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From: "fchelnokov at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/110158] New: Cannot use union with std::string inside in constant expression Date: Wed, 07 Jun 2023 15:22:52 +0000 [thread overview] Message-ID: <bug-110158-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110158 Bug ID: 110158 Summary: Cannot use union with std::string inside in constant expression Product: gcc Version: 13.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: fchelnokov at gmail dot com Target Milestone: --- This program constexpr bool f() { union U{ std::string s; constexpr ~U(){ s.~basic_string(); } } u{}; return true; } static_assert( f() ); is accepted in MSVC and Clang with libc++. But in GCC it produces the error: error: non-constant condition for static assertion in 'constexpr' expansion of 'f()' in 'constexpr' expansion of '(& u)->f()::U::~U()' in 'constexpr' expansion of '((f()::U*)this)->f()::U::s.std::__cxx11::basic_string<char>::~basic_string()' /opt/compiler-explorer/gcc-13.1.0/include/c++/13.1.0/bits/basic_string.h:803:19: in 'constexpr' expansion of '((std::__cxx11::basic_string<char>*)this)->std::__cxx11::basic_string<char>::_M_dispose()' error: accessing 'std::__cxx11::basic_string<char>::<unnamed union>::_M_allocated_capacity' member instead of initialized 'std::__cxx11::basic_string<char>::<unnamed union>::_M_local_buf' member in constant expression Online demo: https://gcc.godbolt.org/z/bbf4Yo3v9
next reply other threads:[~2023-06-07 15:22 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-07 15:22 fchelnokov at gmail dot com [this message] 2023-06-07 19:40 ` [Bug c++/110158] " pinskia at gcc dot gnu.org 2023-08-03 17:11 ` ppalka at gcc dot gnu.org 2023-08-04 15:55 ` pinskia at gcc dot gnu.org 2023-08-04 16:16 ` danakj at orodu dot net 2023-09-06 18:11 ` danakj at orodu dot net 2023-09-06 18:18 ` danakj at orodu dot net 2023-09-29 11:08 ` redi at gcc dot gnu.org 2023-11-22 0:45 ` ppalka at gcc dot gnu.org 2023-11-22 11:54 ` redi at gcc dot gnu.org
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