Re: [PATCH] org-agenda.el: Avoid dependency on subr-x

[Maxim Nikulin <manikulin@gmail.com>]

The patch is created for the maint branch.

I have reordered some part of the quoted message.

On 05/08/2021 05:11, Tim Cross wrote:
 > I don't think this patch is required, especially since we have not had
 > any bug reported relating to that version.

org-agenda.el (and some other files) should be fixed anyway.

make single
...
Compiling single /home/ubuntu/org-mode/lisp/org-agenda.el...

In end of data:
org-agenda.el:10769:1:Warning: the function ‘string-empty-p’ is not known to
     be defined.

(log for emacs-25.2.2)

> Note that compatibility with 24.3 was not the cause of the OP original
> issue (they were running 26.3).

I just do not have enough experience with elisp to suggest a patch to 
explicitly notify users that they have mixed org install. On the other 
hand, particular symptom from the report can be easily mitigated.

> Do we really want to maintain compatibility with Emacs 24.3?

There is the only place in org where `string-empty-p' is used. There is 
no (require 'subr-x) in org-agenda.el. Notice

lisp/org.el:10: ;; Package-Requires: ((emacs "24.3"))

Till this line is updated, I suppose, patches should respect it, 
especially for the maint branch. Unfortunately new org cite feature 
recently merged to master relies on some rx features unavailable even in 
Emacs-26.3 (Ubuntu-20.04 LTS focal).

> That
> version was released over 8 years ago and I suspect there are other
> areas of org which are not compatible with that version. Note also that
> the subr-x and string-empty-p were introduced in Emacs 24.4. If we are
> going to support Emacs 24, I think it is reasonable it be 24.4 rather
> than aiming for all 24 releases.

It seems, RedHat-7 and thus CentOS-7 were released with Emacs-24.3. I 
have no idea how many users run these flavors on desktops and are 
permitted to update Org to the latest version. Accordingly to
https://wiki.centos.org/About/Product
end of lifetime dates for CentOS-7 are 2020-08-06 for full updates and 
2024-06-30 for maintenance updates.