Update pydantic-duality to fix the infinite recursion bug

[zmievsa]

It was a long one. Here's the entire process for the fix:

Resolves zmievsa/pydantic-duality#21

1. Here's the minimal reproducible example:

import abc

from pydantic import BaseModel
from pydantic_duality import DualBaseModel


class AzureStoredConfig(DualBaseModel):
    resource_group: str


# from cryptography.hazmat.primitives.hashes import HashContext

# Which actually contains the code below:

# ```


class HashContext(metaclass=abc.ABCMeta):
    pass


from cryptography.hazmat.bindings._rust import openssl as rust_openssl

HashContext.register(rust_openssl.hashes.Hash)


# ```


class AzureConfig(AzureStoredConfig, BaseModel):
    pass


class GCPVolumeDiskBackendData(DualBaseModel):
    disk_type: str

2. Here's the fix in pydantic-duality
3. Here's an alternative fix within dstack

I am still not sure what exactly is causing the bug but here's what happens:

1. Because pydantic-duality now uses DualBaseModel.__response__ in subclass checks, the response model gets generated (exactly once though) during the very first subclass check
2. In one of those checks, we have issubclass(annotation, pydantic.BaseModel). The specific class that caused the issue here is str so issubclass(str, pydantic.BaseModel)
3. For some unknown and weird reason, it calls DualBaseModel.__subclasshook__ instead of using BaseModel's or type's default subclass check. Not sure how it is possible but I verified that everything from the code block above is absolutely necessary for this situation to happen

[zmievsa]

NOTICE that I dropped support for python 3.8 as it reached its EOL. Is that fine with you?

[peterschmidt85]

cc @jvstme on Python 3.8

[r4victor]

@zmievsa, thanks for the writeup and the fix! We're going to support 3.13 and drop 3.8 also, so that's fine.

Regarding the issue, I have a hypothesis what can be the root cause:

For some unknown and weird reason, it calls DualBaseModel.__subclasshook__ instead of using BaseModel's or type's default subclass check.

This is due to this ABCMeta.__subclasscheck__ logic that calls __subclasscheck__ of subclassed metaclasses:

https://github.com/python/cpython/blob/19e93e2e269889ecb3c4c039091abff489f247c2/Lib/_py_abc.py#L140-L144

The problem only appears if there is any other MyMetaclass.register() call because it invalidates the negative subclass cache:

https://github.com/python/cpython/blob/19e93e2e269889ecb3c4c039091abff489f247c2/Lib/_py_abc.py#L28-L33

So the behaviour does not depend on any cryptography logic. This example will do:

import abc

from pydantic import BaseModel
from pydantic_duality import DualBaseModel


class AzureStoredConfig(DualBaseModel):
    resource_group: str


class MyMeta(metaclass=abc.ABCMeta):
    pass


MyMeta.register(int)


class AzureConfig(AzureStoredConfig, BaseModel):
    pass


class GCPVolumeDiskBackendData(DualBaseModel):
    disk_type: str

[zmievsa]

@r4victor nice catch! You are likely right.

[jvstme]

I will take care of merging this PR just a bit later, once we drop Python 3.8. Probably today. Thanks, @zmievsa!

upd: will rebase and merge after #1910