[tz] wrong Europe/Dublin dst offset rule

Philip Paeps philip at trouble.is
Wed May 30 11:53:49 UTC 2018

On 2018-05-30 17:16:46 (+0530), Vicky wrote:
>On Sat, 20 Jan 2018, 03:08 Paul Eggert, <eggert at cs.ucla.edu> wrote:
>> On 01/19/2018 12:53 AM, Vicky wrote:
>> > while parsing the data i found the issue in rule Europe/Dublin
>> > Negative DST.. Previous version or not in any other file there is no
>> > negative dst.
>> Yes, although negative DST support is required by POSIX and has been in
>> tzcode for quite some time, that was the first use of it in tzdata. That
>> change was intended to support Irish Standard Time, which is an hour
>> ahead of GMT (which Ireland uses in winter). We're planning to back that
>> change out temporarily, since we found some issues with it with ICU and
>> with OpenJDK.
>> What software are you using to parse the data files? Has the problem
>> been reported to the maintainers of that software?
>In current version also dst is -ve for europe/dublin

This is correct.

>how the dst be negative.. it is always 0 or +1. we are facing issues
>because on this..

Please read through the several threads on this mailing list about this 
topic since December/January.  I don't believe there is any benefit to 
having the discussion again.

>please correct the dst for europe/dublin.

If you can't correct your software to correctly parse tzdb files with 
negative dst, you can use the "rearguard" format of tzdb.

As discussed (at length) though: negative dst is an unfortunate reality 
which your software should be able to deal with.


Philip Paeps
Senior Reality Engineer
Ministry of Information

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