[Pitch] Stop inferring actor isolation based on property wrapper usage

[bjhomer]

@bjhomer

@xwu

To clarify, wouldn't the property wrapper UIUpdating also itself no longer infer actor isolation given your pitch?

That's true; the type UIUpdating itself would no longer be isolated.

Actually, I was wrong. UIUpdating is already not actor-isolated, even in Swift 5. @MainActor var wrappedValue does not have a property wrapper on the property declaration, so the upward propagation from property wrappers does not apply. Simply applying a global actor to a property has never granted isolation to the entire type.

This inconsistency between @MainActor var x and @UIUpdating var x is another issue resolved by this proposal.