Template member of a non-template class as a friend

Question

The following snippet is compiled fine by gcc, icc and msvc (latest question), but trips clang with <source>:6:9: error: calling a private constructor of class 'B<int>' in the marked line. Yet it works fine for the free template function, as shown in the code:

struct A {
    template<class T>
    static void create () {
        T();
    }
};

template<class T>
void create() {
    T();
}

template<typename T>
struct B {

    friend void A::create<B>();
    friend void create<B>();

    private:
    B() = default;
};

int main() {
     A::create<B<int>>(); // clang trips here
     create<B<int>>(); // fine!
}

What might be the difference between a static template member of non-template class and free template function in this context?

Answer 1

I found a bug reported for Clang, "Access to a public template alias declaration that refers to friend's private nested type is not allowed" which seems similar to this issue as it relates to a friend (template within a structure as in the OP) accessing a private member of a class.

The failed test case is:

struct FooAccessor
{
    template <typename T>
    using Foo = typename T::Foo;
};

class Type
{
    friend struct FooAccessor;        
    using Foo = int;
};

int main()
{
    FooAccessor::Foo<Type> t;
}

The result is:

$ clang++ test.cpp -std=c++11
test.cpp:4:5: error: 'Foo' is a private member of 'Type'
    using Foo = typename T::Foo;
    ^
test.cpp:11:11: note: implicitly declared private here
    using Foo = int;
          ^
1 error generated.