* lib/getcwd.c (__getcwd): Don't assume getcwd (NULL, 0) works

[gnulib.git] / m4 / extensions.m4

diff --git a/m4/extensions.m4 b/m4/extensions.m4
index 58bc0be..143a9e5 100644 (file)
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,18 +1,23 @@
+# serial 4  -*- Autoconf -*-
 # Enable extensions on systems that normally disable them.
 
-# Copyright (C) 2003 Free Software Foundation, Inc.
+# Copyright (C) 2003, 2006 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 file is free software, distributed under the terms of the GNU
-# General Public License.  As a special exception to the GNU General
-# Public License, this file may be distributed as part of a program
-# that contains a configuration script generated by Autoconf, under
-# the same distribution terms as the rest of that program.
+# This definition of AC_USE_SYSTEM_EXTENSIONS is stolen from CVS
+# Autoconf.  Perhaps we can remove this once we can assume Autoconf
+# 2.61 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.
 
-# gl_USE_SYSTEM_EXTENSIONS
+# AC_USE_SYSTEM_EXTENSIONS
 # ------------------------
 # Enable extensions on systems that normally disable them,
 # typically due to standards-conformance issues.
-AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS], [
+AC_DEFUN([AC_USE_SYSTEM_EXTENSIONS],
+[
   AC_BEFORE([$0], [AC_COMPILE_IFELSE])
   AC_BEFORE([$0], [AC_RUN_IFELSE])
 
@@ -24,6 +29,30 @@ AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS], [
 [/* Enable extensions on Solaris.  */
 #ifndef __EXTENSIONS__
 # undef __EXTENSIONS__
+#endif
+#ifndef _POSIX_PTHREAD_SEMANTICS
+# undef _POSIX_PTHREAD_SEMANTICS
+#endif
+#ifndef _TANDEM_SOURCE
+# undef _TANDEM_SOURCE
 #endif])
-  AC_DEFINE([__EXTENSIONS__])
+  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([_POSIX_PTHREAD_SEMANTICS])
+  AC_DEFINE([_TANDEM_SOURCE])
 ])
+
+# gl_USE_SYSTEM_EXTENSIONS
+# ------------------------
+# Enable extensions on systems that normally disable them,
+# typically due to standards-conformance issues.
+AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS],
+  [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])])