title: 'typename' and alias templates
body: <p>The following code compiles <a href="http://coliru.stacked-crooked.com/a/dfa72bbc9fc0b209" rel="noreferrer">using both Clang and GCC</a>, even though <code>Foo_t&lt;T&gt;::Bar</code> doesn't have <code>typename</code> in front of it:</p>
  
  <pre><code>struct Foo {
      using Bar = int;
  };
  
  template&lt;class...&gt;
  using Foo_t = Foo;
  
  template&lt;class T&gt;
  void f(){
      Foo_t&lt;T&gt;::Bar b; // No typename!
  }
  
  int main(){
      f&lt;int&gt;();
  }
  </code></pre>
  
  <p>Should it compile?</p>