Use org-time-stamp-format function to obtain the timestamp format

[akirak]

The value of org-time-stamp-formats constant is going to be changed in Emacs 29: https://git.sr.ht/~bzg/org-mode/commit/e3a7c01874c9bb80e04ffa58c578619faf09e7f0

This can break the format of the backlink prefix as in the example below:

:BACKLINKS:
[Y-11-18 Fri 19:%] <- [[id:3bdc7eb2-afc4-4931-a6b1-b60953dc5813][Update on the change of org-time-stamp-formats]]
:END:

Rather than using the value of the variable directly, I would recommend you use `org-time-stamp-format' function to obtain the format. It now correctly renders as follows:

:BACKLINKS:
[2022-11-18 Fri 19:25] <- [[id:3bdc7eb2-afc4-4931-a6b1-b60953dc5813][Update on the change of org-time-stamp-formats]]
:END:

[stefan2904]

Test with fresh emacs 28.2 and org 9.5.5

% docker run -i -t org95 emacs --version
GNU Emacs 28.2
Copyright (C) 2022 Free Software Foundation, Inc.
GNU Emacs comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GNU Emacs
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING.

upstream 0.4 tag

% docker run -i -t org95 emacs --script org-sl-test-04.el
Loading /etc/emacs/site-start.d/00debian.el (source)...

"Test for org version: 9.5.5"

"Test using upstream 0.4 tag:"

"org-time-stamp-formats: <%Y-%m-%d %a %H:%M>"

"substring: %Y-%m-%d %a %H:%M"

"org-super-links-link-prefix-timestamp: [2022-12-13 Tue 18:32] -> "

akirak fix-time-format branch

% docker run -i -t org95 emacs --script org-sl-test-fix.el
Loading /etc/emacs/site-start.d/00debian.el (source)...

"Test for org version: 9.5.5"

"Test using akirak fix-time-format branch:"

"org-time-stamp-formats: <%Y-%m-%d %a %H:%M>"

"substring: %Y-%m-%d %a %H:%M"

"org-super-links-link-prefix-timestamp: [2022-12-13 Tue 18:32] -> "

looks good

[stefan2904]

Test with fresh emacs 28.2 and org 9.6 from git

smore@t480ssm ~/projects/org-super-links-experiments % docker run -i -t org96 emacs --version
GNU Emacs 28.2
Copyright (C) 2022 Free Software Foundation, Inc.
GNU Emacs comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GNU Emacs
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING.

upstream 0.4 tag

% docker run -i -t org96 emacs --script org-sl-test-04.el
Loading /etc/emacs/site-start.d/00debian.el (source)...

"Test for org version: 9.6"

"Test using upstream 0.4 tag:"

"org-time-stamp-formats: %Y-%m-%d %a %H:%M"

"substring: Y-%m-%d %a %H:%"

"org-super-links-link-prefix-timestamp: [Y-12-13 Tue 18:%] -> "

akirak fix-time-format branch

% docker run -i -t org96 emacs --script org-sl-test-fix.el
Loading /etc/emacs/site-start.d/00debian.el (source)...

"Test for org version: 9.6"

"Test using akirak fix-time-format branch:"

"org-time-stamp-formats: %Y-%m-%d %a %H:%M"

"substring: Y-%m-%d %a %H:%"

"org-super-links-link-prefix-timestamp: [2022-12-13 Tue 18:44] -> "

the fixed version looks also good

[stefan2904]

Since org-super-links-backlink-prefix-timestamp was also patched, I added it to the tests; works as expected. 👍

See here for the full output:
https://gist.github.com/stefan2904/85cff4c12a1e0e07e3ddd4a822711c39#gistcomment-4401436

[toshism]

Excellent, LGTM! thanks @akirak and @stefan2904 !