Requiring multiple zope Interfaces

example.py

#! /usr/bin/env python3
from zope.interface import Interface, implementer


class IA(Interface):
    def do_a() -> None:
        ...


class IB(Interface):
    def do_b() -> None:
        ...


@implementer(IA, IB)
class C:
    def do_a(self) -> None:
        ...

    def do_b(self) -> None:
        ...


@implementer(IA, IB)
class D:
    def do_a(self) -> None:
        ...

    def do_b(self) -> None:
        ...


c = C()
d = D()


def needs_IA(a: IA) -> None:
    ...


def needs_IB(b: IB) -> None:
    ...


needs_IA(c)  # ok
needs_IB(c)  # ok
needs_IA(d)  # ok
needs_IB(d)  # ok


class IAB(IA, IB):
    ...


def needs_IA_and_IB(arg: IAB) -> None:
    ...


needs_IA_and_IB(c)  # want this to be checked as ok
needs_IA_and_IB(d)  # and this too
needs_IA_and_IB(object())  # want this to be checked as not okay

gistfile1.txt

 $ mypy example.py 
example.py:59: error: Argument 1 to "needs_IA_and_IB" has incompatible type "C"; expected "IAB"  [arg-type]
example.py:60: error: Argument 1 to "needs_IA_and_IB" has incompatible type "D"; expected "IAB"  [arg-type]
example.py:61: error: Argument 1 to "needs_IA_and_IB" has incompatible type "object"; expected "IAB"  [arg-type]
Found 3 errors in 1 file (checked 1 source file)

$ python --version
Python 3.9.7

$ mypy --version
mypy 0.910

$ pip freeze | grep zope
24:mypy-zope==0.3.2
55:zope.event==4.5.0
56:zope.interface==5.4.0
57:zope.schema==6.1.0