Avoid warnings about unused local typedefs.

	* m4/ax_check_compile_flag.m4: New.
	Imported from
	http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html.
	* configure.ac: Ensure AX_* macros are expanded.
	(WARNINGS_CXXFLAGS): Add `-Wno-unused-local-typedefs' if the C++
	compiler supports this flag.

ChangeLog

+2014-06-27  Roland Levillain  <roland@lrde.epita.fr>
+
+	Avoid warnings about unused local typedefs.
+
+	* m4/ax_check_compile_flag.m4: New.
+	Imported from
+	http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html.
+	* configure.ac: Ensure AX_* macros are expanded.
+	(WARNINGS_CXXFLAGS): Add `-Wno-unused-local-typedefs' if the C++
+	compiler supports this flag.
+
 2014-06-26  Roland Levillain  <roland@lrde.epita.fr>
 
 	Make Olena more compatible with BSD Make.

configure.ac

-# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 EPITA
+# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 EPITA
 # Research and Development Laboratory (LRDE).
 #
 # This file is part of Olena.
@@ -15,7 +15,8 @@
 # You should have received a copy of the GNU General Public License
 # along with Olena.  If not, see <http://www.gnu.org/licenses/>.
 
-m4_pattern_forbid([^OLN_])
+dnl Catch macros that are not expanded.
+m4_pattern_forbid([^(AX|OLN)_])
 
 AC_PREREQ([2.61])
 
@@ -107,6 +108,12 @@ case "$CXX" in
         ;;
 esac
 
+# Avoid warnings about unused local typedefs, which are used as a
+# concept checking means in Milena (`-Wunused-local-typedefs' is
+# enabled by `-Wall' in GCC since version 4.8).
+AX_CHECK_COMPILE_FLAG([-Wno-unused-local-typedefs],
+  [WARNINGS_CXXFLAGS="$WARNINGS_CXXFLAGS -Wno-unused-local-typedefs"])
+
 
 # ------------------------------ #
 # C++ compiler flags for tests.  #

m4/ax_check_compile_flag.m4

+# ===========================================================================
+#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the current language's compiler
+#   or gives an error.  (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 3
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS