@@ -254,6 +254,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator()(long double __val) const noexcept;
};
+#if __cplusplus >= 201703L
+ template<>
+ struct hash<nullptr_t> : public __hash_base<size_t, nullptr_t>
+ {
+ size_t
+ operator()(nullptr_t) const noexcept
+ { return 0; }
+ };
+#endif
+
// @} group hashes
// Hint about performance of hash functor. If not fast the hash-based
new file mode 100644
@@ -0,0 +1,37 @@
+// Copyright (C) 2019 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-options "-std=gnu++17" }
+// { dg-do run { target c++17 } }
+
+#include <functional>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+ auto h1 = std::hash<std::nullptr_t>{}(nullptr);
+ static_assert(std::is_same_v<decltype(h1), std::size_t>);
+ auto h2 = std::hash<std::nullptr_t>{}(nullptr);
+ VERIFY( h1 == h2 );
+}
+
+int
+main()
+{
+ test01();
+}
PR libstdc++/88802 * include/bits/functional_hash.h (hash<nullptr_t>): Define specialization for C++17 (P0513R0, LWG 2817). * testsuite/20_util/hash/nullptr.cc: New test. Tested x86_64-linux, committed to trunk. commit 3ade1f14e79b8bbb4939244e9125fdddd9043de6 Author: Jonathan Wakely <jwakely@redhat.com> Date: Fri Jan 11 14:26:34 2019 +0000 PR libstdc++/88802 define std::hash<nullptr_t> for C++17 PR libstdc++/88802 * include/bits/functional_hash.h (hash<nullptr_t>): Define specialization for C++17 (P0513R0, LWG 2817). * testsuite/20_util/hash/nullptr.cc: New test.