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# serial 9  -*- Autoconf -*-

# Enable extensions on systems that normally disable them.

# Copyright (C) 2003, 2006-2010 Free Software Foundation, Inc.

# This file is free software; the Free Software Foundation

# gives unlimited permission to copy and/or distribute it,

# with or without modifications, as long as this notice is preserved.

# This definition of AC_USE_SYSTEM_EXTENSIONS is stolen from CVS

# Autoconf.  Perhaps we can remove this once we can assume Autoconf

# 2.62 or later everywhere, but since CVS Autoconf mutates rapidly

# enough in this area it's likely we'll need to redefine

# AC_USE_SYSTEM_EXTENSIONS for quite some time.

# If autoconf reports a warning

#     warning: AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS

# or  warning: AC_RUN_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS

# the fix is

#   1) to ensure that AC_USE_SYSTEM_EXTENSIONS is never directly invoked

#      but always AC_REQUIREd,

#   2) to ensure that for each occurrence of

#        AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

#      or

#        AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])

#      the corresponding gnulib module description has 'extensions' among

#      its dependencies. This will ensure that the gl_USE_SYSTEM_EXTENSIONS

#      invocation occurs in gl_EARLY, not in gl_INIT.

# AC_USE_SYSTEM_EXTENSIONS

# ------------------------

# Enable extensions on systems that normally disable them,

# typically due to standards-conformance issues.

# Remember that #undef in AH_VERBATIM gets replaced with #define by

# AC_DEFINE.  The goal here is to define all known feature-enabling

# macros, then, if reports of conflicts are made, disable macros that

# cause problems on some platforms (such as __EXTENSIONS__).

AC_DEFUN_ONCE([AC_USE_SYSTEM_EXTENSIONS],

[AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl

AC_BEFORE([$0], [AC_RUN_IFELSE])dnl

  AC_REQUIRE([AC_CANONICAL_HOST])

  AC_CHECK_HEADER([minix/config.h], [MINIX=yes], [MINIX=])

  if test "$MINIX" = yes; then

    AC_DEFINE([_POSIX_SOURCE], [1],

      [Define to 1 if you need to in order for `stat' and other

       things to work.])

    AC_DEFINE([_POSIX_1_SOURCE], [2],

      [Define to 2 if the system does not provide POSIX.1 features

       except with this defined.])

    AC_DEFINE([_MINIX], [1],

      [Define to 1 if on MINIX.])

  fi

  dnl HP-UX 11.11 defines mbstate_t only if _XOPEN_SOURCE is defined to 500,

  dnl regardless of whether the flags -Ae or _D_HPUX_SOURCE=1 are already

  dnl provided.

  case "$host_os" in

    hpux*)

      AC_DEFINE([_XOPEN_SOURCE], [500],

        [Define to 500 only on HP-UX.])

      ;;

  esac

  AH_VERBATIM([__EXTENSIONS__],

[/* Enable extensions on AIX 3, Interix.  */

#ifndef _ALL_SOURCE

# undef _ALL_SOURCE

#endif

/* Enable GNU extensions on systems that have them.  */

#ifndef _GNU_SOURCE

# undef _GNU_SOURCE

#endif

/* Enable threading extensions on Solaris.  */

#ifndef _POSIX_PTHREAD_SEMANTICS

# undef _POSIX_PTHREAD_SEMANTICS

#endif

/* Enable extensions on HP NonStop.  */

#ifndef _TANDEM_SOURCE

# undef _TANDEM_SOURCE

#endif

/* Enable general extensions on Solaris.  */

#ifndef __EXTENSIONS__

# undef __EXTENSIONS__

#endif

])

  AC_CACHE_CHECK([whether it is safe to define __EXTENSIONS__],

    [ac_cv_safe_to_define___extensions__],

    [AC_COMPILE_IFELSE(

       [AC_LANG_PROGRAM([[

#         define __EXTENSIONS__ 1

          ]AC_INCLUDES_DEFAULT])],

       [ac_cv_safe_to_define___extensions__=yes],

       [ac_cv_safe_to_define___extensions__=no])])

  test $ac_cv_safe_to_define___extensions__ = yes &&

    AC_DEFINE([__EXTENSIONS__])

  AC_DEFINE([_ALL_SOURCE])

  AC_DEFINE([_GNU_SOURCE])

  AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])

  AC_DEFINE([_TANDEM_SOURCE])

])# AC_USE_SYSTEM_EXTENSIONS

# gl_USE_SYSTEM_EXTENSIONS

# ------------------------

# Enable extensions on systems that normally disable them,

# typically due to standards-conformance issues.

AC_DEFUN_ONCE([gl_USE_SYSTEM_EXTENSIONS],

[

  dnl Require this macro before AC_USE_SYSTEM_EXTENSIONS.

  dnl gnulib does not need it. But if it gets required by third-party macros

  dnl after AC_USE_SYSTEM_EXTENSIONS is required, autoconf 2.62..2.63 emit a

  dnl warning: "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".

  dnl Note: We can do this only for one of the macros AC_AIX, AC_GNU_SOURCE,

  dnl AC_MINIX. If people still use AC_AIX or AC_MINIX, they are out of luck.

  AC_REQUIRE([AC_GNU_SOURCE])

  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

])