Cython fails to build with Python 3.12.0a3.

Traceback (most recent call last):
  File "/builddir/build/BUILD/cython-0.29.32/TEST_TMP/0/run/py35_asyncio_async_def/main.py", line 9, in <module>
    with closing(asyncio.get_event_loop()) as loop:
                 ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/asyncio/events.py", line 676, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'MainThread'.

asyncio.get_event_loop() and many other asyncio
functions like ensure_future(), shield() or gather(), and also the
get_event_loop() method of BaseDefaultEventLoopPolicy now raise a RuntimeError
if called when there is no running event loop and the current event loop was
not set. Previously they implicitly created and set a new current event loop.
DeprecationWarning is no longer emitted if there is no running event loop but
the current event loop is set in the policy. (Contributed by Serhiy Storchaka
in gh-93453.)

https://github.com/python/cpython/issues/93453

https://docs.python.org/3.12/whatsnew/3.12.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.12/fedora-rawhide-x86_64/05157645-Cython/

For all our attempts to build Cython with Python 3.12, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/package/Cython/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.12:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/

Let us know here if you have any questions.

Python 3.12 is planned to be included in Fedora 39. To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.12.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.