X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fextensions.m4;h=49760791865fb81bb80f0e649d8a72bddfc0cd04;hb=1d9734dc428383f0573c39c3ee92d84c78b84436;hp=58bc0beb6d5b674c128208b3678c02e1e789adcc;hpb=d9b9fc6b5b56633edd136536aea68a03fa33bd0f;p=gnulib.git

diff --git a/m4/extensions.m4 b/m4/extensions.m4
index 58bc0beb6..497607918 100644
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,12 +1,12 @@
 # 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 file is only needed in autoconf <= 2.59.  Newer versions of autoconf
+# have a macro AC_USE_SYSTEM_EXTENSIONS with identical semantics.
 
 # gl_USE_SYSTEM_EXTENSIONS
 # ------------------------
@@ -24,6 +24,19 @@ AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS], [
 [/* Enable extensions on Solaris.  */
 #ifndef __EXTENSIONS__
 # undef __EXTENSIONS__
+#endif
+#ifndef _POSIX_PTHREAD_SEMANTICS
+# undef _POSIX_PTHREAD_SEMANTICS
 #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])
 ])