Subject: reviewer for time-related bugs (srfi-19)

From: Andy Wingo <[email-masked]>
Date: Sat, 25 Jun 2016 11:36:48 +0200

Thanks, that's great :)

For this and the other time-related bugs it sounds like you know what
you're doing but I would like someone to check the work just to make
sure we're not introducing new errors.

To that end, I ask guile-devel, in this top-post so that people will see
it :), for a volunteer!

Are you a person who is interested in the specifics of time
representation?  TAI, UTC, and all that?

If so your input is very much appreciated on the patch quoted below from
bug 21902, and also on these other bugs:

 https://debbugs.gnu.org/21902  doc incorrectly describes Julian Date
 https://debbugs.gnu.org/21903  date->string duff ISO 8601 negative years
 https://debbugs.gnu.org/21904  date->string duff ISO 8601 format for non-4-digit years
 https://debbugs.gnu.org/21906  julian-day->date negative input breakage
 https://debbugs.gnu.org/21907  date->string duff ISO 8601 zone format
 https://debbugs.gnu.org/21911  TAI-to-UTC conversion leaps at wrong time
 https://debbugs.gnu.org/21912  TAI<->UTC conversion botches the unknown
 https://debbugs.gnu.org/22033  time-utc format is lossy
 https://debbugs.gnu.org/22034  time-utc->date shows bogus zone-dependent leap second

To give feedback is very easy.  The first thing is to confirm the bug
report: does it make sense to you?  If you or Zefram comes up with a
patch to fix the issue, as below, that's even better of course, but
already just a confirmation of the bug would be great.

To comment on the bug, just send a mail to [email-masked], where
NNNN is the bug number.  Super easy.

Cheers, and thanks in advance!

Andy

On Fri 24 Jun 2016 20:01, Zefram <[email-masked]> writes:

> Andy Wingo wrote:
>>Would you like to propose a specific patch to the documentation?
>
> Sure.  Patch attached.
>
> -zefram
>
> --- a/doc/ref/srfi-modules.texi	2014-03-20 20:21:21.000000000 +0000
> +++ b/doc/ref/srfi-modules.texi	2016-06-24 18:57:59.088243245 +0100
> @@ -2461,8 +2461,8 @@
>  @cindex UTC
>  @cindex TAI
>  This module implements time and date representations and calculations,
> -in various time systems, including universal time (UTC) and atomic
> -time (TAI).
> +in various time systems, including Coordinated Universal Time (UTC)
> +and International Atomic Time (TAI).
>  
>  For those not familiar with these time systems, TAI is based on a
>  fixed length second derived from oscillations of certain atoms.  UTC
> @@ -2494,18 +2494,12 @@
>  @cindex julian day
>  @cindex modified julian day
>  Also, for those not familiar with the terminology, a @dfn{Julian Day}
> -is a real number which is a count of days and fraction of a day, in
> -UTC, starting from -4713-01-01T12:00:00Z, ie.@: midday Monday 1 Jan
> -4713 B.C.  A @dfn{Modified Julian Day} is the same, but starting from
> -1858-11-17T00:00:00Z, ie.@: midnight 17 November 1858 UTC.  That time
> -is julian day 2400000.5.
> -
> -@c  The SRFI-1 spec says -4714-11-24T12:00:00Z (November 24, -4714 at
> -@c  noon, UTC), but this is incorrect.  It looks like it might have
> -@c  arisen from the code incorrectly treating years a multiple of 100
> -@c  but not 400 prior to 1582 as non-leap years, where instead the Julian
> -@c  calendar should be used so all multiples of 4 before 1582 are leap
> -@c  years.
> +is a real number which is a count of days and fraction of a day, in UT,
> +starting from -4713-11-24T12:00:00Z, ie.@: midday UT on Monday 24 November
> +4714 BC in the proleptic Gregorian calendar (1 January 4713 BC in the
> +proleptic Julian calendar).  A @dfn{Modified Julian Day} is the same,
> +but starting from 1858-11-17T00:00:00Z, ie.@: midnight UT on Wednesday
> +17 November AD 1858.  That time is julian day 2400000.5.
>  
>  
>  @node SRFI-19 Time