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[69.118.112.187]) by smtp.gmail.com with ESMTPSA id dp20-20020a05621409d400b005dd8b9345d6sm871169qvb.110.2023.04.13.21.00.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Apr 2023 21:00:45 -0700 (PDT) From: Patrick Palka To: gcc-patches@gcc.gnu.org Cc: libstdc++@gcc.gnu.org, Patrick Palka Subject: [PATCH 2/2] libstdc++: Implement P2278R4 "cbegin should always return a constant iterator" Date: Fri, 14 Apr 2023 00:00:42 -0400 Message-ID: <20230414040042.1498825-2-ppalka@redhat.com> X-Mailer: git-send-email 2.40.0.335.g9857273be0 In-Reply-To: <20230414040042.1498825-1-ppalka@redhat.com> References: <20230414040042.1498825-1-ppalka@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-13.7 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: This also implements the approved follow-up LWG issues 3765, 3766, 3769, 3770, 3811, 3850, 3853, 3862 and 3872. Tested on x86_64-pc-linux-gnu, does this look OK for trunk? libstdc++-v3/ChangeLog: * include/bits/ranges_base.h (const_iterator_t): Define for C++23. (const_sentinel_t): Likewise. (range_const_reference_t): Likewise. (constant_range): Likewise. (__cust_access::__possibly_const_range): Likewise, replacing ... (__cust_access::__as_const): ... this. (__cust_access::_CBegin::operator()): Redefine for C++23 as per P2278R4. (__cust_access::_CEnd::operator()): Likewise. (__cust_access::_CRBegin::operator()): Likewise. (__cust_access::_CREnd::operator()): Likewise. (__cust_access::_CData::operator()): Likewise. (__cust_access::_CData::__as_const_pointer): Define for C++23 * include/bits/ranges_util.h (ranges::__detail::__different_from): Make it an alias of std::__detail::__different_from. (view_interface::cbegin): Define for C++23. (view_interface::cend): Likewise. * include/bits/stl_iterator.h (__detail::__different_from): Define. (iter_const_reference_t): Define for C++23. (__detail::__constant_iterator): Likewise. (__detail::__is_const_iterator): Likewise. (__detail::__not_a_const_iterator: Likewise. (__detail::__iter_const_rvalue_reference_t): Likewise. (__detail::__basic_const_iter_cat):: Likewise. (const_iterator): Likewise. (__detail::__const_sentinel): Likewise. (const_sentinel): Likewise. (basic_const_iterator): Likewise. (common_type, _Up>): Likewise. (common_type<_Up, basic_const_iterator<_Tp>>): Likewise. (common_type, basic_const_iterator>): Likewise. (make_const_iterator): Define for C++23. (make_const_sentinel): Likewise. * include/std/ranges (__cpp_lib_ranges_as_const): Likewise. (as_const_view): Likewise. (enable_borrowed_range): Likewise. (views::__detail::__is_ref_view): Likewise. (views::__detail::__can_is_const_view): Likewise. (views::_AsConst, views::as_const): Likewise. * include/std/span (span::const_iterator): Likewise. (span::const_reverse_iterator): Likewise. (span::cbegin): Likewise. (span::cend): Likewise. (span::crbegin): Likewise. (span::crend): Likewise. * include/std/version (__cpp_lib_ranges_as_const): Likewise. * testsuite/std/ranges/adaptors/join.cc (test06): Adjust to behave independently of C++20 vs C++23. * testsuite/std/ranges/version_c++23.cc: Verify value of __cpp_lib_ranges_as_const macro. * testsuite/24_iterators/const_iterator/1.cc: New test. * testsuite/std/ranges/adaptors/as_const/1.cc: New test. --- libstdc++-v3/include/bits/ranges_base.h | 99 +++++ libstdc++-v3/include/bits/ranges_util.h | 22 +- libstdc++-v3/include/bits/stl_iterator.h | 366 ++++++++++++++++++ libstdc++-v3/include/std/ranges | 106 +++++ libstdc++-v3/include/std/span | 22 ++ libstdc++-v3/include/std/version | 1 + .../24_iterators/const_iterator/1.cc | 140 +++++++ .../std/ranges/adaptors/as_const/1.cc | 64 +++ .../testsuite/std/ranges/adaptors/join.cc | 5 +- .../testsuite/std/ranges/version_c++23.cc | 4 + 10 files changed, 824 insertions(+), 5 deletions(-) create mode 100644 libstdc++-v3/testsuite/24_iterators/const_iterator/1.cc create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h index c89cb3e976a..b3144bbae4d 100644 --- a/libstdc++-v3/include/bits/ranges_base.h +++ b/libstdc++-v3/include/bits/ranges_base.h @@ -515,6 +515,17 @@ namespace ranges template using sentinel_t = decltype(ranges::end(std::declval<_Range&>())); +#if __cplusplus > 202002L + template + using const_iterator_t = const_iterator>; + + template + using const_sentinel_t = const_sentinel>; + + template + using range_const_reference_t = iter_const_reference_t>; +#endif + template using range_difference_t = iter_difference_t>; @@ -607,8 +618,25 @@ namespace ranges concept common_range = range<_Tp> && same_as, sentinel_t<_Tp>>; +#if __cplusplus > 202002L + template + concept constant_range + = input_range<_Tp> && std::__detail::__constant_iterator>; +#endif + namespace __cust_access { +#if __cplusplus > 202020L + template + constexpr auto& + __possibly_const_range(_Range& __r) noexcept + { + if constexpr (constant_range && !constant_range<_Range>) + return const_cast(__r); + else + return __r; + } +#else // If _To is an lvalue-reference, return const _Tp&, otherwise const _Tp&&. template constexpr decltype(auto) @@ -621,9 +649,23 @@ namespace ranges else return static_cast(__t); } +#endif struct _CBegin { +#if __cplusplus > 202002L + template<__maybe_borrowed_range _Tp> + constexpr auto + operator() [[nodiscard]] (_Tp&& __t) const + noexcept(noexcept(std::make_const_iterator + (ranges::begin(__cust_access::__possibly_const_range(__t))))) + requires requires { std::make_const_iterator + (ranges::begin(__cust_access::__possibly_const_range(__t))); } + { + auto& __r = __cust_access::__possibly_const_range(__t); + return const_iterator_t(ranges::begin(__r)); + } +#else template [[nodiscard]] constexpr auto @@ -633,10 +675,24 @@ namespace ranges { return _Begin{}(__cust_access::__as_const<_Tp>(__e)); } +#endif }; struct _CEnd final { +#if __cplusplus > 202002L + template<__maybe_borrowed_range _Tp> + constexpr auto + operator() [[nodiscard]] (_Tp&& __t) const + noexcept(noexcept(std::make_const_sentinel + (ranges::end(__cust_access::__possibly_const_range(__t))))) + requires requires { std::make_const_sentinel + (ranges::end(__cust_access::__possibly_const_range(__t))); } + { + auto& __r = __cust_access::__possibly_const_range(__t); + return const_sentinel_t(ranges::end(__r)); + } +#else template [[nodiscard]] constexpr auto @@ -646,10 +702,24 @@ namespace ranges { return _End{}(__cust_access::__as_const<_Tp>(__e)); } +#endif }; struct _CRBegin { +#if __cplusplus > 202002L + template<__maybe_borrowed_range _Tp> + constexpr auto + operator() [[nodiscard]] (_Tp&& __t) const + noexcept(noexcept(std::make_const_iterator + (ranges::rbegin(__cust_access::__possibly_const_range(__t))))) + requires requires { std::make_const_iterator + (ranges::rbegin(__cust_access::__possibly_const_range(__t))); } + { + auto& __r = __cust_access::__possibly_const_range(__t); + return const_iterator(ranges::rbegin(__r)); + } +#else template [[nodiscard]] constexpr auto @@ -659,10 +729,24 @@ namespace ranges { return _RBegin{}(__cust_access::__as_const<_Tp>(__e)); } +#endif }; struct _CREnd { +#if __cplusplus > 202002L + template<__maybe_borrowed_range _Tp> + constexpr auto + operator() [[nodiscard]] (_Tp&& __t) const + noexcept(noexcept(std::make_const_sentinel + (ranges::rend(__cust_access::__possibly_const_range(__t))))) + requires requires { std::make_const_sentinel + (ranges::rend(__cust_access::__possibly_const_range(__t))); } + { + auto& __r = __cust_access::__possibly_const_range(__t); + return const_sentinel(ranges::rend(__r)); + } +#else template [[nodiscard]] constexpr auto @@ -672,10 +756,24 @@ namespace ranges { return _REnd{}(__cust_access::__as_const<_Tp>(__e)); } +#endif }; struct _CData { +#if __cplusplus > 202002L + template + static constexpr auto + __as_const_pointer(const _Tp* __p) noexcept + { return __p; } + + template<__maybe_borrowed_range _Tp> + constexpr auto + operator() [[nodiscard]] (_Tp&& __t) const + noexcept(noexcept(ranges::data(__cust_access::__possibly_const_range(__t)))) + requires requires { ranges::data(__cust_access::__possibly_const_range(__t)); } + { return __as_const_pointer(ranges::data(__cust_access::__possibly_const_range(__t))); } +#else template [[nodiscard]] constexpr auto @@ -685,6 +783,7 @@ namespace ranges { return _Data{}(__cust_access::__as_const<_Tp>(__e)); } +#endif }; } // namespace __cust_access diff --git a/libstdc++-v3/include/bits/ranges_util.h b/libstdc++-v3/include/bits/ranges_util.h index 880a0ce0143..f7e3538af97 100644 --- a/libstdc++-v3/include/bits/ranges_util.h +++ b/libstdc++-v3/include/bits/ranges_util.h @@ -53,9 +53,7 @@ namespace ranges concept __has_arrow = input_iterator<_It> && (is_pointer_v<_It> || requires(_It __it) { __it.operator->(); }); - template - concept __different_from - = !same_as, remove_cvref_t<_Up>>; + using std::__detail::__different_from; } // namespace __detail /// The ranges::view_interface class template @@ -192,6 +190,24 @@ namespace ranges constexpr decltype(auto) operator[](range_difference_t<_Range> __n) const { return ranges::begin(_M_derived())[__n]; } + +#if __cplusplus > 202002L + constexpr auto + cbegin() requires input_range<_Derived> + { return ranges::cbegin(_M_derived()); } + + constexpr auto + cbegin() const requires input_range + { return ranges::cbegin(_M_derived()); } + + constexpr auto + cend() requires input_range<_Derived> + { return ranges::cend(_M_derived()); } + + constexpr auto + cend() const requires input_range + { return ranges::cend(_M_derived()); } +#endif }; namespace __detail diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index a6a09dbac16..0974d735328 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -102,6 +102,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template using __clamp_iter_cat = __conditional_t, _Limit, _Otherwise>; + + template + concept __different_from + = !same_as, remove_cvref_t<_Up>>; } #endif @@ -2578,6 +2582,368 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION add_pointer_t>, void>; }; + +#if __cplusplus > 202020L + template + using iter_const_reference_t + = common_reference_t&&, iter_reference_t<_It>>; + + template class basic_const_iterator; + + namespace __detail + { + template + concept __constant_iterator = input_iterator<_It> + && same_as, iter_reference_t<_It>>; + + template + inline constexpr bool __is_const_iterator = false; + + template + inline constexpr bool __is_const_iterator> = true; + + template + concept __not_a_const_iterator = !__is_const_iterator<_Tp>; + + template + using __iter_const_rvalue_reference_t + = common_reference_t&&, iter_rvalue_reference_t<_It>>; + + template + struct __basic_const_iterator_iter_cat + { }; + + template + struct __basic_const_iterator_iter_cat<_It> + { using iterator_category = iterator_traits<_It>::iterator_category; }; + } // namespace detail + + template + using const_iterator + = __conditional_t<__detail::__constant_iterator<_It>, _It, basic_const_iterator<_It>>; + + namespace __detail + { + template + struct __const_sentinel + { using type = _Sent; }; + + template + struct __const_sentinel<_Sent> + { using type = const_iterator<_Sent>; }; + } // namespace __detail + + template + using const_sentinel = typename __detail::__const_sentinel<_Sent>::type; + + template + class basic_const_iterator : public __detail::__basic_const_iterator_iter_cat<_It> + { + _It _M_current = _It(); + using __reference = iter_const_reference_t<_It>; + using __rvalue_reference = __detail::__iter_const_rvalue_reference_t<_It>; + + static auto + _S_iter_concept() + { + if constexpr (contiguous_iterator<_It>) + return contiguous_iterator_tag{}; + else if constexpr (random_access_iterator<_It>) + return random_access_iterator_tag{}; + else if constexpr (bidirectional_iterator<_It>) + return bidirectional_iterator_tag{}; + else if constexpr (forward_iterator<_It>) + return forward_iterator_tag{}; + else + return input_iterator_tag{}; + } + + template friend class basic_const_iterator; + + public: + using iterator_concept = decltype(_S_iter_concept()); + using value_type = iter_value_t<_It>; + using difference_type = iter_difference_t<_It>; + + basic_const_iterator() requires default_initializable<_It> = default; + + constexpr + basic_const_iterator(_It __current) + noexcept(is_nothrow_move_constructible_v<_It>) + : _M_current(std::move(__current)) + { } + + template _It2> + constexpr + basic_const_iterator(basic_const_iterator<_It2> __current) + noexcept(is_nothrow_constructible_v<_It, _It2>) + : _M_current(std::move(__current._M_current)) + { } + + template<__detail::__different_from _Tp> + requires convertible_to<_Tp, _It> + constexpr + basic_const_iterator(_Tp&& __current) + noexcept(is_nothrow_constructible_v<_It, _Tp>) + : _M_current(std::forward<_Tp>(__current)) + { } + + constexpr const _It& + base() const & noexcept + { return _M_current; } + + constexpr _It + base() && + noexcept(is_nothrow_move_constructible_v<_It>) + { return std::move(_M_current); } + + constexpr __reference + operator*() const + noexcept(noexcept(static_cast<__reference>(*_M_current))) + { return static_cast<__reference>(*_M_current); } + + constexpr const auto* + operator->() const + noexcept(contiguous_iterator<_It> || noexcept(*_M_current)) + requires is_lvalue_reference_v> + && same_as>, value_type> + { + if constexpr (contiguous_iterator<_It>) + return std::to_address(_M_current); + else + return std::__addressof(*_M_current); + } + + constexpr basic_const_iterator& + operator++() + noexcept(noexcept(++_M_current)) + { + ++_M_current; + return *this; + } + + constexpr void + operator++(int) + noexcept(noexcept(++_M_current)) + { ++_M_current; } + + constexpr basic_const_iterator + operator++(int) + noexcept(noexcept(++*this) && is_nothrow_copy_constructible_v) + requires forward_iterator<_It> + { + auto __tmp = *this; + ++*this; + return __tmp; + } + + constexpr basic_const_iterator& + operator--() + noexcept(noexcept(--_M_current)) + requires bidirectional_iterator<_It> + { + --_M_current; + return *this; + } + + constexpr basic_const_iterator + operator--(int) + noexcept(noexcept(--*this) && is_nothrow_copy_constructible_v) + requires bidirectional_iterator<_It> + { + auto __tmp = *this; + --*this; + return __tmp; + } + + constexpr basic_const_iterator& + operator+=(difference_type __n) + noexcept(noexcept(_M_current += __n)) + requires random_access_iterator<_It> + { + _M_current += __n; + return *this; + } + + constexpr basic_const_iterator& + operator-=(difference_type __n) + noexcept(noexcept(_M_current -= __n)) + requires random_access_iterator<_It> + { + _M_current -= __n; + return *this; + } + + constexpr __reference + operator[](difference_type __n) const + noexcept(noexcept(static_cast<__reference>(_M_current[__n]))) + requires random_access_iterator<_It> + { return static_cast<__reference>(_M_current[__n]); } + + template _Sent> + constexpr bool + operator==(const _Sent& __s) const + noexcept(noexcept(_M_current == __s)) + { return _M_current == __s; } + + constexpr bool + operator<(const basic_const_iterator& __y) const + noexcept(noexcept(_M_current < __y._M_current)) + requires random_access_iterator<_It> + { return _M_current < __y._M_current; } + + constexpr bool + operator>(const basic_const_iterator& __y) const + noexcept(noexcept(_M_current > __y._M_current)) + requires random_access_iterator<_It> + { return _M_current > __y._M_current; } + + constexpr bool + operator<=(const basic_const_iterator& __y) const + noexcept(noexcept(_M_current <= __y._M_current)) + requires random_access_iterator<_It> + { return _M_current <= __y._M_current; } + + constexpr bool + operator>=(const basic_const_iterator& __y) const + noexcept(noexcept(_M_current >= __y._M_current)) + requires random_access_iterator<_It> + { return _M_current >= __y._M_current; } + + constexpr auto + operator<=>(const basic_const_iterator& __y) const + noexcept(noexcept(_M_current <=> __y._M_current)) + requires random_access_iterator<_It> && three_way_comparable<_It> + { return _M_current <=> __y._M_current; } + + template<__detail::__different_from _It2> + constexpr bool + operator<(const _It2& __y) const + noexcept(noexcept(_M_current < __y)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return _M_current < __y; } + + template<__detail::__different_from _It2> + constexpr bool + operator>(const _It2& __y) const + noexcept(noexcept(_M_current > __y)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return _M_current > __y; } + + template<__detail::__different_from _It2> + constexpr bool + operator<=(const _It2& __y) const + noexcept(noexcept(_M_current <= __y)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return _M_current <= __y; } + + template<__detail::__different_from _It2> + constexpr bool + operator>=(const _It2& __y) const + noexcept(noexcept(_M_current >= __y)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return _M_current >= __y; } + + template<__detail::__different_from _It2> + constexpr auto + operator<=>(const _It2& __y) const + noexcept(noexcept(_M_current <=> __y)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + && three_way_comparable_with<_It, _It2> + { return _M_current <=> __y; } + + template<__detail::__not_a_const_iterator _It2> + friend constexpr bool + operator<(const _It2& __x, const basic_const_iterator& __y) + noexcept(noexcept(__x < __y._M_current)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return __x < __y._M_current; } + + template<__detail::__not_a_const_iterator _It2> + friend constexpr bool + operator>(const _It2& __x, const basic_const_iterator& __y) + noexcept(noexcept(__x > __y._M_current)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return __x > __y._M_current; } + + template<__detail::__not_a_const_iterator _It2> + friend constexpr bool + operator<=(const _It2& __x, const basic_const_iterator& __y) + noexcept(noexcept(__x <= __y._M_current)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return __x <= __y._M_current; } + + template<__detail::__not_a_const_iterator _It2> + friend constexpr bool + operator>=(const _It2& __x, const basic_const_iterator& __y) + noexcept(noexcept(__x >= __y._M_current)) + requires random_access_iterator<_It> && totally_ordered_with<_It, _It2> + { return __x >= __y._M_current; } + + friend constexpr basic_const_iterator + operator+(const basic_const_iterator& __i, difference_type __n) + noexcept(noexcept(basic_const_iterator(__i._M_current + __n))) + requires random_access_iterator<_It> + { return basic_const_iterator(__i._M_current + __n); } + + friend constexpr basic_const_iterator + operator+(difference_type __n, const basic_const_iterator& __i) + noexcept(noexcept(basic_const_iterator(__i._M_current + __n))) + requires random_access_iterator<_It> + { return basic_const_iterator(__i._M_current + __n); } + + friend constexpr basic_const_iterator + operator-(const basic_const_iterator& __i, difference_type __n) + noexcept(noexcept(basic_const_iterator(__i._M_current - __n))) + requires random_access_iterator<_It> + { return basic_const_iterator(__i._M_current - __n); } + + template _Sent> + constexpr difference_type + operator-(const _Sent& __y) const + noexcept(noexcept(_M_current - __y)) + { return _M_current - __y; } + + template<__detail::__not_a_const_iterator _Sent> + requires sized_sentinel_for<_Sent, _It> + friend constexpr difference_type + operator-(const _Sent& __x, const basic_const_iterator& __y) + noexcept(noexcept(__x - __y._M_current)) + { return __x - __y._M_current; } + + friend constexpr __rvalue_reference + iter_move(const basic_const_iterator& __i) + noexcept(noexcept(static_cast<__rvalue_reference>(ranges::iter_move(__i._M_current)))) + { return static_cast<__rvalue_reference>(ranges::iter_move(__i._M_current)); } + }; + + template _Up> + requires input_iterator> + struct common_type, _Up> + { using type = basic_const_iterator>; }; + + template _Up> + requires input_iterator> + struct common_type<_Up, basic_const_iterator<_Tp>> + { using type = basic_const_iterator>; }; + + template _Up> + requires input_iterator> + struct common_type, basic_const_iterator<_Up>> + { using type = basic_const_iterator>; }; + + template + constexpr const_iterator<_It> + make_const_iterator(_It __it) + noexcept(is_nothrow_convertible_v<_It, const_iterator<_It>>) + { return __it; } + + template + constexpr const_sentinel<_Sent> + make_const_sentinel(_Sent __s) + noexcept(is_nothrow_convertible_v<_Sent, const_sentinel<_Sent>>) + { return __s; } +#endif // C++23 #endif // C++20 /// @} group iterators diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index 3f6ff505617..283d757faa4 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -8929,6 +8929,112 @@ namespace views::__adaptor inline constexpr _Enumerate enumerate; } + +#define __cpp_lib_ranges_as_const 202207L + + template + requires input_range<_Vp> + class as_const_view : public view_interface> + { + _Vp _M_base = _Vp(); + + public: + as_const_view() requires default_initializable<_Vp> = default; + + constexpr explicit + as_const_view(_Vp __base) + noexcept(is_nothrow_move_constructible_v<_Vp>) + : _M_base(std::move(__base)) + { } + + constexpr _Vp + base() const & + noexcept(is_nothrow_copy_constructible_v<_Vp>) + requires copy_constructible<_Vp> + { return _M_base; } + + constexpr _Vp + base() && + noexcept(is_nothrow_move_constructible_v<_Vp>) + { return std::move(_M_base); } + + constexpr auto + begin() requires (!__detail::__simple_view<_Vp>) + { return ranges::cbegin(_M_base); } + + constexpr auto + begin() const requires range + { return ranges::cbegin(_M_base); } + + constexpr auto + end() requires (!__detail::__simple_view<_Vp>) + { return ranges::cend(_M_base); } + + constexpr auto + end() const requires range + { return ranges::cend(_M_base); } + + constexpr auto + size() requires sized_range<_Vp> + { return ranges::size(_M_base); } + + constexpr auto + size() const requires sized_range + { return ranges::size(_M_base); } + }; + + template + as_const_view(_Range&&) -> as_const_view>; + + template + inline constexpr bool enable_borrowed_range> + = enable_borrowed_range<_Tp>; + + namespace views + { + namespace __detail + { + template + inline constexpr bool __is_ref_view = false; + + template + inline constexpr bool __is_ref_view> = true; + + template + concept __can_as_const_view = requires { as_const_view(std::declval<_Range>()); }; + } + + struct _AsConst : __adaptor::_RangeAdaptorClosure + { + template + constexpr auto + operator()(_Range&& __r) const + noexcept(noexcept(as_const_view(std::declval<_Range>()))) + requires __detail::__can_as_const_view<_Range> + { + using _Tp = remove_cvref_t<_Range>; + using element_type = remove_reference_t>; + if constexpr (constant_range>) + return views::all(std::forward<_Range>(__r)); + else if constexpr (__detail::__is_empty_view<_Tp>) + return views::empty; + else if constexpr (std::__detail::__is_span<_Tp>) + return span(std::forward<_Range>(__r)); + else if constexpr (__detail::__is_ref_view<_Tp> + && constant_range) + return ref_view(static_cast + (std::forward<_Range>(__r).base())); + else if constexpr (is_lvalue_reference_v<_Range> + && constant_range<_Tp> + && !view<_Tp>) + return ref_view(static_cast(__r)); + else + return as_const_view(std::forward<_Range>(__r)); + } + }; + + inline constexpr _AsConst as_const; + } #endif // C++23 } // namespace ranges diff --git a/libstdc++-v3/include/std/span b/libstdc++-v3/include/std/span index 06d5c185880..67633899665 100644 --- a/libstdc++-v3/include/std/span +++ b/libstdc++-v3/include/std/span @@ -137,6 +137,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION using const_reference = const element_type&; using iterator = __gnu_cxx::__normal_iterator; using reverse_iterator = std::reverse_iterator; +#if __cplusplus > 202002L + using const_iterator = std::const_iterator; + using const_reverse_iterator = std::const_iterator; +#endif // member constants static constexpr size_t extent = _Extent; @@ -301,6 +305,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION rend() const noexcept { return reverse_iterator(this->begin()); } +#if __cplusplus > 202002L + constexpr const_iterator + cbegin() const noexcept + { return begin(); } + + constexpr const_iterator + cend() const noexcept + { return end(); } + + constexpr const_reverse_iterator + crbegin() const noexcept + { return rbegin(); } + + constexpr const_reverse_iterator + crend() const noexcept + { return rend(); } +#endif + // subviews template diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version index d233b037d1a..9f31f25f1e9 100644 --- a/libstdc++-v3/include/std/version +++ b/libstdc++-v3/include/std/version @@ -339,6 +339,7 @@ #define __cpp_lib_ranges_stride 202207L #define __cpp_lib_ranges_cartesian_product 202207L #define __cpp_lib_ranges_as_rvalue 202207L +#define __cpp_lib_ranges_as_const 202207L #define __cpp_lib_ranges_enumerate 202302L #define __cpp_lib_fold 202207L #if __cpp_constexpr_dynamic_alloc diff --git a/libstdc++-v3/testsuite/24_iterators/const_iterator/1.cc b/libstdc++-v3/testsuite/24_iterators/const_iterator/1.cc new file mode 100644 index 00000000000..51befd29541 --- /dev/null +++ b/libstdc++-v3/testsuite/24_iterators/const_iterator/1.cc @@ -0,0 +1,140 @@ +// { dg-options "-std=gnu++23" } +// { dg-do run { target c++23 } } + +#include +#include +#include +#include +#include +#include + +using __gnu_test::test_input_range; +using __gnu_test::test_forward_range; +using __gnu_test::test_bidirectional_range; +using __gnu_test::test_random_access_range; + +namespace ranges = std::ranges; + +template +void +test01() +{ + if constexpr (Const) + { + static_assert( std::same_as, Iter> ); + static_assert( std::same_as, Iter> ); + static_assert( std::same_as, + std::iter_reference_t> ); + } + else + { + using Wrapped = std::basic_const_iterator; + + static_assert( std::same_as, Wrapped> ); + static_assert( std::same_as, Wrapped> ); + static_assert( std::same_as, + std::iter_reference_t> ); + + static_assert( std::input_iterator == std::input_iterator ); + static_assert( std::forward_iterator == std::forward_iterator ); + static_assert( std::bidirectional_iterator == std::bidirectional_iterator ); + static_assert( std::random_access_iterator == std::random_access_iterator ); + } +} + +template +void +test02() +{ + if constexpr (Const) + { + static_assert( ranges::constant_range ); + static_assert( std::same_as, ranges::iterator_t> ); + static_assert( std::same_as, ranges::sentinel_t> ); + static_assert( std::same_as, + ranges::range_reference_t> ); + + static_assert( std::same_as())), + decltype(ranges::begin(std::declval()))> ); + static_assert( std::same_as())), + decltype(ranges::end(std::declval()))> ); + } + else + { + static_assert( !ranges::constant_range ); + using Wrapped = std::basic_const_iterator>; + + static_assert( std::same_as, Wrapped> ); + if constexpr (ranges::common_range) + static_assert( std::same_as, Wrapped> ); + static_assert( std::same_as, + std::iter_reference_t> ); + + static_assert( ranges::input_range == std::input_iterator ); + static_assert( ranges::forward_range == std::forward_iterator ); + static_assert( ranges::bidirectional_range == std::bidirectional_iterator ); + static_assert( ranges::random_access_range == std::random_access_iterator ); + + if constexpr (ranges::constant_range) + { + static_assert( std::same_as())), + decltype(ranges::begin(std::declval()))> ); + static_assert( std::same_as())), + decltype(ranges::end(std::declval()))> ); + } + else + { + static_assert( std::same_as())), Wrapped> ); + if constexpr (ranges::common_range) + static_assert( std::same_as())), Wrapped> ); + } + } +} + +void +test03() +{ + static_assert( std::same_as, + std::unreachable_sentinel_t> ); +} + +int +main() +{ + test01(); + test01>, false>(); + test01>, false>(); + test01>, false>(); + test01>, false>(); + test01::iterator, false>(); + test01::iterator, false>(); + + test01(); + test01>, true>(); + test01>, true>(); + test01>, true>(); + test01>, true>(); + test01::iterator, true>(); + test01(); + test01::const_iterator, true>(); + + test02(); + test02, false>(); + test02, false>(); + test02, false>(); + test02, false>(); + test02, false>(); + test02, false>(); + + test02(); + test02, true>(); + test02, true>(); + test02, true>(); + test02, true>(); + test02, true>(); + test02, true>(); + test02(); + test02, true>(); + + test03(); +} diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc new file mode 100644 index 00000000000..d04645f047e --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc @@ -0,0 +1,64 @@ +// { dg-options "-std=gnu++23" } +// { dg-do run { target c++23 } } + +#include +#include +#include +#include +#include +#include + +#if __cpp_lib_ranges_as_const != 202207L +# error "Feature-test macro __cpp_lib_ranges_as_const has wrong value in " +#endif + +namespace ranges = std::ranges; +namespace views = std::views; + +constexpr bool +test01() +{ + int x[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; + auto v = x | views::filter([](int x) { return (x % 2) == 0; }) | views::as_const; + + using ty = decltype(v); + static_assert(ranges::constant_range); + static_assert(!ranges::constant_range); + static_assert(std::same_as, const int&>); + static_assert(std::same_as, int&>); + + VERIFY( ranges::equal(v, (int[]){2, 4, 6, 8, 10}) ); + VERIFY( ranges::equal(v | views::reverse, (int[]){10, 8, 6, 4, 2}) ); + + return true; +} + +constexpr bool +test02() +{ + std::same_as> auto v1 + = views::empty | views::as_const; + + int x[] = {1, 2, 3}; + std::same_as>> auto v2 + = x | views::as_const; + std::same_as> auto v3 + = std::as_const(x) | views::as_const; + std::same_as> auto v4 + = std::as_const(x) | views::all | views::as_const; + std::same_as> auto v5 + = std::span{x, x+3} | views::as_const; + + std::same_as>>> auto v6 + = x | views::chunk(2) | views::as_const; + VERIFY( v6.size() == 2 ); + + return true; +} + +int +main() +{ + static_assert(test01()); + static_assert(test02()); +} diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc index e5ae9b7be20..cda2cbfc577 100644 --- a/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/join.cc @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -120,8 +121,8 @@ test06() // Verify that _Sentinel is implicitly convertible to _Sentinel. static_assert(!ranges::common_range); static_assert(!std::same_as); - auto b = ranges::cend(v); + decltype(std::as_const(v).end())>); + auto b = std::as_const(v).end(); b = ranges::end(v); } diff --git a/libstdc++-v3/testsuite/std/ranges/version_c++23.cc b/libstdc++-v3/testsuite/std/ranges/version_c++23.cc index fa010bf166b..e2c14edc8ef 100644 --- a/libstdc++-v3/testsuite/std/ranges/version_c++23.cc +++ b/libstdc++-v3/testsuite/std/ranges/version_c++23.cc @@ -45,6 +45,10 @@ # error "Feature-test macro __cpp_lib_ranges_as_rvalue has wrong value in " #endif +#if __cpp_lib_ranges_as_const != 202207L +# error "Feature-test macro __cpp_lib_ranges_as_const has wrong value in " +#endif + #if __cpp_lib_ranges_enumerate != 202302L # error "Feature-test macro __cpp_lib_ranges_enumerate has wrong value in " #endif -- 2.40.0.335.g9857273be0