title: Class reference member - Not an error in a class with synthesized constructor but error in user defined constructor
body: <p>Below errors out. Understood.</p>
  <pre><code>class a {
     int b;
     int &amp;c; // uninitialized
     a(int x): b(x) {}
  };
  </code></pre>
  <p>Below uses synthesized constructor. Why no error below? How does the synthesized constructor initialize the reference or will it even do that? Reference has to be user initialized from what I understand.</p>
  <pre><code>class a {
     int b;
     int &amp;c;
  };
  </code></pre>