Re: Unexec dumping results in "Segmentation fault" on Windows Msys2

[Eli Zaretskii <eliz@gnu.org>]

> From: Nikolay Kudryavtsev <nikolay.kudryavtsev@gmail.com>
> Cc: emacs-devel@gnu.org
> Date: Thu, 29 Apr 2021 22:17:10 +0300
> 
> I now know what's going on there.
> 
> buffer.c/init_buffer has some unexec-specific code that remaps memory 
> for the special buffers inherited from temacs. We fail at 
> Fprin1_to_string which uses the " prin1" special buffer. cddf85d256 
> removed FOR_EACH_BUFFER macro and replaced it everywhere with the use of 
> FOR_EACH_LIVE_BUFFER. Because FOR_EACH_LIVE_BUFFER does not iterate over 
> the " prin1" buffer, it does not get its memory remapped and this breaks 
> print functionality and elisp compilation, which depends on it.
> 
> FOR_EACH_BUFFER worked before due to buffer structure operating as a 
> linked list and since it's kind of an ugly way of doing things, make 
> sense why Stefan removed it. But I'm not if adding those special buffers 
> to Vbuffer_alist(FOR_EACH_LIVE_BUFFER uses it) would not break anything.

Thanks.  The " prin1" buffer is not in Vbuffer_alist intentionally.  I
installed a possible fix for this on master (100% untested), please
see if it fixes the problem.