From 3bf5e7657b752cc2352778e8c20ac9cdddca4f93 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Tue, 26 May 2020 16:17:34 -0400 Subject: [PATCH] libstdc++: Fix common_iterator::operator-> [PR95322] This patch fixes the definition of common_iterator::operator-> when the underlying iterator's operator* returns a non-reference. The first problem is that the class __detail::_Common_iter_proxy is used unqualified. Fixing that revealed another problem: the class's template friend declaration of common_iterator doesn't match up with the definition of common_iterator, because the friend declaration isn't constrained. If we try to make the friend declaration match up by adding constraints, we run into frontend bug PR93467. So we currently can't correctly express this friend relation between __detail::_Common_iter_proxy and common_iterator. As a workaround to this frontend bug, this patch moves the definition of _Common_iter_proxy into the class template of common_iterator so that we could instead express the friend relation via the injected-class-name. (This bug was found when attempting to use views::common to work around the compile failure with the testcase in PR95322.) libstdc++-v3/ChangeLog: PR libstdc++/95322 * include/bits/stl_iterator.h (__detail::_Common_iter_proxy): Remove and instead define it ... (common_iterator::_Proxy): ... here. (common_iterator::operator->): Use it. * testsuite/24_iterators/common_iterator/2.cc: New test. * testsuite/std/ranges/adaptors/95322.cc: New test. --- libstdc++-v3/include/bits/stl_iterator.h | 34 +++++----- .../24_iterators/common_iterator/2.cc | 63 +++++++++++++++++++ .../testsuite/std/ranges/adaptors/95322.cc | 50 +++++++++++++++ 3 files changed, 129 insertions(+), 18 deletions(-) create mode 100644 libstdc++-v3/testsuite/24_iterators/common_iterator/2.cc create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index fdb1121f823..19b1d53f781 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -1568,23 +1568,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace __detail { - template - class _Common_iter_proxy - { - iter_value_t<_It> _M_keep; - - _Common_iter_proxy(iter_reference_t<_It>&& __x) - : _M_keep(std::move(__x)) { } - - template - friend class common_iterator; - - public: - const iter_value_t<_It>* - operator->() const - { return std::__addressof(_M_keep); } - }; - template concept __common_iter_has_arrow = indirectly_readable && (requires(const _It& __it) { __it.operator->(); } @@ -1613,6 +1596,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _S_noexcept() { return _S_noexcept1<_It, _It2>() && _S_noexcept1<_Sent, _Sent2>(); } + class _Proxy + { + iter_value_t<_It> _M_keep; + + _Proxy(iter_reference_t<_It>&& __x) + : _M_keep(std::move(__x)) { } + + friend class common_iterator; + + public: + const iter_value_t<_It>* + operator->() const + { return std::__addressof(_M_keep); } + }; + public: constexpr common_iterator() @@ -1769,7 +1767,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION return std::__addressof(__tmp); } else - return _Common_iter_proxy(*_M_it); + return _Proxy{*_M_it}; } common_iterator& diff --git a/libstdc++-v3/testsuite/24_iterators/common_iterator/2.cc b/libstdc++-v3/testsuite/24_iterators/common_iterator/2.cc new file mode 100644 index 00000000000..270e8eaa91c --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/common_iterator/2.cc @@ -0,0 +1,63 @@ +// 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 +// . + +// { dg-options "-std=gnu++2a" } +// { dg-do run { target c++2a } } + +#include +#include + +struct value { int n; }; + +struct sentinel { int limit; }; + +struct iterator +{ + using iterator_category = std::input_iterator_tag; + using value_type = value; + using difference_type = std::ptrdiff_t; + using reference = value; + + value operator*() const { return value{counter}; } + + iterator& operator++() { ++counter; return *this; } + + iterator operator++(int) { auto i = *this; ++counter; return i; } + + bool operator==(sentinel s) const { return counter == s.limit; } + + int counter = 0; +}; + +void +test01() +{ + iterator i; + sentinel s{2}; + std::common_iterator begin = i, end = s; + VERIFY( begin->n == 0 ); + ++begin; + VERIFY( begin->n == 1 ); + ++begin; + VERIFY( begin == end ); +} + +int +main() +{ + test01(); +} diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc new file mode 100644 index 00000000000..44619d6719a --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc @@ -0,0 +1,50 @@ +// 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 +// . + +// { dg-options "-std=gnu++2a" } +// { dg-do run { target c++2a } } + +#include +#include +#include + +namespace ranges = std::ranges; +namespace views = std::views; + +void +test01() +{ + std::list container{1, 2, 3, 4, 5}; + auto v = (container + | views::take(3) + | views::transform(std::negate{}) + | views::common); + auto i = ranges::cbegin(v); + VERIFY( *i == -1 ); + ++i; + VERIFY( *i == -2 ); + ++i; + VERIFY( *i == -3 ); + ++i; + VERIFY( i == ranges::end(v) ); +} + +int +main() +{ + test01(); +} -- 2.30.2