The definition of ranges::subrange was moved to the new <bits/ranges_util.h> header so that it could be used in <algorithm> without including the whole of <ranges>. However, the tuple-like support that enables subrange to be used with structured bindings was left in <ranges>. This is arguably conforming (to use a subrange you should include <ranges>) but it's inconvenient and probably confusing.
This change makes the tuple-like support available whenever subrange itself is available. libstdc++-v3/ChangeLog: PR libstdc++/97512 * include/bits/ranges_util.h (tuple_size<subrange>) (tuple_element<I, cv subrange>): Move here from ... * include/std/ranges: ... here. * testsuite/std/ranges/subrange/97512.cc: New test. Tested powerpc64le-linux. Committed to trunk.
commit a186ab670e97c4c3883d96506655c4621e7c5515 Author: Jonathan Wakely <jwak...@redhat.com> Date: Wed Oct 21 14:40:54 2020 libstdc++: Make structured bindings always work for subranges [PR 97512] The definition of ranges::subrange was moved to the new <bits/ranges_util.h> header so that it could be used in <algorithm> without including the whole of <ranges>. However, the tuple-like support that enables subrange to be used with structured bindings was left in <ranges>. This is arguably conforming (to use a subrange you should include <ranges>) but it's inconvenient and probably confusing. This change makes the tuple-like support available whenever subrange itself is available. libstdc++-v3/ChangeLog: PR libstdc++/97512 * include/bits/ranges_util.h (tuple_size<subrange>) (tuple_element<I, cv subrange>): Move here from ... * include/std/ranges: ... here. * testsuite/std/ranges/subrange/97512.cc: New test. diff --git a/libstdc++-v3/include/bits/ranges_util.h b/libstdc++-v3/include/bits/ranges_util.h index a98658ff5c8..cc50e2ad4e4 100644 --- a/libstdc++-v3/include/bits/ranges_util.h +++ b/libstdc++-v3/include/bits/ranges_util.h @@ -410,6 +410,27 @@ namespace ranges using ranges::get; + template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> + struct tuple_size<ranges::subrange<_Iter, _Sent, _Kind>> + : integral_constant<size_t, 2> + { }; + + template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> + struct tuple_element<0, ranges::subrange<_Iter, _Sent, _Kind>> + { using type = _Iter; }; + + template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> + struct tuple_element<1, ranges::subrange<_Iter, _Sent, _Kind>> + { using type = _Sent; }; + + template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> + struct tuple_element<0, const ranges::subrange<_Iter, _Sent, _Kind>> + { using type = _Iter; }; + + template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> + struct tuple_element<1, const ranges::subrange<_Iter, _Sent, _Kind>> + { using type = _Sent; }; + _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // library concepts diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index b03ae399fa6..4d3a4940c6f 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -3320,27 +3320,6 @@ namespace views namespace views = ranges::views; - template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> - struct tuple_size<ranges::subrange<_Iter, _Sent, _Kind>> - : integral_constant<size_t, 2> - { }; - - template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> - struct tuple_element<0, ranges::subrange<_Iter, _Sent, _Kind>> - { using type = _Iter; }; - - template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> - struct tuple_element<1, ranges::subrange<_Iter, _Sent, _Kind>> - { using type = _Sent; }; - - template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> - struct tuple_element<0, const ranges::subrange<_Iter, _Sent, _Kind>> - { using type = _Iter; }; - - template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> - struct tuple_element<1, const ranges::subrange<_Iter, _Sent, _Kind>> - { using type = _Sent; }; - _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif // library concepts diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/97512.cc b/libstdc++-v3/testsuite/std/ranges/subrange/97512.cc new file mode 100644 index 00000000000..b0fd0e2577f --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/subrange/97512.cc @@ -0,0 +1,33 @@ +// 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 } } + +// PR libstdc++/97512 +// Check that structured bindings work for subranges without <ranges>. +#include <algorithm> + +constexpr bool +test01() +{ + int r[] = { 1, 2, 2, 3, 3, 3 }; + auto [first, last] = std::ranges::unique(r); + return first == std::ranges::begin(r) + 3 && last == std::ranges::end(r); +} + +static_assert( test01() );