title: std::array constructor behaves different between compilers
body: <p>I have the following code where <code>b</code> is list-initialized with another array.</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;array&gt;
  
  int main()
  {
      std::array&lt;int, 4&gt; a{1,2,3,4};
      std::array&lt;int, 4&gt; b{a};
      std::cout&lt;&lt;b[3]&lt;&lt;std::endl;
      return 0;
  }
  
  </code></pre>
  
  <p>I am wondering why this code compiles under one compiler used by <a href="https://wandbox.org/permlink/q3v1OtzNHXvvV5PP" rel="nofollow noreferrer">wandbox</a>.</p>
  
  <p>But it fails by another compiler used by <a href="http://cpp.sh/9pzba" rel="nofollow noreferrer">cpp.sh</a>.</p>