https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61806
Bug ID: 61806 Summary: [C++11] Expression sfinae w/o access gives hard error in partial template specializations Product: gcc Version: 4.10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: daniel.kruegler at googlemail dot com The following code, compiled with gcc 4.10.0 20140714 (experimental) using the flags -Wall -Wextra -std=c++11 -pedantic or - alternatively - -Wall -Wextra -std=c++1y -pedantic //----------------------- struct true_type { static const bool value = true; }; struct false_type { static const bool value = false; }; template<class T> T&& declval(); template<typename> struct check { typedef void type; }; template<typename T, typename Enable = void> struct has_public_f : false_type {}; template<typename T> struct has_public_f< T, typename check< decltype( declval<T&>().f() ) >::type > : true_type {}; struct Spub { public: void f(); }; struct Spriv { private: void f(); }; static_assert( has_public_f<Spub>::value, "Ouch"); static_assert(!has_public_f<Spriv>::value, "Ouch"); int main() {} //----------------------- is rejected with the following diagnostics: <quote> prog.cc: In instantiation of 'struct has_public_f<Spriv>': prog.cc:33:35: required from here prog.cc:30:30: error: 'void Spriv::f()' is private struct Spriv { private: void f(); }; ^ prog.cc:27:15: error: within this context > : true_type {}; ^ prog.cc:30:30: error: 'void Spriv::f()' is private struct Spriv { private: void f(); }; ^ prog.cc:27:15: error: within this context > : true_type {}; ^ prog.cc:30:30: error: 'void Spriv::f()' is private struct Spriv { private: void f(); }; ^ prog.cc:33:16: error: within this context static_assert(!has_public_f<Spriv>::value, "Ouch"); ^ prog.cc:33:1: error: static assertion failed: Ouch static_assert(!has_public_f<Spriv>::value, "Ouch"); ^ </quote> It seems that in this context there is no silent rejection of the partial specialization, albeit it should.