emacs-28 4d52fe6b96: * lisp/find-file.el (ff-other-file-alist): Doc fix. (Bug#57325)

[Eli Zaretskii]

branch: emacs-28
commit 4d52fe6b968b63e9c9025121147d4930ca65a05f
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    * lisp/find-file.el (ff-other-file-alist): Doc fix.  (Bug#57325)
---
 lisp/find-file.el | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lisp/find-file.el b/lisp/find-file.el
index 614ff420f2..e9aba883ae 100644
--- a/lisp/find-file.el
+++ b/lisp/find-file.el
@@ -204,7 +204,12 @@ The list of extensions should contain the most used 
extensions before the
 others, since the search algorithm searches sequentially through each
 directory specified in `ff-search-directories'.  If a file is not found,
 a new one is created with the first matching extension (`.cc' yields `.hh').
-This alist should be set by the major mode."
+This alist should be set by the major mode.
+
+Note: if an element of the alist names a FUNCTION as its cdr, that
+function must return a non-nil list of file-name extensions.  It cannot
+return nil, nor can it signal in any way a failure to find a suitable
+list of extensions."
   :type '(choice (repeat (list regexp (choice (repeat string) function)))
                 symbol))