Re: Calling C++ hackers. Please try out the new handling of C++11 lambda functions in CC Mode.

[Richard Copley <rcopley@gmail.com>]

On 24 August 2016 at 20:43, Alan Mackenzie <acm@muc.de> wrote:
> Hello, Richard.
>
> On Wed, Aug 24, 2016 at 08:27:58PM +0100, Richard Copley wrote:
>> Hi Alan,
>
>> Thanks for this!
>
>> I encountered a problem while trying to come up with an
>> example so I could suggest a different default indentation
>> style for lambda bodies:
>
>> int main ()
>> {
>>   std::cout << ([] (int x) -> int {
>>     return 2 * x;
>>   } (10)) << std::endl;
>> }
>
>> Never mind the default indentation style, life's too short!
>> But here is the problem I mentioned. I just pulled from master
>> and recompiled and the bug is still present (as of your
>> commit 799a8a3338389013e8a76a70f507664ccb09a14f).
>
>> >>From emacs -Q:
>
>> C-x b x RET ; switch to a new buffer
>> M-x c++-mode RET
>> { } C-p ; insert a pair of braces and put point between them
>> [ ; insert a left square bracket
>
>> Emacs freezes. It can be woken up by holding down C-g
>> for a few seconds, at which point the *Messages*
>> buffer has this:
>
>> Error during redisplay: (jit-lock-function 55) signaled (quit)
>> Error during redisplay: (jit-lock-function 57) signaled (quit)
>> Error during redisplay: (jit-lock-function 60) signaled (quit)
>> Quit [7 times]
>
> Thanks for taking the trouble to report this.  What appears to be the
> same problem was reported by Yakov Markovitch on the CC Mode list
> yesterday evening.  I've investigated this and prepared a putative fix.
>
> That fix is in the patch below.  Could you please apply the patch,
> recompile CC Mode and try it out in normal C++ code, then let me know (a
> second opinion besides Yakov's) whether it fixes the problem completely.
>
> Thanks!  At the moment, I'm trying to get everything tidied up to
> release CC Mode 5.33, and I'm hoping that this is the _last_ "last
> minute" bug.
>
>
>
> diff -r f3c92d9e3424 cc-fonts.el
> --- a/cc-fonts.el       Sun Aug 21 15:17:45 2016 +0000
> +++ b/cc-fonts.el       Tue Aug 23 20:36:35 2016 +0000
> @@ -1654,7 +1654,7 @@
>             (c-backward-token-2)))
>
>         ;; Go round the following loop once per captured item.
> -       (while (and (not (eq (char-after) ?\]))
> +       (while (and (not (looking-at "\\s)"))
>                     (< (point) limit))
>           (if (eq (char-after) ?&)
>               (progn (setq mode ?&)
> @@ -1703,7 +1703,7 @@
>             (c-forward-syntactic-ws)))
>
>         (setq capture-default nil)
> -       (forward-char))))                       ; over the terminating "]".
> +       (forward-char))))              ; over the terminating "]" or whatever.
>    nil)
>
>
>
> --
> Alan Mackenzie (Nuremberg, Germany).

Great, thank you. I didn't have time to test much, but I haven't
noticed any problems with the patch installed. Couldn't reproduce
the problem I was talking about.