mv-call and a declaration on &rest

(funcall (compile nil `(lambda (list)
                         (multiple-value-call
                             (lambda (&optional a &rest r)
                               (declare (cons r)
                                        (ignore r))
                               (list a))
                           (values-list list))))
         '(1 2))

Value of NIL in
#'(LAMBDA (&OPTIONAL A &REST R)
    (DECLARE (CONS R)
             (IGNORE R))
    (LIST A))

is
  NIL,
not a
  CONS.