Import new gnulib.

m4/extensions.m4

@@ -1,14 +1,14 @@
-# serial 9  -*- Autoconf -*-
+# serial 13  -*- Autoconf -*-
 # Enable extensions on systems that normally disable them.
 
-# Copyright (C) 2003, 2006-2010 Free Software Foundation, Inc.
+# Copyright (C) 2003, 2006-2013 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 definition of AC_USE_SYSTEM_EXTENSIONS is stolen from CVS
 # Autoconf.  Perhaps we can remove this once we can assume Autoconf
-# 2.62 or later everywhere, but since CVS Autoconf mutates rapidly
+# 2.70 or later everywhere, but since Autoconf mutates rapidly
 # enough in this area it's likely we'll need to redefine
 # AC_USE_SYSTEM_EXTENSIONS for quite some time.
 
@@ -30,6 +30,7 @@
 # ------------------------
 # Enable extensions on systems that normally disable them,
 # typically due to standards-conformance issues.
+#
 # Remember that #undef in AH_VERBATIM gets replaced with #define by
 # AC_DEFINE.  The goal here is to define all known feature-enabling
 # macros, then, if reports of conflicts are made, disable macros that
@@ -38,35 +39,31 @@ AC_DEFUN_ONCE([AC_USE_SYSTEM_EXTENSIONS],
 [AC_BEFORE([$0], [AC_COMPILE_IFELSE])dnl
 AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
 
-  AC_REQUIRE([AC_CANONICAL_HOST])
-
   AC_CHECK_HEADER([minix/config.h], [MINIX=yes], [MINIX=])
   if test "$MINIX" = yes; then
     AC_DEFINE([_POSIX_SOURCE], [1],
-      [Define to 1 if you need to in order for `stat' and other
+      [Define to 1 if you need to in order for 'stat' and other
        things to work.])
     AC_DEFINE([_POSIX_1_SOURCE], [2],
       [Define to 2 if the system does not provide POSIX.1 features
        except with this defined.])
     AC_DEFINE([_MINIX], [1],
       [Define to 1 if on MINIX.])
+    AC_DEFINE([_NETBSD_SOURCE], [1],
+      [Define to 1 to make NetBSD features available.  MINIX 3 needs this.])
   fi
 
-  dnl HP-UX 11.11 defines mbstate_t only if _XOPEN_SOURCE is defined to 500,
-  dnl regardless of whether the flags -Ae or _D_HPUX_SOURCE=1 are already
-  dnl provided.
-  case "$host_os" in
-    hpux*)
-      AC_DEFINE([_XOPEN_SOURCE], [500],
-        [Define to 500 only on HP-UX.])
-      ;;
-  esac
-
-  AH_VERBATIM([__EXTENSIONS__],
+dnl Use a different key than __EXTENSIONS__, as that name broke existing
+dnl configure.ac when using autoheader 2.62.
+  AH_VERBATIM([USE_SYSTEM_EXTENSIONS],
 [/* Enable extensions on AIX 3, Interix.  */
 #ifndef _ALL_SOURCE
 # undef _ALL_SOURCE
 #endif
+/* Enable general extensions on OS X.  */
+#ifndef _DARWIN_C_SOURCE
+# undef _DARWIN_C_SOURCE
+#endif
 /* Enable GNU extensions on systems that have them.  */
 #ifndef _GNU_SOURCE
 # undef _GNU_SOURCE
@@ -79,6 +76,12 @@ AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
 #ifndef _TANDEM_SOURCE
 # undef _TANDEM_SOURCE
 #endif
+/* Enable X/Open extensions if necessary.  HP-UX 11.11 defines
+   mbstate_t only if _XOPEN_SOURCE is defined to 500, regardless of
+   whether compiling with -Ae or -D_HPUX_SOURCE=1.  */
+#ifndef _XOPEN_SOURCE
+# undef _XOPEN_SOURCE
+#endif
 /* Enable general extensions on Solaris.  */
 #ifndef __EXTENSIONS__
 # undef __EXTENSIONS__
@@ -95,9 +98,26 @@ AC_BEFORE([$0], [AC_RUN_IFELSE])dnl
   test $ac_cv_safe_to_define___extensions__ = yes &&
     AC_DEFINE([__EXTENSIONS__])
   AC_DEFINE([_ALL_SOURCE])
+  AC_DEFINE([_DARWIN_C_SOURCE])
   AC_DEFINE([_GNU_SOURCE])
   AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
   AC_DEFINE([_TANDEM_SOURCE])
+  AC_CACHE_CHECK([whether _XOPEN_SOURCE should be defined],
+    [ac_cv_should_define__xopen_source],
+    [ac_cv_should_define__xopen_source=no
+     AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[
+          #include <wchar.h>
+          mbstate_t x;]])],
+       [],
+       [AC_COMPILE_IFELSE(
+          [AC_LANG_PROGRAM([[
+             #define _XOPEN_SOURCE 500
+             #include <wchar.h>
+             mbstate_t x;]])],
+          [ac_cv_should_define__xopen_source=yes])])])
+  test $ac_cv_should_define__xopen_source = yes &&
+    AC_DEFINE([_XOPEN_SOURCE], [500])
 ])# AC_USE_SYSTEM_EXTENSIONS
 
 # gl_USE_SYSTEM_EXTENSIONS