X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fextensions.m4;h=49760791865fb81bb80f0e649d8a72bddfc0cd04;hb=1d9734dc428383f0573c39c3ee92d84c78b84436;hp=6f34a8d35c04f921214bbefe62da6993dc875fd0;hpb=8a38d6958a3e36936829cb8b4074fb22296ed600;p=gnulib.git

diff --git a/m4/extensions.m4 b/m4/extensions.m4
index 6f34a8d35..497607918 100644
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,10 +1,13 @@
 # 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 only needed in autoconf <= 2.59.  Newer versions of autoconf
+# have a macro AC_USE_SYSTEM_EXTENSIONS with identical semantics.
+
 # gl_USE_SYSTEM_EXTENSIONS
 # ------------------------
 # Enable extensions on systems that normally disable them,
@@ -21,6 +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])
 ])