What is “template<class T> using owner = T;”?

问题

Below is excerpted from gsl.h of Microsoft's gsl library (https://github.com/microsoft/gsl):

namespace gsl
{
    //
    // GSL.owner: ownership pointers 
    //
    using std::unique_ptr;
    using std::shared_ptr;

    template<class T>
    using owner = T;
    ...
};

I cannot understand what the following alias template means:

template<class T>
using owner = T;

Any explanations?

回答1:

It means that for every T, owner<T> is an alias for T.

回答2:

It can be used as annotation to show which pointers are 'owner' ie:

Example of non owning raw pointer

template<typename T>
class X2 {
    // ...
public:
    owner<T*> p;  // OK: p is owning
    T* q;         // OK: q is not owning
};

来源：https://stackoverflow.com/questions/38449366/what-is-templateclass-t-using-owner-t