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emacs/m4/extensions.m4
2011-01-08 22:57:07 -08:00

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# serial 9 -*- Autoconf -*-
# Enable extensions on systems that normally disable them.
# Copyright (C) 2003, 2006-2011 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])
])