[3.11] gh-93453: Only emit deprecation warning in asyncio.get_event_loop when a new event loop is created

[serhiy-storchaka]

It no longer emits a deprecation warning if the current event loop was set.

• Issue: Finish deprecation in asyncio.get_event_loop() #93453

[ambv]

This will need to also be backported to 3.10. In the light of that, I'm nervous about the removal of _asyncio._get_event_loop here. The point of the change as named in the PR is to stop emitting deprecation warnings when a loop exists on the policy. Serhiy's comment here explains this intent as well:
#98440 (comment)

@serhiy-storchaka, @gvanrossum, @kumaraditya303: would you be okay if I changed this PR to keep _asyncio._get_event_loop intact? I think that makes more sense for a change that's supposed to land in 3.10.9 too.

[ambv]

Note that I'm fine with _get_event_loop() to disappear in 3.12 as it's an underscored name. I simply think it's going to be disruptive to change this in 3.11.1 and 3.10.9.

(I also resolved a conflict in any case to have CI green.)

[serhiy-storchaka]

I do not think it is necessary, but I have no objections.

[ambv]

OK, @serhiy-storchaka, then I'll adapt this PR to leave _asyncio._get_event_loop existing.

[gvanrossum]

Do read my comments first!

[serhiy-storchaka]

I afraid that I can create conflicts with Łukasz, so from now I'm stopping committing in this branch. In any case my internet connection is currently too bad and can disappear at any time.

[ambv]

Thanks, @serhiy-storchaka, I reverted removal of asyncio.events._get_event_loop and _asyncio._get_event_loop. Look how obvious the remaining changes now look in the "Files changed" tab. I like this.

I will wait for everything to pass and then merge this to create a 3.10 backport.

[miss-islington]

Thanks @serhiy-storchaka for the PR, and @ambv for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖

[miss-islington]

Sorry @serhiy-storchaka and @ambv, I had trouble checking out the 3.10 backport branch.
Please retry by removing and re-adding the "needs backport to 3.10" label.
Alternatively, you can backport using cherry_picker on the command line.
cherry_picker 3fae04b10e2655a20a3aadb5e0d63e87206d0c67 3.10

[ambv]

Note: I'm working on the backport now manually, there's some test conflicts with 3.10.

Now backporting '3fae04b10e2655a20a3aadb5e0d63e87206d0c67' into '3.10'
Error cherry-pick 3fae04b10e2655a20a3aadb5e0d63e87206d0c67.
Auto-merging Doc/library/asyncio-eventloop.rst
Auto-merging Doc/library/asyncio-llapi-index.rst
Auto-merging Lib/asyncio/events.py
Auto-merging Lib/test/test_asyncio/test_base_events.py
Auto-merging Lib/test/test_asyncio/test_events.py
CONFLICT (content): Merge conflict in Lib/test/test_asyncio/test_events.py
Auto-merging Lib/test/test_asyncio/test_futures.py
CONFLICT (content): Merge conflict in Lib/test/test_asyncio/test_futures.py
Auto-merging Lib/test/test_asyncio/test_streams.py
CONFLICT (content): Merge conflict in Lib/test/test_asyncio/test_streams.py
Auto-merging Lib/test/test_asyncio/test_tasks.py
CONFLICT (content): Merge conflict in Lib/test/test_asyncio/test_tasks.py
Auto-merging Lib/test/test_coroutines.py
Auto-merging Modules/_asynciomodule.c
error: could not apply 3fae04b10e... [3.11] gh-93453: Only emit deprecation warning in asyncio.get_event_loop when a new event loop is created (#99949)
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".