Re: Pasting preprocessor in header files sometimes break indentation

[Alan M. <ac...@mu...>]

Hi, Sezaru.

On Wed, May 22, 2013 at 09:08:37PM +0000, Sezaru wrote:
> cc-mode sometimes loose the indentation when working with c++ header files,
> there is another thread with some similar problem here but the workaround
> shown there does not work and it was said that in emacs-24.3 it was fixed,
> which is the version I'm using and it still have the problem, so I decided
> to create a new thread as it look like a diferent issue is causing the
> problem.

> I've tested this problem in my gentoo emacs 24.3 build and in a vanilla one
> download from the official website. The bug persists in both even when
> using the built-in cc-mode or the lastest direct from the repositories. It
> also persistis when using -q option, so it is not another mode conflicting
> with cc-mode.

> I've made a little example to reproduce the problem:

> #ifndef TEST_H_
> #define TEST_H_
> 
> 
> 
> class Test
> {
> public:
>   Test(void);
> 
>   Foo(void);
>   Bar(void);
> };

> #endif // TEST_H_


> Save this code as test.hpp, now open it, and there will be 3 empty lines
> between #define TEST_H and class Test, in the second empty line paste this:
> #include <iostream>

> Now the indentation will fail and every line you try to indentate will not.

> Beware that you need to paste the #include <iostream> in the code and not
> simply write it, if you write character by character the indentation will
> still works as it should, it only breaks when you paste it (or at least it
> was the only way I've found to reproduce it)

Thanks for taking the trouble to report this, and thanks even more for
such an accurate description.

I think I've tracked this down, it's an ugly (mis)feature in the innards
of Emacs's `yank' which messes around with text properties.

Would you please try out the following patch, and let me know whether or
not it fixes the problem fully.



diff -r 10c9ed75910b cc-mode.el
--- a/cc-mode.el	Thu May 02 11:03:15 2013 +0000
+++ b/cc-mode.el	Sun May 26 13:47:14 2013 +0000
@@ -1100,13 +1100,14 @@
 	    (setq beg end)))
 
 	;; C-y is capable of spuriously converting category properties
-	;; c-</>-as-paren-syntax into hard syntax-table properties.  Remove
-	;; these when it happens.
+	;; c-</>-as-paren-syntax and c-cpp-delimiter into hard syntax-table
+	;; properties.  Remove these when it happens.
 	(when (memq 'category-properties c-emacs-features)
 	  (c-clear-char-property-with-value beg end 'syntax-table
 					    c-<-as-paren-syntax)
 	  (c-clear-char-property-with-value beg end 'syntax-table
-					    c->-as-paren-syntax))
+					    c->-as-paren-syntax)
+	  (c-clear-char-property-with-value beg end 'syntax-table nil))
 
 	(c-trim-found-types beg end old-len) ; maybe we don't need all of these.
 	(c-invalidate-sws-region-after beg end)


> Thanks!

-- 
Alan Mackenzie (Nuremberg, Germany).