swift

42d0dea4 - [Concurrency] Inherit parent's deadlines into structured child tasks

[Concurrency] Inherit parent's deadlines into structured child tasks Structured children (async let, task groups) run within the same deadline scope as their parent, so Task.hasActiveDeadline and Task.activeDeadline(for:) should observe the same deadlines on the child that the parent would. Implementation: swift_task_create_common calls a new AsyncTask::inheritDeadlinesFrom(parent) helper right after the parent-cancellation-propagation block. The helper snapshots the parent's deadline records under its status-record lock, then pushes copies onto the child (retaining each record's _ClockBox<C>). The push happens through addStatusRecord so the child's HasDeadline flag is set naturally. Ordering: parent records are collected innermost-first; the child's chain is built by pushing them in reverse so the child's chain matches the parent's exactly. This preserves the 'innermost = tightest' invariant the runtime relies on to make swift_task_findNearestDeadlineForClock's single-walk answer correct. Cleanup: ~AsyncTask calls a new cleanupInheritedDeadlines() that walks the residual chain and swift_releases each deadline record's box. Inherited records never go through the user-visible push/pop pair, so without this the retains would leak. The record memory itself lives in the task's slab allocator and is torn down by Private.destroy(), so we don't individually dealloc them. Detached tasks do NOT inherit deadlines - they aren't structured children of the enclosing withDeadline scope. This is the correct behavior: an unstructured task escapes its creator's lifetime. Runtime tests in with_deadline_basic.swift: - test_async_let_inherits_deadline: async let sees parent's deadline - test_task_group_child_inherits_deadline: TaskGroup child sees it too - test_detached_task_does_not_inherit_deadline: Task.detached does not - test_nested_deadlines_inherited_correctly: child inside a nested scope sees the inner (tighter) deadline, not the outer Also updates test_custom_clock_deadline_subsumption and test_outer_deadline_subsumes_inner_no_scope to use the new _findNearestDeadline return type (C.Instant? instead of the old _DeadlineComponents tuple). Concurrency dylib builds cleanly.