[CM] __func__ in lisp?

[Heinrich Taube]

http://www.faqs.org/faqs/lisp-faq/part2/section-14.html
gives a few old implementation details.  the pure cltl method is  
really gross!:
  If a vendor-dependent function does not exist, the following  
(inefficient) code maps over all symbols looking for one whose  
function-cell matches the function object. (defun function-name  
(fobject) (do-all-symbols (fsymbol) (when (and (fboundp fsymbol) (eq  
(symbol-function fsymbol) fobject)) (return fsymbol))))