(declaim (ignore ignore))

[hall@allegra.att.com (Bob Hall)]

The toplevel form
  (DECLAIM (IGNORE IGNORE))
works nicely in MCL to allow me to write, e.g.
  (DEFUN FOO (IGNORE) 4)
and avoid a compiler warning.  Also nicely, it issues a warning
if I DO use IGNORE when I declaimed it to be ignored.

What I'm having trouble with is whether this is defined in
"the" language (CLtL2? ANSI?) or is it an
extension?  It doesn't work in, for example, Allegro CL v4.1.
The DECLAIM above appears to have no effect, though it doesn't warn/error.
My recollection is that Symbolics CL just implicitly does the DECLAIM;
that is, if you name a local variable IGNORE, then the compiler
knows not to issue "unused" warnings.  (I don't remember if it warns
if you DO use such a var).

-- Bob