PR 79798 Fix incorrect use of std::result_of in std::bind

	PR libstdc++/79798
	* include/std/functional (bind::_Res_type_impl): Fix incorrect use of
	result_of that loses top-level cv-qualifiers.
	* testsuite/20_util/bind/79798.cc: New test.

From-SVN: r245827

libstdc++-v3/ChangeLog

+2017-03-02  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/79798
+	* include/std/functional (bind::_Res_type_impl): Fix incorrect use of
+	result_of that loses top-level cv-qualifiers.
+	* testsuite/20_util/bind/79798.cc: New test.
+
 2017-03-01  Gerald Pfeifer  <gerald@pfeifer.com>
 
 	* doc/xml/manual/documentation_hacking.xml: Tweak link to

libstdc++-v3/include/std/functional

@@ -502,7 +502,7 @@ _GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)
 
       template<typename _Fn, typename _CallArgs, typename... _BArgs>
 	using _Res_type_impl
-	  = typename result_of< _Fn&(_Mu_type<_BArgs, _CallArgs>...) >::type;
+	  = typename result_of< _Fn&(_Mu_type<_BArgs, _CallArgs>&&...) >::type;
 
       template<typename _CallArgs>
 	using _Res_type = _Res_type_impl<_Functor, _CallArgs, _Bound_args...>;

libstdc++-v3/testsuite/20_util/bind/79798.cc

+// Copyright (C) 2017 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library 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, or (at your option)
+// any later version.
+
+// This library 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 library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do compile { target c++11 } }
+
+#include <functional>
+
+// PR libstdc++/79798
+
+struct X { };
+const X f(int);
+
+struct Y {
+  void operator()(X&&) = delete;
+  int operator()(const X&&);
+};
+
+auto b = std::bind(Y(), std::bind(f, std::placeholders::_1));
+auto i = b(1);