swift

1e5d30f5 - [Concurrency] Import Objective-C methods with completion handlers as async

[Concurrency] Import Objective-C methods with completion handlers as async When a given Objective-C method has a completion handler parameter with an appropriate signature, import that Objective-C method as async. For example, consider the following CloudKit API: - (void)fetchShareParticipantWithUserRecordID:(CKRecordID *)userRecordID completionHandler:(void (^)(CKShareParticipant * _Nullable shareParticipant, NSError * _Nullable error))completionHandler; With the experimental concurrency model, this would import as: func fetchShareParticipant(withUserRecordID userRecordID: CKRecord.ID) async throws -> CKShare.Participant? The compiler will be responsible for turning the caller's continuation into a block to pass along to the completion handler. When the error parameter of the completion handler is non-null, the async call will result in that error being thrown. Otherwise, the other arguments passed to that completion handler will be returned as the result of the async call. async versions of methods are imported alongside their completion-handler versions, to maintain source compatibility with existing code that provides a completion handler. Note that this only covers the Clang importer portion of this task.