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Re: template constructor overload problems
- From: Paolo Carlini <pcarlini at suse dot de>
- To: Peter Dimov <pdimov at mmltd dot net>
- Cc: libstdc++ at gcc dot gnu dot org, Pedro LamarÃo <pedro dot lamarao at gmail dot com>
- Date: Mon, 18 Feb 2008 14:33:37 +0100
- Subject: Re: template constructor overload problems
- References: <fp55jo$c2n$1@ger.gmane.org> <007501c87031$4c0fc730$6407a80a@pdimov2>
Peter Dimov wrote:
> You need to add
>
> template <typename UElements>
> tuple (tuple<UElements>& foo)
> { static_assert(!sizeof(UElements), "third constructor"); }
Many thanks to you and Pedro, of course. For now I committed to mainline
the below, which seems a net improvement to me... Tested x86_64-linux.
Paolo.
//////////////
2008-02-18 Pedro Lamarao <pedro.lamarao@mndfck.org>
* include/std/tuple: Fixes for moveable, non-copyable types.
* testsuite/20_util/tuple/moveable2.cc: New.
2008-02-18 Paolo Carlini <pcarlini@suse.de>
* include/std/tuple (operator+(tuple<>&&, tuple<>&&): Remove.
Index: include/std/tuple
===================================================================
--- include/std/tuple (revision 132379)
+++ include/std/tuple (working copy)
@@ -72,11 +72,12 @@
_Head_base()
: _Head() { }
- _Head_base(typename __add_c_ref<_Head>::type __h)
+ _Head_base(const _Head& __h)
: _Head(__h) { }
- _Head_base(typename std::remove_reference<_Head>::type&& __h)
- : _Head(std::forward<_Head>(__h)) { }
+ template<typename _UHead>
+ _Head_base(_UHead&& __h)
+ : _Head(std::forward<_UHead>(__h)) { }
_Head& _M_head() { return *this; }
const _Head& _M_head() const { return *this; }
@@ -88,11 +89,12 @@
_Head_base()
: _M_head_impl() { }
- _Head_base(typename __add_c_ref<_Head>::type __h)
+ _Head_base(const _Head& __h)
: _M_head_impl(__h) { }
- _Head_base(typename std::remove_reference<_Head>::type&& __h)
- : _M_head_impl(std::move(__h)) { }
+ template<typename _UHead>
+ _Head_base(_UHead&& __h)
+ : _M_head_impl(std::forward<_UHead>(__h)) { }
_Head& _M_head() { return _M_head_impl; }
const _Head& _M_head() const { return _M_head_impl; }
@@ -141,23 +143,21 @@
: _Inherited(), _Base() { }
explicit
- _Tuple_impl(typename __add_c_ref<_Head>::type __head,
- typename __add_c_ref<_Tail>::type... __tail)
+ _Tuple_impl(const _Head& __head, const _Tail&... __tail)
: _Inherited(__tail...), _Base(__head) { }
template<typename _UHead, typename... _UTail>
explicit
- _Tuple_impl(typename std::remove_reference<_UHead>::type&& __head,
- typename std::remove_reference<_UTail>::type&&... __tail)
- : _Inherited(std::forward<_Inherited>(__tail)...),
- _Base(std::forward<_Base>(__head)) { }
+ _Tuple_impl(_UHead&& __head, _UTail&&... __tail)
+ : _Inherited(std::forward<_UTail>(__tail)...),
+ _Base(std::forward<_UHead>(__head)) { }
_Tuple_impl(const _Tuple_impl& __in)
: _Inherited(__in._M_tail()), _Base(__in._M_head()) { }
_Tuple_impl(_Tuple_impl&& __in)
- : _Inherited(std::forward<_Inherited>(__in._M_tail())),
- _Base(std::forward<_Base>(__in._M_head())) { }
+ : _Inherited(std::move<_Inherited&&>(__in._M_tail())),
+ _Base(std::forward<_Head>(__in._M_head())) { }
template<typename... _UElements>
_Tuple_impl(const _Tuple_impl<_Idx, _UElements...>& __in)
@@ -165,8 +165,10 @@
template<typename... _UElements>
_Tuple_impl(_Tuple_impl<_Idx, _UElements...>&& __in)
- : _Inherited(std::forward<_Inherited>(__in._M_tail())),
- _Base(std::forward<_Base>(__in._M_head())) { }
+ : _Inherited(std::move<typename _Tuple_impl<_Idx, _UElements...>::
+ _Inherited&&>(__in._M_tail())),
+ _Base(std::forward<typename _Tuple_impl<_Idx, _UElements...>::
+ _Base>(__in._M_head())) { }
_Tuple_impl&
operator=(const _Tuple_impl& __in)
@@ -219,21 +221,28 @@
template<typename... _UElements>
explicit
tuple(_UElements&&... __elements)
- : _Inherited(std::forward<_UElements>(__elements)...) { }
+ : _Inherited(std::forward<_UElements>(__elements)...) { }
tuple(const tuple& __in)
- : _Inherited(__in) { }
+ : _Inherited(static_cast<const _Inherited&>(__in)) { }
tuple(tuple&& __in)
- : _Inherited(std::move(__in)) { }
+ : _Inherited(std::move<_Inherited>(__in)) { }
template<typename... _UElements>
tuple(const tuple<_UElements...>& __in)
- : _Inherited(__in) { }
+ : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
+ { }
template<typename... _UElements>
tuple(tuple<_UElements...>&& __in)
- : _Inherited(std::move(__in)) { }
+ : _Inherited(std::move<_Tuple_impl<0, _UElements...> >(__in)) { }
+
+ // XXX http://gcc.gnu.org/ml/libstdc++/2008-02/msg00047.html
+ template<typename... _UElements>
+ tuple(tuple<_UElements...>& __in)
+ : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
+ { }
tuple&
operator=(const tuple& __in)
@@ -288,34 +297,26 @@
: _Inherited(std::forward<_U1>(__a1), std::forward<_U2>(__a2)) { }
tuple(const tuple& __in)
- : _Inherited(__in) { }
+ : _Inherited(static_cast<const _Inherited&>(__in)) { }
tuple(tuple&& __in)
- : _Inherited(std::move(__in)) { }
+ : _Inherited(std::move<_Inherited>(__in)) { }
template<typename _U1, typename _U2>
tuple(const tuple<_U1, _U2>& __in)
- : _Inherited(__in) { }
+ : _Inherited(static_cast<const _Tuple_impl<0, _U1, _U2>&>(__in)) { }
template<typename _U1, typename _U2>
tuple(tuple<_U1, _U2>&& __in)
- : _Inherited(std::move(__in)) { }
+ : _Inherited(std::move<_Tuple_impl<0, _U1, _U2> >(__in)) { }
template<typename _U1, typename _U2>
tuple(const pair<_U1, _U2>& __in)
- : _Inherited(_Tuple_impl<0,
- typename __add_c_ref<_U1>::type,
- typename __add_c_ref<_U2>::type>(__in.first,
- __in.second))
- { }
+ : _Inherited(__in.first, __in.second) { }
template<typename _U1, typename _U2>
tuple(pair<_U1, _U2>&& __in)
- : _Inherited(_Tuple_impl<0,
- typename std::remove_reference<_U1>::type&&,
- typename std::remove_reference<_U2>::type&&>
- (std::move(__in.first), std::move(__in.second)))
- { }
+ : _Inherited(std::move(__in.first), std::move(__in.second)) { }
tuple&
operator=(const tuple& __in)
@@ -555,8 +556,8 @@
const __index_holder<_TIdx...>&,
const tuple<_UElements...>& __u,
const __index_holder<_UIdx...>&)
- { return tuple<_TElements..., _UElements...>(std::move(get<_TIdx>(__t))...,
- get<_UIdx>(__u)...); }
+ { return tuple<_TElements..., _UElements...>
+ (std::move(get<_TIdx>(__t))..., get<_UIdx>(__u)...); }
template<typename... _TElements, int... _TIdx,
typename... _UElements, int... _UIdx>
@@ -565,8 +566,8 @@
const __index_holder<_TIdx...>&,
tuple<_UElements...>&& __u,
const __index_holder<_UIdx...>&)
- { return tuple<_TElements..., _UElements...>(get<_TIdx>(__t)...,
- std::move(get<_UIdx>(__u))...); }
+ { return tuple<_TElements..., _UElements...>
+ (get<_TIdx>(__t)..., std::move(get<_UIdx>(__u))...); }
template<typename... _TElements, int... _TIdx,
typename... _UElements, int... _UIdx>
@@ -575,8 +576,8 @@
const __index_holder<_TIdx...>&,
tuple<_UElements...>&& __u,
const __index_holder<_UIdx...>&)
- { return tuple<_TElements..., _UElements...>(std::move(get<_TIdx>(__t))...,
- std::move(get<_UIdx>(__u))...); }
+ { return tuple<_TElements..., _UElements...>
+ (std::move(get<_TIdx>(__t))..., std::move(get<_UIdx>(__u))...); }
template<typename... _TElements, typename... _UElements>
inline tuple<_TElements..., _UElements...>
@@ -618,12 +619,6 @@
__make_index_holder<_UElements...>::type());
}
- template<typename... _TElements, typename... _UElements>
- tuple<_TElements..., _UElements...>
- operator+(tuple<_TElements...>&& __t, tuple<_UElements...>&& __u)
- { return tuple_cat(std::forward<decltype(__t)>(__t),
- std::forward<decltype(__u)>(__u)); }
-
template<typename... _Elements>
inline tuple<_Elements&...>
tie(_Elements&... __args)
Index: testsuite/20_util/tuple/moveable2.cc
===================================================================
--- testsuite/20_util/tuple/moveable2.cc (revision 0)
+++ testsuite/20_util/tuple/moveable2.cc (revision 0)
@@ -0,0 +1,73 @@
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2008 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 2, 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 COPYING. If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// As a special exception, you may use this file as part of a free software
+// library without restriction. Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License. This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+
+#include <tuple>
+#include <utility>
+
+struct MoveOnly
+{
+ MoveOnly () { }
+
+ MoveOnly (MoveOnly&&) { }
+
+ MoveOnly& operator=(MoveOnly&&)
+ { return *this; }
+
+private:
+ MoveOnly(MoveOnly const&); // = delete
+ MoveOnly& operator=(MoveOnly const&); // = delete
+};
+
+MoveOnly
+make_move_only ()
+{ return MoveOnly(); }
+
+// http://gcc.gnu.org/ml/libstdc++/2008-02/msg00046.html
+void test01()
+{
+ typedef std::tuple<MoveOnly> move_only_tuple;
+
+ move_only_tuple t1(make_move_only());
+ move_only_tuple t2(std::move(t1));
+ move_only_tuple t3 = std::move(t2);
+ t1 = std::move(t3);
+
+ typedef std::tuple<MoveOnly, MoveOnly> move_only_tuple2;
+
+ move_only_tuple2 t4(make_move_only(), make_move_only());
+ move_only_tuple2 t5(std::move(t4));
+ move_only_tuple2 t6 = std::move(t5);
+ t4 = std::move(t6);
+}
+
+int main()
+{
+ test01();
+ return 0;
+}