class MyViewModel: ObservableObject {
  @Published var array = ["A", "B", "C"]

  func removeFirst() {
    // warning: Result of call to 'withAnimation' is unused
    withAnimation {
      self.array.removeFirst()
    }
  }
}

struct MyView: View {
  @State var array = ["A", "B", "C"]

  // error: Failed to produce diagnostic for expression
  var body: some View {
    Button("Remove first") {
      withAnimation {
        self.array.removeFirst()
      }
    }
  }
}