Subject: Re: bug#24316: Mistake in GNU Emacs Lisp Reference Manual, Section 5.3

From: Ken Brown <[email-masked]>
Date: Fri, 26 Aug 2016 17:04:15 -0400

On 8/26/2016 4:53 PM, Eric Wayman wrote:
> With respect to
>
>  -- Function: safe-length list
>
> the text says
>
>     "If LIST is not ‘nil’ or a cons cell, ‘safe-length’ returns 0."
>
> But running
>
>     (safe-length nil)
>
> gives 0.

That case is covered by the first paragraph of the documentation, which 
you didn't quote:

      This function returns the length of LIST, with no risk of either an
      error or an infinite loop.  It generally returns the number of
      distinct cons cells in the list.  However, for circular lists, the
      value is just an upper bound; it is often too large.

Ken