isolation in Swift

@isolated(any) allows you to recover the isolation of a function value as an (any Actor)? value. It has no impact on the inferred isolation of a closure whose type includes @isolated(any), and that's where I think people get confused. If you take @isolated(any) away, isolation inference behaves exactly the same way. For non-@Sendable/sending closures, isolation is already effectively "inherited" from the enclosing context where the closure is formed.

@_inheritActorContext is only useful when you have a closure that either @Sendable or passed to a sending parameter, and it applies the same isolation inference behavior that you would get if that closure didn't have those other concurrency annotations.

• Holly Borla