Public alias for non-public type : <p>I wonder if it is valid C++ :</p>

<pre><code>class Test {
    struct PrivateInner {
        PrivateInner(std::string const &amp;str) {
            std::cout &lt;&lt; str &lt;&lt; "\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 ?
</code></pre>
