Define trio.Event.__bool__() to reduce bugs

[CoolCat467]

In this pull request, we implement trio.Event.__bool__() to reduce bugs.

Closes #3238

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00000%. Comparing base (77dd921) to head (02c3794).

Additional details and impacted files

@@               Coverage Diff               @@
##                 main        #3322   +/-   ##
===============================================
  Coverage   100.00000%   100.00000%           
===============================================
  Files             125          125           
  Lines           19251        19263   +12     
  Branches         1304         1304           
===============================================
+ Hits            19251        19263   +12     

Files with missing lines	Coverage Δ
src/trio/_sync.py	100.00000% <100.00000%> (ø)
src/trio/_tests/test_sync.py	100.00000% <100.00000%> (ø)

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Zac-HD]

This is a strange request, but could we raise an error if some global variable is set? That way I could monkeypatch in the error behavior, even before we deal with every other trio deprecation.

[A5rocks]

I think you can set a specific filterwarning configuration s.t. a specific warning will raise instead of warning.

(in this case, I think just setting the PYTHONWARNINGS envvar to error:<the message>:DeprecationWarning should work?)

[A5rocks]

Thanks!

[A5rocks]

It's probably going to be 0.31.0 but I can update this whenever I make a release...

[A5rocks]

The unfortunate thing is this actually breaks --enable-error-code=truthy-bool because that only warns about inheriting __bool__ from object. But, I doubt anyone actually relies on that behavior! (in turn, it should now get flagged by --enable-error-code=redundant-expr... but doesn't? I think that's a bug)

[TeamSpen210]

Define it only if not TYPE_CHECKING, then mypy should continue to warn. Or typing_extensions.deprecated. Hmm might want to start using the latter in general...

[A5rocks]

Well, supposedly if not TYPE_CHECKING annoys jedi. But yeah one of those might be nice if it works.