{"id":2221790,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2221790/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/orjyuf10ra.fsf@lxoliva.fsfla.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/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},"msgid":"","date":"2026-04-10T12:02:49","name":"libstdc++: check value in std::{con,dis}junction","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"6dbc1e79140c69fe264d23f3dffc87cd4c170ebc","submitter":{"id":74937,"url":"http://patchwork.ozlabs.org/api/1.1/people/74937/?format=json","name":"Alexandre Oliva","email":"oliva@adacore.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/orjyuf10ra.fsf@lxoliva.fsfla.org/mbox/","series":[{"id":499447,"url":"http://patchwork.ozlabs.org/api/1.1/series/499447/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=499447","date":"2026-04-10T12:02:49","name":"libstdc++: check value in std::{con,dis}junction","version":1,"mbox":"http://patchwork.ozlabs.org/series/499447/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2221790/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2221790/checks/","tags":{},"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 (2048-bit key;\n secure) header.d=adacore.com header.i=@adacore.com header.a=rsa-sha256\n header.s=google header.b=Q+qGsaPj;\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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Ok to install? Not a regression, so\nfor stage1 maybe?\n\n\nfor libstdc++-v3/ChangeLog\n\n\t* include/std/type_traits (disjunction, conjunction): Check\n\tthat value converts to bool.\n---\n libstdc++-v3/include/std/type_traits | 15 ++++++++++-\n .../logical_traits/requirements/junction_neg.cc | 27 ++++++++++++++++++++\n 2 files changed, 40 insertions(+), 2 deletions(-)\n create mode 100644 libstdc++-v3/testsuite/20_util/logical_traits/requirements/junction_neg.cc","diff":"diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits\nindex 59be925e10a6c..238450518c083 100644\n--- a/libstdc++-v3/include/std/type_traits\n+++ b/libstdc++-v3/include/std/type_traits\n@@ -241,10 +241,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n } // namespace __detail\n /// @endcond\n \n+ template\n+ struct is_convertible;\n+\n template\n struct conjunction\n : __detail::__conjunction_impl::type\n- { };\n+ {\n+ static_assert(is_convertible\n+\t\t\t\t\t ::type::value), bool>::value,\n+\t\t \"result type's value is not convertible to bool\");\n+ };\n \n template<>\n struct conjunction<>\n@@ -254,7 +261,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n template\n struct disjunction\n : __detail::__disjunction_impl::type\n- { };\n+ {\n+ static_assert(is_convertible\n+\t\t\t\t\t ::type::value), bool>::value,\n+\t\t \"result type's value is not convertible to bool\");\n+ };\n \n template<>\n struct disjunction<>\ndiff --git a/libstdc++-v3/testsuite/20_util/logical_traits/requirements/junction_neg.cc b/libstdc++-v3/testsuite/20_util/logical_traits/requirements/junction_neg.cc\nnew file mode 100644\nindex 0000000000000..eb0f246367f11\n--- /dev/null\n+++ b/libstdc++-v3/testsuite/20_util/logical_traits/requirements/junction_neg.cc\n@@ -0,0 +1,27 @@\n+// { dg-do compile { target c++17 } }\n+\n+#include \n+\n+class S {}; // not convertible to bool\n+\n+struct T {\n+ static constexpr S value{};\n+};\n+\n+// 4 Every template type argument for which Bi::value is instantiated shall be\n+// usable as a base class and shall have a member value which is convertible to\n+// bool, is not hidden, and is unambiguously available in the type.\n+\n+std::conjunction cT; // { dg-error \"here\" }\n+std::conjunction cTt; // { dg-error \"here\" }\n+std::conjunction cTf; // { dg-error \"here\" }\n+std::conjunction ctTtf; // { dg-error \"here\" }\n+std::conjunction cfTtf;\n+\n+std::disjunction dT; // { dg-error \"here\" }\n+std::disjunction dTt; // { dg-error \"here\" }\n+std::disjunction dTf; // { dg-error \"here\" }\n+std::disjunction dfTtf; // { dg-error \"here\" }\n+std::disjunction dtTtf;\n+\n+// { dg-prune-output \"not convertible to bool|evaluates to false\" }\n","prefixes":[]}