Re: [bug-gnulib] problem with getdate

[Ian Abbott]

On 12/04/05 08:24, Paul Eggert wrote:
> Derek Price <address@hidden> writes:
>
> > If I pass these times in as "EDT" (Eastern Daylight Time), then they
> > work.  Ian mentioned doing something similar with "BST" (British
> > Summer Time) in a separate email.  Is this an intentional failure?
>
>
> No, it's not.  I installed this fix into gnulib.  Thanks for reporting
> it.
>
> 2005-04-12  Paul Eggert  <address@hidden>
>
>         * getdate.y (universal_time_zone_table): New constant.
>         (time_zone_table): Remove GMT, UT, UTC entries; they're now in
>         universal_time_zone_table.
>         (lookup_zone): Prefer universal_time_zone_table to
>         local_time_zone_table, so that "GMT" time stamps are allowed in
>         London during the summer.  Problem reported by Ian Abbott.

I realize GMT is something of a special case, since it is both a local 
timezone in the UK and a universal timezone (historically as a 
predecessor of UTC and currently in certain applications).  However, in 
the general case, should the validity of a timespec depend on the local 
timezone in effect when running the code?  Going back to the "EST" 
(Eastern Standard Time) example, the validity of dates that fall within 
the daylight savings period varies according to the local timezone:

$ TZ=Europe/London ./getdate
Enter date, or blank line to exit.
        > 2005-5-1 EST
2005-05-01 06:00:00.000000000
        > $
$ TZ=America/New_York ./getdate
Enter date, or blank line to exit.
        > 2005-5-1 EST
Bad format - couldn't convert.
        > $
$

The timespec "2005-5-1 EST" is not valid if EST time periods and EDT 
time periods should be considered mutually exclusive (except when they 
overlap at the end of EDT).  But I don't think the validity should 
depend on the local timezone and a forgiving implementation should 
probably allow "2005-5-1 EST" regardless of whether EST or EDT is in effect.

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