title: Global is external, but doesn't have external or weak linkage
body: <p>Upgrading to swift 1.2 prevents me from compiling. Error do not show inside the files, but it's a general compilation error message.</p>
  
  <p>Logging the compilation text, i'm able to spot this error on a specific file:</p>
  
  <pre><code>Global is external, but doesn't have external or weak linkage! 
  invalid  linkage type for function declaration
  LLVM ERROR: Broken module found, compilation aborted!
  </code></pre>
  
  <p>Here is the content of the file, do you know what causes the error:</p>
  
  <pre><code>import Foundation
  
  class appDisabled {
      func check(currentViewController: UIViewController, isLoginScreen: Bool) {
  
          var disabledStatus: Bool? {
              didSet {
                  if let result = disabledStatus {
                      if result == true &amp;&amp; isLoginScreen == false{
                              currentViewController.performSegueWithIdentifier("unwindToLoginScreen", sender: nil)
                      }
                  }
              }
          }
  
          PFConfig.getConfigInBackgroundWithBlock {
              (config: PFConfig!, error: NSError!) -&gt; Void in
  
              if error == nil {
                  disabledStatus = config["appDisabled"] as? Bool
                  if disabledStatus! == true  {
                      appStatus.isAppDisabled = true
                  } else {
                      appStatus.isAppDisabled = false
                  }
              }
          }
      }
  }
  </code></pre>
  
  <p>Removing the second function block PFConfig.getConfigInBackgroundWithBlock... does allow the compilation to pass, so i'm not sure if it's that block itself that causes the problem, or the relation with the variable observer above.
  Do you see any part of this code that could trigger the compiler error ?</p>