bug(stubgen): instance variables defined in `__init__` method are missing from generated stubs

[tobyh-canva]

Summary

Classes in generated stubs are missing attributes if those attributes are not explicitly annotated at the class-level. The classic canonical, non-dataclass way of defining attributes in __init__(self, ...) is seemingly incompatible with stubgen.

Example

Input

class A:
    def __init__(self, name: str) -> None:
        self.name = name

Expected result

class A:
    name: str

    def __init__(self, name: str) -> None: ...

Actual result

class A:
    def __init__(self, name: str) -> None: ...