setf bug

[Alan Bawden <ALAN at MIT-MC>]

    Date: 12 May 1981 05:44-EDT
    From: Gail Zacharias <GZ at MIT-MC>

    (SETF (FIXNUM-IDENTITY (CAR SOME-LIST)) 17.)

    wants that SOME-LIST should be a fixnum...

This is becase it expands into:

(progn (fixnum-identity (rplaca some-list 17.)) 17.)

While you people are fixing this, could you make it expand into:

(fixnum-identity (progn (rplaca some-list (fixnum-identity 17.)) 17.))

or some other variation that does a fixnum-identity BEFORE performing
the side-effect?  This would be a useful error check to have in the
interpreter.