Hi,
tested x86_64-linux, committed to mainline.
Thanks,
Paolo.
/////////////////
2012-04-11 Paolo Carlini <paolo.carl...@oracle.com>
PR libstdc++/52931
* include/bits/functional_hash.h (struct hash): Remove definition.
* testsuite/20_util/hash/52931.cc: New.
Index: include/bits/functional_hash.h
===================================================================
--- include/bits/functional_hash.h (revision 186297)
+++ include/bits/functional_hash.h (working copy)
@@ -1,6 +1,7 @@
// functional_hash.h header -*- C++ -*-
-// Copyright (C) 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012
+// 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
@@ -55,12 +56,7 @@
/// Primary class template hash.
template<typename _Tp>
- struct hash : public __hash_base<size_t, _Tp>
- {
- static_assert(sizeof(_Tp) < 0,
- "std::hash is not specialized for this type");
- size_t operator()(const _Tp&) const noexcept;
- };
+ struct hash;
/// Partial specializations for pointer types.
template<typename _Tp>
Index: testsuite/20_util/hash/52931.cc
===================================================================
--- testsuite/20_util/hash/52931.cc (revision 0)
+++ testsuite/20_util/hash/52931.cc (revision 0)
@@ -0,0 +1,32 @@
+// { dg-options "-std=gnu++11" }
+// { dg-do compile }
+
+// Copyright (C) 2012 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/>.
+
+#include <type_traits>
+#include <functional>
+
+class S{}; // No hash specialization
+
+template<class T>
+auto f(int) -> decltype(std::hash<T>(), std::true_type());
+
+template<class T>
+auto f(...) -> decltype(std::false_type());
+
+static_assert(!decltype(f<S>(0))::value, "");
