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bug#22302: 25.1.50; time-stamp ignores time-stamp-time-zone
From: |
Eli Zaretskii |
Subject: |
bug#22302: 25.1.50; time-stamp ignores time-stamp-time-zone |
Date: |
Wed, 13 Jan 2016 17:47:39 +0200 |
> Cc: rgm@gnu.org, 22302@debbugs.gnu.org, hanche@math.ntnu.no
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Tue, 12 Jan 2016 13:29:23 -0800
>
> On 01/12/2016 12:51 PM, Eli Zaretskii wrote:
> >> don't know what MS-Windows does with TZ="UTC"
> > Nothing. It doesn't understand that. The MS-Windows time routines
> > need an explicit offset from UTC to be able to account for the
> > timezone. So unless you say UTC-0, nothing will happen.
>
> In that case I'm a bit puzzled. Before today, lines like this:
>
> # time-stamp-time-zone: "UTC"
>
> appeared in files like build-aux/gitlog-to-changelog. Emacs implements
> these lines by temporarily setting the TZ environment variable to "UTC".
> If that setting is ineffective on MS-Windows, presumably any relevant
> time stamps were generated in local time instead, which is not wanted.
>
> Perhaps no MS-Windows users noticed, or none of them bothered to file a
> bug report.
>
> Or perhaps "nothing will happen" means "no offset from UTC will be
> applied", which means that unrecognized TZ settings act like UTC; this
> is what tzcode does.
I see that what I said was inaccurate: the MS-Windows runtime indeed
doesn't interpret the 3-letter TZ name, but if the offset is missing,
it is taken as zero. So "UTC" will indeed be interpreted as "UTC+0"
(and so will "EDT" and any other "XXX" with no offset).
Of course, currently this doesn't work in time-stamp, for the reasons
described in the original bug report. But format-time-string does
behave on Windows as described above.
Sorry for any confusion I could cause.