bug#9199: Imenu does not work any more with C/C++ mode

[Stefan Monnier]

> $ cat init.el
> (add-hook 'c-mode-hook
>           '(lambda()
>              (imenu-add-to-menubar "Functions")
>              )
>           )

Running for the Useless Use of Quote Award? ;-)

> $ cat test.c
> int main(){}
> void foo1(){}
> void foo2(){}
> void foo2(){}
> $ emacs test.c &
> Now click on 'Functions' in the menu bar, the result is as in

Hmm... indeed.

> If I remove init.el completely and
> $ emacs test.c &
> M-x imenu-add-to-menubar <RET>
> Functions <RET>
> Now clicking on Functions works as expected!

Yup: the reason why this (and other major modes) works is that the bug
only manifests itself if you call imenu-add-to-menubar more than once
(and it so happens that c-mode-hook is run twice for some reason).

I believe this is fixed in the trunk now thanks the the patch below,


        Stefan


=== modified file 'lisp/ChangeLog'
--- lisp/ChangeLog      2012-03-13 23:27:56 +0000
+++ lisp/ChangeLog      2012-03-15 01:37:45 +0000
@@ -1,3 +1,9 @@
+2012-03-15  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+       * imenu.el: Fix multiple inheritance breakage (bug#9199).
+       (imenu-add-to-menubar): Don't add a redundant index.
+       (imenu-update-menubar): Handle a dynamically composed keymap.
+
 2012-03-13  Katsumi Yamaoka  <yamaoka@jpl.org>
 
        * mail/sendmail.el (mail-encode-header):

=== modified file 'lisp/imenu.el'
--- lisp/imenu.el       2012-01-19 07:21:25 +0000
+++ lisp/imenu.el       2012-03-15 01:32:35 +0000
@@ -963,13 +963,14 @@
          imenu-generic-expression
          (not (eq imenu-create-index-function
                   'imenu-default-create-index-function)))
+      (unless (keymapp (lookup-key (current-local-map) [menu-bar index]))
       (let ((newmap (make-sparse-keymap)))
        (set-keymap-parent newmap (current-local-map))
        (setq imenu--last-menubar-index-alist nil)
        (define-key newmap [menu-bar index]
          `(menu-item ,name ,(make-sparse-keymap "Imenu")))
        (use-local-map newmap)
-       (add-hook 'menu-bar-update-hook 'imenu-update-menubar))
+         (add-hook 'menu-bar-update-hook 'imenu-update-menubar)))
     (error "The mode `%s' does not support Imenu"
            (format-mode-line mode-name))))
 
@@ -1008,6 +1009,9 @@
                                                   (car (cdr menu))))
                                            'imenu--menubar-select))
          (setq old (lookup-key (current-local-map) [menu-bar index]))
+         ;; This should never happen, but in some odd cases, potentially,
+         ;; lookup-key may return a dynamically composed keymap.
+         (if (keymapp (cadr old)) (setq old (cadr old)))
          (setcdr old (cdr menu1)))))))
 
 (defun imenu--menubar-select (item)