title: Swift failed to produce diagnostic for expression
body: <p>I am trying to use a switch statement on an enum within a View, and it confuses the compiler:</p>
  <p><a href="https://i.stack.imgur.com/0Gc4d.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0Gc4d.png" alt="enter image description here" /></a></p>
  <p>Here is the code:</p>
  <pre><code>import Foundation
  import SwiftUI
  
  struct LexicalItemView : View {
      let lexicalItem: LexicalItem
      var body: some View {
          switch self.lexicalItem {
          case .noun(let nounModel):
              Text(nounModel.gender)
          case .verb(let verbModel):
              Text(verbModel.aspect)
          }
      }
  }
  </code></pre>
  <p>Here is my enum:</p>
  <pre><code>enum LexicalItemEnum {
      case noun(Noun)
      case verb(Verb)
  }
  </code></pre>
  <p>How can I unconfuse the swift compiler or otherwise get this to compile?</p>