title: Error: Variable "BOOL" is not a type name
body: <p>I am trying to create a very simple MFC application when suddenly Visual Studio decides it no longer recognizes what a <code>BOOL</code> is.</p>
  
  <p>I cannot figure out why this is happening. Does anyone know why this is going on and how to fix it?</p>
  
  <p><img src="https://i.stack.imgur.com/Z040S.png" alt="Error"></p>