dnl CF_SYSV version: 14 updated: 2012/06/11 17:37:05
dnl -------
dnl Check if this is a SYSV platform, e.g., as used in <X11/Xos.h>, and whether
dnl defining it will be helpful.  The following features are used to check:
dnl
dnl a) bona-fide SVSV doesn't use const for sys_errlist[].  Since this is a
dnl legacy (pre-ANSI) feature, const should not apply.  Modern systems only
dnl declare strerror().  Xos.h declares the legacy form of str_errlist[], and
dnl a compile-time error will result from trying to assign to a const array.
dnl
dnl b) compile with headers that exist on SYSV hosts.
dnl
dnl c) compile with type definitions that differ on SYSV hosts from standard C.
AC_DEFUN([CF_SYSV],
[
AC_CHECK_HEADERS( \
termios.h \
stdlib.h \
X11/Intrinsic.h \
)

AC_REQUIRE([CF_SYS_ERRLIST])

AC_CACHE_CHECK(if we should define SYSV,cf_cv_sysv,[
AC_TRY_COMPILE([
#undef  SYSV
#define SYSV 1			/* get Xos.h to declare sys_errlist[] */
#ifdef HAVE_STDLIB_H
#include <stdlib.h>		/* look for wchar_t */
#endif
#ifdef HAVE_X11_INTRINSIC_H
#include <X11/Intrinsic.h>	/* Intrinsic.h has other traps... */
#endif
#ifdef HAVE_TERMIOS_H		/* needed for HPUX 10.20 */
#include <termios.h>
#define STRUCT_TERMIOS struct termios
#else
#define STRUCT_TERMIOS struct termio
#endif
#include <curses.h>
#include <term.h>		/* eliminate most BSD hacks */
#include <errno.h>		/* declare sys_errlist on older systems */
#include <sys/termio.h>		/* eliminate most of the remaining ones */
],[
static STRUCT_TERMIOS d_tio;
	d_tio.c_cc[VINTR] = 0;
	d_tio.c_cc[VQUIT] = 0;
	d_tio.c_cc[VERASE] = 0;
	d_tio.c_cc[VKILL] = 0;
	d_tio.c_cc[VEOF] = 0;
	d_tio.c_cc[VEOL] = 0;
	d_tio.c_cc[VMIN] = 0;
	d_tio.c_cc[VTIME] = 0;
#if defined(HAVE_SYS_ERRLIST) && !defined(DECL_SYS_ERRLIST)
sys_errlist[0] = "";		/* Cygwin mis-declares this */
#endif
],
[cf_cv_sysv=yes],
[cf_cv_sysv=no])
])
test "$cf_cv_sysv" = yes && AC_DEFINE(SYSV)
])dnl
