title: Is direct-initialization equivalent to direct-list-initialization?
body: <p>I have the following example:</p>
  <pre><code>struct S{
     int x, y;
  }
  
  S s1{1};    // direct-initialization or direct-list-initialization ?
  S s2{1, 2}; // direct-initialization or direct-list-initialization ?
  S s3(1);    // direct-initialization or direct-list-initialization ?
  S s4(1, 2); // direct-initialization or direct-list-initialization ?
  int i1{10}; // direct-initialization or direct-list-initialization ?
  int i2(10); // direct-initialization or direct-list-initialization ?
  </code></pre>
  <p>My questions</p>
  <ul>
  <li>I just need to know what's the type of initialization in the above statements?</li>
  <li>Is there any standard quote applied here?</li>
  </ul>
  <p>I am already checked the question <a href="https://stackoverflow.com/q/47366453/16972547">direct-initialization vs direct-list-initialization (C++)</a>, but it hasn't strict answer yet.</p>