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From: Giuliano Belinassi <giulianob@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc(refs/users/giulianob/heads/autopar_rebase2)] libstdc++: Constrain reverse_iterator and move_iterator conversions [LWG 3435] Date: Tue, 18 Aug 2020 01:04:20 +0000 (GMT) [thread overview] Message-ID: <20200818010420.A2F5A38618A8@sourceware.org> (raw) https://gcc.gnu.org/g:9a06d1c82f5ba7b0ef820e6e8a1ad330e8c09cf1 commit 9a06d1c82f5ba7b0ef820e6e8a1ad330e8c09cf1 Author: Jonathan Wakely <jwakely@redhat.com> Date: Wed Jul 22 13:25:11 2020 +0100 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. Diff: --- libstdc++-v3/include/bits/stl_iterator.h | 55 ++++++++++++++++++++-- .../testsuite/24_iterators/move_iterator/dr3435.cc | 37 +++++++++++++++ .../24_iterators/reverse_iterator/dr3435.cc | 36 ++++++++++++++ 3 files changed, 125 insertions(+), 3 deletions(-) diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index 6d2d19eb068..60bb40a659f 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -129,6 +129,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION typename iterator_traits<_Iterator>::pointer, typename iterator_traits<_Iterator>::reference> { +#if __cplusplus >= 201103L + template<typename _Iter> + friend class reverse_iterator; +#endif + +#if __cpp_lib_concepts + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3435. three_way_comparable_with<reverse_iterator<int*>, [...]> + template<typename _Iter> + static constexpr bool __convertible = !is_same_v<_Iter, _Iterator> + && convertible_to<const _Iter&, _Iterator>; +#endif + protected: _Iterator current; @@ -182,9 +195,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION * underlying %iterator can be converted to the type of @c current. */ template<typename _Iter> +#if __cpp_lib_concepts + requires __convertible<_Iter> +#endif _GLIBCXX17_CONSTEXPR reverse_iterator(const reverse_iterator<_Iter>& __x) - : current(__x.base()) { } + : current(__x.current) { } + +#if __cplusplus >= 201103L + template<typename _Iter> +#if __cpp_lib_concepts + requires __convertible<_Iter> + && assignable_from<_Iterator&, const _Iter&> +#endif + _GLIBCXX17_CONSTEXPR + reverse_iterator& + operator=(const reverse_iterator<_Iter>& __x) + { + current = __x.current; + return *this; + } +#endif /** * @return @c current, the %iterator used for underlying work. @@ -1270,6 +1301,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION using __base_ref = typename __traits_type::reference; #endif + template<typename _Iter2> + friend class move_iterator; + +#if __cpp_lib_concepts + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3435. three_way_comparable_with<reverse_iterator<int*>, [...]> + template<typename _Iter2> + static constexpr bool __convertible = !is_same_v<_Iter2, _Iterator> + && convertible_to<const _Iter2&, _Iterator>; +#endif + public: using iterator_type = _Iterator; @@ -1303,15 +1345,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION : _M_current(std::move(__i)) { } template<typename _Iter> +#if __cpp_lib_concepts + requires __convertible<_Iter> +#endif _GLIBCXX17_CONSTEXPR move_iterator(const move_iterator<_Iter>& __i) - : _M_current(__i.base()) { } + : _M_current(__i._M_current) { } template<typename _Iter> +#if __cpp_lib_concepts + requires __convertible<_Iter> + && assignable_from<_Iterator&, const _Iter&> +#endif _GLIBCXX17_CONSTEXPR move_iterator& operator=(const move_iterator<_Iter>& __i) { - _M_current = __i.base(); + _M_current = __i._M_current; return *this; } diff --git a/libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc b/libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc new file mode 100644 index 00000000000..170d4977df1 --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/move_iterator/dr3435.cc @@ -0,0 +1,37 @@ +// Copyright (C) 2020 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++2a" } +// { dg-do compile { target c++2a } } + +#include <iterator> +#include <compare> + +// LWG 3435. three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>> +// and +// LWG 3265. move_iterator's conversions are more broken after P1207 + +using RI = std::move_iterator<int*>; +using CRI = std::move_iterator<const int*>; + +static_assert( std::three_way_comparable_with<RI, CRI> ); + +static_assert( std::is_convertible_v<const RI&, CRI> ); +static_assert( ! std::is_convertible_v<const CRI&, RI> ); + +static_assert( std::is_assignable_v<CRI, const RI&> ); +static_assert( ! std::is_assignable_v<RI, const CRI&> ); diff --git a/libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr3435.cc b/libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr3435.cc new file mode 100644 index 00000000000..77b0f39c535 --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/reverse_iterator/dr3435.cc @@ -0,0 +1,36 @@ +// Copyright (C) 2020 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++2a" } +// { dg-do compile { target c++2a } } + +#include <iterator> +#include <compare> + +// LWG 3435. +// three_way_comparable_with<reverse_iterator<int*>, reverse_iterator<const int*>> + +using RI = std::reverse_iterator<int*>; +using CRI = std::reverse_iterator<const int*>; + +static_assert( std::three_way_comparable_with<RI, CRI> ); + +static_assert( std::is_convertible_v<const RI&, CRI> ); +static_assert( ! std::is_convertible_v<const CRI&, RI> ); + +static_assert( std::is_assignable_v<CRI, const RI&> ); +static_assert( ! std::is_assignable_v<RI, const CRI&> );
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