[Concurrency] Fix null pointer dereference for task-to-thread model. #82204
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In task-to-thread concurrency mode, `_getMainExecutorAsSerialExecutor` returns `SerialExecutorRef::generic()`, which is, give or take, NULL. Unfortunately we'd declared it as returning `any SerialExecutor`, rather than `(any SerialExecutor)?`, and then the `getMainExecutor()` function was calling `asUnownedSerialExecutor()` on it, which then crashes. rdar://153152063
al45tair
added
🍒 release cherry pick
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Explanation: Fixes a null pointer dereference (caused by the combination of task-to-thread model concurrency and the shenanigans we get up to to avoid reference counting the executors). |
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@swift-ci Please test |
ktoso
approved these changes
Jun 12, 2025
tbkka
approved these changes
Jun 12, 2025
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In task-to-thread concurrency mode,
_getMainExecutorAsSerialExecutorreturnsSerialExecutorRef::generic(), which is, give or take, NULL. Unfortunately we'd declared it as returningany SerialExecutor, rather than(any SerialExecutor)?, and then thegetMainExecutor()function was callingasUnownedSerialExecutor()on it, which then crashes.rdar://153152063