gistfile1.txt

import Dispatch

extension Task {
    static func sync(_ code: sending () async throws(Failure) -> Success) throws(Failure) -> Success {
        let semaphore = DispatchSemaphore(value: 0)
        nonisolated(unsafe) var result: Result<Success, Failure>? = nil
        withoutActuallyEscaping(code) {
            nonisolated(unsafe) let sendableCode = $0
            let coreTask = Task<Void, Never>.detached(priority: .userInitiated) { @Sendable () async -> Void in
                do {
                    result = .success(try await sendableCode())
                } catch {
                    result = .failure(error as! Failure)
                }
            }
            
            Task<Void, Never>.detached(priority: .userInitiated) {
                await coreTask.value
                semaphore.signal()
            }
            
            semaphore.wait()
        }
        return try result!.get()
    }
}