Question

This code unexplicably doesn’t compile:

struct sometype
{
    template <typename T>
    T* get() { return nullptr; }
};

template <typename T>
struct anothertype
{
#if 1
    template <typename T2> struct some_wrapper { typedef T2 type; };
    typedef typename some_wrapper<sometype>::type thetype;
#else
    typedef sometype thetype;
#endif
    typedef thetype* Ptr;

    Ptr m_ptr;
    T* get() { return m_ptr->get<T>(); }
};

If I change the #if argument to 0, it is somehow fixed. Can somebody shed some light in this? Please note that the apparently pointless some_wrapper thing actually does something useful in my real code.

I’m using g++ 4.7.1 with -fstd=gnu++11, the error is as follows (pointing to the line where I declare anothertype<T>::get:

error: expected primary-expression before '>' token
error: expected primary-expression before ')' token

Answer 1

You should fix your function call as follows, adding the template keyword:

T* get() { return m_ptr->template get<T>(); }

You can check this link for an explanation of the syntax.