swift

e1ddd40c - [Concurrency] TaskGroup children remove their records as they complete

[Concurrency] TaskGroup children remove their records as they complete If we didn't do this (and we didn't), the tasks get released as we perform the next() impl, and move the value from the ready task to the waiting task. Then, the ready task gets destroyed. But as the task group exists, it performs a cancelAll() and that iterates over all records. Those records were not removed previously (!!!) which meant we were pointing at now deallocated tasks. Previously this worked because we didn't deallocate the tasks, so they leaked, but we didn't crash. With the memory leak fixed, this began to crash since we'd attempt to cancel already destroyed tasks. Solution: - Remove task records whenever they complete a waiting task. - This can ONLY be done by the "group owning task" itself, becuause the contract of ONLY this task being allowed to modify records. o It MUST NOT be done by the completing tasks as they complete, as it would race with the owning task modifying this linked list of child tasks in the group record. (cherry picked from commit f336404ae92a355e9cf1939956adb39e053e6d4a)