mypy_repro.py

# mypy mypy_repro.py fails with
# mypy_repro.py:28: error: Incompatible return value type (got "Union[List[Bar], List[Baz]]", expected "List[A]")  [return-value]
# no issues with pyright
# mypy --version: mypy 1.2.0 (compiled: yes)

from typing import List, TypeVar, Union

TFoo = TypeVar("TFoo", bound="Foo")


class Foo:
    def wrap(self: TFoo) -> List[TFoo]:
        return [self]


class Bar(Foo):
    ...


class Baz(Foo):
    ...


A = TypeVar("A", bound=Union[Bar, Baz])


def foo(x: A) -> List[A]:
    return x.wrap()