Doesn't quite understand that dynamically created classes are classes

[wiml]

Python allows you to create new classes using the three-argument form of the type() builtin. I can't tell if it's a mypy-zope problem or a mypy problem, but this doesn't typecheck properly:

import zope.interface
from zope.interface import Interface, Attribute, declarations

class IFoo(Interface):
    x = Attribute("Some thing or other")

class NormalClass:
    x = 12
declarations.classImplements(NormalClass, IFoo)

print(list(zope.interface.implementedBy(NormalClass)))

DynamicClass = type("DynamicClass", (object,), { "x": 42 })
declarations.classImplements(DynamicClass, IFoo)

print(list(zope.interface.implementedBy(DynamicClass)))

In this example NormalClass and DynamicClass are equivalent (except for their names and the initial value of x). At runtime they behave similarly and the classImplements() calls do what you'd think. Mypy however produces this error:

error: dyntest.DynamicClass is not a class, cannot mark it as a interface implementation  [misc]

[fschulze]

I get a similar issue when I try to pass in the class of an instance with .__class__. I use that in an adapter to mark classes I don't control as having an interface and verifying it afterwards. I already tried these variants on a wrapper function:

T = TypeVar("T")

def get_class(obj: T) -> Type[T]:
    return obj.__class__

def get_class(obj: Any) -> Type[Any]:
    return obj.__class__