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1.5.0 regression: register enum member typed as callable #15870
Description
Bug Report
When an enum has a register member, with mypy 1.5.0, mypy falsely considers it being of type Callable[[Type[_T]], Type[_T]] rather than the enum type.
Bisected to 21cc1c7:
To Reproduce
import enum
class E(enum.Enum):
register = enum.auto()
def fun(a: E) -> None:
pass
fun(E.register)https://mypy-play.net/?mypy=latest&python=3.11&gist=6115e84d079dcb7d03fe44174ddf5fb1
Actual Behavior
test.py:10: error: Argument 1 to "fun" has incompatible type "Callable[[type[_T]], type[_T]]"; expected "E" [arg-type]
I believe this happens somehow because in typeshed (and only there), EnumMeta inherits ABCMeta:
and ABCMeta has a register method:
https://docs.python.org/3/library/abc.html#abc.ABCMeta.register
Your Environment
- Mypy version used: mypy 1.5.0 (compiled: yes)
- Mypy command-line flags: none
- Mypy configuration options from
mypy.ini(and other config files): none - Python version used: Python 3.11.4
Activity
Ignore mypy regression
AlexWaygood commentedon Aug 14, 2023
Fixed in python/typeshed#10577.
@svalentin FYI — this is another small typeshed tweak that fixes a regression in mypy 1.5.0 — it could possibly be worth cherry-picking to a 1.5 patch release if the PyPI overlords ever let us make another mypy release :-)
Having said that, idk how many people are defining enums with a
registermember — it seems unlikely to me that too many people will be hitting this regression!svalentin commentedon Aug 14, 2023
We should be starting 1.6 really soon since 1.5 was delayed quite a bit and there's already quite a number of changes to pick up. So it's probably best to just wait for 1.6.
If we want to pick this up for 1.5, we would need 1.5.2 as 1.5.1 is "cut" and just waiting for PyPI gods. (1.5 ended up being such an odd release)
The-Compiler commentedon Aug 15, 2023
Thanks for the quick fix!
Agreed, especially given that it's recommended to use
ALL_CAPSfor enum members. I hit this by pure chance, by not following that convention for historical reasons, and by having aKeyMode.register(as in vim registers) enum member. 😅davidhalter commentedon Aug 16, 2023
Does anybody here know how Mypy resolves the metaclass conflict (in typeshed) for
StrEnum?StrEnumbases are:So AFAIK there's this conflict, which normally would raise
Metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases. However Mypy seems to stay silent on this one.