Fix Enum.value inference for Enums with @cached methods

[kmurphy4]

Before this, adding an annotation like @functools.cache to any method on an Enum caused the inference for the class's .value to fail (i.e., become Any).

Fixes#19368

[kmurphy4]

Should I add something to the changelog? I think this is a user-facing change.

[sterliakov]

We build changelog from the commit history, like #19138, so no need to add CHANGELOG entries in every PR:)

[sterliakov]

I'm not sure this check is still needed - can there be any enum_members that are implicit? That should never happen AFAIC

[kmurphy4]

Seems like it is? With

diff --git i/mypy/plugins/enums.py w/mypy/plugins/enums.py
index 35338d091..c6e9f21b6 100644
--- i/mypy/plugins/enums.py+++ w/mypy/plugins/enums.py@@ -192,7 +192,7 @@ def enum_value_callback(ctx: mypy.plugin.AttributeContext) -> Type:
node_types = (
get_proper_type(n.type) if n else None
for n in stnodes
- if n is None or not n.implicit+ if n is None
)
proper_types = [_infer_value_type_with_auto_fallback(ctx, t) for t in node_types]
underlying_type = _first(proper_types)

I get

$ pytest-ktestValueFallbackWithCachedMethod=============================testsessionstarts==============================platformlinux--Python3.12.6, pytest-8.3.5, pluggy-1.6.0rootdir: /home/kevinmurphy/src/python/mypyconfigfile: pyproject.tomltestpaths: mypy/test, mypyc/testplugins: xdist-3.7.0, cov-6.1.16workers [1item] F [100%]
===================================FAILURES===================================______________________testValueFallbackWithCachedMethod_______________________
[gw0] linux--Python3.12.6/home/kevinmurphy/src/python/mypy/venv/bin/python3data: /home/kevinmurphy/src/python/mypy/test-data/unit/check-enum.test:2543:
Failed: Unexpectedtypecheckeroutput (/home/kevinmurphy/src/python/mypy/test-data/unit/check-enum.test, line2543)
-----------------------------Capturedstderrcall-----------------------------Expected:
main:19: note: Revealedtypeis"builtins.int"main:22: note: Revealedtypeis"builtins.int" (diff)
Actual:
main:19: note: Revealedtypeis"builtins.int"main:22: note: Revealedtypeis"Any" (diff)
Alignmentoffirstlinedifference:
E: ...ote: Revealedtypeis"builtins.int"A: ...ote: Revealedtypeis"Any"^Updatethetestoutputusing--update-data (implies-n0; youcanadditionallyusethe-kselectortoupdateonlyspecifictests)
===========================shorttestsummaryinfo============================FAILEDmypy/test/testcheck.py::TypeCheckSuite::check-enum.test::testValueFallbackWithCachedMethod==============================1failedin2.26s===============================

[sterliakov]

Sorry, I didn't mean to suggest only retaining None items:) I asked if the if clause can be removed altogether: n is None or not n.implicit should be true for all n coming from enum_members (all members should not be implicit - attrs with annotation and without value are assumed to be nonmembers according to the spec). Probably none of them should be None either, maybe just

node_types = (get_proper_type(info[name].type) for name in info.enum_members)

is enough now?

[kmurphy4]

Ah, yes, I think 1cedcf9 will work! I'll go ahead and squash that into the other commit.

[kmurphy4]

.. and resolve the upstream conflict while I'm at it.

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[kmurphy4]

@sterliakov bump?

[kmurphy4]

@sterliakov bump?