bug#52341: Fwd: 29.0.50; org-priority 'SPC to remove' doesn't work

[Kyle Meyer <kyle@kyleam.com>]

bruce robertson writes:

> 1. in init.el:
> (custom-set-variables
>  '(org-priority-default 32)
>  '(org-priority-highest 0)
>  '(org-priority-lowest 31)
> )
> 2. position to line in .org file:
> ** TODO [#0] test line
>
> 3. from M-x view-lossage:
>  C-c ,         ;; org-priority
>
> 4. mini-buffer displays:
> "Priority 0-31, SPC to remove: "
>
> 5. further in view-lossage:
> SPC           ;; self-insert-command
>  <return>      ;; exit-minibuffer
>
> 4. from *Messages* (and mini-buffer):
> Priority of current item set to 0
>
> 5. PROBLEM:
> I wanted to remove priority.
>
> 6. WORK-AROUND:
> set priority to 32. Then priority disappears. Perhaps this is because 32
> is space code or because I've set org-priority-default to 32.
> ( I spent a medium amount of time to find this behavior. )
>
> 7. SUGGESTION:
> rewrite org-priority to have a clear distinction between numbers and
> characters and whatever will be used to remove the priority.
> ( I gave a look at this but my emacs-fu is too weak. Or my time-fu is
> too small. )

Right, this stems from org-priority feeding " " to string-to-number and
ending up with 0 instead of the ?\s (32) that's used downstream to
signal "remove".  The problem goes back to when support for numeric
priorities was added in Org v9.4's 4f98694bf (Allow numeric values for
priorities, 2020-01-30).

I suppose one solution would be to check for " " and translate that to
the ?\s so that the remove is triggered.  I'll plan to apply the change
below to Org's bugfix branch in a day or two unless the author of the
above commit (+cc) or someone else has another suggestion.

diff --git a/lisp/org.el b/lisp/org.el
index 1a1375461..998da0656 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -11323,13 +11323,14 @@ (defun org-priority (&optional action show)
 	    (setq
 	     new
 	     (if nump
-                 (let ((msg (format "Priority %s-%s, SPC to remove: "
-				    (number-to-string org-priority-highest)
-				    (number-to-string org-priority-lowest))))
-                   (if (< 9 org-priority-lowest)
-		       (string-to-number (read-string msg))
-                     (message msg)
-                     (string-to-number (char-to-string (read-char-exclusive)))))
+                 (let* ((msg (format "Priority %s-%s, SPC to remove: "
+                                     (number-to-string org-priority-highest)
+                                     (number-to-string org-priority-lowest)))
+                        (s (if (< 9 org-priority-lowest)
+                               (read-string msg)
+                             (message msg)
+                             (char-to-string (read-char-exclusive)))))
+                   (if (equal s " ") ?\s (string-to-number s)))
 	       (progn (message "Priority %c-%c, SPC to remove: "
 			       org-priority-highest org-priority-lowest)
 		      (save-match-data