bug#11841: 24.1; emacs hangs when opening cpp file with mixed eol styles

[Alan Mackenzie]

Hello, Stefan.

On Sun, Jul 08, 2012 at 10:50:03AM -0400, Stefan Monnier wrote:
> >> > Just as an observation, (forward-comment -1) doesn't move back over a ^M.

> >> Why should it?  It's not a whitespace, and while it has "comment end"
> >> syntax, it does not have a matching comment-start.

> >> I think you should give it whitespace syntax.
> >> Currently "foo // bar ^M baz ^J" is treated in CC-mode as "foo <comment>
> >> baz", which I think is wrong.

I've tried setting ^M's syntax to WS.  The code no longer loops.
However, ^M is syntactically a comment ender so that it can end a comment
when selective-display is active.

> > Perhaps so, but in the file in question you have ^M^J with northing
> > between them.  So a lone ^M is not an issue here.

> Yes it is: without a "//" in front of it, a ^M is not a comment-ender
> and syntax.c then treats it as a "strange char" (for \n used as comment
> ender, syntax.c knows to treat it as whitespace when there's no
> matching comment-starter, but that's a special case, for other chars
> this is not so, e.g. for pascal's } it would be wrong to treat it as
> whitespace).

Would it not be better for ^M to be treated as WS by syntax.c?  The
current problem isn't really a CC Mode one; mixed line enders could
happen in a file of any major mode.  Emacs really ought to treat all line
endings the same.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).