Why do enum labels have type _StrOrPromise rather than _StrPromise?

[rchen152]

Hi there! First of all, thank you for creating django-stubs - I'm a maintainer of a type checker called pyrefly, and we've been building support for django on top of django-stubs.

I had a question about some of the asserted types in tests/assert_type/db/models/test_enums.py. The gettext_lazy function is annotated as returning _StrPromise, but calls to gettext_lazy have asserted types of _StrOrPromise, e.g.:

class Suit(IntegerChoices):
    DIAMOND = 1, _("Diamond")
    SPADE = 2, _("Spade")
    HEART = 3, _("Heart")
    CLUB = 4, _("Club")
assert_type(Suit.CLUB.label, _StrOrPromise)  # why is this not _StrPromise?

class Vehicle(IntegerChoices):
    CAR = 1, "Carriage"
    TRUCK = 2
    JET_SKI = 3

    __empty__ = _("(Unknown)")
assert_type(Vehicle.__empty__, _StrOrPromise)  # why is this not _StrPromise?

Is there some Django magic I'm not aware of that is widening these types? Or is mypy inferring types that are less precise than they could be?

I'm pretty unfamiliar with Django, so apologies if this is a silly question. Thanks in advance!

[sobolevn]

Hi @rchen152 👋
Great to see you here!

It looks like a bug to me.
Why?

1. We can't inherit from enum with values, so no "freedom to override" of StrOrPromise is required
2. We know the type of this value precisly
3. Removing str from the result union type should not really break anything

Would you like to send a PR with the fix? :)

[rchen152]

👋
I'll give it a try!