[6.0][Concurrency] TaskExecutors may be non-swift objects; dont swift_rele… #75060
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…ase them Since we introduced proper ownership of task executors, they are now released and retained. The problem appears with a dispatch_queue_t which conforms to TaskExecutor being passed to Task initializer and retains work okey because it is __owned. However, upon destroy we swift_released the executor reference, which is incorrect as we must be using object specific release methods -- in this case the safe way to support all kinds of objects is `swift_unknownObjectRelease` resolves rdar://131151645
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@swift-ci please test |
DougGregor
approved these changes
Jul 8, 2024
DougGregor
approved these changes
Jul 8, 2024
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Added a test to cover the fixed situation |
ktoso
added
concurrency
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@swift-ci please test |
mikeash
reviewed
Jul 9, 2024
| // This test specifically checks that our reference counting accounts for existence of | ||
| // objective-c types as TaskExecutors -- which was a bug where we'd swift_release | ||
| // obj-c excecutors by accident (rdar://131151645). | ||
| final class NSQueueTaskExecutor: NSData, TaskExecutor, @unchecked Sendable { |
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Using Swift refcounting on this class will end up working on the field after the end of the instance, since instances of this object will just contain a single pointer. Presumably this does fail in practice, but it might be good to make it more certain by adding a field with a value that will provoke a crash. var dummy = 0 or var dummy = -1 ought to do it.
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Description: Since we introduced proper ownership of task executors, they are now released and retained. The problem appears with a dispatch_queue_t which conforms to TaskExecutor being passed to Task initializer and retains work okey because it is __owned. However, upon destroy we swift_released the executor reference, which is incorrect as we must be using object specific release methods -- in this case the safe way to support all kinds of objects is swift_unknownObjectRelease
Scope/Impact: Unbreaks users of task executors who use a raw dispatchqueue as the executor.
Risk: Low, changes swift_release to swift_unknownObjectRelease which is stricly more accepting.
Testing: Verified in a reproducer project
Reviewed by: @mikeash
Original PR: #75059
Radar: rdar://131151645