GNU bug report logs - #43828
invalid date converting from UTC, near DST

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Martin Fido" <mart <at> fidolab.org>
To: bug-coreutils <at> gnu.org
Subject: invalid date converting from UTC, near DST
Date: Tue, 06 Oct 2020 22:24:03 +1100

[Message part 1 (text/plain, inline)]

Hi,

I seem to have found a bug in the date utility, converting from UTC to Sydney time. It returns invalid date for what should be perfectly valid:

    $ TZ='Australia/Sydney' date -d '2020-10-04T02:00:00Z'
    date: invalid date ‘2020-10-04T02:00:00Z’

    $ TZ='Australia/Sydney' date -d '2020-10-04T02:59:59Z'
    date: invalid date ‘2020-10-04T02:59:59Z’

Note DST in Sydney changed 10 hours earlier:

    $ TZ='Australia/Sydney' date -d '2020-10-03T15:59:59Z'
    Sunday 4 October  01:59:59 AEST 2020

    $ TZ='Australia/Sydney' date -d '2020-10-03T16:00:00Z'
    Sunday 4 October  03:00:00 AEDT 2020

I have version 8.25:

    $ date --version
    date (GNU coreutils) 8.25
    Copyright (C) 2016 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.

    Written by David MacKenzie.

Thanks,

Martin.

[Message part 2 (text/html, inline)]

Message #10 received at 43828-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Martin Fido <mart <at> fidolab.org>
Cc: 43828-done <at> debbugs.gnu.org
Subject: Re: bug#43828: invalid date converting from UTC, near DST
Date: Tue, 6 Oct 2020 10:28:07 -0700

On 10/6/20 4:24 AM, Martin Fido wrote:
> I have version 8.25:

Seems to have been fixed by coreutils 8.30:

$ TZ='Australia/Sydney' date -d '2020-10-04T02:00:00Z'
Sun 04 Oct 2020 01:00:00 PM AEDT

Message #13 received at 43828 <at> debbugs.gnu.org (full text, mbox):

From: Bob Proulx <bob <at> proulx.com>
To: Martin Fido <mart <at> fidolab.org>
Cc: 43828 <at> debbugs.gnu.org
Subject: Re: bug#43828: invalid date converting from UTC, near DST
Date: Thu, 15 Oct 2020 22:30:17 -0600

Martin Fido wrote:
> I seem to have found a bug in the date utility, converting from UTC
> to Sydney time. It returns invalid date for what should be perfectly
> valid:
> 
>     $ TZ='Australia/Sydney' date -d '2020-10-04T02:00:00Z'
>     date: invalid date ‘2020-10-04T02:00:00Z’
> 
>     $ TZ='Australia/Sydney' date -d '2020-10-04T02:59:59Z'
>     date: invalid date ‘2020-10-04T02:59:59Z’

This is more likely to be in the tzdata zoneinfo database rather than
in date itself.  Could you please report what version of tzdata you
have on your system?  Current on my system is tzdata version 2020b-1.

And also this information too.

    $ zdump -v Australia/Sydney | grep 2020
    Australia/Sydney  Sat Apr  4 15:59:59 2020 UT = Sun Apr  5 02:59:59 2020 AEDT isdst=1 gmtoff=39600
    Australia/Sydney  Sat Apr  4 16:00:00 2020 UT = Sun Apr  5 02:00:00 2020 AEST isdst=0 gmtoff=36000
    Australia/Sydney  Sat Oct  3 15:59:59 2020 UT = Sun Oct  4 01:59:59 2020 AEST isdst=0 gmtoff=36000
    Australia/Sydney  Sat Oct  3 16:00:00 2020 UT = Sun Oct  4 03:00:00 2020 AEDT isdst=1 gmtoff=39600

> Note DST in Sydney changed 10 hours earlier:
> 
>     $ TZ='Australia/Sydney' date -d '2020-10-03T15:59:59Z'
>     Sunday 4 October  01:59:59 AEST 2020
> 
>     $ TZ='Australia/Sydney' date -d '2020-10-03T16:00:00Z'
>     Sunday 4 October  03:00:00 AEDT 2020

Yes.  And I think that is suspicious.  Hopefully the zdump information
will show that database is in need of an update and that is the root
of the problem.  I suspect that DST was moved at some point in time.

> I have version 8.25:
> 
>     $ date --version
>     date (GNU coreutils) 8.25

I tried this on 8.13, 8.23, 8.26, and 8.32 and was unable to reproduce
the problem on any of those versions of date.  But I suspect the root
cause is in the tzdata zoneinfo database.

Bob

Message #16 received at 43828 <at> debbugs.gnu.org (full text, mbox):

From: "Martin Fido" <mart <at> fidolab.org>
To: "Bob Proulx" <bob <at> proulx.com>
Cc: 43828 <at> debbugs.gnu.org
Subject: Re: bug#43828: invalid date converting from UTC, near DST
Date: Fri, 16 Oct 2020 17:00:22 +1100

I have tzdata version 2020a:

    $ apt-cache policy tzdata
    tzdata:
      Installed: 2020a-0ubuntu0.16.04
      Candidate: 2020a-0ubuntu0.16.04
    ...

    $ zdump -v Australia/Sydney | grep 2020
    Australia/Sydney  Sat Apr  4 15:59:59 2020 UT = Sun Apr  5 02:59:59 2020 AEDT isdst=1 gmtoff=39600
    Australia/Sydney  Sat Apr  4 16:00:00 2020 UT = Sun Apr  5 02:00:00 2020 AEST isdst=0 gmtoff=36000
    Australia/Sydney  Sat Oct  3 15:59:59 2020 UT = Sun Oct  4 01:59:59 2020 AEST isdst=0 gmtoff=36000
    Australia/Sydney  Sat Oct  3 16:00:00 2020 UT = Sun Oct  4 03:00:00 2020 AEDT isdst=1 gmtoff=39600

Message #19 received at 43828 <at> debbugs.gnu.org (full text, mbox):

From: Bob Proulx <bob <at> proulx.com>
To: Martin Fido <mart <at> fidolab.org>
Cc: 43828 <at> debbugs.gnu.org
Subject: Re: bug#43828: invalid date converting from UTC, near DST
Date: Wed, 28 Oct 2020 23:10:39 -0600

Martin Fido wrote:
> I have tzdata version 2020a:
> 
>     $ apt-cache policy tzdata
>     tzdata:
>       Installed: 2020a-0ubuntu0.16.04
>       Candidate: 2020a-0ubuntu0.16.04
>     ...
> 
>     $ zdump -v Australia/Sydney | grep 2020
>     Australia/Sydney  Sat Apr  4 15:59:59 2020 UT = Sun Apr  5 02:59:59 2020 AEDT isdst=1 gmtoff=39600
>     Australia/Sydney  Sat Apr  4 16:00:00 2020 UT = Sun Apr  5 02:00:00 2020 AEST isdst=0 gmtoff=36000
>     Australia/Sydney  Sat Oct  3 15:59:59 2020 UT = Sun Oct  4 01:59:59 2020 AEST isdst=0 gmtoff=36000
>     Australia/Sydney  Sat Oct  3 16:00:00 2020 UT = Sun Oct  4 03:00:00 2020 AEDT isdst=1 gmtoff=39600

I see this is Ubuntu 16.04.  I found a 16.04 system and I was able to
recreate this exact problem there.  However trying this on an 18.04
system and it is no longer an invalid date.

Bob

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