From 8f0d8cd852255f9767626b084fc7926cbbea166f Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Mon, 9 Mar 2020 12:10:16 -0400 Subject: [PATCH] libstdc++: LWG 3286 ranges::size is not required to be valid after ... ... a call to ranges::begin on an input range. This implements LWG 3286. The new wording for the single-argument constructor for subrange is implemented by splitting the constructor into two delegating constructors, one constrained by _S_store_size and the other by !_S_store_size. Tested on x86_64-pc-linux-gnu, both added tests fail before the patch and pass with the patch. libstdc++-v3/ChangeLog: LWG 3286 ranges::size is not required to be valid after a call to ranges::begin on an input range * include/std/ranges (subrange::subrange): Split single-argument constructor into two, one constrained by _S_store_size and another by !_S_store_size. (take_view::begin): Call size() before calling ranges::begin(_M_base). * testsuite/std/ranges/adaptors/lwg3286.cc: New test. * testsuite/std/ranges/subrange/lwg3286.cc: New test. --- libstdc++-v3/ChangeLog | 11 +++ libstdc++-v3/include/std/ranges | 26 +++++-- .../testsuite/std/ranges/adaptors/lwg3286.cc | 72 +++++++++++++++++++ .../testsuite/std/ranges/subrange/lwg3286.cc | 71 ++++++++++++++++++ 4 files changed, 173 insertions(+), 7 deletions(-) create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc create mode 100644 libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 7197663e6a1..27ef7e39087 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,14 @@ +2020-03-11 Patrick Palka + + LWG 3286 ranges::size is not required to be valid after a call to + ranges::begin on an input range + * include/std/ranges (subrange::subrange): Split single-argument + constructor into two, one constrained by _S_store_size and another by + !_S_store_size. + (take_view::begin): Call size() before calling ranges::begin(_M_base). + * testsuite/std/ranges/adaptors/lwg3286.cc: New test. + * testsuite/std/ranges/subrange/lwg3286.cc: New test. + 2020-03-10 Jonathan Wakely * include/std/ranges (split_view::_OuterIter::__at_end): Use __current diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index de120d6b55d..5b06a9e6f43 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -281,12 +281,18 @@ namespace ranges && __detail::__convertible_to_non_slicing, _It> && convertible_to, _Sent> constexpr - subrange(_Rng&& __r) requires (!_S_store_size || sized_range<_Rng>) + subrange(_Rng&& __r) requires _S_store_size && sized_range<_Rng> + : subrange{__r, ranges::size(__r)} + { } + + template<__detail::__not_same_as _Rng> + requires borrowed_range<_Rng> + && __detail::__convertible_to_non_slicing, _It> + && convertible_to, _Sent> + constexpr + subrange(_Rng&& __r) requires (!_S_store_size) : subrange{ranges::begin(__r), ranges::end(__r)} - { - if constexpr (_S_store_size) - _M_size._M_size = ranges::size(__r); - } + { } template requires __detail::__convertible_to_non_slicing, _It> @@ -2032,7 +2038,10 @@ namespace views if constexpr (random_access_range<_Vp>) return ranges::begin(_M_base); else - return counted_iterator{ranges::begin(_M_base), size()}; + { + auto __sz = size(); + return counted_iterator{ranges::begin(_M_base), __sz}; + } } else return counted_iterator{ranges::begin(_M_base), _M_count}; @@ -2046,7 +2055,10 @@ namespace views if constexpr (random_access_range) return ranges::begin(_M_base); else - return counted_iterator{ranges::begin(_M_base), size()}; + { + auto __sz = size(); + return counted_iterator{ranges::begin(_M_base), __sz}; + } } else return counted_iterator{ranges::begin(_M_base), _M_count}; diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc new file mode 100644 index 00000000000..07a0f63fe23 --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/lwg3286.cc @@ -0,0 +1,72 @@ +// 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 + +using __gnu_test::test_input_range; + +namespace ranges = std::ranges; +namespace views = std::views; + +struct my_range +{ + static inline int x[] = {1,2,3}; + static inline test_input_range r{x}; + + bool called_begin = false; + + auto + begin() + { + called_begin = true; + return r.begin(); + } + + auto + end() + { + return r.end(); + } + + ranges::range_difference_t + size() + { + VERIFY( !called_begin ); + return 3; + } +}; + +void +test01() +{ + my_range r; + static_assert(!ranges::forward_range); + static_assert(ranges::sized_range); + auto v = r | views::take(3); + auto i = ranges::begin(v); +} + +int +main() +{ + test01(); +} diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc b/libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc new file mode 100644 index 00000000000..3ddec7004a7 --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/subrange/lwg3286.cc @@ -0,0 +1,71 @@ +// 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 + +using __gnu_test::test_input_range; + +namespace ranges = std::ranges; + +struct my_range +{ + static inline int x[] = {1,2,3}; + static inline test_input_range r{x}; + + bool called_begin = false; + + auto + begin() + { + called_begin = true; + return r.begin(); + } + + auto + end() + { + return r.end(); + } + + ranges::range_difference_t + size() + { + VERIFY( !called_begin ); + return 3; + } +}; + +void +test01() +{ + my_range r; + static_assert(!ranges::forward_range); + static_assert(ranges::sized_range); + ranges::subrange sr = r; + VERIFY( ranges::size(sr) == 3 ); +} + +int +main() +{ + test01(); +} -- 2.30.2