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From: "pdimov at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/104867] New: Base class matching ignores type of `auto` template parameter Date: Thu, 10 Mar 2022 16:56:06 +0000 [thread overview] Message-ID: <bug-104867-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104867 Bug ID: 104867 Summary: Base class matching ignores type of `auto` template parameter Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: pdimov at gmail dot com Target Milestone: --- The following program ``` enum class Foo { A1 }; enum class Bar { B1 }; template <auto EnumVal> struct enum_ { }; template<class...> struct list {}; struct enum_type_map: list<enum_<Foo::A1>, int>, list<enum_<Bar::B1>, double> {}; template<class V> V f( list<enum_<Bar::B1>, V> const& ) { return {}; } int main() { f( enum_type_map() ); } ``` yields ``` <source>: In function 'int main()': <source>:26:6: error: no matching function for call to 'f(enum_type_map)' 26 | f( enum_type_map() ); | ~^~~~~~~~~~~~~~~~~~~ <source>:19:21: note: candidate: 'template<class V> V f(const list<enum_<Bar::B1>, V>&)' 19 | template<class V> V f( list<enum_<Bar::B1>, V> const& ) | ^ <source>:19:21: note: template argument deduction/substitution failed: <source>:26:6: note: 'const list<enum_<Bar::B1>, V>' is an ambiguous base class of 'enum_type_map' 26 | f( enum_type_map() ); | ~^~~~~~~~~~~~~~~~~~~ ``` which is caused by `A1` and `B1` having the same value 0, even though their types differ. (https://godbolt.org/z/3854zrY7x) Clang successfully compiles the code (https://godbolt.org/z/eKEdf1zdo). This is a distilled version of a bug report against `mp_map_find` from Mp11: https://github.com/boostorg/mp11/issues/72
next reply other threads:[~2022-03-10 16:56 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-10 16:56 pdimov at gmail dot com [this message] 2022-03-11 14:40 ` [Bug c++/104867] " ppalka at gcc dot gnu.org 2023-12-13 20:57 ` cvs-commit at gcc dot gnu.org 2023-12-16 17:15 ` ppalka at gcc dot gnu.org
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