Re: Variable ignored warning in defsetf?

[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

e