can't specify generic types when instantiating frozen dataclass with slots

[daddinuz]

Bug report

Bug description:

from dataclasses import dataclass

@dataclass(frozen=True, slots=True)
class Foo[T]:
  pass

foo = Foo() # this line works
foo = Foo[int]() # this one does not

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.12/typing.py", line 1142, in __call__
    result.__orig_class__ = self
    ^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 5, in __setattr__
TypeError: super(type, obj): obj must be an instance or subtype of type

Python 3.12.2 (main, Feb 21 2024, 00:00:00) [GCC 13.2.1 20231205 (Red Hat 13.2.1-6)]

CPython versions tested on:

3.12

Operating systems tested on:

Linux

[Eclips4]

FYI: this doesn't relate to the new (PEP 695) syntax.
Example with the old syntax:

from dataclasses import dataclass
from typing import TypeVar, Generic


T = TypeVar("T")


@dataclass(frozen=True, slots=True)
class Foo(Generic[T]):
  pass

foo = Foo() # this line works
foo = Foo[int]() # this one does not

Traceback (most recent call last):
  File "/home/eclips4/CLionProjects/cpython/example.py", line 13, in <module>
    foo = Foo[int]() # this one does not
          ^^^^^^^^^^
  File "/usr/local/lib/python3.11/typing.py", line 1277, in __call__
    result.__orig_class__ = self
    ^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 5, in __setattr__
TypeError: super(type, obj): obj must be an instance or subtype of type

[AlexWaygood]

Happily, this specific exception was fixed just last month, in #115213. The fix was backported, so it will be included in the next releases of Python 3.12 and Python 3.11. The typing module is in the clear here.

However, it looks like dataclasses might also be using super() incorrectly there? Not sure.

[Eclips4]

Oh, this do not reproducible on the current main.

[JelleZijlstra]

This is a symptom of the general problem where slotted dataclasses work by creating a new class, which breaks super(). There are several other similar issues and there's no obvious solution.

cc @ericvsmith for dataclasses.

[AlexWaygood]

This is a symptom of the general problem where slotted dataclasses work by creating a new class, which breaks super(). There are several other similar issues and there's no obvious solution.

cc @ericvsmith for dataclasses.

If there are already other similar issues regarding super() in dataclasses, then we can probably close this one, as the user-visible bug here has already been fixed by #115213

[JelleZijlstra]

https://github.com/python/cpython/issues?q=is%3Aissue+is%3Aopen+dataclasses+slots+super lists several.

[AlexWaygood]

Thanks for the report, @daddinuz! Your bug was valid; we'd just already fixed it before you filed the issue ;)