Digging some more, I think the issue is
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=24065 . Emacs trunk is
depending on undefined C behaviour, which gcc 5 has started optimising,
breaking the code.

I've updated https://www.emacswiki.org/emacs/GuileEmacsBuild to note this.
You can work around with -fno-builtin-malloc or simply compile with clang
(my current solution).

Emacs trunk has fixed this (in 4b1436b702d56eedd27a0777fc7232cdfb7ac4f6
IIUC), but I believe that commit does not exist in the guile-emacs fork.

Wilfred

On 4 September 2016 at 04:48, Stefan Husmann <stefan-husmann@t-online.de>
wrote:

> Wilfred Hughes <me@wilfred.me.uk> writes:
>
> > I've had a play with the AUR packages too. The guile4emacs PKGBUILD works
> > perfectly, but the guile-emacs build process segfaults when
> bootstrap-emacs
> > attempts to load calendar/cal-loaddefs.el:
> >
> > make[2]: Leaving directory
> > '/home/wilfred/aur/guile-emacs-git/src/guilemacs/lisp'
> > if test "yes" = "yes"; then \
> >   rm -f bootstrap-emacs; \
> >   ln temacs bootstrap-emacs; \
> > else \
> >   ./temacs --batch --load loadup bootstrap || exit 1; \
> >   test "X" = X ||  -zex emacs; \
> >   mv -f emacs bootstrap-emacs; \
> > fi
> > make -C ../lisp autoloads EMACS="../src/bootstrap-emacs"
> > make[2]: Entering directory
> > '/home/wilfred/aur/guile-emacs-git/src/guilemacs/lisp'
> > EMACSLOADPATH= '../src/bootstrap-emacs' -batch --no-site-file
> > --no-site-lisp -l autoload \
> >    --eval "(setq generate-autoload-cookie \";;;###cal-autoload\")" \
> >    --eval "(setq generated-autoload-file (expand-file-name
> > (unmsys--file-name \"calendar/cal-loaddefs.el\")))" \
> >    -f batch-update-autoloads ./calendar
> > make[2]: *** [Makefile:466: calendar/cal-loaddefs.el] Segmentation fault
> > (core dumped)
> > make[2]: Leaving directory
> > '/home/wilfred/aur/guile-emacs-git/src/guilemacs/lisp'
> > make[1]: *** [Makefile:805: ../lisp/loaddefs.el] Error 2
> > make[1]: Leaving directory
> > '/home/wilfred/aur/guile-emacs-git/src/guilemacs/src'
> > make: *** [Makefile:376: src] Error 2
> > ==> ERROR: A failure occurred in build().
> >     Aborting...
> >
> > Any suggestions?
> >
> > On 30 August 2016 at 20:32, Wilfred Hughes <me@wilfred.me.uk> wrote:
> >
> Hello,
>
> I can confirm this, but currently have no ideas what is going on
> here. This definitely used to work, but gcc was updated since then.
>
> Sorry for inconveniance. I will try to dig deeper into it.
>
> Best Regards
>
> Stefan
>