commit 65e06eb5b8ee42fb024307538380f8a375aba7ca
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Jun 23 23:41:08 2014 +0100
PR libstdc++/56785
* include/std/tuple (_Tuple_impl): Remove zero-element specialization
and define one-element specialization.
* testsuite/20_util/tuple/56785.cc: New.
@@ -158,30 +158,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<std::size_t _Idx, typename... _Elements>
struct _Tuple_impl;
- /**
- * Zero-element tuple implementation. This is the basis case for the
- * inheritance recursion.
- */
- template<std::size_t _Idx>
- struct _Tuple_impl<_Idx>
- {
- template<std::size_t, typename...> friend class _Tuple_impl;
-
- _Tuple_impl() = default;
-
- template<typename _Alloc>
- _Tuple_impl(allocator_arg_t, const _Alloc&) { }
-
- template<typename _Alloc>
- _Tuple_impl(allocator_arg_t, const _Alloc&, const _Tuple_impl&) { }
-
- template<typename _Alloc>
- _Tuple_impl(allocator_arg_t, const _Alloc&, _Tuple_impl&&) { }
-
- protected:
- void _M_swap(_Tuple_impl&) noexcept { /* no-op */ }
- };
-
template<typename _Tp>
struct __is_empty_non_tuple : is_empty<_Tp> { };
@@ -358,6 +334,130 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
+ // Basis case of inheritance recursion.
+ template<std::size_t _Idx, typename _Head>
+ struct _Tuple_impl<_Idx, _Head>
+ : private _Head_base<_Idx, _Head, __empty_not_final<_Head>::value>
+ {
+ template<std::size_t, typename...> friend class _Tuple_impl;
+
+ typedef _Head_base<_Idx, _Head, __empty_not_final<_Head>::value> _Base;
+
+ static constexpr _Head&
+ _M_head(_Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
+
+ static constexpr const _Head&
+ _M_head(const _Tuple_impl& __t) noexcept { return _Base::_M_head(__t); }
+
+ constexpr _Tuple_impl()
+ : _Base() { }
+
+ explicit
+ constexpr _Tuple_impl(const _Head& __head)
+ : _Base(__head) { }
+
+ template<typename _UHead>
+ explicit
+ constexpr _Tuple_impl(_UHead&& __head)
+ : _Base(std::forward<_UHead>(__head)) { }
+
+ constexpr _Tuple_impl(const _Tuple_impl&) = default;
+
+ constexpr
+ _Tuple_impl(_Tuple_impl&& __in)
+ noexcept(is_nothrow_move_constructible<_Head>::value)
+ : _Base(std::forward<_Head>(_M_head(__in))) { }
+
+ template<typename _UHead>
+ constexpr _Tuple_impl(const _Tuple_impl<_Idx, _UHead>& __in)
+ : _Base(_Tuple_impl<_Idx, _UHead>::_M_head(__in)) { }
+
+ template<typename _UHead>
+ constexpr _Tuple_impl(_Tuple_impl<_Idx, _UHead>&& __in)
+ : _Base(std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
+ { }
+
+ template<typename _Alloc>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
+ : _Base(__tag, __use_alloc<_Head>(__a)) { }
+
+ template<typename _Alloc>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
+ const _Head& __head)
+ : _Base(__use_alloc<_Head, _Alloc, _Head>(__a), __head) { }
+
+ template<typename _Alloc, typename _UHead>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
+ _UHead&& __head)
+ : _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
+ std::forward<_UHead>(__head)) { }
+
+ template<typename _Alloc>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
+ const _Tuple_impl& __in)
+ : _Base(__use_alloc<_Head, _Alloc, _Head>(__a), _M_head(__in)) { }
+
+ template<typename _Alloc>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
+ _Tuple_impl&& __in)
+ : _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
+ std::forward<_Head>(_M_head(__in))) { }
+
+ template<typename _Alloc, typename _UHead>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
+ const _Tuple_impl<_Idx, _UHead>& __in)
+ : _Base(__use_alloc<_Head, _Alloc, _Head>(__a),
+ _Tuple_impl<_Idx, _UHead>::_M_head(__in)) { }
+
+ template<typename _Alloc, typename _UHead>
+ _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a,
+ _Tuple_impl<_Idx, _UHead>&& __in)
+ : _Base(__use_alloc<_Head, _Alloc, _UHead>(__a),
+ std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in)))
+ { }
+
+ _Tuple_impl&
+ operator=(const _Tuple_impl& __in)
+ {
+ _M_head(*this) = _M_head(__in);
+ return *this;
+ }
+
+ _Tuple_impl&
+ operator=(_Tuple_impl&& __in)
+ noexcept(is_nothrow_move_assignable<_Head>::value)
+ {
+ _M_head(*this) = std::forward<_Head>(_M_head(__in));
+ return *this;
+ }
+
+ template<typename _UHead>
+ _Tuple_impl&
+ operator=(const _Tuple_impl<_Idx, _UHead>& __in)
+ {
+ _M_head(*this) = _Tuple_impl<_Idx, _UHead>::_M_head(__in);
+ return *this;
+ }
+
+ template<typename _UHead>
+ _Tuple_impl&
+ operator=(_Tuple_impl<_Idx, _UHead>&& __in)
+ {
+ _M_head(*this)
+ = std::forward<_UHead>(_Tuple_impl<_Idx, _UHead>::_M_head(__in));
+ return *this;
+ }
+
+ protected:
+ void
+ _M_swap(_Tuple_impl& __in)
+ noexcept(noexcept(swap(std::declval<_Head&>(), std::declval<_Head&>())))
+ {
+ using std::swap;
+ swap(_M_head(*this), _M_head(__in));
+ }
+ };
+
/// Primary class template, tuple
template<typename... _Elements>
class tuple : public _Tuple_impl<0, _Elements...>
new file mode 100644
@@ -0,0 +1,32 @@
+// Copyright (C) 2015 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++11" }
+// { dg-do compile }
+
+#include <tuple>
+
+class Empty { };
+
+using std::tuple;
+using char_pair = tuple<char, char>;
+
+static_assert( sizeof(tuple<Empty, char_pair>) == sizeof(char_pair),
+ "Nested tuple tuple<Empty, tuple<T,T>> is too big");
+
+static_assert( sizeof(tuple<char_pair, char_pair>) == (2 * sizeof(char_pair)),
+ "Nested tuple<tuple<T,T, tuple<T,T>> is too big" );