bug#11476: 23.1; which-func-cleanup-function call and documentation mismatch

[Glenn Morris]

Jack Duthen wrote:

> emacs -Q
> open any emacs-lisp file and move point inside any function
> M-x imenu-add-menubar-index
> M-x which-func-mode
> M-:
> (defun jd-test-which-func-cleanup-function (fun-name)
>   (message "Type of fun-name '%s' is %s" fun-name (type-of fun-name))
>   (when (consp fun-name)
>     (message "Type of (car fun-name) '%s' is %s" (car fun-name)
> (type-of (car fun-name))))
>   (setq jd-ielm-fun-name fun-name)          ; to explore it using ielm
>   fun-name)
> M-: (setq which-func-cleanup-function 'jd-test-which-func-cleanup-function)

I cannot reproduce a problem with this, in either 23.1 or current trunk.
The type remains resolutely a string, never a cons. If it were not a
string, I would think that the which-function mode line would break.