我想知道它是否有效的C ++：

class Test {
    struct PrivateInner {
        PrivateInner(std::string const &str) {
            std::cout << str << "\n";
        }
    };

public:
    using PublicInner = PrivateInner;
};

//Test::PrivateInner priv("Hello world");        // Ok,private so we can't use that
Test::PublicInner publ("Hello World");           // ?,by using public alias we can access private type,is it ok ?