Re: emacs-lisp/cl.el (pushnew): void-variable x

[Richard Stallman]

    Honestly, I think using `add-to-list' here makes no sense.
    Since we have the variable as a symbol and we're macro-expanding, we can
    just use `(unless (member ,element ,var) (setq ,var (cons ,element ,var)))
    That'll be a lot more efficient than going through a function call to
    add-to-list, using an aux-var accessed via symbol-value and set and checking
    `append' arg etc...

Maybe you're right, but note that it can't actually be `member' in
this case, not by default, since the default comparison function for
pushnew is `eql'.