title: Codable 'has no initializers' in Xcode 9.3 (Swift 4.1)
body: <p>After updating to Xcode 9.3 (which uses Swift 4.1), the following issue was found:</p>
  
  <ol>
  <li><p>Create an empty project, add a new .swift file to it and create two new classes:</p>
  
  <p><a href="https://i.stack.imgur.com/sdou1.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sdou1.png" alt="Created to Codable classes"></a> </p>
  
  <pre><code>class CodableOne: Codable {
  
      let some: String
  
  }
  
  class CodableTwo: Codable {
  
      var some: String
  
  }
  </code></pre>
  
  <p><strong>Build succeeds</strong></p></li>
  <li><p>Add a new constant to <code>CodableOne</code> of type <code>CodableTwo</code>:</p>
  
  <p><a href="https://i.stack.imgur.com/HvGh3.png" rel="noreferrer"><img src="https://i.stack.imgur.com/HvGh3.png" alt="Added a new constant to CodableOne"></a> </p>
  
  <pre><code>class CodableOne: Codable {
  
      let some: String
      let another: CodableTwo
  
  }
  
  class CodableTwo: Codable {
  
      var some: String
  
  }
  </code></pre>
  
  <p><strong>Build succeeds</strong></p></li>
  <li><p>Now move class <code>CodableTwo</code> to another file (ViewController.swift, for example)</p>
  
  <p><a href="https://i.stack.imgur.com/esUdg.png" rel="noreferrer"><img src="https://i.stack.imgur.com/esUdg.png" alt="CodableTwo moved to another file"></a></p>
  
  <p><strong>Build fails</strong>.</p></li>
  </ol>
  
  <p>Now there's an error, which won't go away. <strong><code>Codable</code> classes should not require initializers</strong> (as demonstrated in previous steps).</p>
  
  <p>Any ideas on what could be the problem behind this and how it could be resolved will be much appreciated!</p>
  
  <hr>
  
  <p>P.S. Issue is not present in Xcode 9.2. Nor cleaning the project/build path, neither re-installing Xcode 9.3 helps.</p>