Open Radar

 
Problem:
Application crashes when a row is deleted in a SwiftUI List populated with NSManagedObject instances.
Example project: https://www.icloud.com/iclouddrive/0HttLnRotPLk2C3RmSXZ7NDXw#CoreData_SwiftUI

Steps to reproduce:
In the example project attached, run the app in one of the simulators, tap “Add” in the top right corner to add a few items, swipe a row to delete it.

What is expected:
Row to be deleted and CoreData context to be saved.

What happens:
Application crashes with the following log:

Simultaneous accesses to 0x7fc8e5e29fb8, but modification requires exclusive access.
Previous access (a modification) started at SwiftUI`closure #2 in ListCoreCoordinator.tableView(_:commit:forRowAt:) + 53 (0x10af83e05).
Current access (a read) started at:
0    libswiftCore.dylib                 0x000000010e1b6890 swift_beginAccess + 568
1    SwiftUI                            0x000000010af7fc50 ListCoreCoordinator.dataSource.getter + 50
2    SwiftUI                            0x000000010af80720 ListCoreCoordinator.updateUITableView(_:to:transaction:) + 608
3    SwiftUI                            0x000000010af7f510 ListRepresentable.updateUIView(_:context:) + 911
4    SwiftUI                            0x000000010b3d7860 PlatformViewRepresentableAdaptor.updateViewProvider(_:context:) + 263
5    SwiftUI                            0x000000010b0255a0 closure #1 in closure #1 in closure #4 in closure #1 in PlatformViewChild.updateValue() + 229
6    SwiftUI                            0x000000010b0254f0 closure #1 in closure #4 in closure #1 in PlatformViewChild.updateValue() + 114
7    SwiftUI                            0x000000010b2cd480 ViewRendererHost.performExternalUpdate(_:) + 186
8    SwiftUI                            0x000000010b025480 closure #4 in closure #1 in PlatformViewChild.updateValue() + 73
9    SwiftUI                            0x000000010b023ec0 closure #1 in PlatformViewChild.updateValue() + 2079
10   SwiftUI                            0x000000010b023920 PlatformViewChild.updateValue() + 650
11   SwiftUI                            0x000000010ad50820 partial apply for implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 26
12   AttributeGraph                     0x0000000111669b0a AG::Graph::UpdateStack::update() + 505
13   AttributeGraph                     0x000000011166a04a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
14   AttributeGraph                     0x0000000111671f38 AG::Subgraph::update(unsigned int) + 781
15   SwiftUI                            0x000000010b367b20 GraphHost.runTransaction() + 186
16   SwiftUI                            0x000000010b36b6a0 GraphHost.runTransaction(_:) + 79
17   SwiftUI                            0x000000010b36a140 GraphHost.flushTransactions() + 211
18   SwiftUI                            0x000000010b3692b0 specialized GraphHost.asyncTransaction<A>(_:mutation:style:) + 484
19   SwiftUI                            0x000000010af49de0 AttributeInvalidatingSubscriber.invalidateAttribute() + 236
20   SwiftUI                            0x000000010af49d60 AttributeInvalidatingSubscriber.receive(_:) + 105
21   SwiftUI                            0x000000010af4a3f0 protocol witness for Subscriber.receive(_:) in conformance AttributeInvalidatingSubscriber<A> + 16
22   SwiftUI                            0x000000010b0d7af0 SubscriptionLifetime.Connection.receive(_:) + 89
23   Combine                            0x0000000111b3f5f0 ObservableObjectPublisher.Inner.send() + 122
24   Combine                            0x0000000111b3ebe0 ObservableObjectPublisher.send() + 801
25   libswiftCoreData.dylib             0x000000010e5aa880 @objc NSManagedObject._willChange_Swift_Trampoline() + 114
26   CoreData                           0x000000010a40956f -[NSManagedObjectContext _postObjectsDidChangeNotificationWithUserInfo:] + 773
27   CoreData                           0x000000010a41828f -[NSManagedObjectContext _createAndPostChangeNotification:deletions:updates:refreshes:deferrals:wasMerge:] + 1825
28   CoreData                           0x000000010a40a32d -[NSManagedObjectContext _processRecentChanges:] + 1041
29   CoreData                           0x000000010a36e9bd -[NSManagedObjectContext save:] + 356
30   CDSUI                              0x0000000109a9bcc0 closure #2 in closure #1 in ListView.body.getter + 439
31   SwiftUI                            0x000000010ab318a0 partial apply for thunk for @escaping @callee_guaranteed (@in_guaranteed IndexSet) -> () + 17
32   SwiftUI                            0x000000010b142a10 partial apply for thunk for @escaping @callee_guaranteed (@in_guaranteed IndexSet) -> (@out ()) + 17
33   SwiftUI                            0x000000010ab31a30 DeleteInteraction.delete() + 125
34   SwiftUI                            0x000000010aee2e20 SystemListDataSource.deleteCell(forRowAt:) + 64
35   SwiftUI                            0x000000010b09e230 ShadowListDataSource.commitUpdates() + 963
36   SwiftUI                            0x000000010af83dd0 closure #2 in ListCoreCoordinator.tableView(_:commit:forRowAt:) + 76
37   SwiftUI                            0x000000010af83ab0 ListCoreCoordinator.tableView(_:commit:forRowAt:) + 455
38   SwiftUI                            0x000000010af83e30 @objc ListCoreCoordinator.tableView(_:commit:forRowAt:) + 131
39   UIKitCore                          0x00000001146a0891 -[UITableView _animateDeletionOfRowAtIndexPath:] + 188
40   UIKitCore                          0x00000001146a901a __82-[UITableView _contextualActionForDeletingRowAtIndexPath:usingPresentationValues:]_block_invoke + 60
41   UIKitCore                          0x00000001145f1b0b -[UIContextualAction executeHandlerWithView:completionHandler:] + 148
42   UIKitCore                          0x00000001145ff9f8 -[UISwipeOccurrence _executeLifecycleForPerformedAction:sourceView:completionHandler:] + 514
43   UIKitCore                          0x0000000114600047 -[UISwipeOccurrence _performSwipeAction:inPullView:swipeInfo:] + 621
44   UIKitCore                          0x0000000114601d6d -[UISwipeOccurrence swipeActionPullView:tappedAction:] + 92
45   UIKitCore                          0x0000000114609bae -[UISwipeActionPullView _tappedButton:] + 148
46   UIKitCore                          0x00000001144711dc -[UIApplication sendAction:to:from:forEvent:] + 83
47   UIKitCore                          0x0000000113d9ed49 -[UIControl sendAction:to:forEvent:] + 223
48   UIKitCore                          0x0000000113d9efff -[UIControl _sendActionsForEvents:withEvent:] + 332
49   UIKitCore                          0x0000000113d9d840 -[UIControl touchesEnded:withEvent:] + 500
50   UIKitCore                          0x0000000113f9d9fa _UIGestureEnvironmentUpdate + 8849
51   UIKitCore                          0x0000000113f9d207 -[UIGestureEnvironment _updateForEvent:window:] + 887
52   UIKitCore                          0x00000001144ae829 -[UIWindow sendEvent:] + 4752
53   UIKitCore                          0x000000011448927d -[UIApplication sendEvent:] + 633
54   UIKit                              0x0000000136b6dc99 -[UIApplicationAccessibility sendEvent:] + 85
55   UIKitCore                          0x00000001145163eb __processEventQueue + 13895
56   UIKitCore                          0x0000000114510360 __eventFetcherSourceCallback + 104
57   CoreFoundation                     0x000000010f732834 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
58   CoreFoundation                     0x000000010f732689 __CFRunLoopDoSource0 + 180
59   CoreFoundation                     0x000000010f731b27 __CFRunLoopDoSources0 + 248
60   CoreFoundation                     0x000000010f72c089 __CFRunLoopRun + 878
61   CoreFoundation                     0x000000010f72b967 CFRunLoopRunSpecific + 567
62   GraphicsServices                   0x0000000111532d28 GSEventRunModal + 139
63   UIKitCore                          0x000000011446a8e3 -[UIApplication _run] + 912
64   UIKitCore                          0x000000011446fb1f UIApplicationMain + 101
65   libswiftUIKit.dylib                0x000000010ea0f750 UIApplicationMain(_:_:_:_:) + 98
66   CDSUI                              0x0000000109a98ff0 static UIApplicationDelegate.main() + 122
67   CDSUI                              0x0000000109a98fb0 static AppDelegate.$main() + 46
68   CDSUI                              0x0000000109a99090 main + 41
69   libdyld.dylib                      0x000000011022e414 start + 1