Release v0.23.0 · python-trio/trio

Full Changelog: v0.22.2...v0.23.0

Headline features

When exiting a nursery block, the parent task always waits for child tasks to exit. This wait cannot be cancelled. However, previously, if you tried to cancel it, it would inject a Cancelled exception, even though it wasn't cancelled. Most users probably never noticed either way, but injecting a Cancelled here is not really useful, and in some rare cases caused confusion or problems, so Trio no longer does that. (#1457)
If called from a thread spawned by trio.to_thread.run_sync, trio.from_thread.run and trio.from_thread.run_sync now reuse the task and cancellation status of the host task; this means that context variables and cancel scopes naturally propagate 'through' threads spawned by Trio. You can also use trio.from_thread.check_cancelled to efficiently check for cancellation without reentering the Trio thread. (#2392)
trio.lowlevel.start_guest_run now does a bit more setup of the guest run before it returns to its caller, so that the caller can immediately make calls to trio.current_time, trio.lowlevel.spawn_system_task, trio.lowlevel.current_trio_token, etc. (#2696)

When a starting function raises before calling trio.TaskStatus.started, trio.Nursery.start will no longer wrap the exception in an undocumented ExceptionGroup. Previously, trio.Nursery.start would incorrectly raise an ExceptionGroup containing it when using trio.run(..., strict_exception_groups=True). (#2611)

To better reflect the underlying thread handling semantics, the keyword argument for trio.to_thread.run_sync that was previously called cancellable is now named abandon_on_cancel. It still does the same thing -- allow the thread to be abandoned if the call to trio.to_thread.run_sync is cancelled -- but since we now have other ways to propagate a cancellation without abandoning the thread, "cancellable" has become somewhat of a misnomer. The old cancellable name is now deprecated. (#2841)
Deprecated support for math.inf for the backlog argument in open_tcp_listeners, making its docstring correct in the fact that only TypeError is raised if invalid arguments are passed. (#2842)

Drop support for Python3.7 and PyPy3.7/3.8. (#2668)
Removed special MultiError traceback handling for IPython. As of version 8.15 ExceptionGroup is handled natively. (#2702)

Trio now indicates its presence to sniffio using the sniffio.thread_local interface that is preferred since sniffio v1.3.0. This should be less likely than the previous approach to cause sniffio.current_async_library to return incorrect results due to unintended inheritance of contextvars. (#2700)
On windows, if SIO_BASE_HANDLE failed and SIO_BSP_HANDLE_POLL didn't return a different socket, runtime error will now raise from the OSError that indicated the issue so that in the event it does happen it might help with debugging. (#2807)