Patch Detail
get:
Show a patch.
patch:
Update a patch.
put:
Update a patch.
GET /api/patches/2226712/?format=api
{ "id": 2226712, "url": "http://patchwork.ozlabs.org/api/patches/2226712/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhuoj2uk6c.gcc.gcc-TEST.ppalka.57.1.6@forge-stage.sourceware.org/", "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": "<bmm.hhuoj2uk6c.gcc.gcc-TEST.ppalka.57.1.6@forge-stage.sourceware.org>", "list_archive_url": null, "date": "2026-04-22T18:27:30", "name": "[v1,6/8] libstdc++: Directly implement ranges::nth_element [PR100795]", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "0fce56554f3501293c747b6fb2084a2108da2377", "submitter": { "id": 93215, "url": "http://patchwork.ozlabs.org/api/people/93215/?format=api", "name": "ppalka via Sourceware Forge", "email": "forge-bot+ppalka@forge-stage.sourceware.org" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhuoj2uk6c.gcc.gcc-TEST.ppalka.57.1.6@forge-stage.sourceware.org/mbox/", "series": [ { "id": 501079, "url": "http://patchwork.ozlabs.org/api/series/501079/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=501079", "date": "2026-04-22T18:27:24", "name": "libstdc++: C++20 iterator awareness fixes for various Ranges algorithms [PR100795]", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/501079/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2226712/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2226712/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 spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=38.145.34.32; helo=vm01.sourceware.org;\n envelope-from=gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org;\n receiver=patchwork.ozlabs.org)", "sourceware.org; dmarc=none (p=none dis=none)\n header.from=forge-stage.sourceware.org", "sourceware.org;\n spf=pass smtp.mailfrom=forge-stage.sourceware.org", "server2.sourceware.org;\n arc=none smtp.remote-ip=38.145.34.39" ], "Received": [ "from vm01.sourceware.org (vm01.sourceware.org [38.145.34.32])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g17W56SgVz1yD5\n\tfor <incoming@patchwork.ozlabs.org>; Thu, 23 Apr 2026 04:47:13 +1000 (AEST)", "from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id E0F4A4318B55\n\tfor <incoming@patchwork.ozlabs.org>; Wed, 22 Apr 2026 18:47:11 +0000 (GMT)", "from forge-stage.sourceware.org (vm08.sourceware.org [38.145.34.39])\n by sourceware.org (Postfix) with ESMTPS id B670448FEC25\n for <gcc-patches@gcc.gnu.org>; Wed, 22 Apr 2026 18:28:36 +0000 (GMT)", "from forge-stage.sourceware.org (localhost [IPv6:::1])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange x25519 server-signature ECDSA (prime256v1) server-digest SHA256)\n (No client certificate requested)\n by forge-stage.sourceware.org (Postfix) with ESMTPS id 3BC78434A1\n for <gcc-patches@gcc.gnu.org>; Wed, 22 Apr 2026 18:28:35 +0000 (UTC)" ], "DKIM-Filter": [ "OpenDKIM Filter v2.11.0 sourceware.org E0F4A4318B55", "OpenDKIM Filter v2.11.0 sourceware.org B670448FEC25" ], "DMARC-Filter": "OpenDMARC Filter v1.4.2 sourceware.org B670448FEC25", "ARC-Filter": "OpenARC Filter v1.0.0 sourceware.org B670448FEC25", "ARC-Seal": "i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1776882516; cv=none;\n b=Smyz4ZFbZaRlExuuU40mGLnffIj3oQGKLdy2HA2SOOwoy219P96/Cf1MfpNlfxYDn0AUAkORA2w6sqw+/OZSR4iNlgEJVM7W7Pwak4lEJS43GgzeNrGV1IR2IOn9OpZNdqL7XkNXLTjBHZ5q8whdKrUo87ArrZhuK+dfbpAPsAU=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776882516; c=relaxed/simple;\n bh=A+pko5QOjmtMx1UZzJXI/zdIhJpzZLDwsEhiffb8vec=;\n h=From:Date:Subject:To:Message-ID;\n b=bCb+DZnztKa64n0VZ9uWYWcDeiK4kh109RbfVxtenrija2LjdlmcVfUpuItTLYWrR57cobw9Ys/gPSL35L94RdwMMPCfypujdlWyOPvD+v/gn9k83T+wo3uuc/WxF6bUahtKjCjg0iIRF2XU5LxULzVSqCc0Lq2B/IRIIkZ3W5c=", "ARC-Authentication-Results": "i=1; server2.sourceware.org", "From": "ppalka via Sourceware Forge\n <forge-bot+ppalka@forge-stage.sourceware.org>", "Date": "Wed, 22 Apr 2026 18:27:30 +0000", "Subject": "[PATCH v1 6/8] libstdc++: Directly implement ranges::nth_element\n [PR100795]", "To": "gcc-patches mailing list <gcc-patches@gcc.gnu.org>", "Message-ID": "\n <bmm.hhuoj2uk6c.gcc.gcc-TEST.ppalka.57.1.6@forge-stage.sourceware.org>", "X-Mailer": "batrachomyomachia", "X-Pull-Request-Organization": "gcc", "X-Pull-Request-Repository": "gcc-TEST", "X-Pull-Request": "https://forge.sourceware.org/gcc/gcc-TEST/pulls/57", "References": "\n <bmm.hhuoj2uk6c.gcc.gcc-TEST.ppalka.57.1.0@forge-stage.sourceware.org>", "In-Reply-To": "\n <bmm.hhuoj2uk6c.gcc.gcc-TEST.ppalka.57.1.0@forge-stage.sourceware.org>", "X-Patch-URL": "\n https://forge.sourceware.org/gcc/gcc-TEST/commit/bcc6be79abb3bcb9e14086f033d7c7025245dba0", "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>", "Reply-To": "gcc-patches mailing list <gcc-patches@gcc.gnu.org>,\n ppalka@gcc.gnu.org", "Errors-To": "gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org" }, "content": "From: Patrick Palka <ppalka@redhat.com>\n\n\tPR libstdc++/100795\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/ranges_algo.h (__detail::__introselect): New,\n\tbased on the stl_algo.h implementation.\n\t(nth_element_fn::operator()): Reimplement in terms of the above.\n\t* testsuite/25_algorithms/nth_element/constrained.cc:\n---\n libstdc++-v3/include/bits/ranges_algo.h | 47 +++++++++++++++++--\n .../25_algorithms/nth_element/constrained.cc | 31 ++++++++++++\n 2 files changed, 73 insertions(+), 5 deletions(-)", "diff": "diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h\nindex a9924cd9c49e..b12da2af1263 100644\n--- a/libstdc++-v3/include/bits/ranges_algo.h\n+++ b/libstdc++-v3/include/bits/ranges_algo.h\n@@ -2805,6 +2805,33 @@ namespace ranges\n \n inline constexpr __is_sorted_fn is_sorted{};\n \n+ namespace __detail\n+ {\n+ template<typename _Iter, typename _Comp>\n+ constexpr void\n+ __introselect(_Iter __first, _Iter __nth, _Iter __last,\n+\t\t iter_difference_t<_Iter> __depth_limit, _Comp __comp)\n+ {\n+\twhile (__last - __first > 3)\n+\t {\n+\t if (__depth_limit == 0)\n+\t {\n+\t\t__detail::__heap_select(__first, __nth + 1, __last, __comp);\n+\t\t// Place the nth largest element in its final position.\n+\t\tranges::iter_swap(__first, __nth);\n+\t\treturn;\n+\t }\n+\t --__depth_limit;\n+\t _Iter __cut = __detail::__unguarded_partition_pivot(__first, __last, __comp);\n+\t if (__cut <= __nth)\n+\t __first = __cut;\n+\t else\n+\t __last = __cut;\n+\t }\n+\t__detail::__insertion_sort(__first, __last, __comp);\n+ }\n+ } // namespace __detail\n+\n struct __nth_element_fn\n {\n template<random_access_iterator _Iter, sentinel_for<_Iter> _Sent,\n@@ -2814,11 +2841,21 @@ namespace ranges\n operator()(_Iter __first, _Iter __nth, _Sent __last,\n \t\t _Comp __comp = {}, _Proj __proj = {}) const\n {\n-\tauto __lasti = ranges::next(__first, __last);\n-\t_GLIBCXX_STD_A::nth_element(std::move(__first), std::move(__nth),\n-\t\t\t\t __lasti,\n-\t\t\t\t __detail::__make_comp_proj(__comp, __proj));\n-\treturn __lasti;\n+\tif constexpr (!same_as<_Iter, _Sent>)\n+\t return (*this)(__first, __nth, ranges::next(__first, __last),\n+\t\t\t std::move(__comp), std::move(__proj));\n+\telse\n+\t {\n+\t if (__first == __last || __nth == __last)\n+\t return __last;\n+\n+\t auto __comp_proj = __detail::__make_comp_proj(__comp, __proj);\n+\t auto __n = __detail::__to_unsigned_like(__last - __first);\n+\t __detail::__introselect(__first, __nth, __last,\n+\t\t\t\t std::__bit_width(__n) * 2,\n+\t\t\t\t __comp_proj);\n+\t return __last;\n+\t }\n }\n \n template<random_access_range _Range,\ndiff --git a/libstdc++-v3/testsuite/25_algorithms/nth_element/constrained.cc b/libstdc++-v3/testsuite/25_algorithms/nth_element/constrained.cc\nindex 3189b225610e..8cb1625dd4d5 100644\n--- a/libstdc++-v3/testsuite/25_algorithms/nth_element/constrained.cc\n+++ b/libstdc++-v3/testsuite/25_algorithms/nth_element/constrained.cc\n@@ -20,6 +20,7 @@\n \n #include <algorithm>\n #include <random>\n+#include <ranges>\n #include <testsuite_hooks.h>\n #include <testsuite_iterators.h>\n \n@@ -67,9 +68,39 @@ test02()\n return x[3] == 4;\n }\n \n+constexpr bool\n+test03()\n+{\n+ // PR libstdc++/100795 - ranges::sort should not use std::sort directly\n+#if __SIZEOF_INT128__\n+ auto v = std::views::iota(__int128(0), __int128(20));\n+#else\n+ auto v = std::views::iota(0ll, 20ll);\n+#endif\n+\n+ int storage[20] = {2,5,4,3,1,6,7,9,10,8,11,14,12,13,15,16,18,0,19,17};\n+ auto w = v | std::views::transform([&](auto i) -> int& { return storage[i]; });\n+ using type = decltype(w);\n+ using cat = std::iterator_traits<std::ranges::iterator_t<type>>::iterator_category;\n+ static_assert( std::same_as<cat, std::output_iterator_tag> );\n+ static_assert( std::ranges::random_access_range<type> );\n+\n+ ranges::nth_element(w, w.begin() + 10);\n+ VERIFY( w[10] == 10 );\n+\n+ ranges::nth_element(w, w.begin() + 5, std::ranges::greater{});\n+ VERIFY( w[5] == 19 - 5 );\n+\n+ ranges::nth_element(w, w.begin() + 15, std::ranges::greater{}, std::negate{});\n+ VERIFY( w[15] == 15 );\n+\n+ return true;\n+}\n+\n int\n main()\n {\n test01();\n static_assert(test02());\n+ static_assert(test03());\n }\n", "prefixes": [ "v1", "6/8" ] }