unofficial mirror of bug-gnu-emacs@gnu.org 
 help / color / mirror / code / Atom feed
* bug#11281: DST has not effect on windows XP when system DST adjustment is disabled
@ 2012-04-19 16:35 Shuguang Sun
  2019-11-01 19:54 ` Stefan Kangas
  0 siblings, 1 reply; 3+ messages in thread
From: Shuguang Sun @ 2012-04-19 16:35 UTC (permalink / raw)
  To: 11281

I'm using GNU Emacs 24.0.95.1 (i386-mingw-nt5.1.2600) of 2012-04-02 on
MARVIN on WindowsXP SP3. I believe the issue exists in other version
as well.

In windows,
1. If I select the time zone GMP-5 EST (East Standard Time) and  check
the enable Daylight Saving Time checkbox, the command
display-time-world in emacs can show the time of New York correctly
with DST.
2. If I select the time zone GMP-5 EST (East Standard Time) and
UNCHECK the enable Daylight Saving Time checkbox, or if I select a
time zone without DST, the command display-time-world in emacs can not
show the time of New York correctly with DST.
But actually the display-time-world-list for New York is ("EST5EDT"
"New York"), which (EST5EDT) supposes to enable the Daylight Saving
Time to show the time.

I try the following code to trace the issue:
(setq old-tz (getenv "TZ"))
(setenv "TZ" "EST+5EDT")
(message (format "%s" (getenv "TZ")))
(message (format-time-string "%A %d %B %R %Z"))
(decode-time)
(setenv "TZ" "EST+5")
(message (format "%s" (getenv "TZ")))
(message (format-time-string "%A %d %B %R %Z"))
(decode-time)
(setenv "TZ" old-tz)

The output is (Because I select a timezone without DST in windows, the
time in the outputs is no DST as I described above):
"EST+5EDT"
"Thursday 19 April 11:27 EDT"
(26 27 11 19 4 2012 4 t -18000)

"EST+5"
"Thursday 19 April 11:27 EST"
(34 27 11 19 4 2012 4 nil -18000)

(DST is t if daylight saving time is in effect,otherwise nil.from the
doc of decode-time) From the output of decode-time, it is clear that
if the TZ is set to "EST+5EDT", the DST is effect. So it is most
likely the function format-time-string can not catch this information.
But it is still weird that it DOES has effect if I enable the DST in
the Windows system.





^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2020-08-07 11:12 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-04-19 16:35 bug#11281: DST has not effect on windows XP when system DST adjustment is disabled Shuguang Sun
2019-11-01 19:54 ` Stefan Kangas
2020-08-07 11:12   ` Stefan Kangas

Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).