Re: [PATCH v2] date.c: allow ISO 8601 reduced precision times

Đoàn Trần Công Danh  [off-list ref] writes:

ISO 8601 permits "reduced precision" time representations to omit the
seconds value or both the minutes and the seconds values.  The
abbreviate times could look like 17:45 or 1745 to omit the seconds,
or simply as 17 to omit both the minutes and the seconds.

parse_date_basic accepts the 17:45 format but it rejects the other two.
Change it to accept 4-digit and 2-digit time values when they follow a
recognized date and a 'T'.

Before this change:

$ TZ=UTC test-tool date approxidate 2022-12-13T23:00 2022-12-13T2300 2022-12-13T23
2022-12-13T23:00 -> 2022-12-13 23:00:00 +0000
2022-12-13T2300 -> 2022-12-13 23:54:13 +0000
2022-12-13T23 -> 2022-12-13 23:54:13 +0000

After this change:

$ TZ=UTC helper/test-tool date approxidate 2022-12-13T23:00 2022-12-13T2300 2022-12-13T23
2022-12-13T23:00 -> 2022-12-13 23:00:00 +0000
2022-12-13T2300 -> 2022-12-13 23:00:00 +0000
2022-12-13T23 -> 2022-12-13 23:00:00 +0000

Note: ISO 8601 also allows reduced precision date strings such as
"2022-12" and "2022". This patch does not attempt to address these.

Reported-by: Pat LaVarre <redacted>
Signed-off-by: Phil Hord <redacted>
Signed-off-by: Đoàn Trần Công Danh <redacted>
---

Since this is a complete re-implementation from Phil Hord's version.
I'm reassigning the author to me.

This version change the implementation to only treat the string as ISO8601 if
a 'T' existed and date has been parsed. I also added a test for parsing
RFC-822, which Hord accidentally broke.

The commit message has been changed:
* The example has been changed to be independent from local timezone
* Remove the mention of adding test-cases, since it's obviously necessary.

Will replace Phil's patch with this (hence even under your
authorship, the topic name will be reused).

Thanks, both.