Re: Can't build previous versions of Emacs?

[Po Lu <luangruo@yahoo.com>]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> Hi all,
>
> I have the Emacs 25, 26 and 27 branches checked out in git worktrees,
> and I was going to build them to test some backwards compatibility. On a
> clean checkout, "make" failed for all three of them with this error:
>
> sysdep.c:1795:22: error: variably modified ‘sigsegv_stack’ at file scope
>  1795 | static unsigned char sigsegv_stack[SIGSTKSZ];
>       |                      ^~~~~~~~~~~~~
> make[2]: *** [Makefile:377: sysdep.o] Error 1
> make[2]: Leaving directory '/home/eric/dev/emacs-26/src'
> make[1]: *** [Makefile:421: src] Error 2
> make[1]: Leaving directory '/home/eric/dev/emacs-26'
> make: *** [Makefile:1107: bootstrap] Error 2
>
> This is on Arch Linux, I can send the config.status file for any of the
> branches if that would help.

That's expected.  glibc recently changed in that SIGSTKSZ is now a call
to a function.  Emacs wasn't modified to be compatible with that until
28.1.