Subject: Re: bug#18134: 24.3; Doxygen comments trigger anomalous C++ major mode behavior

From: Alan Mackenzie <[email-masked]>
Date: Mon, 7 Oct 2019 18:51:35 +0000

Hello, Stefan.

On Mon, Oct 07, 2019 at 00:42:46 +0200, Stefan Kangas wrote:
> found 27.0.50
> thanks

> Sam Varshavchik <[email-masked]> writes:

> > I am seeing anomalous behavior in C++ major mode that's triggered by
> > long, but not excessively long -- only a few hundred lines -- Doxygen-style
> > comments.

> > Cursor navigation at the end of the Doxygen comment block in the
> > following file (just before the first typedef), and trying to add some
> > additional text there, results in 3-5 seconds' worth of delays for
> > nearly typed character.

> > Highlighting the entire Doxygen comment block: M-x indent-region takes
> > several minutes (!) with emacs consuming 100% CPU.
> [Snipped a long C++ example file here.]

> I can reproduce both issues on current master using the provided example
> file.

> 1. Editing is very slow after the Doxygen comment block.

> 2. Opening the example file under "emacs -Q", pressing C-x h TAB takes
>    several minutes and sees the emacs process consume 100 % CPU (on one
>    core at least).

I will be looking at this in the coming days.  It is likely to take
several (or even many) days to resolve, not hours.

[ .... ]

> Best regards,
> Stefan Kangas

-- 
Alan Mackenzie (Nuremberg, Germany).