Re: [BUG] LANG=fr_FR.UTF-8 org-clock "not at timestamp"

[Ihor Radchenko]

Ruijie Yu via "General discussions about Org-mode."
<emacs-orgmode@gnu.org> writes:

> I am investigating test failures with LANG=fr_FR.UTF-8 amongst some
> other locales.  I noticed that the test
> `test-org-clok/org-clock-timestamps-change' in
> testing/lisp/test-org-clock.el around line 92 failed with "not at
> timestamp", which I presume reveals a genuine bug.
>
> To simplify, here is a reproducer:
>
> --8<---------------cut here---------------start------------->8---
> (require 'org-clock)
> (with-temp-buffer
>   (org-mode)
>   (insert "CLOCK: [2023-02-19 Sun 22:30]--[2023-02-20 Mon 00:35] =>  2:05")
>   (goto-char 25)                        ; 2|2:30
>   (org-clock-timestamps-change 'down 1))
> --8<---------------cut here---------------end--------------->8---

Confirmed.

> The error appears: "Not at timestamp".  I think it is due to the "." in
> French day-of-week words, such as "dim.", "lun.", etc.  Something must
> not be expecting punctuations in that place.

Nope. It is because the total length of the timestamp changes.
`org-clock-timestamps-change' records buffer positions before changing
the timestamps and when the timestamp changes in length, positions may
no longer be accurate. In your reproducer, begts2 points one char before
the actual timestamp upon modification and thus the logic fails.

Note that we cannot use markers here because `org-timestamp-up'/down use
`replace-match' that shuffles the markers around. (see FIXME in
`org-timestamp-change').

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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