+
+(let ((fn (handler-case
+ (compile nil '(lambda ()
+ (declare (special x y))
+ (loop thereis (pop x) thereis (pop y))))
+ (warning (c) (error "Warned: ~S" c)))))
+ (let ((x (list nil nil 1))
+ (y (list nil 2 nil)))
+ (declare (special x y))
+ (assert (= (funcall fn) 2))))