ジュニア

@swift-6.0.3 -swift-version 6

final class NonSendableCounter { var count = 0 nonisolated func increment() async { count += 1 } } @MainActor func foo() async { let counter = NonSendableCounter() await withTaskGroup(of: Void.self) { group in for _ in 0..<10000 { group.addTask { await counter.increment() } } } print(counter.count) } await foo()

(edited)

exit status: 1 with

<stdin>:14:27: error: passing closure as a 'sending' parameter risks causing data races between main actor-isolated code and concurrent execution of the closure 12 | await withTaskGroup(of: Void.self) { group in 13 | for _ in 0..<10000 { 14 | group.addTask { | `- error: passing closure as a 'sending' parameter risks causing data races between main actor-isolated code and concurrent execution of the closure 15 | await counter.increment() | `- note: closure captures 'counter' which is accessible to main actor-isolated code 16 | } 17 | }

(edited)