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GET /api/1.1/patches/2229617/?format=api
{ "id": 2229617, "url": "http://patchwork.ozlabs.org/api/1.1/patches/2229617/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/20260428144100.672367-1-tkaminsk@redhat.com/", "project": { "id": 17, "url": "http://patchwork.ozlabs.org/api/1.1/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 }, "msgid": "<20260428144100.672367-1-tkaminsk@redhat.com>", "date": "2026-04-28T14:40:33", "name": "libstdc++: Make pointer_traits::pointer_to constexpr for main template.", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "c260cbfb92b18a84da5affb1f7945a5a646ce03b", "submitter": { "id": 90409, "url": "http://patchwork.ozlabs.org/api/1.1/people/90409/?format=api", "name": "Tomasz Kaminski", "email": "tkaminsk@redhat.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/20260428144100.672367-1-tkaminsk@redhat.com/mbox/", "series": [ { "id": 501870, "url": "http://patchwork.ozlabs.org/api/1.1/series/501870/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=501870", "date": "2026-04-28T14:40:33", "name": "libstdc++: Make pointer_traits::pointer_to constexpr for main template.", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/501870/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2229617/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2229617/checks/", "tags": {}, "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=ATVgxLOw;\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": "This resolves LWG3454, \"pointer_traits::pointer_to should be constexpr\",\naccepted in Kona 2025.\n\nThe change is applied since C++20, i.e. standard in which pointer_to\nwas made constexpr for T* specialization.\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/ptr_traits.h (__ptr_traits_ptr_to::pointer_to):\n\tDefine as constexpr since C++20.\n\t* testsuite/20_util/pointer_traits/pointer_to_constexpr.cc:\n\tNew test for custom pointer-like type.\n---\nTested on x86_64-linux locally. OK for trunk?\n\n libstdc++-v3/include/bits/ptr_traits.h | 4 +++-\n .../20_util/pointer_traits/pointer_to_constexpr.cc | 14 ++++++++++++++\n 2 files changed, 17 insertions(+), 1 deletion(-)", "diff": "diff --git a/libstdc++-v3/include/bits/ptr_traits.h b/libstdc++-v3/include/bits/ptr_traits.h\nindex df83e0cad1d..c1dc76509ce 100644\n--- a/libstdc++-v3/include/bits/ptr_traits.h\n+++ b/libstdc++-v3/include/bits/ptr_traits.h\n@@ -97,13 +97,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n using pointer = _Ptr;\n using element_type = _Elt;\n \n+ // _GLIBCXX_RESOLVE_LIB_DEFECTS\n+ // 3454. pointer_traits::pointer_to should be constexpr\n /**\n * @brief Obtain a pointer to an object\n * @param __r A reference to an object of type `element_type`\n * @return `pointer::pointer_to(__r)`\n * @pre `pointer::pointer_to(__r)` is a valid expression.\n */\n- static pointer\n+ static _GLIBCXX20_CONSTEXPR pointer\n pointer_to(element_type& __r)\n #if __cpp_lib_concepts\n requires requires {\ndiff --git a/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc b/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc\nindex cfd35f899c4..929d004fd4a 100644\n--- a/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc\n+++ b/libstdc++-v3/testsuite/20_util/pointer_traits/pointer_to_constexpr.cc\n@@ -24,3 +24,17 @@ static_assert( std::pointer_traits<int*>::pointer_to(i) == &i );\n \n struct X { } x;\n static_assert( std::pointer_traits<X*>::pointer_to(x) == &x );\n+\n+template<typename T>\n+struct Ptr\n+{\n+ T* value;\n+\n+ constexpr static Ptr\n+ pointer_to(T& t) { return Ptr{&t}; }\n+\n+ friend bool operator==(Ptr, Ptr) = default;\n+};\n+\n+static_assert( std::pointer_traits<Ptr<int>>::pointer_to(i) == Ptr<int>{&i} );\n+static_assert( std::pointer_traits<Ptr<X>>::pointer_to(x) == Ptr<X>{&x} );\n", "prefixes": [] }