Connect electric-indent-mode up with CC Mode. Bug #15478.

* progmodes/cc-mode.el (c-initialize-cc-mode): add CC Mode hooks
to electric-indent-{,local-}-mode.
(c-basic-common-init): Set electric-indent-inhibit.  Initialise
c-electric-flag from electric-indent-mode.
(c-electric-indent-mode-hook, c-electric-indent-local-mode-hook):
New hook functions which propagate electric-indent-mode to CC Mode.

* progmodes/cc-cmds.el (c-toggle-electric-state): When C-c C-l is
hit, toggle electric-indent-local-moode.

* electric.el (electric-indent-mode-has-been-called): New variable.

4 files changed, 61 insertions, 2 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 27a0ffd30a5..5dad77bcdf9 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,20 @@
+2014-02-17  Alan Mackenzie  <acm@muc.de>
+
+        Connect electric-indent-mode up with CC Mode.  Bug #15478.
+        * progmodes/cc-mode.el (c-initialize-cc-mode): add CC Mode hooks
+        to electric-indent-{,local-}-mode.
+        (c-basic-common-init): Set electric-indent-inhibit.  Initialise
+        c-electric-flag from electric-indent-mode.
+        (c-electric-indent-mode-hook, c-electric-indent-local-mode-hook):
+        New hook functions which propagate electric-indent-mode to CC
+        Mode.
+
+        * progmodes/cc-cmds.el (c-toggle-electric-state): When C-c C-l is
+        hit, toggle electric-indent-local-moode.
+
+        * electric.el (electric-indent-mode-has-been-called): New
+        variable.
+
 2014-02-17  Juanma Barranquero  <lekktu@gmail.com>
 
         * frameset.el (frameset-cfg-id): New function.
diff --git a/lisp/electric.el b/lisp/electric.el
index 32c4a824491..4549fcad83c 100644
--- a/lisp/electric.el
+++ b/lisp/electric.el
@@ -286,6 +286,9 @@ mode set `electric-indent-inhibit', but this can be used as a workaround.")
   (let ((electric-indent-mode nil))
     (newline arg 'interactive)))
 
+(defvar electric-indent-mode-has-been-called 0
+  "How many times has `electric-indent-mode' been called?
+It's > 1 if it's been called at least once by the user.")
 ;;;###autoload
 (define-minor-mode electric-indent-mode
   "Toggle on-the-fly reindentation (Electric Indent mode).
@@ -299,6 +302,8 @@ insert a character from `electric-indent-chars'."
   :global t :group 'electricity
   :initialize 'custom-initialize-delay
   :init-value t
+  (setq electric-indent-mode-has-been-called
+        (1+ electric-indent-mode-has-been-called))
   (if (not electric-indent-mode)
       (progn
         (when (eq (lookup-key global-map [?\C-j])
diff --git a/lisp/progmodes/cc-cmds.el b/lisp/progmodes/cc-cmds.el
index bf651f8ae99..4f205d62a4c 100644
--- a/lisp/progmodes/cc-cmds.el
+++ b/lisp/progmodes/cc-cmds.el
@@ -356,6 +356,8 @@ left out."
   (interactive "P")
   (setq c-electric-flag (c-calculate-state arg c-electric-flag))
   (c-update-modeline)
+  (when (fboundp 'electric-indent-local-mode) ; Emacs 24.4 or later.
+    (electric-indent-local-mode (if c-electric-flag 1 0)))
   (c-keep-region-active))
 
 
diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index e8d447cd1fa..9b18bbf82a9 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -188,7 +188,13 @@ control).  See \"cc-mode.el\" for more info."
                 (setq c-block-comment-prefix
                       (symbol-value 'c-comment-continuation-stars)))
             (add-hook 'change-major-mode-hook 'c-leave-cc-mode-mode)
-            (setq c-initialization-ok t))
+            (setq c-initialization-ok t)
+            ;; Connect up with Emacs's electric-indent-mode, for >= Emacs 24.4
+            (when (fboundp 'electric-indent-mode)
+              (add-hook 'electric-indent-mode-hook 'c-electric-indent-mode-hook)
+              (when (fboundp 'electric-indent-local-mode)
+                (add-hook 'electric-indent-local-mode-hook
+                            'c-electric-indent-local-mode-hook))))
         ;; Will try initialization hooks again if they failed.
         (put 'c-initialize-cc-mode initprop c-initialization-ok))))
 
@@ -578,6 +584,14 @@ that requires a literal mode spec at compile time."
   ;; setup the comment indent variable in a Emacs version portable way
   (set (make-local-variable 'comment-indent-function) 'c-comment-indent)
 
+  ;; In Emacs 24.4 onwards, prevent Emacs's built in electric indentation from
+  ;; messing up CC Mode's, and set `c-electric-flag' if `electric-indent-mode'
+  ;; has been called by the user.
+  (when (boundp 'electric-indent-inhibit) (setq electric-indent-inhibit t))
+  (when (and (boundp 'electric-indent-mode-has-been-called)
+             (> electric-indent-mode-has-been-called 1))
+    (setq c-electric-flag electric-indent-mode))
+
 ;;   ;; Put submode indicators onto minor-mode-alist, but only once.
 ;;   (or (assq 'c-submode-indicators minor-mode-alist)
 ;;       (setq minor-mode-alist
@@ -807,7 +821,7 @@ Note that the style variables are always made local to the buffer."
     `(progn ,@(mapcar (lambda (hook) `(run-hooks ,hook)) hooks))))
 
 
-;;; Change hooks, linking with Font Lock.
+;;; Change hooks, linking with Font Lock and electric-indent-mode.
 
 ;; Buffer local variables recording Beginning/End-of-Macro position before a
 ;; change, when a macro straddles, respectively, the BEG or END (or both) of
@@ -1238,6 +1252,27 @@ This function is called from `c-common-init', once per mode initialization."
   ;; function.
   (cons c-new-BEG c-new-END))
 
+;; Connect up to `electric-indent-mode' (Emacs 24.4 and later).
+(defun c-electric-indent-mode-hook ()
+  ;; Emacs has en/disabled `electric-indent-mode'.  Propagate this through to
+  ;; each CC Mode buffer.
+  (when (and (boundp 'electric-indent-mode-has-been-called)
+             (> electric-indent-mode-has-been-called 1))
+    (mapc (lambda (buf)
+            (with-current-buffer buf
+              (when c-buffer-is-cc-mode
+                ;; Don't use `c-toggle-electric-state' here due to recursion.
+                (setq c-electric-flag electric-indent-mode)
+                (c-update-modeline))))
+          (buffer-list))))
+
+(defun c-electric-indent-local-mode-hook ()
+  ;; Emacs has en/disabled `electric-indent-local-mode' for this buffer.
+  ;; Propagate this through to this buffer's value of `c-electric-flag'
+  (when c-buffer-is-cc-mode
+    (setq c-electric-flag electric-indent-mode)
+    (c-update-modeline)))
+
 
 ;; Support for C