bug#14812: 24.3; build failure on FreeBSD 9.1

[Paul Eggert]

On 07/09/2013 07:04 AM, Wolfgang Jenkner wrote:
> I don't know if this is because of
> the way emacs uses this stuff or because of a FreeBSD bug.

I suspect that the root problem is that FreeBSD 9.1 lacks
a working stdalign.h.  Perhaps this is because they're
implementing C11 gradually and added _Alignof before
adding stdalign.h.  Or maybe their stdalign.h fails
the 'configure' test for stdalign.

When implementing that part of Emacs I assumed that
implementations that had _Alignof would also implement
stdalign.h, but FreeBSD appears to be an exception.
The change in trunk bzr 113322 removes the assumption
that _Alignof is missing if stdalign.h is missing, so
I hope it fixes this porting glitch.

Strictly speaking this would be a bug in FreeBSD only if they're
saying they support C11.  If they claim only C99 support they're
allowed to define _Alignof without providing stdalign.h.  But
in the long run they should provide stdalign.h so the problem
would go away even without the bzr 113322 fix.

I don't know whether the fix (once it's tested)
is worth backporting to Emacs 24.