{"id":2226340,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2226340/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260422113908.795344-1-tkaminsk@redhat.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.2/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":"<20260422113908.795344-1-tkaminsk@redhat.com>","list_archive_url":null,"date":"2026-04-22T11:38:40","name":"libstdc++: Mandate power of two alignment for std::is_sufficiently_aligned.","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"4fd684a8c96a9848af28dca90a026adb59306687","submitter":{"id":90409,"url":"http://patchwork.ozlabs.org/api/1.2/people/90409/?format=json","name":"Tomasz Kamiński","email":"tkaminsk@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260422113908.795344-1-tkaminsk@redhat.com/mbox/","series":[{"id":500995,"url":"http://patchwork.ozlabs.org/api/1.2/series/500995/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500995","date":"2026-04-22T11:38:40","name":"libstdc++: Mandate power of two alignment for std::is_sufficiently_aligned.","version":1,"mbox":"http://patchwork.ozlabs.org/series/500995/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226340/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226340/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=QQOWTpzh;\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 ","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":"This implements LWG4290. Missing Mandates clauses on is_sufficiently_aligned.\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/align.h (is_sufficiently_aligned): Mandate\n\tthat _Align is power of two.\n\t* testsuite/std/time/format/simple.cc: New test.\n---\nNo adding resolve issue comment, as this is C++26 feature.\n\nTested on x86_64-linux. OK for trunk?\n\n libstdc++-v3/include/bits/align.h | 5 ++++-\n libstdc++-v3/testsuite/std/time/format/simple.cc | 11 +++++++++++\n 2 files changed, 15 insertions(+), 1 deletion(-)\n create mode 100644 libstdc++-v3/testsuite/std/time/format/simple.cc","diff":"diff --git a/libstdc++-v3/include/bits/align.h b/libstdc++-v3/include/bits/align.h\nindex 1a14e282216..3c8355d0e07 100644\n--- a/libstdc++-v3/include/bits/align.h\n+++ b/libstdc++-v3/include/bits/align.h\n@@ -116,7 +116,10 @@ align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept\n [[nodiscard,__gnu__::__always_inline__]]\n inline bool\n is_sufficiently_aligned(_Tp* __ptr)\n- { return reinterpret_cast<__UINTPTR_TYPE__>(__ptr) % _Align == 0; }\n+ { \n+ static_assert(std::has_single_bit(_Align));\n+ return reinterpret_cast<__UINTPTR_TYPE__>(__ptr) % _Align == 0;\n+ }\n #endif // __glibcxx_is_sufficiently_aligned\n \n _GLIBCXX_END_NAMESPACE_VERSION\ndiff --git a/libstdc++-v3/testsuite/std/time/format/simple.cc b/libstdc++-v3/testsuite/std/time/format/simple.cc\nnew file mode 100644\nindex 00000000000..db25a460bf7\n--- /dev/null\n+++ b/libstdc++-v3/testsuite/std/time/format/simple.cc\n@@ -0,0 +1,11 @@\n+// { dg-do run { target c++20 } }\n+// { dg-timeout-factor 2 }\n+\n+#include \n+#include \n+#include \n+\n+int main()\n+{\n+ auto s = std::format(\"{:%F %T}\", std::chrono::system_clock::now());\n+}\n","prefixes":[]}