Mypy 1.7.0 Tuple unpacking gives errors

[shreyasvinaya]

Bug Report

Tuple unpacking gives error: Never object is not iterable

To Reproduce

from typing import TypeVar, Union, Tuple, Any, Sequence

T = TypeVar("T")
OneOrMany = Union[T, Sequence[T]]


def create_dataset(inputs: Union[OneOrMany[str], Tuple[Any]], ):
    if isinstance(inputs, tuple):
        if len(inputs) == 1:
            input_files = inputs[0]
            if isinstance(inputs, str):
                input_files = [inputs]
        elif len(inputs) == 2:
            input_files, labels = inputs
        elif len(inputs) == 3:
            input_files, labels, weights = inputs

Expected Behavior

No errors, gave no errors in mypy 1.6.1 release

Actual Behavior

sample.py:14: error: Never object is not iterable  [misc]
sample.py:16: error: Never object is not iterable  [misc]

Your Environment

• Mypy version used: 1.7.0
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.10.10

[AlexWaygood]

Thanks for the bug report! This was fixed yesterday, in efa5dcb (this issue is a duplicate of #16468).

The fix will be released in either mypy 1.7.1 or mypy 1.8 (follow #16341 for updates on possible patch releases for mypy 1.7)