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From: Alexandre Oliva <aoliva@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc(refs/users/aoliva/heads/testme)] libstdc++: elements_view's sentinel and iterator not comparable [LWG 3406] Date: Thu, 3 Sep 2020 16:03:09 +0000 (GMT) [thread overview] Message-ID: <20200903160309.27DBF3985827@sourceware.org> (raw) https://gcc.gnu.org/g:4be16d1c1cfa6d151d2853ce509c1a797189c9ad commit 4be16d1c1cfa6d151d2853ce509c1a797189c9ad Author: Patrick Palka <ppalka@redhat.com> Date: Wed Aug 26 21:52:58 2020 -0400 libstdc++: elements_view's sentinel and iterator not comparable [LWG 3406] This implements the proposed resolution for LWG 3406, and adds a testcase for the example from P1994R1. libstdc++-v3/ChangeLog: * include/std/ranges (elements_view::begin): Adjust constraints. (elements_view::end): Likewise. (elements_view::_Sentinel::operator==): Templatize to take both _Iterator<true> and _Iterator<false>. (elements_view::_Sentinel::operator-): Likewise. * testsuite/std/ranges/adaptors/elements.cc: Add testcase for the example from P1994R1. * testsuite/std/ranges/adaptors/lwg3406.cc: New test. Diff: --- libstdc++-v3/include/std/ranges | 39 ++++++++++++--------- .../testsuite/std/ranges/adaptors/elements.cc | 22 ++++++++++++ .../testsuite/std/ranges/adaptors/lwg3406.cc | 40 ++++++++++++++++++++++ 3 files changed, 85 insertions(+), 16 deletions(-) diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index efa8d2cf9f4..42028354b81 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -3362,15 +3362,15 @@ namespace views { return _Iterator<false>(ranges::begin(_M_base)); } constexpr auto - begin() const requires __detail::__simple_view<_Vp> + begin() const requires range<const _Vp> { return _Iterator<true>(ranges::begin(_M_base)); } constexpr auto - end() + end() requires (!__detail::__simple_view<_Vp> && !common_range<_Vp>) { return _Sentinel<false>{ranges::end(_M_base)}; } constexpr auto - end() requires common_range<_Vp> + end() requires (!__detail::__simple_view<_Vp> && common_range<_Vp>) { return _Iterator<false>{ranges::end(_M_base)}; } constexpr auto @@ -3576,19 +3576,26 @@ namespace views base() const { return _M_end; } - friend constexpr bool - operator==(const _Iterator<_Const>& __x, const _Sentinel& __y) - { return __y._M_equal(__x); } - - friend constexpr range_difference_t<_Base> - operator-(const _Iterator<_Const>& __x, const _Sentinel& __y) - requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>> - { return __x._M_current - __y._M_end; } - - friend constexpr range_difference_t<_Base> - operator-(const _Sentinel& __x, const _Iterator<_Const>& __y) - requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>> - { return __x._M_end - __y._M_current; } + template<bool _Const2> + requires sentinel_for<sentinel_t<_Base>, + iterator_t<__detail::__maybe_const_t<_Const2, _Vp>>> + friend constexpr bool + operator==(const _Iterator<_Const2>& __x, const _Sentinel& __y) + { return __y._M_equal(__x); } + + template<bool _Const2, + typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>> + requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>> + friend constexpr range_difference_t<_Base2> + operator-(const _Iterator<_Const2>& __x, const _Sentinel& __y) + { return __x._M_current - __y._M_end; } + + template<bool _Const2, + typename _Base2 = __detail::__maybe_const_t<_Const2, _Vp>> + requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>> + friend constexpr range_difference_t<_Base> + operator-(const _Sentinel& __x, const _Iterator<_Const2>& __y) + { return __x._M_end - __y._M_current; } friend _Sentinel<!_Const>; }; diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc index d846c4cf33e..3026adf4f28 100644 --- a/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/elements.cc @@ -45,8 +45,30 @@ test01() VERIFY( ranges::equal(v1, x | views::values) ); } +struct S +{ + friend bool + operator==(std::input_iterator auto const& i, S) + { return std::get<1>(*i) == 0; } +}; + +void +test02() +{ + // This verifies that P1994R1 (and LWG3406) is implemented. + std::pair<std::pair<char, int>, long> x[] + = {{{1,2},3l}, {{1,0},2l}, {{1,2},0l}}; + ranges::subrange r{ranges::begin(x), S{}}; + + auto v = r | views::keys; + VERIFY( ranges::equal(v, (std::pair<char, int>[]){{1,2},{1,0}}) ); + ranges::subrange v2{ranges::begin(v), S{}}; + VERIFY( ranges::equal(v2, (std::pair<char, int>[]){{1,2}}) ); +} + int main() { test01(); + test02(); } diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3406.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3406.cc new file mode 100644 index 00000000000..72190cc2e8a --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3406.cc @@ -0,0 +1,40 @@ +// 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 <ranges> + +namespace ranges = std::ranges; +namespace views = std::views; + +void +test01() +{ + std::tuple<int, int> x[] = {{0,0}}; + auto v = x | views::elements<0>; + bool b = ranges::cbegin(v) == ranges::end(v); +} + +void +test02() +{ + std::tuple x = {0, 1}; + auto v = views::single(x) | views::elements<0>; + auto i = ranges::cbegin(v); +}
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