; Add commentary to 'describe-function's completion

* lisp/help-fns.el
(help-fns--describe-function-or-command-prompt): Add a comment
(bug#64902).

lisp/help-fns.el

@@ -229,6 +229,10 @@ interactive command."
                (lambda (f) (if want-command
                           (commandp f)
                         (or (fboundp f) (get f 'function-documentation))))
+               ;; We use 'confirm' here, unlike in other describe-*
+               ;; commands, for cases like a function that is advised
+               ;; but not yet defined (e.g., if 'advice-add' is called
+               ;; before defining the function).
                'confirm nil nil
                (and fn (symbol-name fn)))))
     (unless (equal val "")