master 78a10d17c69: Convert outline-search-function to defcustom

branch: master
commit 78a10d17c69970687f8330f6c896170bcf936ef3
Author: Paul H. McClelland <[email protected]>
Commit: Juri Linkov <[email protected]>

    Convert outline-search-function to defcustom
    
    Make 'outline-search-function' a user option with named choices for
    its predefined values, so users can configure it via Customize.
    Preserves existing docstring and runtime semantics (bug#81053).
    
    * lisp/outline.el (outline-search-function): Convert to defcustom.
    * etc/NEWS: Announce it.
---
 etc/NEWS        |  7 +++++++
 lisp/outline.el | 16 +++++++++++++---
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index b76b18cdc8c..f2005196353 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -126,6 +126,13 @@ Install it with:
 
   (setq-local outline-search-function #'outline-search-from-regexp)
 
+---
+*** 'outline-search-function' is now a user option.
+Previously a plain variable, it is now a 'defcustom'
+with named choices for the predefined search functions
+('outline-search-from-regexp' and 'outline-search-level')
+as well as the default nil and arbitrary user functions.
+
 
 * New Modes and Packages in Emacs 32.1
 
diff --git a/lisp/outline.el b/lisp/outline.el
index 3eb354a22ce..4b4f3c2d520 100644
--- a/lisp/outline.el
+++ b/lisp/outline.el
@@ -61,8 +61,10 @@ The recommended way to set this is with a `Local Variables:' list
 in the file it applies to.")
 ;;;###autoload(put 'outline-heading-end-regexp 'safe-local-variable 'stringp)
 
-(defvar outline-search-function nil
-  "Function to search the next outline heading.
+(defcustom outline-search-function nil
+  "If non-nil, the function to search the next outline heading.
+When nil, headings are found by searching for `outline-regexp'.
+
 The function is called with four optional arguments: BOUND, MOVE, BACKWARD,
 LOOKING-AT.  The first two arguments BOUND and MOVE are almost the same as
 the BOUND and NOERROR arguments of `re-search-forward', with the difference
@@ -71,7 +73,15 @@ BACKWARD is non-nil, the search should search backward like
 `re-search-backward' does.  In case of a successful search, the
 function should return non-nil, move point, and set match-data
 appropriately.  When the argument LOOKING-AT is non-nil, it should
-imitate the function `looking-at'.")
+imitate the function `looking-at'."
+  :type '(choice (const :tag "Use `outline-regexp'" nil)
+                 (function-item :tag "Search by `outline-regexp' (regexp-based)"
+                                outline-search-from-regexp)
+                 (function-item :tag "Search by `outline-level' text property"
+                                outline-search-level)
+                 (function :tag "Other function"))
+  :group 'outlines
+  :version "32.1")
 
 (defvar-keymap outline-mode-prefix-map
   "@"   #'outline-mark-subtree