http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51213
Shane <w.shane.grant at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |w.shane.grant at gmail dot com --- Comment #16 from Shane <w.shane.grant at gmail dot com> --- I think some variant of this bug may still exist (using g++ (Ubuntu 4.8.1-2ubuntu1~13.04) 4.8.1). The following code will fail to compile under g++ but will correctly compile under a recent version of clang++ (3.3). template <class T> T && declval(); template <class T> constexpr auto hasSize(int) -> decltype(declval<T&>().size(), bool()) { return true; } template <class T> constexpr bool hasSize(...) { return false; } struct A { int size(); }; struct B : private A { }; static_assert(hasSize<A>(0), "A"); static_assert(!hasSize<B>(0), "B"); int main() {} The error produced is: test.cpp: In substitution of ‘template<class T> constexpr decltype ((declval<T&>().size(), bool())) hasSize(int) [with T = B]’: test.cpp:22:28: required from here test.cpp:5:61: error: ‘A’ is not an accessible base of ‘B’ constexpr auto hasSize(int) -> decltype(declval<T&>().size(), bool()) ^ test.cpp: In substitution of ‘template<class T> constexpr decltype ((declval<T&>().size(), bool())) hasSize(int) [with T = B]’: test.cpp:22:28: required from here test.cpp:5:61: error: ‘A’ is not an accessible base of ‘B’