AttributeError when using PEP 695 syntax SerializableType subclass

[Feuermurmel]

• mashumaro version: 3.15
• Python version: 3.12.8
• Operating System: macOS 14.7.2

Description

SerializableType.__init_subclass__() does not call object.__init_subclass__(), making it impossible to use PEP 695 syntax on subclasses of SerializableType.

What I Did

The following example creates a generic SerializableType subclass using PEP 695 syntax.

from dataclasses import dataclass
from typing import Any

from mashumaro import DataClassDictMixin
from mashumaro.types import SerializableType

@dataclass
class Foo[T](SerializableType):
    @classmethod
    def _deserialize(cls, value: Any) -> Any: ...

class Model(DataClassDictMixin):
    int_foo: Foo[int]

It should be possible to use the generic type using the Foo[int] syntax, but this leads to an AttributeError.

Traceback (most recent call last):
  File "[...]/example.py", line 12, in <module>
    class Model(DataClassDictMixin):
  File "[...]/example.py", line 13, in Model
    int_foo: Foo[int]
             ~~~^^^^^
  File "[...]/opt/homebrew/Cellar/[email protected]/3.12.8/Frameworks/Python.framework/Versions/3.12/lib/python3.12/typing.py", line 395, in inner
    return _caches[func](*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "[...]/opt/homebrew/Cellar/[email protected]/3.12.8/Frameworks/Python.framework/Versions/3.12/lib/python3.12/typing.py", line 1106, in _generic_class_getitem
    for param in cls.__parameters__:
                 ^^^^^^^^^^^^^^^^^^
AttributeError: type object 'Foo' has no attribute '__parameters__'
Exit code: 1

The problem is that __parameters__ on SerializableType does not get initialized, which is probably done by object.__init_subclass__(). SerializableType.__init_subclass__() does not call object.__init_subclass__(), which leads to this problem.

[Fatal1ty]

This is interesting 🤔 I don't know why but running super().__init_subclass__() at the beginning of __init_subclass__ indeed fixes this issue.

@Feuermurmel Since you discovered this, would you be willing to become a contributor and prepare a PR? If not, I will do it anyway after the holidays.

[Feuermurmel]

I had a go at creating a PR, please have a look. I tried creating an appropriate test case based on what I found. Please provide feedback or suggestions if you'd like this to be done differently. :)