anchor.diff:               (format s "Encountered an error (~A) in ~A.  ~A"
                        (syscall-errno c)
                        (syscall-error-function c)
  -                     (strerror (syscall-errno c))))))
  +                     (strerror (syscall-errno c)))))
  +  (:documentation
  +   "A condition to represent an error in a POSIX C function.
  +
  +Use `syscall-errno' to access the error code."))
   
   (defun pass (value)
     "Returns t."
  
positive.code:            (let* ((whole (gensym "WHOLE"))
                    (args (apply 'concatenate 'list (mapcar #'macro-argify arg-descriptions))))
               `(defmacro ,lisp-name (&whole ,whole ,@args)
                  (declare (ignore ,@(remove '&rest args)))
                  `(let ((,',result (,',lisp-impl-name ,@(cdr ,whole))))
                     (unless (funcall ,',error-checker ,',result)
  
negative.code: 
  (optimization-settings)
  
  (defgeneric syscall-errno (syscall-error)
    (:documentation
     "Return the errno that was set when the given condition was
  signaled."))
  
  (define-condition syscall-error (error)
    ((errno
      :initform errno
  