[Bug c++/51213] [C++11][DR 1170] Access control checking has to be done under SFINAE conditions

[w.shane.grant at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51213

Shane <w.shane.grant at gmail dot com> changed:

           What    |Removed                     |Added
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                 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’