For example, After I move ShippingOptions inside the function, the compiler will report an error: <img width="685" alt="image" src="https://github.com/DougGregor/swift-macro-examples/assets/24806909/4111d779-27ae-4fa9-9472-8362d4fc18ed"> <img width="834" alt="image" src="https://github.com/DougGregor/swift-macro-examples/assets/24806909/947a04e4-18e6-4aa3-87f6-0167bd79ccbf">
For example, After I move ShippingOptions inside the function, the compiler will report an error: