dnl Check if the compiler supports -Wall
dnl
dnl
AC_DEFUN([VIM_GXX_WALL],
[EXTRA_CPPFLAGS=""
if test -n "$GXX"
then
	changequote(,)dnl
	cat > conftest.$ac_ext <<EOF
#line __oline__ "configure"
int main(int argc, char *argv[]) { return argv[argc-1] == 0; }
EOF
	changequote([,])dnl
	AC_MSG_CHECKING(for g++ -Wall option)
	cf_save_CPPFLAGS="$CPPFLAGS"
	CPPFLAGS="$cf_save_CPPFLAGS -Wall"
	if AC_TRY_EVAL(ac_compile); then
		AC_MSG_RESULT(... -Wall)
		EXTRA_CPPFLAGS="-Wall"
	else
		AC_MSG_RESULT(NO)
	fi
	rm -f conftest*
	CPPFLAGS="$cf_save_CPPFLAGS"
fi
CPPFLAGS="$CPPFLAGS $EXTRA_CPPFLAGS"
])dnl