gh-127274: Defer nested methods

[mpage]

Methods (functions defined in class scope) are likely to be cleaned up by the GC anyway, so deferring nested methods will not prolong their lifetime.

Add a new code flag, CO_METHOD, that is set for functions defined in a class scope. Use that when deciding to defer functions.

• Issue: Defer functions defined in nested classes in free-threaded builds #127274

[colesbury]

LGTM

[JelleZijlstra]

The other CO_* constants are documented and exposed in the inspect module (e.g. https://docs.python.org/3.14/library/inspect.html#inspect.CO_HAS_DOCSTRING); we'll have to do that for this one too.

[mpage]

The other CO_* constants are documented and exposed in the inspect module

Should that be done for CO_NO_MONITORING_EVENTS as well (in a separate PR)?

[JelleZijlstra]

Should that be done for CO_NO_MONITORING_EVENTS as well (in a separate PR)?

Wasn't aware of that flag, but if we also added that one recently, then yes.

[mpage]

MacOS-13 build failure looks like an issue with homebrew that is unrelated to this PR.

[mpage]

@JelleZijlstra - would you please have another look?

[JelleZijlstra]

Looks good.

Could also add tests that look directly at the flags of a code object, but flags are documented as internal and an implementation detail and CO_HAS_DOCSTRINGS doesn't have tests either, so I think it's fine not to test this.