Re: GNU Emacs crashes with longlines-mode and outline-mode

[Jason Rumney <jasonr@gnu.org>]

Rainer Thiel wrote:
> I can reproduce the problem with the following file:
>
> ----------,
> -*- mode: text; mode: outline -*-
>
> * One chapter
>
> Some text. Some text that must be longer than one line, to test if
> Emacs really fails to handle outline mode and longlines-mode together.
> ----------´
>
> [last paragraph is supposed to be one long line, but may be wrapped by
> my mail client.
>
> When I load the file, I can only see
>
> ---,
> -*- mode: text; mode: outline -*-
>
> * One chapter...
> ---
>   

To reproduce this, the following is required:
(setq longlines-show-hard-newlines t)

C-c l after the file above is visited.

> as expected.  When I now press M-x longlines-mode<RET>, the crash occurs.
>   

I can reproduce this crash on both Windows XP and GNU/Linux.

The crash occurs in next_element_from_display_vector in xdisp.c (line
5961 in my current trunk sandbox), because it->dpvec is NULL and we try
to take its address. There is an xassert at the beginning of the
function that should catch this, but it must be compiled out in my
build.     

Emacs crashes in the same place regardless of whether longlines-mode is
enabled before or after the C-c l in the outline buffer, and regardless
of whether there are long lines in the buffer (the important things seem
to be longlines-show-hard-newlines and hidden text containing a hard
newline).