Running an async task with a timeout

[ph1ps (Philipp Gabriel)]

@lyzkov
Most (if not all) of the snippets posted in this thread have some rough edges (though I am not criticizing any solution, since some things were just not available back then):

• Using Foundation is not necessary (anymore). You can use Task.sleep(until:tolerance:clock:).
• R should conform to Sendable. This is a requirement of TaskGroup and it warns you if you use strict concurrency.
• If you cancel the Task in which withTimeout was started it could swallow the cancellation behavior of operation and just throw CancellationError from the Task.sleep because TaskGroup will forward the first error it receives from its children.
• The try Task.checkCancellation() is awkward, as @ktoso already mentioned here:

@ktoso

I would not recommend checking cancellation AFTER the work was already completed. It's a bit of a waste of computation -- cancellation is useful to avoid un-necessary work. But if the work was already done... there's not much reason to discard the result.

If someone wanted to discard the result they can do so on the calling function still.