X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fextensions.m4;h=49760791865fb81bb80f0e649d8a72bddfc0cd04;hb=ad7e0cc967251bc0d09999503a51e5fbcfac021d;hp=95a54a6f10f5a019879e041340252d651846bbd5;hpb=106fa09ff377cf9a21c57d804cb3f16fbed99c53;p=gnulib.git

diff --git a/m4/extensions.m4 b/m4/extensions.m4
index 95a54a6f1..497607918 100644
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,17 +1,42 @@
+# Enable extensions on systems that normally disable them.
+
+# 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,
 # typically due to standards-conformance issues.
 AC_DEFUN([gl_USE_SYSTEM_EXTENSIONS], [
-  AC_REQUIRE([AC_AIX])
+  AC_BEFORE([$0], [AC_COMPILE_IFELSE])
+  AC_BEFORE([$0], [AC_RUN_IFELSE])
+
   AC_REQUIRE([AC_GNU_SOURCE])
+  AC_REQUIRE([AC_AIX])
   AC_REQUIRE([AC_MINIX])
+
   AH_VERBATIM([__EXTENSIONS__],
 [/* Enable extensions on Solaris.  */
 #ifndef __EXTENSIONS__
 # undef __EXTENSIONS__
+#endif
+#ifndef _POSIX_PTHREAD_SEMANTICS
+# undef _POSIX_PTHREAD_SEMANTICS
 #endif])
-  AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
-  AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
-  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])
 ])