DeprecationWarning scope expanded in asyncio.events · Issue #100160 · python/cpython (original) (raw)

As discovered in prompt-toolkit/python-prompt-toolkit#1696, it appears that the DeprecationWarning introduced in Python 3.10 has expanded its scope, now with 3.11.1 and 3.10.9 emitting during get_event_loop_policy() where it did not before:

 ~ $ py -3.11 -W error
Python 3.11.0 (main, Oct 26 2022, 19:06:18) [Clang 14.0.0 (clang-1400.0.29.202)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import asyncio
>>> asyncio.get_event_loop_policy().get_event_loop()
<_UnixSelectorEventLoop running=False closed=False debug=False>
>>> ^D
 ~ $ docker run -it jaraco/multipy-tox py -3.11 -W error
Python 3.11.1 (main, Dec  7 2022, 01:11:34) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import asyncio
>>> asyncio.get_event_loop_policy().get_event_loop()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.11/asyncio/events.py", line 687, in get_event_loop
    warnings.warn('There is no current event loop',
DeprecationWarning: There is no current event loop

It's not obvious if it was intentional to expand the scope of the DeprecationWarning, but it does come as a surprise as the calling code had previously attempted to address the deprecation.