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From: Patrick Palka <ppalka@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r10-9104] libstdc++: Apply proposed resolution for LWG 3449 [PR95322] Date: Tue, 1 Dec 2020 16:20:46 +0000 (GMT) [thread overview] Message-ID: <20201201162046.85B753944803@sourceware.org> (raw) https://gcc.gnu.org/g:be5f22ebe964244223f178330a66b67d3f58334e commit r10-9104-gbe5f22ebe964244223f178330a66b67d3f58334e Author: Patrick Palka <ppalka@redhat.com> Date: Mon Oct 12 13:46:21 2020 -0400 libstdc++: Apply proposed resolution for LWG 3449 [PR95322] Now that the frontend bug PR96805 is fixed, we can cleanly apply the proposed resolution for this issue. This slightly deviates from the proposed resolution by declaring _CI a member of take_view instead of take_view::_Sentinel, since it doesn't depend on anything within _Sentinel anymore. libstdc++-v3/ChangeLog: PR libstdc++/95322 * include/std/ranges (take_view::_CI): Define this alias template as per LWG 3449 and remove ... (take_view::_Sentinel::_CI): ... this type alias. (take_view::_Sentinel::operator==): Adjust use of _CI accordingly. Define a second overload that accepts an iterator of the opposite constness as per LWG 3449. (take_while_view::_Sentinel::operator==): Likewise. * testsuite/std/ranges/adaptors/95322.cc: Add tests for LWG 3449. (cherry picked from commit e066821b6f6b7332c7a67981f7b33c9ba0ccaee7) Diff: --- libstdc++-v3/include/std/ranges | 23 +++++++++++++++--- .../testsuite/std/ranges/adaptors/95322.cc | 28 +++++++++++++++++++++- 2 files changed, 47 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index e2ad6a313c7..6edc4313533 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -1994,13 +1994,15 @@ namespace views class take_view : public view_interface<take_view<_Vp>> { private: + template<bool _Const> + using _CI = counted_iterator< + iterator_t<__detail::__maybe_const_t<_Const, _Vp>>>; + template<bool _Const> struct _Sentinel { private: using _Base = __detail::__maybe_const_t<_Const, _Vp>; - using _CI = counted_iterator<iterator_t<_Base>>; - sentinel_t<_Base> _M_end = sentinel_t<_Base>(); public: @@ -2021,7 +2023,15 @@ namespace views base() const { return _M_end; } - friend constexpr bool operator==(const _CI& __y, const _Sentinel& __x) + friend constexpr bool + operator==(const _CI<_Const>& __y, const _Sentinel& __x) + { return __y.count() == 0 || __y.base() == __x._M_end; } + + template<bool _OtherConst = !_Const, + typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>> + requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>> + friend constexpr bool + operator==(const _CI<_OtherConst>& __y, const _Sentinel& __x) { return __y.count() == 0 || __y.base() == __x._M_end; } friend _Sentinel<!_Const>; @@ -2174,6 +2184,13 @@ namespace views operator==(const iterator_t<_Base>& __x, const _Sentinel& __y) { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); } + template<bool _OtherConst = !_Const, + typename _Base2 = __detail::__maybe_const_t<_OtherConst, _Vp>> + requires sentinel_for<sentinel_t<_Base>, iterator_t<_Base2>> + friend constexpr bool + operator==(const iterator_t<_Base2>& __x, const _Sentinel& __y) + { return __y._M_end == __x || !std::__invoke(*__y._M_pred, *__x); } + friend _Sentinel<!_Const>; }; diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc index 67bc7d33917..41785a0a8fa 100644 --- a/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/95322.cc @@ -26,7 +26,7 @@ using __gnu_test::test_forward_range; void test01() { - // PR libstdc++/95322 and LWG 3488 + // PR libstdc++/95322 and LWG 3448 int a[2]{1, 2}; test_forward_range<int> v{a}; auto view1 = v | std::views::take(2); @@ -51,8 +51,34 @@ test02() VERIFY( !eq ); } +void +test03() +{ + // LWG 3449, for take_view + int a[2]{1, 2}; + test_forward_range<int> v{a}; + auto view1 = v | std::views::transform(std::identity{}); + auto view2 = view1 | std::views::take(2); + const bool eq = std::ranges::cbegin(view2) == std::ranges::end(view2); + VERIFY( !eq ); +} + +void +test04() +{ + // LWG 3449, for take_while_view + int a[2]{1, 2}; + test_forward_range<int> v{a}; + auto view1 = v | std::views::transform(std::identity{}); + auto view2 = view1 | std::views::take_while([] (int i) { return true; }); + const bool eq = std::ranges::cbegin(view2) == std::ranges::end(view2); + VERIFY( !eq ); +} + int main() { test01(); test02(); + test03(); + test04(); }
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