From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1464) id 831053851C19; Thu, 25 Jun 2020 00:27:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 831053851C19 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1593044852; bh=bqgLOzshQdGsmHX+eGD3ceg5Dqwj0D6cmrGkvD4EvYc=; h=From:To:Subject:Date:From; b=HCdtYAw84RGVH84nLiM2j1HLAOSAn1u9ajsNzlZ3nAFzQClOvciAnZmIDUSl5DRWp uxC8JvmMiQRuQbHcNBEdDcRQNkxSoo/K6Vr5b73jscLbnjfjjvil2qK93xmcT0zqOH rqm9wyg+0ufrFr/VtC+KS5ohmfWBKTotjxGXWLLo= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Peter Bergner To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc(refs/vendors/ibm/heads/gcc-10-branch)] libstdc++: Fix some ranges algos optimizations [PR95578] X-Act-Checkin: gcc X-Git-Author: Patrick Palka X-Git-Refname: refs/vendors/ibm/heads/gcc-10-branch X-Git-Oldrev: 36b4ff352d5f78951ebb870d7f06ffe8d925218a X-Git-Newrev: 3e9261f0e013108135bf09f0f91b279b9c5cbd9e Message-Id: <20200625002732.831053851C19@sourceware.org> Date: Thu, 25 Jun 2020 00:27:32 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Jun 2020 00:27:32 -0000 https://gcc.gnu.org/g:3e9261f0e013108135bf09f0f91b279b9c5cbd9e commit 3e9261f0e013108135bf09f0f91b279b9c5cbd9e Author: Patrick Palka Date: Wed Jun 10 17:37:53 2020 -0400 libstdc++: Fix some ranges algos optimizations [PR95578] ranges::copy and a number of other ranges algorithms have unwrapping optimizations for iterators of type __normal_iterator, move_iterator and reverse_iterator. But in the checks that guard these optimizations we currently only test that the iterator of the iterator/sentinel pair has the appropriate type before proceeding with the corresponding optimization, and do not also test the sentinel type. This breaks the testcase in this PR because this testcase constructs via range adaptors a range whose begin() is a __normal_iterator and whose end() is a custom sentinel type, and then performs ranges::copy on it. From there we bogusly perform the __normal_iterator unwrapping optimization on this iterator/sentinel pair, which immediately leads to a constraint failure since the custom sentinel type does not model sentinel_for. This patch fixes this issue by refining each of the problematic checks to also test that the iterator and sentinel types are the same before applying the corresponding unwrapping optimization. Along the way, some code simplifications are made. libstdc++-v3/ChangeLog: PR libstdc++/95578 * include/bits/ranges_algo.h (__lexicographical_compare_fn): Also check that the iterator and sentinel have the same type before applying the unwrapping optimization for __normal_iterator. Split the check into two, one for the first iterator/sentinel pair and another for second iterator/sentinel pair. Remove uses of __niter_base, and remove uses of std::move on a __normal_iterator. * include/bits/ranges_algobase.h (__equal_fn): Likewise. (__copy_or_move): Likewise. Perform similar adjustments for the reverse_iterator and move_iterator optimizations. Inline the checks into the if-constexprs, and use using-declarations to make them less visually noisy. Remove uses of __niter_wrap. (__copy_or_move_backward): Likewise. * testsuite/25_algorithms/copy/95578.cc: New test. * testsuite/25_algorithms/copy_backward/95578.cc: New test. * testsuite/25_algorithms/equal/95578.cc: New test. * testsuite/25_algorithms/lexicographical_compare/95578.cc: New test. * testsuite/25_algorithms/move/95578.cc: New test. * testsuite/25_algorithms/move_backward/95578.cc: New test. (cherry picked from commit a73051a0ea9ce8281e748a74dd924a6eb8fb3723) Diff: --- libstdc++-v3/include/bits/ranges_algo.h | 14 ++-- libstdc++-v3/include/bits/ranges_algobase.h | 88 ++++++++++++---------- libstdc++-v3/testsuite/25_algorithms/copy/95578.cc | 74 ++++++++++++++++++ .../testsuite/25_algorithms/copy_backward/95578.cc | 62 +++++++++++++++ .../testsuite/25_algorithms/equal/95578.cc | 74 ++++++++++++++++++ .../25_algorithms/lexicographical_compare/95578.cc | 74 ++++++++++++++++++ libstdc++-v3/testsuite/25_algorithms/move/95578.cc | 62 +++++++++++++++ .../testsuite/25_algorithms/move_backward/95578.cc | 62 +++++++++++++++ 8 files changed, 465 insertions(+), 45 deletions(-) diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h index aa07cb97ea6..d82c5873625 100644 --- a/libstdc++-v3/include/bits/ranges_algo.h +++ b/libstdc++-v3/include/bits/ranges_algo.h @@ -3450,11 +3450,15 @@ namespace ranges _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const { if constexpr (__detail::__is_normal_iterator<_Iter1> - || __detail::__is_normal_iterator<_Iter2>) - return (*this)(std::__niter_base(std::move(__first1)), - std::__niter_base(std::move(__last1)), - std::__niter_base(std::move(__first2)), - std::__niter_base(std::move(__last2)), + && same_as<_Iter1, _Sent1>) + return (*this)(__first1.base(), __last1.base(), + std::move(__first2), std::move(__last2), + std::move(__comp), + std::move(__proj1), std::move(__proj2)); + else if constexpr (__detail::__is_normal_iterator<_Iter2> + && same_as<_Iter2, _Sent2>) + return (*this)(std::move(__first1), std::move(__last1), + __first2.base(), __last2.base(), std::move(__comp), std::move(__proj1), std::move(__proj2)); else diff --git a/libstdc++-v3/include/bits/ranges_algobase.h b/libstdc++-v3/include/bits/ranges_algobase.h index 80c9a774301..618bc7d1006 100644 --- a/libstdc++-v3/include/bits/ranges_algobase.h +++ b/libstdc++-v3/include/bits/ranges_algobase.h @@ -85,11 +85,15 @@ namespace ranges // TODO: implement more specializations to at least have parity with // std::equal. if constexpr (__detail::__is_normal_iterator<_Iter1> - || __detail::__is_normal_iterator<_Iter2>) - return (*this)(std::__niter_base(std::move(__first1)), - std::__niter_base(std::move(__last1)), - std::__niter_base(std::move(__first2)), - std::__niter_base(std::move(__last2)), + && same_as<_Iter1, _Sent1>) + return (*this)(__first1.base(), __last1.base(), + std::move(__first2), std::move(__last2), + std::move(__pred), + std::move(__proj1), std::move(__proj2)); + else if constexpr (__detail::__is_normal_iterator<_Iter2> + && same_as<_Iter2, _Sent2>) + return (*this)(std::move(__first1), std::move(__last1), + __first2.base(), __last2.base(), std::move(__pred), std::move(__proj1), std::move(__proj2)); else if constexpr (sized_sentinel_for<_Sent1, _Iter1> @@ -211,14 +215,10 @@ namespace ranges { // TODO: implement more specializations to be at least on par with // std::copy/std::move. - constexpr bool __normal_iterator_p - = (__detail::__is_normal_iterator<_Iter> - || __detail::__is_normal_iterator<_Out>); - constexpr bool __reverse_p - = (__detail::__is_reverse_iterator<_Iter> - && __detail::__is_reverse_iterator<_Out>); - constexpr bool __move_iterator_p = __detail::__is_move_iterator<_Iter>; - if constexpr (__move_iterator_p) + using __detail::__is_move_iterator; + using __detail::__is_reverse_iterator; + using __detail::__is_normal_iterator; + if constexpr (__is_move_iterator<_Iter> && same_as<_Iter, _Sent>) { auto [__in, __out] = ranges::__copy_or_move(std::move(__first).base(), @@ -226,23 +226,28 @@ namespace ranges std::move(__result)); return {move_iterator{std::move(__in)}, std::move(__out)}; } - else if constexpr (__reverse_p) + else if constexpr (__is_reverse_iterator<_Iter> && same_as<_Iter, _Sent> + && __is_reverse_iterator<_Out>) { auto [__in,__out] - = ranges::__copy_or_move_backward<_IsMove>(__last.base(), - __first.base(), - __result.base()); + = ranges::__copy_or_move_backward<_IsMove>(std::move(__last).base(), + std::move(__first).base(), + std::move(__result).base()); return {reverse_iterator{std::move(__in)}, reverse_iterator{std::move(__out)}}; } - else if constexpr (__normal_iterator_p) + else if constexpr (__is_normal_iterator<_Iter> && same_as<_Iter, _Sent>) + { + auto [__in,__out] + = ranges::__copy_or_move<_IsMove>(__first.base(), __last.base(), + __result); + return {decltype(__first){__in}, std::move(__out)}; + } + else if constexpr (__is_normal_iterator<_Out>) { auto [__in,__out] - = ranges::__copy_or_move<_IsMove>(std::__niter_base(__first), - std::__niter_base(__last), - std::__niter_base(__result)); - return {std::__niter_wrap(__first, std::move(__in)), - std::__niter_wrap(__result, std::move(__out))}; + = ranges::__copy_or_move<_IsMove>(__first, __last, __result.base()); + return {std::move(__in), decltype(__result){__out}}; } else if constexpr (sized_sentinel_for<_Sent, _Iter>) { @@ -353,30 +358,33 @@ namespace ranges { // TODO: implement more specializations to be at least on par with // std::copy_backward/std::move_backward. - constexpr bool __normal_iterator_p - = (__detail::__is_normal_iterator<_Iter> - || __detail::__is_normal_iterator<_Out>); - constexpr bool __reverse_p - = (__detail::__is_reverse_iterator<_Iter> - && __detail::__is_reverse_iterator<_Out>); - if constexpr (__reverse_p) + using __detail::__is_reverse_iterator; + using __detail::__is_normal_iterator; + if constexpr (__is_reverse_iterator<_Iter> && same_as<_Iter, _Sent> + && __is_reverse_iterator<_Out>) { auto [__in,__out] - = ranges::__copy_or_move<_IsMove>(__last.base(), - __first.base(), - __result.base()); + = ranges::__copy_or_move<_IsMove>(std::move(__last).base(), + std::move(__first).base(), + std::move(__result).base()); return {reverse_iterator{std::move(__in)}, reverse_iterator{std::move(__out)}}; } - else if constexpr (__normal_iterator_p) + else if constexpr (__is_normal_iterator<_Iter> && same_as<_Iter, _Sent>) { auto [__in,__out] - = ranges::__copy_or_move_backward<_IsMove> - (std::__niter_base(__first), - std::__niter_base(__last), - std::__niter_base(__result)); - return {std::__niter_wrap(__first, std::move(__in)), - std::__niter_wrap(__result, std::move(__out))}; + = ranges::__copy_or_move_backward<_IsMove>(__first.base(), + __last.base(), + std::move(__result)); + return {decltype(__first){__in}, std::move(__out)}; + } + else if constexpr (__is_normal_iterator<_Out>) + { + auto [__in,__out] + = ranges::__copy_or_move_backward<_IsMove>(std::move(__first), + std::move(__last), + __result.base()); + return {std::move(__in), decltype(__result){__out}}; } else if constexpr (sized_sentinel_for<_Sent, _Iter>) { diff --git a/libstdc++-v3/testsuite/25_algorithms/copy/95578.cc b/libstdc++-v3/testsuite/25_algorithms/copy/95578.cc new file mode 100644 index 00000000000..7aaefba454c --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/copy/95578.cc @@ -0,0 +1,74 @@ +// 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; + +template +struct sentinel +{ + It it; + + friend bool + operator==(It x, sentinel y) + { return x == y.it; } +}; + +void +test01() +{ + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr = {v.begin(), sentinel{v.end()}}; + ranges::copy(sr, w.begin()); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +void +test02() +{ + using std::reverse_iterator; + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr + = {reverse_iterator{v.end()}, sentinel{reverse_iterator{v.begin()}}}; + ranges::copy(sr, reverse_iterator{w.end()}); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +void +test03() +{ + using std::move_iterator; + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr + = {move_iterator{v.begin()}, sentinel{move_iterator{v.end()}}}; + ranges::copy(sr, w.begin()); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +int +main() +{ + test01(); + test02(); + test03(); +} diff --git a/libstdc++-v3/testsuite/25_algorithms/copy_backward/95578.cc b/libstdc++-v3/testsuite/25_algorithms/copy_backward/95578.cc new file mode 100644 index 00000000000..6e3d1b62401 --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/copy_backward/95578.cc @@ -0,0 +1,62 @@ +// 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; + +template +struct sentinel +{ + It it; + + friend bool + operator==(It x, sentinel y) + { return x == y.it; } +}; + +void +test01() +{ + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr = {v.begin(), sentinel{v.end()}}; + ranges::copy_backward(sr, w.end()); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +void +test02() +{ + using std::reverse_iterator; + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr + = {reverse_iterator{v.end()}, sentinel{reverse_iterator{v.begin()}}}; + ranges::copy_backward(sr, reverse_iterator{w.begin()}); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +int +main() +{ + test01(); + test02(); +} diff --git a/libstdc++-v3/testsuite/25_algorithms/equal/95578.cc b/libstdc++-v3/testsuite/25_algorithms/equal/95578.cc new file mode 100644 index 00000000000..b69d877e4e3 --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/equal/95578.cc @@ -0,0 +1,74 @@ +// 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; + +template +struct sentinel +{ + It it; + + friend bool + operator==(It x, sentinel y) + { return x == y.it; } +}; + +void +test01() +{ + std::vector v = {1,2,3,4,5}; + ranges::subrange sr = {v.begin(), sentinel{v.end()}}; + VERIFY( ranges::equal(sr, v) ); + VERIFY( ranges::equal(v, sr) ); +} + +void +test02() +{ + using std::reverse_iterator; + std::vector v = {1,2,3,4,5}; + ranges::subrange sr + = {reverse_iterator{v.end()}, sentinel{reverse_iterator{v.begin()}}}; + VERIFY( ranges::equal(sr, (int[]){5,4,3,2,1}) ); + VERIFY( ranges::equal((int[]){5,4,3,2,1}, sr) ); +} + +void +test03() +{ + using std::move_iterator; + std::vector v = {1,2,3,4,5}; + ranges::subrange sr + = {move_iterator{v.begin()}, sentinel{move_iterator{v.end()}}}; + VERIFY( ranges::equal(sr, v) ); + VERIFY( ranges::equal(v, sr) ); +} + +int +main() +{ + test01(); + test02(); + test03(); +} diff --git a/libstdc++-v3/testsuite/25_algorithms/lexicographical_compare/95578.cc b/libstdc++-v3/testsuite/25_algorithms/lexicographical_compare/95578.cc new file mode 100644 index 00000000000..693506826bc --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/lexicographical_compare/95578.cc @@ -0,0 +1,74 @@ +// 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; + +template +struct sentinel +{ + It it; + + friend bool + operator==(It x, sentinel y) + { return x == y.it; } +}; + +void +test01() +{ + std::vector v = {1,2,3,4,5}; + ranges::subrange sr = {v.begin(), sentinel{v.end()}}; + VERIFY( ranges::lexicographical_compare(sr, (int[]){1,2,3,5,5}) ); + VERIFY( !ranges::lexicographical_compare((int[]){1,2,3,5,5}, sr) ); +} + +void +test02() +{ + using std::reverse_iterator; + std::vector v = {1,2,3,4,5}; + ranges::subrange sr + = {reverse_iterator{v.end()}, sentinel{reverse_iterator{v.begin()}}}; + VERIFY( ranges::lexicographical_compare(sr, (int[]){5,4,3,2,2}) ); + VERIFY( !ranges::lexicographical_compare((int[]){5,4,3,2,2}, sr) ); +} + +void +test03() +{ + using std::move_iterator; + std::vector v = {1,2,3,4,5}; + ranges::subrange sr + = {move_iterator{v.begin()}, sentinel{move_iterator{v.end()}}}; + VERIFY( ranges::lexicographical_compare(sr, (int[]){1,2,3,5,5}) ); + VERIFY( !ranges::lexicographical_compare((int[]){1,2,3,5,5}, sr) ); +} + +int +main() +{ + test01(); + test02(); + test03(); +} diff --git a/libstdc++-v3/testsuite/25_algorithms/move/95578.cc b/libstdc++-v3/testsuite/25_algorithms/move/95578.cc new file mode 100644 index 00000000000..e5c494d55d2 --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/move/95578.cc @@ -0,0 +1,62 @@ +// 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; + +template +struct sentinel +{ + It it; + + friend bool + operator==(It x, sentinel y) + { return x == y.it; } +}; + +void +test01() +{ + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr = {v.begin(), sentinel{v.end()}}; + ranges::move(sr, w.begin()); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +void +test02() +{ + using std::reverse_iterator; + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr + = {reverse_iterator{v.end()}, sentinel{reverse_iterator{v.begin()}}}; + ranges::move(sr, reverse_iterator{w.end()}); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +int +main() +{ + test01(); + test02(); +} diff --git a/libstdc++-v3/testsuite/25_algorithms/move_backward/95578.cc b/libstdc++-v3/testsuite/25_algorithms/move_backward/95578.cc new file mode 100644 index 00000000000..694e4a75c83 --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/move_backward/95578.cc @@ -0,0 +1,62 @@ +// 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; + +template +struct sentinel +{ + It it; + + friend bool + operator==(It x, sentinel y) + { return x == y.it; } +}; + +void +test01() +{ + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr = {v.begin(), sentinel{v.end()}}; + ranges::move_backward(sr, w.end()); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +void +test02() +{ + using std::reverse_iterator; + std::vector v = {1,2,3,4,5}, w = {0,0,0,0,0}; + ranges::subrange sr + = {reverse_iterator{v.end()}, sentinel{reverse_iterator{v.begin()}}}; + ranges::move_backward(sr, reverse_iterator{w.begin()}); + VERIFY( ranges::equal(w, (int[]){1,2,3,4,5}) ); +} + +int +main() +{ + test01(); + test02(); +}