- (when (member (find-class 'method) cpl)
- (error 'metaobject-initialization-violation
- :format-control "~@<Cannot ~S objects into ~S metaobjects.~@:>"
- :format-arguments (list 'change-class 'method)
- :references (list '(:amop :initialization "Method")))))
+ (dolist (class cpl)
+ (macrolet
+ ((frob (class-name)
+ `(when (eq class (find-class ',class-name))
+ (error 'metaobject-initialization-violation
+ :format-control "~@<Cannot ~S objects into ~S metaobjects.~@:>"
+ :format-arguments (list 'change-class ',class-name)
+ :references (list '(:amop :initialization ,class-name))))))
+ (frob class)
+ (frob generic-function)
+ (frob method)
+ (frob slot-definition))))
+ (change-class-internal instance new-class initargs))
+
+(defmethod change-class ((instance forward-referenced-class)
+ (new-class standard-class) &rest initargs)
+ (let ((cpl (class-precedence-list new-class)))
+ (dolist (class cpl
+ (error 'metaobject-initialization-violation
+ :format-control
+ "~@<Cannot ~S ~S objects into non-~S objects.~@:>"
+ :format-arguments
+ (list 'change-class 'forward-referenced-class 'class)
+ :references
+ (list '(:amop :generic-function ensure-class-using-class)
+ '(:amop :initialization class))))
+ (when (eq class (find-class 'class))
+ (return nil))))