Bootstrapping Emacs (trunk) with GCC >= 4.5.1 [Cygwin]

[Angelo Graziosi]

On Cygwin, I have tried to bootstrap Emacs-trunk using gcc-4.5.1 (just 
released) and gcc-4.6-20100731 (snapshot), but the build fails as follows:

===================================================================
[...]
gcc-4.6 -c  -Demacs -DHAVE_CONFIG_H  -I. -I/tmp/emacs/src   -D_REENTRANT 
-I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/atk-1.0 
-I/usr/include/cairo -I/usr/include/pango-1.0 
-I/usr/include/gio-unix-2.0/ -I/usr/include/glib-2.0 
-I/usr/lib/glib-2.0/include -I/usr/include/pixman-1 
-I/usr/include/freetype2 -I/usr/include/libpng12 
-I/usr/include/freetype2     -D_REENTRANT -I/usr/include/librsvg-2 
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include 
-I/usr/include/gtk-2.0 -I/usr/include/cairo -I/usr/include/pixman-1 
-I/usr/include/freetype2 -I/usr/include/libpng12 
-I/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include   -DORBIT2=1 
-D_REENTRANT -I/usr/include/gconf/2 -I/usr/include/orbit-2.0 
-I/usr/include/dbus-1.0 -I/usr/lib/dbus-1.0/include 
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include       -MMD -MF 
deps/xfns.d  -Wold-style-definition -Wdeclaration-after-statement 
-Wno-pointer-sign  -g -O2 /tmp/emacs/src/xfns.c
In file included from /usr/include/X11/Xos.h:146:0,
                 from /tmp/emacs/src/xfaces.c:277:
/usr/include/X11/Xarch.h:43:30: fatal error: sys/byteorder.h: No such 
file or directory
compilation terminated.
make[2]: *** [xfaces.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[2]: Leaving directory `/tmp/emacs/Work/src'
make[1]: *** [src] Error 2
make[1]: Leaving directory `/tmp/emacs/Work'
make: *** [bootstrap] Error 2
===================================================================

The culprit are these statements in '/usr/include/X11/Xarch.h':

[...]
#  if defined(SVR4) || defined(__SVR4)
#   include <sys/byteorder.h>
#  elif [...]

On Cygwin, it seems that the

if defined(SVR4)...

branch is executed and the header 'byteorder.h' is not found because it 
lives in /usr/include/asm not in /usr/include/sys!

Now I have tried the same on GNU/Linux Kubuntu 10.04, on which that 
header, 'byteorder.h', lives in the same /usr/include/asm directory as 
on Cygwin, but the bootstrap passes, almost surely because the 'elif' 
branch is executed!

So, on Cygwin, I adopted the workaround to create a symbolic link:

cd /usr/include/sys
ln -sf ../asm/byteorder.h byteorder.h

Now the bootstrap (with GCC >= 4.5.1) passes also on Cygwin, and works.

Have you better ideas on this issue?

Thanks,
Angelo.