Summary

I identified another problem that "blocks" the merge of astral-sh/ruff#18007 (in the sense that there are hundreds of false positives caused by this). It can be reproduced on main by explicitly annotating self: Self, and occurs when trying to initialize a generic class with a type parameter default value:

from typing import Self

class MyClass[T = int]:
    def __init__(self: Self, x: T) -> None:
        self.x = x

# error: Argument to bound method `__init__` is incorrect: Argument type `MyClass[T@MyClass]` does not satisfy upper bound of type variable `Self`
MyClass(1)

https://play.ty.dev/adc72fc1-667d-4956-aa06-ed72e1403e1f

Version

Current main (25853e237)