Why does C++ require me to repeat template arguments of my base class in initalizer list?

Question

I was porting some code from MSVC(without permissive-) to linux and I learned that if you call constructor of a template base class in initializer list of your class you must sp

Answer 1

You only need to do that when Derived is a template and the type of the base depends on its template parameters.

This compiles, for example:

template <typename T>
class Derived : public Base<int, false>
{
public:
    Derived(const T& t) : Base(t) {}
};

As far as I know, here (in member initializer list) Base is actually the injected-class-name of Base<...>, inherited from it like everything else.

And if the type of the base does depend on the template parameters, its inherited injected-class-name becomes inaccessible (at least directly), just like any other member inherited from it.

For a member variable/function, you'd add this-> to access it, but for a type member you need Derived:::

template <typename T>
class Derived : public Base<T, false>
{
public:
    Derived(const T& t) : Derived::Base(t) {}
};