libstdc++: Constrain reverse_iterator and move_iterator conversions [LWG 3435]
libstdc++-v3/ChangeLog: * include/bits/stl_iterator.h (reverse_iterator): Constrain converting constructor and converting assignment operator. Access source iterator's data member directly instead of calling base(). (move_iterator): Likewise. * testsuite/24_iterators/move_iterator/dr3435.cc: New test. * testsuite/24_iterators/reverse_iterator/dr3435.cc: New test.
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Jonathan Wakely
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259c3965b1
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a5a8a4e615
@ -129,6 +129,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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typename iterator_traits<_Iterator>::pointer,
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typename iterator_traits<_Iterator>::reference>
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{
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#if __cplusplus >= 201103L
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template<typename _Iter>
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friend class reverse_iterator;
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#endif
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#if __cpp_lib_concepts
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 3435. three_way_comparable_with<reverse_iterator<int*>, [...]>
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template<typename _Iter>
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static constexpr bool __convertible = !is_same_v<_Iter, _Iterator>
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&& convertible_to<const _Iter&, _Iterator>;
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#endif
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protected:
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_Iterator current;
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@ -182,9 +195,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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* underlying %iterator can be converted to the type of @c current.
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*/
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template<typename _Iter>
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#if __cpp_lib_concepts
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requires __convertible<_Iter>
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#endif
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_GLIBCXX17_CONSTEXPR
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reverse_iterator(const reverse_iterator<_Iter>& __x)
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: current(__x.base()) { }
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: current(__x.current) { }
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#if __cplusplus >= 201103L
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template<typename _Iter>
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#if __cpp_lib_concepts
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requires __convertible<_Iter>
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&& assignable_from<_Iterator&, const _Iter&>
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#endif
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_GLIBCXX17_CONSTEXPR
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reverse_iterator&
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operator=(const reverse_iterator<_Iter>& __x)
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{
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current = __x.current;
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return *this;
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}
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#endif
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/**
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* @return @c current, the %iterator used for underlying work.
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@ -1270,6 +1301,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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using __base_ref = typename __traits_type::reference;
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#endif
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template<typename _Iter2>
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friend class move_iterator;
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#if __cpp_lib_concepts
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 3435. three_way_comparable_with<reverse_iterator<int*>, [...]>
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template<typename _Iter2>
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static constexpr bool __convertible = !is_same_v<_Iter2, _Iterator>
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&& convertible_to<const _Iter2&, _Iterator>;
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#endif
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public:
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using iterator_type = _Iterator;
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@ -1303,15 +1345,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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: _M_current(std::move(__i)) { }
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template<typename _Iter>
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#if __cpp_lib_concepts
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requires __convertible<_Iter>
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#endif
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_GLIBCXX17_CONSTEXPR
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move_iterator(const move_iterator<_Iter>& __i)
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: _M_current(__i.base()) { }
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: _M_current(__i._M_current) { }
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template<typename _Iter>
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#if __cpp_lib_concepts
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requires __convertible<_Iter>
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&& assignable_from<_Iterator&, const _Iter&>
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#endif
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_GLIBCXX17_CONSTEXPR
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move_iterator& operator=(const move_iterator<_Iter>& __i)
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{
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_M_current = __i.base();
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_M_current = __i._M_current;
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return *this;
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}
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37
libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc
Normal file
37
libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc
Normal file
@ -0,0 +1,37 @@
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// Copyright (C) 2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// { dg-options "-std=gnu++2a" }
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// { dg-do compile { target c++2a } }
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#include <iterator>
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#include <compare>
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// LWG 3435. three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>>
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// and
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// LWG 3265. move_iterator's conversions are more broken after P1207
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using RI = std::move_iterator<int*>;
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using CRI = std::move_iterator<const int*>;
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static_assert( std::three_way_comparable_with<RI, CRI> );
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static_assert( std::is_convertible_v<const RI&, CRI> );
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static_assert( ! std::is_convertible_v<const CRI&, RI> );
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static_assert( std::is_assignable_v<CRI, const RI&> );
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static_assert( ! std::is_assignable_v<RI, const CRI&> );
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@ -0,0 +1,36 @@
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// Copyright (C) 2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// { dg-options "-std=gnu++2a" }
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// { dg-do compile { target c++2a } }
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#include <iterator>
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#include <compare>
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// LWG 3435.
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// three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>>
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using RI = std::reverse_iterator<int*>;
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using CRI = std::reverse_iterator<const int*>;
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static_assert( std::three_way_comparable_with<RI, CRI> );
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static_assert( std::is_convertible_v<const RI&, CRI> );
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static_assert( ! std::is_convertible_v<const CRI&, RI> );
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static_assert( std::is_assignable_v<CRI, const RI&> );
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static_assert( ! std::is_assignable_v<RI, const CRI&> );
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