{"id":2224566,"url":"http://patchwork.ozlabs.org/api/patches/2224566/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260417154009.1140472-1-ppalka@redhat.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/projects/17/?format=json","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":"<20260417154009.1140472-1-ppalka@redhat.com>","list_archive_url":null,"date":"2026-04-17T15:40:09","name":"libstdc++: Fix constraint recursion in std:indirect's operator== [PR124890]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"758610638ce6e21a4ee6eec93cb010e0cc4bd5f4","submitter":{"id":78319,"url":"http://patchwork.ozlabs.org/api/people/78319/?format=json","name":"Patrick Palka","email":"ppalka@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260417154009.1140472-1-ppalka@redhat.com/mbox/","series":[{"id":500367,"url":"http://patchwork.ozlabs.org/api/series/500367/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500367","date":"2026-04-17T15:40:09","name":"libstdc++: Fix constraint recursion in std:indirect's operator== [PR124890]","version":1,"mbox":"http://patchwork.ozlabs.org/series/500367/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224566/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224566/checks/","tags":{},"related":[],"headers":{"Return-Path":"","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=KcpylH25;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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charset=UTF-8","Content-Transfer-Encoding":"8bit","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","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?\n\nWe can also just implement the Mandates as a static_assert as pointed\nout by Lénárd. Otherwise, I prefer this approach rather than the\nforwarding reference approach since it's cleaner and we use this approach\nin other parts of the library with no complaints so far.\n\n-- >8 --\n\nLike in r16-559 for std::expected, std::indirect's operator== is also\nprone to constraint recursion due to CWG 2369. This patch works around\nthe recursion in a similar manner.\n\n\tPR libstdc++/124890\n\tPR libstdc++/119714\n\tPR libstdc++/112490\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/indirect.h (indirect::operator==): Replace\n\tnon-dependent std::indirect function parameter with a\n\tdependent one of type indirect<_Tp2> where _Tp2 matches _Tp.\n\t* testsuite/std/memory/indirect/124890.cc: New test.\n---\n libstdc++-v3/include/bits/indirect.h | 4 ++--\n libstdc++-v3/testsuite/std/memory/indirect/124890.cc | 9 +++++++++\n 2 files changed, 11 insertions(+), 2 deletions(-)\n create mode 100644 libstdc++-v3/testsuite/std/memory/indirect/124890.cc","diff":"diff --git a/libstdc++-v3/include/bits/indirect.h b/libstdc++-v3/include/bits/indirect.h\nindex 2df46cc39a21..e1f7d1968b56 100644\n--- a/libstdc++-v3/include/bits/indirect.h\n+++ b/libstdc++-v3/include/bits/indirect.h\n@@ -344,11 +344,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t return __lhs.__get() == __rhs.__get();\n \t}\n \n- template\n+ template _Tp2, typename _Up>\n \trequires (!__is_indirect<_Up>) // See PR c++/99599\n \t && requires (const _Tp& __t, const _Up& __u) { __t == __u; }\n \tfriend constexpr bool\n-\toperator==(const indirect& __lhs, const _Up& __rhs)\n+\toperator==(const indirect<_Tp2>& __lhs, const _Up& __rhs)\n \tnoexcept(noexcept(*__lhs == __rhs))\n \t{\n \t if (!__lhs._M_objp)\ndiff --git a/libstdc++-v3/testsuite/std/memory/indirect/124890.cc b/libstdc++-v3/testsuite/std/memory/indirect/124890.cc\nnew file mode 100644\nindex 000000000000..ce44256f2244\n--- /dev/null\n+++ b/libstdc++-v3/testsuite/std/memory/indirect/124890.cc\n@@ -0,0 +1,9 @@\n+// { dg-do compile { target c++26 } }\n+\n+// PR libstdc++/124890 - Circular constraint in std::indirect::operator==\n+\n+#include \n+#include \n+\n+using I = std::vector>::iterator;\n+static_assert(std::totally_ordered);\n","prefixes":[]}