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GET /api/patches/2218238/?format=api
{ "id": 2218238, "url": "http://patchwork.ozlabs.org/api/patches/2218238/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/20260331184249.2895803-1-ppalka@redhat.com/", "project": { "id": 17, "url": "http://patchwork.ozlabs.org/api/projects/17/?format=api", "name": "GNU Compiler Collection", "link_name": "gcc", "list_id": "gcc-patches.gcc.gnu.org", "list_email": "gcc-patches@gcc.gnu.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260331184249.2895803-1-ppalka@redhat.com>", "list_archive_url": null, "date": "2026-03-31T18:42:48", "name": "[1/2] libstdc++: Implement P3725R3 Filter View Extensions for Safer Use", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "239c71a3c3ae623967c7256e9c5ab290c566e2ea", "submitter": { "id": 78319, "url": "http://patchwork.ozlabs.org/api/people/78319/?format=api", "name": "Patrick Palka", "email": "ppalka@redhat.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/20260331184249.2895803-1-ppalka@redhat.com/mbox/", "series": [ { "id": 498240, "url": "http://patchwork.ozlabs.org/api/series/498240/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=498240", "date": "2026-03-31T18:42:49", "name": "[1/2] libstdc++: Implement P3725R3 Filter View Extensions for Safer Use", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/498240/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2218238/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2218238/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "gcc-patches@gcc.gnu.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "gcc-patches@gcc.gnu.org" ], "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=BeK3fknl;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=38.145.34.32; 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charset=\"US-ASCII\"; x-default=true", "X-BeenThere": "gcc-patches@gcc.gnu.org", "X-Mailman-Version": "2.1.30", "Precedence": "list", "List-Id": "Gcc-patches mailing list <gcc-patches.gcc.gnu.org>", "List-Unsubscribe": "<https://gcc.gnu.org/mailman/options/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe>", "List-Archive": "<https://gcc.gnu.org/pipermail/gcc-patches/>", "List-Post": "<mailto:gcc-patches@gcc.gnu.org>", "List-Help": "<mailto:gcc-patches-request@gcc.gnu.org?subject=help>", "List-Subscribe": "<https://gcc.gnu.org/mailman/listinfo/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe>", "Errors-To": "gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org" }, "content": "Tested on x86_64-pc-linux-gnu, does this look OK for trunk and\neventually backports?\n\n-- >8 --\n\nThis implements the recently approved C++26 paper P3725R3, which\nwe treat as a Defect Report against C++20.\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/version.def (ranges_filter): Define for C++20.\n\t* include/bits/version.h: Regenerate.\n\t* include/std/ranges: Provide __cpp_lib_ranges_filter.\n\t(filter_view::_Iterator): Add _Const template parameter.\n\t(filter_view::_Iterator::_S_iter_concept): Return\n\tinput_iterator_tag if _Const.\n\t(filter_view::_Iterator::_Parent): New.\n\t(filter_view::_Iterator::_Base): New.\n\t(filter_view::_Iterator::_Vp_iter): Replace with ...\n\t(filter_view::_Iterator::_Base_iter): ... this.\n\t(filter_view::_Iterator::_M_current): Adjust to consider _Const.\n\t(filter_view::_Iterator::_M_parent): Likewise.\n\t(filter_view::_Iterator::value_type): Likewise.\n\t(filter_view::_Iterator::difference_type): Likewise.\n\t(filter_view::_Iterator::_Iterator): Likewise. Add\n\tconst-converting overload.\n\t(filter_view::_Iterator::base): Adjust to consider _Const.\n\t(filter_view::_Iterator::operator*): Likewise.\n\t(filter_view::_Iterator::operator->): Likewise.\n\t(filter_view::_Iterator::operator++): Likewise.\n\t(filter_view::_Iterator::operator--): Likewise.\n\t(filter_view::_Iterator::iter_move): Likewise.\n\t(filter_view::_Iterator::iter_swap): Likewise.\n\t(filter_view::_Sentinel): Add _Const template parameter.\n\t(filter_view::_Sentinel::_Parent): New.\n\t(filter_view::_Sentinel::_Base): New.\n\t(filter_view::_Sentinel::_M_end): Adjust to consider _Const.\n\t(filter_view::_Sentinel::_Sentinel): Likewise. Add\n\tconst-converting overload.\n\t(filter_view::_Sentinel::base): Adjust to consider _Const.\n\t(filter_view::_Sentinel::operator==): Likewise. Inline the\n\thelper member function __equal.\n\t(filter_view::begin): Adjust return type of non-const overload.\n\tNew const overload.\n\t(filter_view::end): Likewise.\n\t* testsuite/std/ranges/adaptors/filter.cc: Verify value of\n\t__cpp_lib_ranges_filter.\n\t(test08): New test.\n---\n libstdc++-v3/include/bits/version.def | 9 ++\n libstdc++-v3/include/bits/version.h | 10 ++\n libstdc++-v3/include/std/ranges | 104 ++++++++++++------\n .../testsuite/std/ranges/adaptors/filter.cc | 29 ++++-\n 4 files changed, 120 insertions(+), 32 deletions(-)", "diff": "diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def\nindex bb513e391d76..d23fb2903e24 100644\n--- a/libstdc++-v3/include/bits/version.def\n+++ b/libstdc++-v3/include/bits/version.def\n@@ -2180,6 +2180,15 @@ ftms = {\n };\n };\n \n+ftms = {\n+ name = ranges_filter;\n+ values = {\n+ // This is P3725R3, a C++26 change, but we treat it as a DR against C++20.\n+ v = 202603;\n+ cxxmin = 20;\n+ };\n+};\n+\n ftms = {\n name = ranges_to_input;\n values = {\ndiff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h\nindex e469944208a7..5a9d7e2bc14e 100644\n--- a/libstdc++-v3/include/bits/version.h\n+++ b/libstdc++-v3/include/bits/version.h\n@@ -2446,6 +2446,16 @@\n #endif /* !defined(__cpp_lib_text_encoding) */\n #undef __glibcxx_want_text_encoding\n \n+#if !defined(__cpp_lib_ranges_filter)\n+# if (__cplusplus >= 202002L)\n+# define __glibcxx_ranges_filter 202603L\n+# if defined(__glibcxx_want_all) || defined(__glibcxx_want_ranges_filter)\n+# define __cpp_lib_ranges_filter 202603L\n+# endif\n+# endif\n+#endif /* !defined(__cpp_lib_ranges_filter) */\n+#undef __glibcxx_want_ranges_filter\n+\n #if !defined(__cpp_lib_ranges_to_input)\n # if (__cplusplus > 202302L)\n # define __glibcxx_ranges_to_input 202502L\ndiff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges\nindex 95e0109a10cf..80c3f922c201 100644\n--- a/libstdc++-v3/include/std/ranges\n+++ b/libstdc++-v3/include/std/ranges\n@@ -65,6 +65,7 @@\n #define __glibcxx_want_ranges_chunk\n #define __glibcxx_want_ranges_chunk_by\n #define __glibcxx_want_ranges_enumerate\n+#define __glibcxx_want_ranges_filter\n #define __glibcxx_want_ranges_indices\n #define __glibcxx_want_ranges_join_with\n #define __glibcxx_want_ranges_repeat\n@@ -1738,15 +1739,19 @@ namespace views::__adaptor\n class filter_view : public view_interface<filter_view<_Vp, _Pred>>\n {\n private:\n+ template<bool _Const>\n struct _Sentinel;\n \n+ template<bool _Const>\n struct _Iterator : __detail::__filter_view_iter_cat<_Vp>\n {\n private:\n \tstatic constexpr auto\n \t_S_iter_concept()\n \t{\n-\t if constexpr (bidirectional_range<_Vp>)\n+\t if constexpr (_Const)\n+\t return input_iterator_tag{};\n+\t else if constexpr (bidirectional_range<_Vp>)\n \t return bidirectional_iterator_tag{};\n \t else if constexpr (forward_range<_Vp>)\n \t return forward_iterator_tag{};\n@@ -1755,42 +1760,52 @@ namespace views::__adaptor\n \t}\n \n \tfriend filter_view;\n+\tfriend _Iterator<!_Const>;\n \n-\tusing _Vp_iter = iterator_t<_Vp>;\n+\tusing _Parent = __maybe_const_t<_Const, filter_view>;\n+\tusing _Base = __maybe_const_t<_Const, _Vp>;\n+\tusing _Base_iter = iterator_t<_Base>;\n \n-\t_Vp_iter _M_current = _Vp_iter();\n-\tfilter_view* _M_parent = nullptr;\n+\t_Base_iter _M_current = _Base_iter();\n+\t_Parent* _M_parent = nullptr;\n \n public:\n \tusing iterator_concept = decltype(_S_iter_concept());\n \t// iterator_category defined in __filter_view_iter_cat\n-\tusing value_type = range_value_t<_Vp>;\n-\tusing difference_type = range_difference_t<_Vp>;\n+\tusing value_type = range_value_t<_Base>;\n+\tusing difference_type = range_difference_t<_Base>;\n \n-\t_Iterator() requires default_initializable<_Vp_iter> = default;\n+\t_Iterator() requires default_initializable<_Base_iter> = default;\n \n \tconstexpr\n-\t_Iterator(filter_view* __parent, _Vp_iter __current)\n+\t_Iterator(_Parent* __parent, _Base_iter __current)\n \t : _M_current(std::move(__current)),\n \t _M_parent(__parent)\n \t{ }\n \n-\tconstexpr const _Vp_iter&\n+\tconstexpr\n+\t_Iterator(_Iterator<!_Const> __i)\n+\t requires _Const && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>\n+\t : _M_current(std::move(__i._M_current)),\n+\t _M_parent(std::move(__i._M_parent))\n+\t{ }\n+\n+\tconstexpr const _Base_iter&\n \tbase() const & noexcept\n \t{ return _M_current; }\n \n-\tconstexpr _Vp_iter\n+\tconstexpr _Base_iter\n \tbase() &&\n \t{ return std::move(_M_current); }\n \n-\tconstexpr range_reference_t<_Vp>\n+\tconstexpr range_reference_t<_Base>\n \toperator*() const\n \t{ return *_M_current; }\n \n-\tconstexpr _Vp_iter\n+\tconstexpr _Base_iter\n \toperator->() const\n-\t requires __detail::__has_arrow<_Vp_iter>\n-\t && copyable<_Vp_iter>\n+\t requires __detail::__has_arrow<_Base_iter>\n+\t && copyable<_Base_iter>\n \t{ return _M_current; }\n \n \tconstexpr _Iterator&\n@@ -1807,7 +1822,7 @@ namespace views::__adaptor\n \t{ ++*this; }\n \n \tconstexpr _Iterator\n-\toperator++(int) requires forward_range<_Vp>\n+\toperator++(int) requires forward_range<_Base>\n \t{\n \t auto __tmp = *this;\n \t ++*this;\n@@ -1815,7 +1830,7 @@ namespace views::__adaptor\n \t}\n \n \tconstexpr _Iterator&\n-\toperator--() requires bidirectional_range<_Vp>\n+\toperator--() requires bidirectional_range<_Base>\n \t{\n \t do\n \t --_M_current;\n@@ -1824,7 +1839,7 @@ namespace views::__adaptor\n \t}\n \n \tconstexpr _Iterator\n-\toperator--(int) requires bidirectional_range<_Vp>\n+\toperator--(int) requires bidirectional_range<_Base>\n \t{\n \t auto __tmp = *this;\n \t --*this;\n@@ -1833,10 +1848,10 @@ namespace views::__adaptor\n \n \tfriend constexpr bool\n \toperator==(const _Iterator& __x, const _Iterator& __y)\n-\t requires equality_comparable<_Vp_iter>\n+\t requires equality_comparable<_Base_iter>\n \t{ return __x._M_current == __y._M_current; }\n \n-\tfriend constexpr range_rvalue_reference_t<_Vp>\n+\tfriend constexpr range_rvalue_reference_t<_Base>\n \titer_move(const _Iterator& __i)\n \t noexcept(noexcept(ranges::iter_move(__i._M_current)))\n \t{ return ranges::iter_move(__i._M_current); }\n@@ -1844,34 +1859,43 @@ namespace views::__adaptor\n \tfriend constexpr void\n \titer_swap(const _Iterator& __x, const _Iterator& __y)\n \t noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))\n-\t requires indirectly_swappable<_Vp_iter>\n+\t requires indirectly_swappable<_Base_iter>\n \t{ ranges::iter_swap(__x._M_current, __y._M_current); }\n };\n \n+ template<bool _Const>\n struct _Sentinel\n {\n private:\n-\tsentinel_t<_Vp> _M_end = sentinel_t<_Vp>();\n+\tusing _Parent = __maybe_const_t<_Const, filter_view>;\n+\tusing _Base = __maybe_const_t<_Const, _Vp>;\n+\tsentinel_t<_Base> _M_end = sentinel_t<_Base>();\n \n-\tconstexpr bool\n-\t__equal(const _Iterator& __i) const\n-\t{ return __i._M_current == _M_end; }\n+\tfriend _Sentinel<!_Const>;\n \n public:\n \t_Sentinel() = default;\n \n \tconstexpr explicit\n-\t_Sentinel(filter_view* __parent)\n+\t_Sentinel(_Parent* __parent)\n \t : _M_end(ranges::end(__parent->_M_base))\n \t{ }\n \n-\tconstexpr sentinel_t<_Vp>\n+\tconstexpr\n+\t_Sentinel(_Sentinel<!_Const> __i)\n+\t requires _Const && convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>\n+\t : _M_end(std::move(__i._M_end))\n+\t{ }\n+\n+\tconstexpr sentinel_t<_Base>\n \tbase() const\n \t{ return _M_end; }\n \n+\ttemplate<bool _Const2>\n+\t requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const_t<_Const2, _Vp>>>\n \tfriend constexpr bool\n-\toperator==(const _Iterator& __x, const _Sentinel& __y)\n-\t{ return __y.__equal(__x); }\n+\toperator==(const _Iterator<_Const2>& __x, const _Sentinel& __y)\n+\t{ return __x._M_current == __y._M_end; }\n };\n \n _Vp _M_base = _Vp();\n@@ -1900,7 +1924,7 @@ namespace views::__adaptor\n pred() const\n { return *_M_pred; }\n \n- constexpr _Iterator\n+ constexpr _Iterator<false>\n begin()\n {\n \tif (_M_cached_begin._M_has_value())\n@@ -1914,14 +1938,32 @@ namespace views::__adaptor\n \treturn {this, std::move(__it)};\n }\n \n+ constexpr _Iterator<true>\n+ begin() const\n+\trequires (input_range<const _Vp> && !forward_range<const _Vp>\n+\t\t && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>)\n+ {\n+\t__glibcxx_assert(_M_pred.has_value());\n+\tauto __it = ranges::find_if(ranges::begin(_M_base),\n+\t\t\t\t ranges::end(_M_base),\n+\t\t\t\t std::ref(*_M_pred));\n+\treturn {this, std::move(__it)};\n+ }\n+\n constexpr auto\n end()\n {\n \tif constexpr (common_range<_Vp>)\n-\t return _Iterator{this, ranges::end(_M_base)};\n+\t return _Iterator<false>{this, ranges::end(_M_base)};\n \telse\n-\t return _Sentinel{this};\n+\t return _Sentinel<false>{this};\n }\n+\n+ constexpr auto\n+ end() const\n+\trequires (input_range<const _Vp> && !forward_range<const _Vp>\n+\t\t && indirect_unary_predicate<const _Pred, iterator_t<const _Vp>>)\n+ { return _Sentinel<true>{this}; }\n };\n \n template<typename _Range, typename _Pred>\ndiff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc\nindex 7595e43d4e60..4c67651843fb 100644\n--- a/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc\n+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc\n@@ -17,12 +17,18 @@\n \n // { dg-do run { target c++20 } }\n \n-#include <algorithm>\n #include <ranges>\n+\n+#if __cpp_lib_ranges_filter != 202603L // C++ >= 20\n+# error \"Feature-test macro for ranges_filter has wrong value in <ranges>.\"\n+#endif\n+\n+#include <algorithm>\n #include <testsuite_hooks.h>\n #include <testsuite_iterators.h>\n \n using __gnu_test::test_range;\n+using __gnu_test::input_iterator_wrapper;\n using __gnu_test::bidirectional_iterator_wrapper;\n using __gnu_test::forward_iterator_wrapper;\n using __gnu_test::random_access_iterator_wrapper;\n@@ -166,6 +172,26 @@ test07()\n \n static_assert( test07() );\n \n+void\n+test08()\n+{\n+ // P3725R3 Filter View Extensions for Safer Use\n+ int x[] = {1, 2, 3, 4, 5};\n+ __gnu_test::test_range<int, input_iterator_wrapper> rx(x);\n+ auto v = rx | views::filter([](int x) { return (x % 2) == 0; });\n+ using R = decltype(v);\n+ static_assert( ranges::input_range<R> && !ranges::forward_range<R> );\n+ static_assert( ranges::input_range<const R> && !ranges::forward_range<const R> );\n+ const auto& cv = v;\n+ auto it = v.begin();\n+ decltype(cv.begin()) cit = it;\n+ auto sent = v.end();\n+ decltype(cv.end()) csent = sent;\n+ VERIFY( cit == cit && it == cit && cit == it );\n+ VERIFY( cit != csent && it != csent && cit != sent );\n+ VERIFY( ranges::equal(cv, (int[]){2, 4}) );\n+}\n+\n int\n main()\n {\n@@ -177,4 +203,5 @@ main()\n test05<random_access_iterator_wrapper>();\n test06();\n test07();\n+ test08();\n }\n", "prefixes": [ "1/2" ] }