In the following example, with NonisolatedNonsendingByDefault enabled, the closure passed to a.test() should be executed on actor a. The code does pass the a.assertIsolated() assertion successfully. However, when I try to get the current actor with the #isolation macro, I get a nil.
This also cause functions that use isolated parameter (e.g.: withTaskExecutorPreference) to fail to inherit the actor of their caller.
So what is happening here?
it seems likely that this is a bug. there was this patch that addressed some issues with the macro not working as intended in functions, but it seems it maybe doesn't yet handle closures?
@hborla @John_McCall or @ktoso, could one of you confirm whether this is a bug please? should it ever be the case that an async function/closure can both have an actor isolation assertion pass and the #isolation macro expansion resolve to nil (i assume not)?
as a workaround, it seems you could possibly use a local function instead of a closure:
@concurrent
nonisolated func test() async {
let a = MyActor()
nonisolated(nonsending)
func f() async -> Void {
a.assertIsolated() // OK
let iso = #isolation
print(iso as Any) // Optional(MyActor)
}
await a.test(f)
}
Yes, it looks like Konrad's patch just doesn't properly handle isolated code that doesn't correspond to a function declaration. I'm putting together a fix.