dnl  On the NeXT, #including <utime.h> doesn't give you a definition for
dnl  struct utime, unless you #define _POSIX_SOURCE.

AC_DEFUN(GUILE_STRUCT_UTIMBUF, [
  AC_CACHE_CHECK([whether we need POSIX to get struct utimbuf],
    guile_cv_struct_utimbuf_needs_posix,
    [AC_TRY_CPP([
#ifdef __EMX__
#include <sys/utime.h>
#else
#include <utime.h>
#endif
struct utime blah;
],
                guile_cv_struct_utimbuf_needs_posix=no,
		guile_cv_struct_utimbuf_needs_posix=yes)])
  if test "$guile_cv_struct_utimbuf_needs_posix" = yes; then
     AC_DEFINE(UTIMBUF_NEEDS_POSIX)
  fi])




dnl
dnl Apparently, at CMU they have a weird version of libc.h that is
dnl installed in /usr/local/include and conflicts with unistd.h.
dnl In these situations, we should not #include libc.h.
dnl This test arranges to #define LIBC_H_WITH_UNISTD_H iff libc.h is
dnl present on the system, and is safe to #include.
dnl
AC_DEFUN([GUILE_HEADER_LIBC_WITH_UNISTD],
  [
    AC_CHECK_HEADERS(libc.h unistd.h)
    AC_CACHE_CHECK(
      "whether libc.h and unistd.h can be included together",
      guile_cv_header_libc_with_unistd,
      [
        if test "$ac_cv_header_libc_h" = "no"; then
          guile_cv_header_libc_with_unistd="no"
        elif test "$ac_cv_header_unistd.h" = "no"; then
          guile_cv_header_libc_with_unistd="yes"
        else
          AC_TRY_COMPILE(
	    [
#             include <libc.h>
#             include <unistd.h>
	    ],
	    [],
	    [guile_cv_header_libc_with_unistd=yes],
	    [guile_cv_header_libc_with_unistd=no]
          )
        fi
      ]
    )
    if test "$guile_cv_header_libc_with_unistd" = yes; then
      AC_DEFINE(LIBC_H_WITH_UNISTD_H)
    fi
  ]
)