longlines-show-hard-newlines sets modified flag

[martin rudalics]

longlines.el has a bug you can reproduce with Emacs -Q as follows:

(1) Visit an arbitrary file, for example, longlines.el

(2) M-x longlines-mode

(3) M-x longlines-show-hard-newlines

The buffer is considered modified.  The reason for this bug is bad
handling of `buffer-modified-p' and `inhibit-modification-hooks' in the
associated functions.  The attached patch should cure this.  If no one
objects I'll install in a couple of days.

*** longlines.el.~1.40.~        Fri Nov  2 09:54:54 2007
--- longlines.el        Mon Nov 26 17:55:26 2007
***************
*** 207,239 ****
    "Make hard newlines visible by adding a face.
  With optional argument ARG, make the hard newlines invisible again."
    (interactive "P")
-   (let ((buffer-undo-list t)
-         (mod (buffer-modified-p)))
      (if arg
          (longlines-unshow-hard-newlines)
        (setq longlines-showing t)
!       (longlines-show-region (point-min) (point-max)))
!     (set-buffer-modified-p mod)))

  (defun longlines-show-region (beg end)
    "Make hard newlines between BEG and END visible."
    (let* ((pmin (min beg end))
           (pmax (max beg end))
           (pos (text-property-not-all pmin pmax 'hard nil))
!          (inhibit-read-only t))
      (while pos
        (put-text-property pos (1+ pos) 'display
!                          (copy-sequence longlines-show-effect))
!       (setq pos (text-property-not-all (1+ pos) pmax 'hard nil)))))

  (defun longlines-unshow-hard-newlines ()
    "Make hard newlines invisible again."
    (interactive)
    (setq longlines-showing nil)
!   (let ((pos (text-property-not-all (point-min) (point-max) 'hard nil)))
      (while pos
        (remove-text-properties pos (1+ pos) '(display))
!       (setq pos (text-property-not-all (1+ pos) (point-max) 'hard nil)))))

  ;; Wrapping the paragraphs.

--- 207,245 ----
    "Make hard newlines visible by adding a face.
  With optional argument ARG, make the hard newlines invisible again."
    (interactive "P")
      (if arg
          (longlines-unshow-hard-newlines)
        (setq longlines-showing t)
!       (longlines-show-region (point-min) (point-max))))

  (defun longlines-show-region (beg end)
    "Make hard newlines between BEG and END visible."
    (let* ((pmin (min beg end))
           (pmax (max beg end))
           (pos (text-property-not-all pmin pmax 'hard nil))
!        (mod (buffer-modified-p))
!        (buffer-undo-list t)
!        (inhibit-read-only t)
!        (inhibit-modification-hooks t))
      (while pos
        (put-text-property pos (1+ pos) 'display
!                        (copy-sequence longlines-show-effect))
!       (setq pos (text-property-not-all (1+ pos) pmax 'hard nil)))
!     (set-buffer-modified-p mod)))

  (defun longlines-unshow-hard-newlines ()
    "Make hard newlines invisible again."
    (interactive)
    (setq longlines-showing nil)
!   (let ((pos (text-property-not-all (point-min) (point-max) 'hard nil))
!       (mod (buffer-modified-p))
!       (buffer-undo-list t)
!       (inhibit-read-only t)
!       (inhibit-modification-hooks t))
      (while pos
        (remove-text-properties pos (1+ pos) '(display))
!       (setq pos (text-property-not-all (1+ pos) (point-max) 'hard nil)))
!     (set-buffer-modified-p mod)))

  ;; Wrapping the paragraphs.