+
+(eval
+ '(progn
+ (defgeneric multiple-class-specializers (x)
+ (:generic-function-class cons-generic-function)
+ (:method-combination list))
+ (defmethod multiple-class-specializers list ((x t)) 't)
+ (defmethod multiple-class-specializers list ((x cons)) 'cons)
+ (defmethod multiple-class-specializers list ((x (cons foo))) '(cons foo))
+ (defmethod multiple-class-specializers list ((x (cons bar))) '(cons bar))
+ (defmethod multiple-class-specializers list ((x list)) 'list)
+ (defmethod multiple-class-specializers list ((x null)) 'null)
+ (defmethod multiple-class-specializers list ((x (eql nil))) '(eql nil))
+
+ (assert (equal (multiple-class-specializers nil) '((eql nil) null list t)))
+ (assert (equal (multiple-class-specializers t) '(t)))
+ (assert (equal (multiple-class-specializers (cons nil nil)) '(cons list t)))
+ (assert (equal (multiple-class-specializers (cons 'foo nil)) '((cons foo) cons list t)))
+ (assert (equal (multiple-class-specializers (list 'bar nil t 3)) '((cons bar) cons list t)))))