[PATCH] test-parse-date: fix timezone name used to test local time with DST

[Yuya Nishihara]

On Sat, 13 Feb 2016 07:24:11 +0100, Sébastien Brissaud wrote:
> On 2016-02-11 07:29, Yuya Nishihara wrote:
> > On Sun, 07 Feb 2016 09:31:22 +0100, Sébastien Brissaud wrote:
> >> -  $ TZ="PST+8PDT"
> >> +  $ TZ="PST8PDT"
> >>    $ export TZ
> > 
> > It seems "PST+8PDT" is valid.
> > 
> > http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
> 
> > Do you have any problem with "PST+8PDT" ?
> 
> I'm running Debian testing and test-parse-date.t failed with incorrect 
> DST offsets:
> -  Sat Jul 15 13:30:00 2006 -0700
> +  Sat Jul 15 13:30:00 2006 -0800

Hmm, I'm on Debian sid, but I couldn't reproduce the problem.

ii  libc6:amd64    2.21-7       amd64        GNU C Library: Shared libraries
ii  python         2.7.11-1     amd64        interactive high-level object-ori
ii  tzdata         2016a-1      all          time zone and daylight-saving tim

> Setting TZ to PST8PDT make the test pass.
> But as you said earlier 'PST+8PDT' is a valid TZ value.
> 
> In fact it seems to be related as how TZ is managed on my system.
> 
> Testing it directly in a python shell exhibit the same problem:
> Python 2.7.11 (default, Jan 11 2016, 21:04:40)
> [GCC 5.3.1 20160101] on linux2
> >>> os.environ['TZ'] = 'PST+8PDT'
> >>> time.tzset()
> >>> time.tzname
> ('PST', 'PST')
> >>> 
> >>> os.environ['TZ'] = 'PST8PDT'
> >>> time.tzset()
> >>> time.tzname
> ('PST', 'PDT')
> 
> PST8PDT works for me because it's resolved to a timezone file in
> /usr/share/zoneinfo.
> I'll investigate the posix compliancy/configuration of TZ in my system.
> 
> test-parse-date.t is thus correct and my patch is irrelevant.

That said, since "PST+8PDT" does not specify dst start/end, it would depend
on the system zoneinfo files anyway.

  % TZ=PST+8PDT strace date 2>&1 | grep zoneinfo
  open("/usr/share/zoneinfo/PST+8PDT", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
  open("/usr/share/zoneinfo/posixrules", O_RDONLY|O_CLOEXEC) = 3
  % TZ=PST8PDT strace date 2>&1 | grep zoneinfo
  open("/usr/share/zoneinfo/PST8PDT", O_RDONLY|O_CLOEXEC) = 3

https://sourceware.org/git/?p=glibc.git;a=blob;f=time/tzset.c;h=8bc7a2e05bb83e9e6e37d6f2b6db2d6ad49b9b8b;hb=4e42b5b8f89f0e288e68be7ad70f9525aebc2cff#l278

If PST8PDT can provide more stable result, it will be fine to use that TZ
value. Can you resend the patch with updated commit message?