--- a/ChangeLog	Wed Sep 12 15:59:57 2007 +0000
+++ b/ChangeLog	Wed Sep 12 23:24:15 2007 +0000
@@ -1,3 +1,9 @@
+2007-09-12  Bruno Haible  <bruno@clisp.org>
+
+	* m4/lock.m4: Don't provide an AC_USE_SYSTEM_EXTENSIONS definition.
+	(gl_LOCK_EARLY_BODY): Use AC_GNU_SOURCE when AC_USE_SYSTEM_EXTENSIONS
+	is not defined.
+
 2007-09-12  Eric Blake  <ebb9@byu.net>
 
 	Track CVS Autoconf on AC_USE_SYSTEM_EXTENSIONS.

--- a/m4/lock.m4	Wed Sep 12 15:59:57 2007 +0000
+++ b/m4/lock.m4	Wed Sep 12 23:24:15 2007 +0000
@@ -1,4 +1,4 @@
-# lock.m4 serial 7 (gettext-0.16)
+# lock.m4 serial 7 (gettext-0.16.2)
 dnl Copyright (C) 2005-2007 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -35,7 +35,12 @@
   AC_BEFORE([$0], [gl_ARGP])dnl
 
   AC_REQUIRE([AC_CANONICAL_HOST])
-  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) dnl needed for pthread_rwlock_t on glibc systems
+  dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
+  dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
+  dnl AC_GNU_SOURCE.
+  m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
+    [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
+    [AC_REQUIRE([AC_GNU_SOURCE])])
   dnl Check for multithreading.
   AC_ARG_ENABLE(threads,
 AC_HELP_STRING([--enable-threads={posix|solaris|pth|win32}], [specify multithreading API])
@@ -257,14 +262,6 @@
   AC_REQUIRE([AC_C_INLINE])
 ])
 
-# AC_USE_SYSTEM_EXTENSIONS was only added in autoconf 2.60, but lock.m4
-# wants to work with autoconf 2.54.  Add a fallback until such time as
-# a newer autoconf is standard, if one is not already provided by gnulib
-# extensions.m4.
-m4_if(m4_version_compare(m4_PACKAGE_VERSION, [2.60]), [-1],
-      [m4_ifndef([AC_USE_SYSTEM_EXTENSIONS],
-                 [AC_DEFUN([AC_USE_SYSTEM_EXTENSIONS], [AC_GNU_SOURCE])])])
-
 dnl Survey of platforms:
 dnl
 dnl Platform          Available   Compiler    Supports   test-lock