How to define a type alias for a template in a class

Question

For example

struct Option_1
{
    template<class T> using Vector = std::vector<T>;
};

I can do

typename Option_1::Vector<int> v;

But I prefer the following

Vector<Option_1, int> v;

or similars without the word "typename". I define an alias

template<class Option, class T> using Vector= typename Option::Vector<T>;

but failed with unrecognizable template declaration/definition. How to fix it?

Answer 1

You should use the keyword template for the dependent template name Option::Vector, i.e.

template<class Option, class T> using Vector = typename Option::template Vector<T>;
//                                                              ~~~~~~~~

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