title: Swift Switch case: Default will never be executed warning
body: <p>On Xcode 7b2 with Swift 2 code, I have following:</p>
  
  <p>In a switch case the compiler returns the following warning : </p>
  
  <pre><code>Default will never be executed
  </code></pre>
  
  <p>The code : </p>
  
  <pre><code>switch(type) {
    case .foo:
      return "foo"
    case .bar:
      return "bar"
    case .baz:
      return "baz"
    default:
      return "?"
  }
  </code></pre>
  
  <p>Why would there be a warning ? </p>