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Signature incorrect for Coroutine throw? #9586
Description
I own some code that has been forwarding throw by declaring a three-parameter method with two defaulted to None, but as of py3.11 we have started seeing errors:
TypeError: throw() third argument must be a traceback
This doesn't seem to match the type stubs. Should the second Coroutine.throw overload be changed to remove the final | None?
Line 406 in a9b4fa0
Minimal repro
(Must be run in py3.11)
>>> import asyncio
>>> async def f():
... await asyncio.sleep(0)
>>> async def g():
... await asyncio.gather(f(), f())
>>> h = g()
>>> h.send(None)
<stdin>:2: DeprecationWarning: There is no current event loop
<_GatheringFuture pending>
>>> h.throw(ValueError("some error"), None, None)
Traceback (most recent call last):
...
TypeError: throw() third argument must be a tracebackNotes:
- this does not happen if you instead do
h = f(), nor if you skip theh.send(None), so there is something important about theasyncio.gather. - if you run this in py3.10, you will get
ValueError: some error, so this is a behaviour change in 3.11. - Possibly this is caused by python/cpython@0a8b8e0 ?
Activity
srittau commentedon Jan 25, 2023
I couldn't find anything about this in the release notes. I suspect this is actually a bug in Python 3.11.
hauntsaninja commentedon Jan 25, 2023
Can confirm that this behaviour is changed by the commit you mention python/cpython@0a8b8e0
hauntsaninja commentedon Jan 25, 2023
Not sure why it was changed, possibly unintentionally since the PR is missing a news entry. Let me open an issue against CPython...
srittau commentedon Jan 25, 2023
This has now been fixed in cpython main and a backport PR for 3.11 is open. I don't think we need to do anything here. Thanks, @alicederyn for opening the issue and @hauntsaninja for fixing it in CPython!