bug#36870: date bug

[Bengt Richter]

Hi Ludovic,

Please excuse my direct mail and speculative shot at CC-ing bug-guix ;-/
(Hope to get my email stuff in order RSN :)

Bug: The plain old date command seems confused about zone info,
as you can see from the following:

Bottom line: I would look for a regex that erroneously excludes
embedded forward slashes in forming the TZ key used to look up
the localtime date info in tables like

/gnu/store/xml1s9r9vp98amhyyn3q85p5xls3nivf-tzdata-2019a/share/zoneinfo/tzdata.zi

The date bug ripples into lots of dependents, such as "who -b" that first made 
me notice,
and lots more -- really need to fix! ;-)

$ 
$ echo $TZ # my current zone
America/Los_Angeles
$ # plain America without following slash does not exist in the table, so how 
does date punt then? Insert key itself as %Z?
$ egrep -m3 '^Z America([^/]|$)' 
/gnu/store/xml1s9r9vp98amhyyn3q85p5xls3nivf-tzdata-2019a/share/zoneinfo/tzdata.zi
$ egrep -m3 '^Z America([^/]|$)' 
/gnu/store/xml1s9r9vp98amhyyn3q85p5xls3nivf-tzdata-2019a/share/zoneinfo/tzdata.zi
$ egrep -m3 '^Z America([/]|$)' 
/gnu/store/xml1s9r9vp98amhyyn3q85p5xls3nivf-tzdata-2019a/share/zoneinfo/tzdata.zi
Z America/Danmarkshavn -1:14:40 - LMT 1916 Jul 28
Z America/Scoresbysund -1:27:52 - LMT 1916 Jul 28
Z America/Godthab -3:26:56 - LMT 1916 Jul 28
$ egrep -m3 '^Z America/Los' 
/gnu/store/xml1s9r9vp98amhyyn3q85p5xls3nivf-tzdata-2019a/share/zoneinfo/tzdata.zi
Z America/Los_Angeles -7:52:58 - LMT 1883 N 18 12:7:2
$ 

Earlier experiments, to get to above speculation, taken from emacs M-x shell:

(Many examples below contrast the /usr/bin/ versions from arch linux
with those redirected by guix profile links (more details follow))

-------------------------------------------------------------
[19:13 ~/bs]$ PS1='$ ' # minimize prompt overhead
$ 
$ # first noticed in wrong directory name I generate
$ # based on who -b -- which in turn depends on date
$ # which has the bug (produces UTC, but more to it):
$ date -Is
2019-07-31T02:22:29+00:00
$ /usr/bin/date -Is
2019-07-30T19:22:48-07:00
$ date --version
date (GNU coreutils) 8.30
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://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.
$ /usr/bin/date --version
date (GNU coreutils) 8.31
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://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.
$ # but the real clue is from plain date, which mangles output order and TZ 
info:
$ date
Wed Jul 31 02:24:30 America 2019
$ /usr/bin/date
Tue 30 Jul 2019 07:24:45 PM PDT
$ which -a env
/home/bokr/.guix-profile/bin/env
/usr/bin/env
$ env|grep TZ
TZ=America/Los_Angeles
$ /usr/bin/env|grep TZ
TZ=America/Los_Angeles
$ uname -a
Linux PhantoNv4ArchGx 5.1.15-arch1-1-ARCH #1 SMP PREEMPT Tue Jun 25 04:49:39 
UTC 2019 x86_64 GNU/Linux
$ uname -rv
5.1.15-arch1-1-ARCH #1 SMP PREEMPT Tue Jun 25 04:49:39 UTC 2019
$ grep -m1 'model name' /proc/cpuinfo
model name      : Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
$ ## BTW, for me, arch linux with kernel 5.2.x went glacial with unk busyness
$ ## and forced me to stay for now with 5.1.15 as "foreign distro" for my guix, 
which is
$ guix --version
guix (GNU Guix) 34e549d813113fc57213202fd5e4b885d95d0913
Copyright (C) 2019 the Guix authors
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.
$ guix describe
Generation 6    Jul 11 2019 08:41:53    (current)
  guix 34e549d
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 34e549d813113fc57213202fd5e4b885d95d0913
$ 
$ ## I should probably do a pull and see if this has been fixed already, so, 
will do that...
$
2019-07-30 19:51:35 [ ] going for pull..

-------------------------------------------------------------

Well, that didn't fix it, unless reboot is required ...

$ guix describe
Generation 7    Jul 31 2019 03:25:55    (current)
  guix 274ba54
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 274ba54e535b811acca02e42cffd45f0f625d142
$ date
Wed Jul 31 03:44:28 America 2019
$ /usr/bin/date
Tue 30 Jul 2019 08:44:42 PM PDT
$ date  '+%F %T %z %Z'
2019-07-31 03:45:44 +0000 America
$ /usr/bin/date  '+%F %T %z %Z'
2019-07-30 20:46:12 -0700 PDT
$ file /etc/localtime 
/etc/localtime: symbolic link to /usr/share/zoneinfo/Europe/Stockholm
$ # but TZ env variable usually overrides (seemingly, in my setup), and I am
$ # currently in Seattle zone, and I change TZ in ~/.bash_profile to current
$ env|grep TZ
TZ=America/Los_Angeles
$ /usr/bin/env|grep TZ
TZ=America/Los_Angeles
$ date --version 
$ date --version
date (GNU coreutils) 8.30
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://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.
$ /usr/bin/date --version
date (GNU coreutils) 8.31
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://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.
$
---------------------------------------
Hard to believe the 8.30 to 8.31 version difference accounts for the problem.

HTH,
Regards,
Bengt Richter