Question

Example

template <typename T>
struct A
{
    typedef A<T> super;
};

template <typename T>
struct B : A<T>
{
    B() : super() {} // <-- HERE
};

int main()
{
}

With the MSVC compiler, this compiles as-is. However with gcc, I need to change super() to A<T>::super(). I’m assuming gcc is correct here, however could someone help me understand the rule here and which compiler is technically correct?

Answer 1

No, since it’s a dependant name, since A is a class template. You need to either fully qualify it, or use a shortcut B::super. The latter will also tell the compiler that it’s a dependant name and is very handy if the derived class also has lots of template parameters, since B will expand to B<T, and, stuff> since it’s the injected class name.

MSVC is wrong here thanks to its incomplete two-phase lookup. Basically, with MSVC, all the dependency checks and stuff only happen during instantiation of the template, while it should have been checked at declaration.