Variable ignored warning in defsetf?

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

   Date: Tue, 31 Jan 1995 09:47:02 -0500
   From: e@flavors.com (Doug Currie, Flavors Technology, Inc.)

   At 3:20 PM 95.01.27, Peter Norvig wrote:
   >A user of my code complains that the following generates the error
   >
   >        Variable CONTAINED? not ignored, in an anonymous lambda form
   >
   >under MCL.  Other Lisps don't complain.  Is there some work-around, or
   >some way to tell MCL not to promote such warnings into an error that
   >stops the compilation process?
   >
   >(defsetf grid-contents (env loc &optional contained?) (val)
   >  (declare (ignore contained?))
   >  `(setf (aref (grid-environment-grid ,env)
   >               (floor (xy-x ,loc)) (floor (xy-y ,loc)))
   >         ,val))
   >

   try:   (declare (ignore-if-unused contained?))

   See MCL Ref p. 643

This may then cause the other Lisps to barf, being a nonstandard declaration.
Some Lisps have an IGNORABLE declaration, some have IGNORE-IF-UNUSED, etc.

How about

  #-:MCL (declare (ignore contained?))

in the original code instead?

-- Bob