[BUG] [BUG] inconsistent behavior when reading multiple tags [9.4.6 (9.4.6-g366444 @ /home/n/.emacs.d/straight/build/org/)]

[No Wayman]

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622f9fa76c8ee0766b15945c013b0950d703b955 ("org: Use crm for 
completing tags")
lexically binds crm-separator to ":" while prompting for multiple 
tags in
org-set-tags-command and org-capture-fill-template.

org-set-tags-command correctly parses the tags when using a comma 
(the default
crm-separator) to separate them, but completion is broken unless 
":" is used as
the separator.
org-capture-fill-template incorrectly parses this.

Reproducible from emacs -Q:

org-set-tags-command:
1. Insert a new Org entry in the a buffer 
2. M-x org-set-tags-command 
3. At the prompt enter "one,two,three"
4. Entry's tags are correctly set to :one:two:three: 

org-capture-fill-template:
1. evaluate (org-capture-fill-template "%^g")
2. At the prompt enter "one,two,three"
3. String returned is incorrect: ":one,two,three:"


I can think of a couple ways we could improve this and make the 
behavior consistent.
We could introduce a defcustom which allows the user to choose 
whether or not
Org will rebind crm-separator during commands/functions which 
utilize
completing-read-multiple.
e.g.

#+begin_src emacs-lisp :lexical t
(defcustom org-contextual-crm-separator t
 "Use contextual binding of crm-separator during Org commands.
For example, when setting tags, \":\" is used as the separator.
If nil, `crm-separator' is used.")
#+end_src

Alternatively, we could change the lexical binding we're using 
during these commands/functions.
Instead of binding the separator explicitly to "[ \t]*:[ \t]*", we 
could instead use a regexp
which will match any character not described by org-tag-re. The 
benefit of
this is that completing-read-multiple completion will work for any 
separator
that doesn't match org-tag-re transparently and the results should 
be
consistent between org-set-tags-command and 
org-capture-fill-template.

The attached patch implements that change, which seems to do the 
right thing
from my testing. I can polish it, but I wanted to get opinions on 
the solution first.

Note this does not change the case of org-todo-list, which binds
crm-separator to "|". I chose not to touch that because I'm not 
fully aware 
of what the restrictions on characters for todo-keywords are, if 
any.
org-todo-list also does the right thing by mentioning the 
separator in the prompt.

We could also combine the approaches:

- Introduce a defcustom that determines if we're going to 
 contextually rebind crm-separator
- Use a broader regexp when contextually binding crm-separator
- Mention the separator in the prompt when rebound

Thoughts?


Emacs  : GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ 
Version 3.24.30, cairo version 1.17.4)
of 2021-08-02
Package: Org mode version 9.4.6 (9.4.6-g366444 @ 
/home/n/.emacs.d/straight/build/org/)

0001-RFC-broader-regexp-for-lexically-bound-crm-separator.patch
Description: rfc-broader-regexp-for-lexically-bound-crm-separator