title: Is Option<T> optimized to a single byte when T allows it?
body: <p>Suppose we have an <code>enum Foo { A, B, C }</code>.</p>
  
  <p>Is an <code>Option&lt;Foo&gt;</code> optimized to a single byte in this case?</p>
  
  <p>Bonus question: if so, what are the limits of the optimization process? Enums can be nested and contain other types. Is the compiler always capable of calculating the maximum number of combinations and then choosing the smallest representation?</p>