Dataclass 'transformed' frozen model is not hashable

[layday]

With the new dataclass transform decorator, Pyright reports for frozen models that they are not hashable:

# pyright: strict

from typing import Hashable


from pydantic import BaseModel

class Foo(BaseModel, frozen=True):
    pass

foo: Hashable = Foo()  # Error: Expression of type "Foo" cannot be assigned to declared type "Hashable"
reveal_type(Foo.__hash__)  # Type of "Foo.__hash__" is "None"


from dataclasses import dataclass

@dataclass(frozen=True)
class Bar:
    pass

bar: Hashable = Bar()  # No error
reveal_type(Bar.__hash__)  # Type of "Bar.__hash__" is "(self: Bar) -> int"

Originally posted by @layday in #2721 (comment)

[layday]

Peculiarly if I change eq_default to false on the ModelMetaclass then it type checks but I don't see why that should be.

Okay, yeah, it just straight up doesn't seem to pick up frozen. Because, for dataclasses, "... If eq is true and frozen is false, __hash__() will be set to None" (which is how hashing behaves in Python more generally - implementing __eq__ automatically sets __hash__ to None).

[layday]

I'll open an issue on Pyright's tracker when I get around to it.