Variable: add-log-current-defun-function
add-log-current-defun-function is a customizable variable defined in
add-log.el.gz.
Documentation
If non-nil, function to guess name of surrounding function.
It is called by add-log-current-defun with no argument, and
should return the function's name as a string, or nil if point is
outside a function.
Probably introduced at or before Emacs version 24.4.
Source Code
;; Defined in /usr/src/emacs/lisp/vc/add-log.el.gz
;; Many modes set this variable, so avoid warnings.
;;;###autoload
(defcustom add-log-current-defun-function nil
"If non-nil, function to guess name of surrounding function.
It is called by `add-log-current-defun' with no argument, and
should return the function's name as a string, or nil if point is
outside a function."
:type '(choice (const nil) function))