bug#26658: 25.2; cc-mode doesn't use prog-mode-map as parent for c-mode-base-map

[Alan Mackenzie <acm@muc.de>]

Hello, Vasilij.

On Tue, May 02, 2017 at 23:17:14 +0200, Vasilij Schneidermann wrote:

> I've ensured the bug is present and wrote a patch that fixes the issue.
> A workaround for people not using the latest cc-mode is to put the
> following into their init file:

> (eval-after-load 'cc-mode
>   '(set-keymap-parent c-mode-base-map prog-mode-map))

Thanks for the patch.

[ .... ]

>    (setq c-mode-base-map (make-sparse-keymap))
> +  (c-set-keymap-parent c-mode-base-map prog-mode-map)

It doesn't seem to be quite right in the way it handles XEmacs stuff,
but I don't think it's possible to be "right" here, at least not
sensibly.  If this patch were to be applied to standalone CC Mode, it
would test (derived-mode-p 'prog-mode) before calling
(c-set-keymap-parent c-mode-base-map prog-mode-map).  prog-mode does not
exist in XEmacs, and is unlikely ever to exist there.

But this code is purely for Emacs.  What do you think?

For the commit message, the format is to aim for a complete first line
which makes sense on its own.  (It's a sentence, but without a
terminating full stop.)  So something like this would do:

#########################################################################
Make prog-mode-map the keymap parent of c-mode-base-map

Fixes bug #26658.

* lisp/progmodes/cc-mode.el (c-set-keymap-parent): New function
extracted from c-make-inherited-keymap.
(c-mode-base-map): .......

#########################################################################

Note that the path is given before "cc-mode.el".

Do you have commit access to the Emacs repository?

-- 
Alan Mackenzie (Nuremberg, Germany).