regression involving subclass and overloaded constructor

[cleoold]

Describe the bug
Following code reports error. If we move the method to the parent class the error disappears. If we explicitly annotate the inner() with -> Iterable[ContainerSub[T_co]] instead of a generator the error also disappears. Replacing the __init__'s arg with Union instead of overloading can also avoid the error.

To Reproduce
Steps to reproduce the behavior.

Expected behavior
Code used to type check before 1.1.262

Screenshots or Code

T_co = TypeVar('T_co', covariant=True)

class Container(Generic[T_co]):
    @overload
    def __init__(self, arg: Iterable[T_co]): ...
    @overload
    def __init__(self, arg: Callable[[], Iterable[T_co]]): ...
    def __iter__(self) -> Iterator[T_co]: ...


class ContainerSub(Container[T_co]):
    def method(self) -> 'ContainerSub[ContainerSub[T_co]]':
        def inner():  # Generator[ContainerSub[T_co@ContainerSub], None, None]
            for x in self:
                yield ContainerSub(lambda: [x])
        return ContainerSub(inner)
                   ^~~~~~~~~~~~~
error: Expression of type "ContainerSub[ContainerSub[ContainerSub[T_co@ContainerSub]]]" cannot be assigned to return type "ContainerSub[ContainerSub[T_co@ContainerSub]]"
    TypeVar "T_co@ContainerSub" is covariant
      TypeVar "T_co@ContainerSub" is covariant
        Type "ContainerSub[T_co@ContainerSub]" cannot be assigned to type "T_co@ContainerSub" (reportGeneralTypeIssues)

VS Code extension or command-line
pyright 1.1.270

Additional context
Add any other context about the problem here.

[erictraut]

Thanks for the bug report. This was due to an existing bug that was being masked previously. A change related to another bug fix exposed this one.

I'll need to investigate how to fix this without breaking other cases. In the meantime, you can work around this issue by providing an explicit return type annotation for inner.

        def inner() -> Generator[ContainerSub[T_co], None, None]:
            for x in self:
                yield ContainerSub(lambda: [x])

[cleoold]

Thanks for the bug report. This was due to an existing bug that was being masked previously. A change related to another bug fix exposed this one.

I'll need to investigate how to fix this without breaking other cases. In the meantime, you can work around this issue by providing an explicit return type annotation for inner.

        def inner() -> Generator[ContainerSub[T_co], None, None]:
            for x in self:
                yield ContainerSub(lambda: [x])

thanks. I didn't know annotating Generator would also work

[erictraut]

This will be fixed in the next release.

[erictraut]

This is addressed in pyright 1.1.272. It will also be included in a future release of pylance.