type inference does not complain about DOLIST over a vector type

[Michael Fiano]

(in-package #:cl-user)

(declaim (ftype (function () list) foo))
(defun foo ()
  (declare (optimize speed))
  (let ((items (vector 1 2 3 4))
        (result nil))
    ;; type inference never catches that ITEMS is not a list and falls through
    ;; to a runtime error instead of compile-time.
    (dolist (item items)
      (push item result))
    result))