title: What does "Arg = Exploded" mean in Swift crash log?
body: <p>I get a crash log from Crashlytics/Fabric which reads like the following:</p>
  
  <pre><code>function signature specialization &lt;Arg[0] = Exploded, Arg[1] = Owned To Guaranteed&gt; of
  MyClass.viewWillAppear (MyClass)(Swift.Bool) -&gt; ()
  </code></pre>
  
  <p>what does exploded mean for Arg[0]? It's weird that there are two arguments because we're talking about <code>viewWillAppear</code> here - is the first argument the object itself?</p>