CLSQL with LW 5.1 problem

Hello,

I'm using LWw 5.1 and has to change a declaration in the following CLSQL function (see #+:lispworks) because this error:
Error: #\' is not of type simple-char.

Looks like the compiler is too cautious. Notice using (safety 0) is working too.

Francis

(defmethod database-output-sql ((str string) database)
  (declare (optimize (speed 3) (safety 1)
		     #+cmu (extensions:inhibit-warnings 3)))
  (let ((len (length str)))
    (declare (type fixnum len))
    (cond ((zerop len)
           +empty-string+)
          ((and (null (position #\' str))
                (null (position #\\ str)))
           (concatenate 'string "'" str "'"))
          (t
           (let ((buf (make-string (+ (* len 2) 2) :initial-element #\')))
	     #-:lispworks (declare (simple-string buf))
             #+:lispworks (declare (string buf))
	     (do* ((i 0 (incf i))
                   (j 1 (incf j)))
                  ((= i len) (subseq buf 0 (1+ j)))
               (declare (type fixnum i j))
               (let ((char (aref str i)))
		(declare (character char))
                 (cond ((char= char #\')
                        (setf (aref buf j) #\')
                        (incf j)
                        (setf (aref buf j) #\'))
                       ((and (char= char #\\)
                             ;; MTP: only escape backslash with pgsql/mysql
                             (member (database-underlying-type database)
                                     '(:postgresql :mysql)
                                     :test #'eq))
                        (setf (aref buf j) #\\)
                        (incf j)
                        (setf (aref buf j) #\\))
                       (t
                        (setf (aref buf j) char))))))))))