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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/107049] error: ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator __sv_type() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; __sv_type = std::basic_string_view<char>]’ is inaccessible within this context Date: Tue, 27 Sep 2022 08:20:01 +0000 [thread overview] Message-ID: <bug-107049-4-mdRNTqjZZ6@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-107049-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107049 Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC|jwakely.gcc at gmail dot com |mpolacek at gcc dot gnu.org Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org --- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- It's a front-end bug in the __is_convertible built-in. Reduced: template<bool B> struct bool_constant { static constexpr bool value = B; }; using true_type = bool_constant<true>; using false_type = bool_constant<false>; template<typename T> struct is_void : false_type { }; template<> struct is_void<void> : true_type { }; template<bool> struct enable_if { }; template<> struct enable_if<true> { using type = void; }; template<bool B> using enable_if_t = typename enable_if<B>::type; #ifndef NO_BUILTIN template<typename _From, typename _To> struct is_convertible : public bool_constant<__is_convertible(_From, _To)> { }; #else template<typename T> T&& declval(); template<typename _From, typename _To, bool = is_void<_From>::value> struct __is_convertible_helper { typedef typename is_void<_To>::type type; }; #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wctor-dtor-privacy" template<typename _From, typename _To> class __is_convertible_helper<_From, _To, false> { template<typename _To1> static void __test_aux(_To1) noexcept; template<typename _From1, typename _To1, typename = decltype(__test_aux<_To1>(declval<_From1>()))> static true_type __test(int); template<typename, typename> static false_type __test(...); public: typedef decltype(__test<_From, _To>(0)) type; }; #pragma GCC diagnostic pop /// is_convertible template<typename _From, typename _To> struct is_convertible : public __is_convertible_helper<_From, _To>::type { }; #endif struct string_view { }; struct string { private: template<class T> using If_sv = enable_if_t<is_convertible<const T&, string_view>::value>; public: void append(const string&) { } template<class T> If_sv<T> append(const T&) { } operator string_view() const { return {}; } }; struct PrivateString : private string { void f() { const auto& cthis = *this; static_cast<string&>(*this).append(cthis); } }; conv.cc: In instantiation of 'struct is_convertible<const PrivateString&, string_view>': conv.cc:68:11: required by substitution of 'template<class T> using string::If_sv = enable_if_t<is_convertible<const T&, string_view>::value> [with T = PrivateString]' conv.cc:72:30: required by substitution of 'template<class T> string::If_sv<T> string::append(const T&) [with T = PrivateString]' conv.cc:83:39: required from here conv.cc:16:28: error: 'string::operator sv_type() const' is inaccessible within this context 16 | : public bool_constant<__is_convertible(_From, _To)> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ conv.cc:74:3: note: declared here 74 | operator sv_type() const { return {}; } | ^~~~~~~~ Using -DNO_BUILTIN it works, so I'll revert the library change to use __is_convertible.
next prev parent reply other threads:[~2022-09-27 8:20 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-27 7:54 [Bug libstdc++/107049] New: " marxin at gcc dot gnu.org 2022-09-27 7:55 ` [Bug libstdc++/107049] " marxin at gcc dot gnu.org 2022-09-27 7:56 ` marxin at gcc dot gnu.org 2022-09-27 8:20 ` redi at gcc dot gnu.org [this message] 2022-09-27 8:28 ` redi at gcc dot gnu.org 2022-09-27 8:33 ` redi at gcc dot gnu.org 2022-09-27 8:41 ` [Bug c++/107049] " redi at gcc dot gnu.org 2022-09-27 10:35 ` redi at gcc dot gnu.org 2022-09-27 13:00 ` cvs-commit at gcc dot gnu.org 2022-09-27 13:01 ` redi at gcc dot gnu.org 2022-09-27 14:19 ` ville.voutilainen at gmail dot com
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