bug#14210: 23.4; Timezone handling?

[Eli Zaretskii]

> Date: Mon, 15 Apr 2013 12:40:22 -0300
> From: "Julio Pacheco T." <julio.pacheco@provectis.cl>
> 
> Apparently, Emacs is ignoring the system timezone settings and using its 
> own definitions.

Not really, no.

> In Chile, the switch from daylight savings to standard time has been 
> postponed from March 10 00:00 to April 28 00:00, and the system tzdata 
> files have been properly updated; however, inside Emacs, the timezone is 
> reported as CLT instead of CLST:
> 
> Output of zdump -v Chile/Continental | grep 2013
> ------------------------------------------------
> Chile/Continental  Sun Apr 28 02:59:59 2013 UTC = Sat Apr 27 23:59:59 2013 
> CLST isdst=1 gmtoff=-10800
> Chile/Continental  Sun Apr 28 03:00:00 2013 UTC = Sat Apr 27 23:00:00 2013 
> CLT isdst=0 gmtoff=-14400
> Chile/Continental  Sun Sep  8 03:59:59 2013 UTC = Sat Sep  7 23:59:59 2013 
> CLT isdst=0 gmtoff=-14400
> Chile/Continental  Sun Sep  8 04:00:00 2013 UTC = Sun Sep  8 01:00:00 2013 
> CLST isdst=1 gmtoff=-10800
> 
> Output of emacs Calendar/Lunar phases (note the switch CLST-> CLT in the 
> Mar 4 - Mar 11 interval, instead of Apr25 - May2):
> ---------------------------------------
> Monday, March 4, 2013: Last Quarter Moon 6:59pm (CLST)
> Monday, March 11, 2013: New Moon 3:54pm (CLT)
> Tuesday, March 19, 2013: First Quarter Moon 1:28pm (CLT)
> Wednesday, March 27, 2013: Full Moon 5:26am (CLT)
> Wednesday, April 3, 2013: Last Quarter Moon 12:43am (CLT)
> Wednesday, April 10, 2013: New Moon 5:39am (CLT)
> Thursday, April 18, 2013: First Quarter Moon 8:33am (CLT)
> Thursday, April 25, 2013: Full Moon 3:55pm (CLT)
> Thursday, May 2, 2013: Last Quarter Moon 7:21am (CLT)
> Thursday, May 9, 2013: New Moon 8:32pm (CLT)
> Saturday, May 18, 2013: First Quarter Moon 12:36am (CLT)
> Saturday, May 25, 2013: Full Moon 12:22am (CLT)
> Friday, May 31, 2013: Last Quarter Moon 3:05pm (CLT)
> 
> Also, in org-mode the timestamps created by org-clock-in are off by -1 
> hour, so the discrepancies in timezone are not mode-specific.
> 
> So, where is emacs actually getting the timezone info from?

>From your system, of course.  Although packages like Calendar might
sometimes offer features that use some internal data (but not in this
case, I think).

Let's start with the basics: What does this print:

   M-: (format-time-string "%H:%M %Z %z")

and how does the time it shows compare with your system clock?

Next, do you have a TZ variable in your environment, and if you do,
what is its value?