \ + expires - epoch_minus_NTP, \ + ss_year, ss_month, ss_mday, ss_hour, ss_min, ss_sec + } else { + print "#(expires time unknown)" + } printf "\n%s", last_lines } -- 2.38.1

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Re: [tz] [PROPOSED] Mention the planned obsolescence of leap seconds
by Brian Inglis Dec. 22, 2022

Dec. 22, 2022

On 2022-12-20 17:25, Paul Eggert via tz wrote: > + Changes to commentary > + Note that leap seconds are planned to be discontinued by 2035. > + This affects time stamps during the leap second era (1972–2035). > +Leap seconds were introduced in 1972 to accommodate the > +difference between atomic time and the less-regular rotation of the earth. > +Unfortunately they caused so many problems with civil Civil (e.g. legal etc.) time keeping is not the problem, it is mainly proprietary computer systems and applications, not adequately programmed to deal with the realities of time keeping. > +timekeeping that they > +are <a href="https://www.bipm.org/en/cgpm-2022/resolution-4">planned > +to be discontinued by 2035</a>, with some as-yet-undetermined > +mechanism replacing them, perhaps after the year 2135. > +Despite their impending obsolescence, a record of leap seconds is still > +needed to resolve timestamps from 1972 through 2035. I would expect astronomers and physicists to have divergent views, but both use software which handles varieties of time bases, scales, and conversions. It seems likely that other scientists and disciplines with time concerns would line up behind one or the other, depending on whether their focus is civil, geocentric, or longer term in some way, or more artificial on accuracy, calibration, precision or other short term characteristics. > <a href="https://www.ucolick.org/~sla/leapsecs/"><abbr>UTC</abbr> > might be redefined > without Leap Seconds</a> gives pointers on this > +contentious issue. > +The General Conference on Weights and Measures > +<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">voted in 2022</a> > +to discontinue the use of leap seconds by 2035, replacing them with an > +as-yet-undetermined scheme some time after the year 2135. Expect every lawyer, in any case involving time stamped records, to jump on the technicality of any significant deviation of time keeping from solar time, which is the legal basis in most English common law jurisdictions, possibly also in some continental code and Scandinavian/Nordic jurisdictions e.g. Denmark: https://www.dr.dk/nyheder/indland/uret-paa-din-telefon-viser-en-ulovlig-tid https://www-dr-dk.translate.goog/nyheder/indland/uret-paa-din-telefon-viser… -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut -- Antoine de Saint-Exupéry

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DST in the news
by Arthur David Olson Dec. 22, 2022

Dec. 22, 2022

A 538 piece on the merits and demerits of permanent standard time and permanent daylight time. https://projects.fivethirtyeight.com/daylight-saving-time/ --ado

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[PROPOSED] Document deprecation of ctime, asctime.
by Paul Eggert Dec. 21, 2022

Dec. 21, 2022

--- newctime.3 | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/newctime.3 b/newctime.3 index e25d841..2790c81 100644 --- a/newctime.3 +++ b/newctime.3 @@ -11,13 +11,13 @@ asctime, ctime, difftime, gmtime, localtime, mktime \- convert date and time .PP .BR "extern char *tzname[];" " /\(** (optional) \(**/" .PP -.B char *ctime(time_t const *clock); +.B [[deprecated]] char *ctime(time_t const *clock); .PP .B char *ctime_r(time_t const *clock, char *buf); .PP .B double difftime(time_t time1, time_t time0); .PP -.B char *asctime(struct tm const *tm); +.B [[deprecated]] char *asctime(struct tm const *tm); .PP .B "char *asctime_r(struct tm const *restrict tm," .B " char *restrict result);" @@ -91,6 +91,15 @@ introduction of UTC and are some other flavor of Universal Time (UT). Some implementations support leap seconds, in contradiction to POSIX. .PP The +.B ctime +function is deprecated starting in C23. +Callers can use +.B localtime_r +and +.B strftime +instead. +.PP +The .B localtime and .B gmtime @@ -128,6 +137,10 @@ converts a time value contained in a structure to a string, as shown in the above example, and returns a pointer to the string. +This function is deprecated starting in C23. +Callers can use +.B strftime +instead. .PP The .B mktime -- 2.38.1

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Windows build failures
by Manuela Friedrich Dec. 21, 2022

Dec. 21, 2022

Hello Paul, I noticed new Windows build failures with the latest tz code from git. Hopefully you can shed some light on these. Error 1 d:\iana\tmp\private.h(704): error C2373: 'restrict': redefinition; different type modifiers d:\iana\tmp\private.h(704): note: see declaration of 'restrict' d:\iana\tmp\private.h(780): error C2373: 'restrict': redefinition; different type modifiers d:\iana\tmp\private.h(780): note: see declaration of 'restrict' d:\iana\tmp\private.h(781): error C2371: 'restrict': redefinition; different basic types d:\iana\tmp\private.h(780): note: see declaration of 'restrict' Error 2 zic.c(154): error C2146: syntax error: missing ')' before identifier 'file' zic.c(154): error C2061: syntax error: identifier 'file' zic.c(154): error C2059: syntax error: ';' zic.c(154): error C2059: syntax error: ',' zic.c(154): error C2059: syntax error: ')' Thank you! Kind Regards Manuela Friedrich

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[PROPOSED] Mention the planned obsolescence of leap seconds
by Paul Eggert Dec. 21, 2022

Dec. 21, 2022

--- NEWS | 4 ++++ theory.html | 15 ++++++++++++++- tz-link.html | 8 ++++++-- 3 files changed, 24 insertions(+), 3 deletions(-) diff --git a/NEWS b/NEWS index 9b2d202..9ac3367 100644 --- a/NEWS +++ b/NEWS @@ -42,6 +42,10 @@ Unreleased, experimental changes 'restrict' keyword consistently with their documentation. This may allow future optimizations. + Changes to commentary + + Note that leap seconds are planned to be discontinued by 2035. + Release 2022g - 2022-11-29 08:58:31 -0800 diff --git a/theory.html b/theory.html index fbbb9e4..88bf720 100644 --- a/theory.html +++ b/theory.html @@ -818,7 +818,8 @@ href="https://www.dissentmagazine.org/blog/booked-a-global-history-of-time-vanes <li> The relationship between POSIX time (that is, <abbr>UTC</abbr> but ignoring <a href="https://en.wikipedia.org/wiki/Leap_second">leap - seconds</a>) and <abbr>UTC</abbr> is not agreed upon after 1972. + seconds</a>) and <abbr>UTC</abbr> is not agreed upon. + This affects time stamps during the leap second era (1972–2035). Although the POSIX clock officially stops during an inserted leap second, at least one proposed standard has it jumping back a second instead; and in @@ -1268,6 +1269,18 @@ between now and the future time. <section> <h2 id="leapsec">Leap seconds</h2> +<p> +Leap seconds were introduced in 1972 to accommodate the +difference between atomic time and the less-regular rotation of the earth. +Unfortunately they caused so many problems with civil +timekeeping that they +are <a href="https://www.bipm.org/en/cgpm-2022/resolution-4">planned +to be discontinued by 2035</a>, with some as-yet-undetermined +mechanism replacing them, perhaps after the year 2135. +Despite their impending obsolescence, a record of leap seconds is still +needed to resolve timestamps from 1972 through 2035. +</p> + <p> The <code><abbr>tz</abbr></code> code and data can account for leap seconds, thanks to code contributed by Bradley White. diff --git a/tz-link.html b/tz-link.html index d3b3766..608393f 100644 --- a/tz-link.html +++ b/tz-link.html @@ -1078,8 +1078,12 @@ leap second: its history and possible future</a>. <a href="https://www.ucolick.org/~sla/leapsecs/"><abbr>UTC</abbr> might be redefined without Leap Seconds</a> gives pointers on this -contentious issue, which was active until 2015 and could become active -again.</li> +contentious issue. +The General Conference on Weights and Measures +<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">voted in 2022</a> +to discontinue the use of leap seconds by 2035, replacing them with an +as-yet-undetermined scheme some time after the year 2135. +</li> </ul> </section> -- 2.38.1

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[PROPOSED] Use ‘restrict’ more consistently with standards
by Paul Eggert Dec. 20, 2022

Dec. 20, 2022

Previously, I assumed that if the declaration of a function F declared an argument via ‘T *restrict ARG’ then the compiler could take advantage of the ‘restrict’ when compiling F’s definition. However, apparently this is not the case: a top-level ‘restrict’ like that has no effect semantically unless it’s present in F’s definition. Fix this by using ‘restrict’ consistently in both declarations and definitions of functions where POSIX or the NetBSD API specifies ‘restrict’. (As an exception, do not use ‘restrict’ in tzfree’s argument as this appears to be a typo in NetBSD.) Do not bother using ‘restrict’ in internal functions, as this change is for consistency not for optimization. This change was prompted by a bug report for compiling on MS-Windows; see https://mm.icann.org/pipermail/tz/2022-December/032451.html Although the change does not fix the MS-Windows situation, the idea is to fix the MS-Windows issue another way. * asctime.c (asctime_r): * localtime.c (localtime_rz, localtime_r, gmtime_r, mktime_z): * private.h (asctime) [HAVE_INCOMPATIBLE_CTIME_R]: * strftime.c (strftime_l, strftime): Use ‘restrict’ consistently when POSIX or tzcode’s doc say so. --- NEWS | 4 ++++ asctime.c | 2 +- localtime.c | 9 +++++---- private.h | 2 +- strftime.c | 6 ++++-- 5 files changed, 15 insertions(+), 8 deletions(-) diff --git a/NEWS b/NEWS index 98cc14f..9b2d202 100644 --- a/NEWS +++ b/NEWS @@ -38,6 +38,10 @@ Unreleased, experimental changes '[[noreturn]] static void usage(void);' as strict C23 requires. (Problem reported by Houge Langley.) + The code's functions now constrain their arguments with the C + 'restrict' keyword consistently with their documentation. + This may allow future optimizations. + Release 2022g - 2022-11-29 08:58:31 -0800 diff --git a/asctime.c b/asctime.c index c84fe8c..375c913 100644 --- a/asctime.c +++ b/asctime.c @@ -61,7 +61,7 @@ static char buf_ctime[sizeof buf_asctime]; #endif char * -asctime_r(register const struct tm *timeptr, char *buf) +asctime_r(struct tm const *restrict timeptr, char *restrict buf) { static const char wday_name[][4] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" diff --git a/localtime.c b/localtime.c index f1a8598..9b5d0a5 100644 --- a/localtime.c +++ b/localtime.c @@ -1628,7 +1628,8 @@ localsub(struct state const *sp, time_t const *timep, int_fast32_t setname, #if NETBSD_INSPIRED struct tm * -localtime_rz(struct state *sp, time_t const *timep, struct tm *tmp) +localtime_rz(struct state *restrict sp, time_t const *restrict timep, + struct tm *restrict tmp) { return localsub(sp, timep, 0, tmp); } @@ -1660,7 +1661,7 @@ localtime(const time_t *timep) } struct tm * -localtime_r(const time_t *timep, struct tm *tmp) +localtime_r(const time_t *restrict timep, struct tm *restrict tmp) { return localtime_tzset(timep, tmp, false); } @@ -1693,7 +1694,7 @@ gmtsub(ATTRIBUTE_MAYBE_UNUSED struct state const *sp, time_t const *timep, */ struct tm * -gmtime_r(const time_t *timep, struct tm *tmp) +gmtime_r(time_t const *restrict timep, struct tm *restrict tmp) { gmtcheck(); return gmtsub(gmtptr, timep, 0, tmp); @@ -2297,7 +2298,7 @@ mktime_tzname(struct state *sp, struct tm *tmp, bool setname) #if NETBSD_INSPIRED time_t -mktime_z(struct state *sp, struct tm *tmp) +mktime_z(struct state *restrict sp, struct tm *restrict tmp) { return mktime_tzname(sp, tmp, false); } diff --git a/private.h b/private.h index 7ddf4e5..5043cb8 100644 --- a/private.h +++ b/private.h @@ -920,7 +920,7 @@ static_assert(! TYPE_SIGNED(time_t) || ! SIGNED_PADDING_CHECK_NEEDED #if HAVE_INCOMPATIBLE_CTIME_R #undef asctime_r #undef ctime_r -char *asctime_r(struct tm const *, char *); +char *asctime_r(struct tm const *restrict, char *restrict); char *ctime_r(time_t const *, char *); #endif /* HAVE_INCOMPATIBLE_CTIME_R */ diff --git a/strftime.c b/strftime.c index b23b610..df16983 100644 --- a/strftime.c +++ b/strftime.c @@ -116,7 +116,8 @@ static char * _yconv(int, int, bool, bool, char *, char const *); #if HAVE_STRFTIME_L size_t -strftime_l(char *s, size_t maxsize, char const *format, struct tm const *t, +strftime_l(char *restrict s, size_t maxsize, char const *restrict format, + struct tm const *restrict t, ATTRIBUTE_MAYBE_UNUSED locale_t locale) { /* Just call strftime, as only the C locale is supported. */ @@ -125,7 +126,8 @@ strftime_l(char *s, size_t maxsize, char const *format, struct tm const *t, #endif size_t -strftime(char *s, size_t maxsize, const char *format, const struct tm *t) +strftime(char *restrict s, size_t maxsize, char const *restrict format, + struct tm const *restrict t) { char * p; int saved_errno = errno; -- 2.38.1

1 0

Confusing zdump output for America/Ojinaga
by Dave Rolsky Dec. 14, 2022

Dec. 14, 2022

I'm a bit confused regarding the output from zdump for the new America/Ojinaga zone. Here's the output for 2022: America/Ojinaga Sun Mar 13 08:59:59 2022 UT = Sun Mar 13 01:59:59 2022 MST isdst=0 gmtoff=-25200 America/Ojinaga Sun Mar 13 09:00:00 2022 UT = Sun Mar 13 03:00:00 2022 MDT isdst=1 gmtoff=-21600 America/Ojinaga Sun Oct 30 07:59:59 2022 UT = Sun Oct 30 01:59:59 2022 MDT isdst=1 gmtoff=-21600 America/Ojinaga Sun Oct 30 08:00:00 2022 UT = Sun Oct 30 03:00:00 2022 CDT isdst=1 gmtoff=-18000 America/Ojinaga Sun Nov 6 06:59:59 2022 UT = Sun Nov 6 01:59:59 2022 CDT isdst=1 gmtoff=-18000 America/Ojinaga Sun Nov 6 07:00:00 2022 UT = Sun Nov 6 01:00:00 2022 CST isdst=0 gmtoff=-21600 Note that there's no November 30 event. But based on the zone's definition I'd expect to see these events: Oct 30 - change to _CST_ Nov 30 - No change, I guess, since the change to the US rules on Nov 30 doesn't actually change the offset or isdst flag. But maybe I'm misunderstanding how to interpret the zone file definition? Cheers, Dave Rolsky http://blog.urth.org https://github.com/autarch

3 4

[PATCH v2 1/4] zic.8: Add public domain notice
by Alejandro Colomar Dec. 13, 2022

Dec. 13, 2022

Signed-off-by: Alejandro Colomar <alx(a)kernel.org> --- Hi Paul, v2: - This time I sent them to the tz mailing list too (and also linux-man@). - Added ACK and review from Branden in 3/4 and 4/4. - Added comment from Branden to commit message in 4/4. - Added tweak suggested by Branden in 3/4. zic.8 | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/zic.8 b/zic.8 index f79148f4..c2c61739 100644 --- a/zic.8 +++ b/zic.8 @@ -1,3 +1,7 @@ +.\" %%%LICENSE_START(PUBLIC_DOMAIN) +.\" This page is in the public domain +.\" %%%LICENSE_END +.\" .TH ZIC 8 .SH NAME zic \- timezone compiler -- 2.38.1

3 18

Single source of truth for timezone data
by Benjamin Drung Dec. 11, 2022

Dec. 11, 2022

Hi everyone, I am writing this mail with my distribution maintainer hat on since I am responsible for keeping the tzdata package up-to-date in Ubuntu. I like to propose to have a single source of truth for timezone data, which should be the tzdata source package. Updating this package in a distribution like Debian/Ubuntu should be enough to update all consumers in the distribution. Sadly this is currently not the case. Ubuntu since 20.04 (focal) adds the four icu source files metaZones.txt, timezoneTypes.txt, windowsZones.txt, and zoneinfo64.txt from https://github.com/unicode-org/icu-data to the tzdata source package. Then it uses genrb and icupkg to generate the .res files. Since the icu project lacks behind the tzdata release by hours up to days, Ubuntu has to update tzdata twice (first the tzdata release, then the icu update). metaZones.txt, timezoneTypes.txt, and windowsZones.txt are generated using tools/cldr/cldr-to-icu/build-icu-data.xml from https://github.com/unicode-org/icu. zoneinfo64.txt is generated by tz2icu. build-icu-data.xml uses https://github.com/unicode-org/cldr as input to convert the cldr data to icu. If I saw that correctly, only common/supplemental/metaZones.xml needs to be updated there on an update. Can tzdata include the necessary data and tools to generate metaZones.xml from its source? Then it would be possible to generate the icu data from the tzdata source without the need to wait for icu to catch up. Then Debian/Ubuntu can ship a tzdata-icu package for it [1]. [1] https://bugs.debian.org/954112 -- Benjamin Drung Debian & Ubuntu Developer

9 23

Error in America/Ojinaga
by Nikos (Nikolaos) Papadakos, PhD Dec. 10, 2022

Dec. 10, 2022

Hello, We are suspecting that your timezone update tzdb 2022g is incorrectly accounting for America/Ojinaga. Our customer is a major airline in Mexico and they tell me the time should America/Ojinaga should be the same as America/Denver. They provide as evidence official announcements in Spanish language. For example: https://www.dof.gob.mx/nota_detalle.php?codigo=5672650&fecha=29/11/2022#gsc… which says: "Artículo 5. III. Para el Estado de Baja California, así como para los municipios de Janos, Ascensión, Juárez, Praxedis G. Guerrero y Guadalupe, del Estado de Chihuahua, acorde a sus correlativos a su franja fronteriza, se aplica el meridiano 105 grados al oeste de Greenwich." I don't speak Spanish to be honest, my customer does. In the above the phrase seems to be "Juárez [...] del Estado de Chihuahua" which isreferring specifically to Ciudad Juárez in the State of Chihuahua. And then it says "el meridiano 105 grados al oeste de Greenwich" giving the degrees from Greenwich. They've given me some other references, but the above seems the most official. I would like to ask you to please double check which one is the correct. Best regards, Nikos P.S.: Please do not use my name or my company's name.

2 2

Re: [tz] Error in America/Ojinaga
by Brian Inglis Dec. 10, 2022

Dec. 10, 2022

On 2022-12-09 15:11, Tim Parenti via tz wrote: > On Fri, 9 Dec 2022 at 16:46, Nikos (Nikolaos) Papadakos, PhD wrote: >> Our customer is a major airline in Mexico and they tell me the time >> should America/Ojinaga should be the same as America/Denver. > It is our understanding that the recent changes split time zone observances > along Chihuahua's northern border. According to that split, from 2022-11-30, > Ojinaga is like America/Chicago, while Ciudad Juárez is like America/Denver. >> III. Para el Estado de Baja California, así como para los municipios >> de Janos, Ascensión, Juárez, Praxedis G. Guerrero y Guadalupe, del >> Estado de Chihuahua, acorde a sus correlativos a su franja fronteriza, >> se aplica el meridiano 105 grados al oeste de Greenwich." > While the above describes that the municipio of Juárez (including its municipal > seat, Ciudad Juárez) observes a standard time of UTC-7, which is like > America/Denver, the section immediately prior reads: > II. Para los municipios de Coyame del Sotol, Ojinaga y Manuel Benavides, > del Estado de Chihuahua, acorde a sus correlativos a su franja fronteriza, > se aplica el meridiano 90 grados al oeste de Greenwich; > …meaning that the city and municipio of Ojinaga follow UTC-6, which is like > America/Chicago. > A new zone, America/Ciudad_Juarez, was split off from America/Ojinaga in 2022g > to allow for these differences in timekeeping. Since this zone did not exist > prior to 2022g, those in the western portions of Chihuahua's border region > (including Juárez) will need to switch to it, as the time in and around Juárez > and Chihuahua's northwest no longer matches the time in Ojinaga and Chihuahua's > northeast. Nor the time in Chihuahua's interior which is on CST like Ojinaga. The airline can check the IATA SSIM Schedule Time Zones for CUU/MMC Chihuahua and CJS/MMCS Ciudad Juarez to confirm the changes (Ojinaga has no airport). -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut -- Antoine de Saint-Exupéry

1 0

Re: [tz] Single source of truth for timezone data
by Brian Inglis Dec. 9, 2022

Dec. 9, 2022

On 2022-12-08 13:50, Paul Eggert via tz wrote: > On 2022-12-08 05:24, Almaz Mingaleev wrote: >>>> new timezone abbreviation "XYT", downstream distros like Ubuntu can >>>> immediately ship the new P without waiting for i18n updates. P will >> It is not a problem if a distro ships it, it is a problem if this new >> stuff leaks to the external world. > Sorry, I'm not following. When Ubuntu ships a new tzdata package then surely > that has "leaked" to the outside world? >> It would be naive to expect from a user base of a service to have >> up-to-date time zone data even after a month after TZDB release. > In the past I've gotten my Ubuntu systems updated within 24 hours of a tzdata > release, simply by applying patches as usual from Ubuntu. But as Benjamin > indicates, this is not happening with 2022g. I just now checked for updates and > I'm still stuck on 2022f. So from my point of view, Ubuntu is slow in this case > - instead of taking less than a day, it's taking more than a week. >> being consistently wrong about _new_ changes is better >> than having different answers within the platform. > As a Ubuntu user, I'd prefer tzdata to be up-to-date even though ICU is > out-of-date, over having both tzdata and ICU out-of-date. Of course Ubuntu > differs from Android in that most apps use tzdata not ICU. Still, I'm a bit > curious what end-user-visible problems would occur on Android and/or Ubuntu if > tzdata leads ICU slightly. I know you've seen problems, but were they end-user > problems or just test-case problems? On Ubuntu various other copies of tzdata > (e.g., Python's) can be slightly out of date too, but this doesn't seem to be > much of an issue. >> It is not translations that we are waiting for, but changes like [1 >> <https://github.com/unicode-org/icu/pull/2261/files>]. Recent time zone >> changes were short notice ones and ICU team (thanks Yoshito and others!) >> did these changes very quickly. > Thanks, I didn't know that. > Here's a timeline I see for the latest Mexico change: > * 2022-11-28 17:00 UTC - news article published announcing the change (which is > not official yet, I think) > <http://puentelibre.mx/noticia/ciudad_juarez_cambio_horario_noviembre_2022/> > * 2022-11-29 03:55:31 UTC - tz mailing list notified > <https://mm.icann.org/pipermail/tz/2022-November/032365.html> > * 2022-11-29 17:42:29 UTC (14 hours after notification) - tzdb 2022g announced > <https://mm.icann.org/pipermail/tz-announce/2022-November/000076.html> > * 2022-11-29 18:23:41 UTC (less than an hour after tzdb 2022g announcement) > tzdata 2022g-r0 released for Alpine Linux > <https://pkgs.alpinelinux.org/package/edge/main/x86/tzdata> > * 2022-11-30 07:06 UTC (7 hours after tzdb 2022g announcement) - tzdata 2022g-1 > released for Arch Linux <https://archlinux.org/packages/core/x86_64/tzdata/> > * 2022-12-01 03:08:08 UTC (33 hours after tzdb 2022g announcement) - > abovementioned ICU patch committed > * 2022-12-01 12:38:06 UTC (9 hours after ICU patch committed) - Ubuntu patch > committed <https://launchpad.net/ubuntu/+source/tzdata/2022g-0ubuntu0.22.10.1> > * 2022-12-05 (4 days after ICU patch committed) - Red Hat Enterprise Linux fix > available to users <https://access.redhat.com/errata/RHBA-2022:8785> > * 2022-12-07 (6 days after ICU patch committed) - Android patch committed > <https://android.googlesource.com/platform/system/timezone/+/ea3e0ece71974c1…> > * now (a week after ICU patch committed) - my Ubuntu workstation is still not > updated. > We should be able to do better than this; that is, be more like Alpine or Arch > Linux, or at least more like RHEL (though I see that Fedora still hasn't > released 2022g...). Though ICU is part of the problem (as is tzdb itself :-), > most of the delay seems to be occurring even after ICU patches are applied. Launchpad shows Ubuntu 22.10 Proposed kinetic-proposed/main tzdata 2022g, also jammy- and focal-proposed, released Dec 1 when the maintainer started this thread. You could add the -proposed source to apt sources, and/or set apt preferences to only use it for tzdata, as the -proposed source seems to be first to get ICU updates in tzdata package release yyyyX-0ubuntu0.MM.mm.1; -updates and -security follow. -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut -- Antoine de Saint-Exupéry

1 0

[PROPOSED] America/Yellowknife now links to America/Edmonton
by Paul Eggert Dec. 9, 2022

Dec. 9, 2022

(Thanks to Almaz Mingaleev.) * NEWS: Mention this. * backzone (America/Yellowknife): Move Zone here ... * northamerica: ... from here. * zone.tab, zone1970.tab: Remove America/Yellowknife. --- NEWS | 8 ++++++++ backzone | 5 +++++ northamerica | 7 ------- zone.tab | 3 +-- zone1970.tab | 3 +-- 5 files changed, 15 insertions(+), 11 deletions(-) diff --git a/NEWS b/NEWS index ac0b611a..98cc14f7 100644 --- a/NEWS +++ b/NEWS @@ -4,6 +4,7 @@ Unreleased, experimental changes Briefly: Much of Greenland still uses DST from 2024 on. + America/Yellowknife now links to America/Edmonton. The code now defaults to C99 or later. Fix use of C23 attributes. @@ -17,6 +18,13 @@ Unreleased, experimental changes This change from 2022g doesn't affect timestamps until 2024-03-30, and doesn't affect tm_isdst until 2023-03-25. + Changes to past timestamps + + America/Yellowknife has changed from a Zone to a backward + compatibility Link, as it no longer differs from America/Edmonton + since 1970. (Thanks to Almaz Mingaleev.) This affects some + pre-1948 timestamps. The old data are now in 'backzone'. + Changes to code The code by default is now designed for C99 or later. To build in diff --git a/backzone b/backzone index 7803c57d..1bd23ac6 100644 --- a/backzone +++ b/backzone @@ -928,6 +928,11 @@ Zone America/Thunder_Bay -5:57:00 - LMT 1895 Zone America/Tortola -4:18:28 - LMT 1911 Jul # Road Town -4:00 - AST +# Yellowknife, Northwest Territories +Zone America/Yellowknife 0 - -00 1935 # Yellowknife founded? + -7:00 NT_YK M%sT 1980 + -7:00 Canada M%sT + # Dumont d'Urville, Île des Pétrels, -6640+14001, since 1956-11 # <https://en.wikipedia.org/wiki/Dumont_d'Urville_Station> (2005-12-05) # diff --git a/northamerica b/northamerica index e33701bf..24b68e72 100644 --- a/northamerica +++ b/northamerica @@ -2125,10 +2125,6 @@ Zone America/Fort_Nelson -8:10:47 - LMT 1884 # Nunavut ... moved ... to incorporate the whole territory into one time zone. # Nunavut moves to single time zone Oct. 31 # http://www.nunatsiaq.com/nunavut/nvt90903_13.html -# -# From Antoine Leca (1999-09-06): -# We then need to create a new timezone for the Kitikmeot region of Nunavut -# to differentiate it from the Yellowknife region. # From Paul Eggert (1999-09-20): # Basic Facts: The New Territory @@ -2322,9 +2318,6 @@ Zone America/Cambridge_Bay 0 - -00 1920 # trading post est.? -5:00 - EST 2000 Nov 5 0:00 -6:00 - CST 2001 Apr 1 3:00 -7:00 Canada M%sT -Zone America/Yellowknife 0 - -00 1935 # Yellowknife founded? - -7:00 NT_YK M%sT 1980 - -7:00 Canada M%sT Zone America/Inuvik 0 - -00 1953 # Inuvik founded -8:00 NT_YK P%sT 1979 Apr lastSun 2:00 -7:00 NT_YK M%sT 1980 diff --git a/zone.tab b/zone.tab index 6e5adb9f..5d5c79ff 100644 --- a/zone.tab +++ b/zone.tab @@ -121,9 +121,8 @@ CA +744144-0944945 America/Resolute Central - NU (Resolute) CA +624900-0920459 America/Rankin_Inlet Central - NU (central) CA +5024-10439 America/Regina CST - SK (most areas) CA +5017-10750 America/Swift_Current CST - SK (midwest) -CA +5333-11328 America/Edmonton Mountain - AB; BC (E); SK (W) +CA +5333-11328 America/Edmonton Mountain - AB; BC (E); NT (E); SK (W) CA +690650-1050310 America/Cambridge_Bay Mountain - NU (west) -CA +6227-11421 America/Yellowknife Mountain - NT (central) CA +682059-1334300 America/Inuvik Mountain - NT (west) CA +4906-11631 America/Creston MST - BC (Creston) CA +5546-12014 America/Dawson_Creek MST - BC (Dawson Cr, Ft St John) diff --git a/zone1970.tab b/zone1970.tab index a9b36d36..819316be 100644 --- a/zone1970.tab +++ b/zone1970.tab @@ -108,9 +108,8 @@ CA +744144-0944945 America/Resolute Central - NU (Resolute) CA +624900-0920459 America/Rankin_Inlet Central - NU (central) CA +5024-10439 America/Regina CST - SK (most areas) CA +5017-10750 America/Swift_Current CST - SK (midwest) -CA +5333-11328 America/Edmonton Mountain - AB; BC (E); SK (W) +CA +5333-11328 America/Edmonton Mountain - AB; BC (E); NT (E); SK (W) CA +690650-1050310 America/Cambridge_Bay Mountain - NU (west) -CA +6227-11421 America/Yellowknife Mountain - NT (central) CA +682059-1334300 America/Inuvik Mountain - NT (west) CA +5546-12014 America/Dawson_Creek MST - BC (Dawson Cr, Ft St John) CA +5848-12242 America/Fort_Nelson MST - BC (Ft Nelson) -- 2.37.2

2 2

[PROPOSED] Try to check longstanding padding assumptions
by Paul Eggert Dec. 8, 2022

Dec. 8, 2022

This is helpful only when porting to oddball platforms in some situations where time_t is signed and has padding bits. (Even C23 allows these platforms.) Formerly tzcode would silently have undefined runtime behavior on such platforms; with this patch, there is likely a compile-time diagnostic instead. * private.h (static_assert): New macro, defined for pre-C23 compilers. (SIGNED_PADDING_CHECK_NEEDED): New constant. Try to check that TIME_T_MIN and TIME_T_MAX are actually the min and max time_t values. --- private.h | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/private.h b/private.h index 1d6ddf7..7ddf4e5 100644 --- a/private.h +++ b/private.h @@ -43,6 +43,10 @@ # include <stdbool.h> #endif +#if __STDC_VERSION__ < 202311 +# define static_assert(cond) extern int static_assert_check[(cond) ? 1 : -1] +#endif + /* ** zdump has been made independent of the rest of the time ** conversion package to increase confidence in the verification it provides. @@ -833,10 +837,23 @@ ATTRIBUTE_REPRODUCIBLE time_t time2posix_z(timezone_t, time_t); int: INT_MAX, long: LONG_MAX, long long: LLONG_MAX, \ default: TIME_T_MAX_NO_PADDING) \ : (time_t) -1) +enum { SIGNED_PADDING_CHECK_NEEDED + = _Generic((time_t) 0, + signed char: false, short: false, + int: false, long: false, long long: false, + default: true) }; #else # define TIME_T_MIN TIME_T_MIN_NO_PADDING # define TIME_T_MAX TIME_T_MAX_NO_PADDING -#endif +enum { SIGNED_PADDING_CHECK_NEEDED = true }; +#endif +/* Try to check the padding assumptions. Although TIME_T_MAX and the + following check can both have undefined behavior on oddball + platforms due to shifts exceeding widths of signed integers, these + platforms' compilers are likely to diagnose these issues in integer + constant expressions, so it shouldn't hurt to check statically. */ +static_assert(! TYPE_SIGNED(time_t) || ! SIGNED_PADDING_CHECK_NEEDED + || TIME_T_MAX >> (TYPE_BIT(time_t) - 2) == 1); /* ** 302 / 1000 is log10(2.0) rounded up. -- 2.38.1

1 0

[PROPOSED] Update city lists in theory.html
by Paul Eggert Dec. 7, 2022

Dec. 7, 2022

* theory.html: Update xMT city lists to match what’s currently generated by the default build. --- theory.html | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/theory.html b/theory.html index 6a39ce7a..fbbb9e47 100644 --- a/theory.html +++ b/theory.html @@ -494,7 +494,7 @@ in decreasing order of importance: <p> <small>These abbreviations are: AMT Asunción, Athens; - BMT Baghdad, Bangkok, Batavia, Bermuda, Bern, Bogotá, Bridgetown, + BMT Baghdad, Bangkok, Batavia, Bermuda, Bern, Bogotá, Brussels, Bucharest; CMT Calamarca, Caracas, Chisinau, Colón, Córdoba; DMT Dublin/Dunsink; @@ -506,7 +506,7 @@ in decreasing order of importance: IMT Irkutsk, Istanbul; JMT Jerusalem; KMT Kaunas, Kyiv, Kingston; - LMT Lima, Lisbon, local, Luanda; + LMT Lima, Lisbon, local; MMT Macassar, Madras, Malé, Managua, Minsk, Monrovia, Montevideo, Moratuwa, Moscow; PLMT Phù Liễn; -- 2.37.2

1 0

[PATCH] Update abbreviation lists in theory.html
by Paul Eggert Dec. 7, 2022

Dec. 7, 2022

* theory.html: Update abbreviation lists to match what’s currently generated by the default build. --- theory.html | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/theory.html b/theory.html index f2b798be..6a39ce7a 100644 --- a/theory.html +++ b/theory.html @@ -443,11 +443,11 @@ in decreasing order of importance: CAT/CAST Central Africa, CET/CEST/CEMT Central European, ChST Chamorro, - CST/CDT/CWT/CPT/CDDT Central [North America], + CST/CDT/CWT/CPT Central [North America], CST/CDT China, GMT/BST/IST/BDST Greenwich, EAT East Africa, - EST/EDT/EWT/EPT/EDDT Eastern [North America], + EST/EDT/EWT/EPT Eastern [North America], EET/EEST Eastern European, GST/GDT Guam, HST/HDT/HWT/HPT Hawaii, @@ -460,13 +460,13 @@ in decreasing order of importance: MET/MEST Middle European (a backward-compatibility alias for Central European), MSK/MSD Moscow, - MST/MDT/MWT/MPT/MDDT Mountain, + MST/MDT/MWT/MPT Mountain, NST/NDT/NWT/NPT/NDDT Newfoundland, NST/NDT/NWT/NPT Nome, NZMT/NZST New Zealand through 1945, NZST/NZDT New Zealand 1946–present, PKT/PKST Pakistan, - PST/PDT/PWT/PPT/PDDT Pacific, + PST/PDT/PWT/PPT Pacific, PST/PDT Philippine, SAST South Africa, SST Samoa, @@ -512,6 +512,7 @@ in decreasing order of importance: PLMT Phù Liễn; PMT Paramaribo, Paris, Perm, Pontianak, Prague; PMMT Port Moresby; + PPMT Port-au-Prince; QMT Quito; RMT Rangoon, Riga, Rome; SDMT Santo Domingo; @@ -519,8 +520,7 @@ in decreasing order of importance: SMT Santiago, Simferopol, Singapore, Stanley; TBMT Tbilisi; TMT Tallinn, Tehran; - WMT Warsaw; - ZMT Zomba.</small> + WMT Warsaw.</small> </p> <p> -- 2.37.2

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