BTW, while I looked at this, I found this spurious lookup in
`byte-compile-lexical-variables':

#+begin_src emacs-lisp
(defun byte-compile-form (form &optional for-effect)
  (let ((byte-compile--for-effect for-effect))
    (cond
     ((not (consp form))..10..)
     ((symbolp (car form))
      (let* ((fn (car form))..4..)
        (when (memq fn '(set symbol-value run-hooks..4..)
          (pcase (cdr form)
            (`(',var . ,_)
             (when (assq var byte-compile-lexical-variables) ;; <--- here
               (byte-compile-report-error
                (format-message "%s cannot use lexical var `%s'" fn var)))
             ...)))))))))
#+end_src

shouldn't the `assq' be `memq'?


Michael.