Actor initializer warning

Using Swift
1 
actor Person {
   init() {
     self.name = "Test" // ok. no warning
   } 
}

But

actor Person {
    
    var name: String = ""
    let disposeBag = DisposeBag()
    init() {
        Observable<Int>.interval(.seconds(1), scheduler: MainScheduler.asyncInstance)
            .subscribe(onNext: { _ in
                self.name = "Test" // Actor-isolated property 'name' can not be mutated from a non-isolated context; this is an error in Swift 6
            }).disposed(by: disposeBag)
    }

Why is the warning occurring there?

2

Like the warning/error says, you're performing concurrent (unsafe) access to the actors mutable name property.

The onNext's purpose is to be invoked concurrently, so... "outside of the actor", so that self.name = ... is not synchronized properly and thus the warning.

A safe version of that would do something like await self.setName(name) basically, where the setName has to perform a suspension and hop to the actor to perform the name setting. You may not be able to do that easily from inside the onNext closure unless it supports async closures.

3

"outside of the actor" i'm still confused :joy:

Instance methods are isolated so this problem doesn't happen.
But init isn't isolated and that causes this problem?

4

It depends on the exact declaration of those methods you're showing here; if you want an in depth analysis please provide the method declarations of subscribe etc.

A synchronous initializer is not isolated to the actor; that's right, an async actor initializer becomes isolated to the actor though, so IF (and only if) your closure taking method there does the inherit executor trickery it might work... but I don't expect external libraries to be doing this trick -- it's an underscored attribute.

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