From: Hirotsugu Asari <asari.ruby@...>
Date: 2010-06-09T08:52:28+09:00
Subject: [ruby-core:30682] Re: [Bug #3411] Time.local 1916,5,1 #=> 1916-04-30 23:00:00 +0100

On Jun 8, 2010, at 6:42 PM, Benoit Daloze <eregontp@gmail.com> wrote:

> Hi !
> On 9 June 2010 00:27, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
>> Hi,
>>
>> Cannot reproduce on my timezone.  Could you tell us your timezone
>> setting?
>>
>>                                                        matz.
>
> Yes, I suppose The Land of the Rising Sun is far enough from UTC :)
>
> I am at Brussels, BRU - Belgium, CEST (UTC+2) (and so CET (UTC+1) in  
> winter).
>
> On 9 June 2010 00:34, Hirotsugu Asari <asari.ruby@gmail.com> wrote:
>> I think this is most definitely a time zone thing:
>> $ uname -a; TZ=Europe/Amsterdam ruby1.9 -e 'p Time.local 1916,5,1'
>> Darwin aotearoa.local 10.3.0 Darwin Kernel Version 10.3.0: Fri Feb 26
>> 11:58:09 PST 2010; root:xnu-1504.3.12~1/RELEASE_I386 i386
>> 1916-04-30 23:00:00 +0020
>> Besides Europe/Amsterdam, Asia/Istanbul and Europe/Brussels return  
>> this
>> result on my machine.
>
> Indeed, this seems particular to UTC+1
> Is this expected? :
> $ TZ=Europe/Bucharest ruby -e 'p Time.local 1916,5,1' # 1916-05-01
> 00:00:00 +0144
> $ TZ=Europe/Budapest ruby -e 'p Time.local 1916,5,1' # 1916-05-01  
> 00:00:00 +0200
> $ TZ=Europe/Riga ruby -e 'p Time.local 1916,5,1' # 1916-05-01  
> 00:00:00 +0136
> $ TZ=Europe/Helsinki ruby -e 'p Time.local 1916,5,1' # 1916-05-01  
> 00:00:00 +0140
>
> Should I try to find some history about timezones? (if I use Time.now,
> I get expected results)
>
> Anyway, knowing timezones have changed, I think I should use only
> Time.utc for old dates in which only the day matters.

You can read zoneinfo database and see which dates are "funny" in  
which time zones.

> But this is still surprising me.
>
> Regards,
> B.D.
>