Use special-mode for read-only buffers.

* lisp/progmodes/etags.el (tags-table-mode): Define using
`define-derived-mode', inheriting from `special-mode'.
Not only the buffer is now read-only, but you can bury it with "q".
(select-tags-table-mode): No need to set `buffer-read-only'
explicitly, `special-mode' takes care of that.
* lisp/vc/log-edit.el (log-edit-show-files): Use `special-mode'
instead of setting `buffer-read-only' explicitly.

2 files changed, 4 insertions, 7 deletions

diff --git a/lisp/progmodes/etags.el b/lisp/progmodes/etags.el
index 619c2ed6877..50a9f8190db 100644
--- a/lisp/progmodes/etags.el
+++ b/lisp/progmodes/etags.el
@@ -274,12 +274,9 @@ buffer-local and set them to nil."
   (run-hook-with-args-until-success 'tags-table-format-functions))
 
 ;;;###autoload
-(defun tags-table-mode ()
+(define-derived-mode tags-table-mode special-mode "Tags Table"
   "Major mode for tags table file buffers."
-  (interactive)
-  (setq major-mode 'tags-table-mode     ;FIXME: Use define-derived-mode.
-        mode-name "Tags Table"
-        buffer-undo-list t)
+  (setq buffer-undo-list t)
   (initialize-new-tags-table))
 
 ;;;###autoload
@@ -2060,7 +2057,7 @@ see the doc of that variable if you want to add names to the list."
 
 (define-derived-mode select-tags-table-mode special-mode "Select Tags Table"
   "Major mode for choosing a current tags table among those already loaded."
-  (setq buffer-read-only t))
+  )
 
 (defun select-tags-table-select (button)
   "Select the tags table named on this line."
diff --git a/lisp/vc/log-edit.el b/lisp/vc/log-edit.el
index 44e7cd78ee5..30457d1e2d3 100644
--- a/lisp/vc/log-edit.el
+++ b/lisp/vc/log-edit.el
@@ -623,7 +623,7 @@ Also saves its contents in the comment history and hides
       (setq buffer-read-only nil)
       (erase-buffer)
       (cvs-insert-strings files)
-      (setq buffer-read-only t)
+      (special-mode)
       (goto-char (point-min))
       (save-selected-window
         (cvs-pop-to-buffer-same-frame buf)