public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "dani at danielbertalan dot dev" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/109683] New: [13/14 Regression] False cyclic dependency error reported for constraint Date: Mon, 01 May 2023 09:43:36 +0000 [thread overview] Message-ID: <bug-109683-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109683 Bug ID: 109683 Summary: [13/14 Regression] False cyclic dependency error reported for constraint Product: gcc Version: 13.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: dani at danielbertalan dot dev Target Milestone: --- The following code (reduced from a custom std::variant-like type) compiles with GCC 12.2 and Clang, but is rejected by GCC 13+: ``` template <typename T, typename> struct VariantConstructors { VariantConstructors(T&& t) requires(requires { T(t); }); }; template <typename... Ts> struct InheritFromEntries : Ts... {}; template <typename... Ps> struct InheritFromPack: InheritFromEntries<Ps>... { using InheritFromEntries<Ps>::InheritFromEntries...; }; template <typename... Ts> struct Variant : InheritFromPack<VariantConstructors<Ts, Variant<Ts...>>...> {}; template <typename T> class Outer; struct Inner { Inner(Outer<int>); }; template<typename T> class Outer { Variant<T, Inner> value_; }; struct Empty {}; void fn(Outer<Empty> x) {} ``` The following compiler error is produced (arguments: -std=c++20): <source>: In instantiation of 'VariantConstructors<T, <template-parameter-1-2> >::VariantConstructors(T&&) requires requires{T(VariantConstructors<T, <template-parameter-1-2> >::__ct ::t);} [with T = Inner; <template-parameter-1-2> = Variant<int, Inner>]': <source>:12:51: required from 'struct InheritFromPack<VariantConstructors<int, Variant<int, Inner> >, VariantConstructors<Inner, Variant<int, Inner> > >' <source>:16:8: required from 'struct Variant<int, Inner>' <source>:25:23: required from 'class Outer<int>' <source>:4:25: required from 'VariantConstructors<T, <template-parameter-1-2> >::VariantConstructors(T&&) requires requires{T(VariantConstructors<T, <template-parameter-1-2> >::__ct ::t);} [with T = Inner; <template-parameter-1-2> = Variant<Empty, Inner>]' <source>:12:51: required from 'struct InheritFromPack<VariantConstructors<Empty, Variant<Empty, Inner> >, VariantConstructors<Inner, Variant<Empty, Inner> > >' <source>:16:8: required from 'struct Variant<Empty, Inner>' <source>:25:23: required from 'class Outer<Empty>' <source>:29:23: required from here <source>:3:3: required by the constraints of 'template<class T, class> VariantConstructors<T, <template-parameter-1-2> >::VariantConstructors(T&&) requires requires{T(VariantConstructors<T, <template-parameter-1-2> >::__ct ::t);}' <source>:4:14: in requirements [with T = Inner] <source>:4:14: error: satisfaction of atomic constraint 'requires{T(VariantConstructors<T, <template-parameter-1-2> >::__ct ::t);} [with T = T]' depends on itself 4 | requires(requires { T(t); }); | ~^~~~~~~~~~~~~~~~~~~ Reproducer on Compiler Explorer: https://godbolt.org/z/TbcoanG5T The non-reduced preprocessed source can be found here: https://godbolt.org/z/69dMMoWKh
next reply other threads:[~2023-05-01 9:43 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-05-01 9:43 dani at danielbertalan dot dev [this message] 2023-05-01 11:23 ` [Bug c++/109683] " ali.mpfard at gmail dot com 2023-05-01 11:58 ` ppalka at gcc dot gnu.org 2023-05-02 6:25 ` rguenth at gcc dot gnu.org 2023-07-27 9:26 ` rguenth at gcc dot gnu.org 2024-05-21 9:14 ` [Bug c++/109683] [13/14/15 " jakub at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-109683-4@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).