False positive used-before-assignment for variable annotations when using TYPE_CHECKING

[mew1033]

Bug description

I know this has been looked at before, but I just ran into it again with pylint 2.15.4. If an import is guarded behind TYPE_CHECKING, I'm getting an used-before-assignment error when using that import in a type definition.

Configuration

No response

Command used

pylint file.py

Pylint output

file.py:7:19: E0601: Using variable 'PublishBatchRequestEntryTypeDef' before assignment (used-before-assignment)

Expected behavior

It shouldn't error

Pylint version

pylint 2.15.4
astroid 2.12.11
Python 3.9.14 (main, Sep  7 2022, 23:43:29) 
[GCC 9.4.0]

OS / Environment

No response

Additional dependencies

No response

[mbyrnepr2]

Thanks for reporting this @mew1033. Can you please provide a minimal reproducible example to help us dig into this one?

[mew1033]

@mbyrnepr2 So sorry, I got the example ready and then completely forgot to add it to the issue. Here's a snippet that shows the issue. If you remove the if TYPE_CHECKING: line, the issues goes away.

from typing import TYPE_CHECKING
import boto3

if TYPE_CHECKING:
    from mypy_boto3_sns.type_defs import PublishBatchRequestEntryTypeDef


def publish_to_sns():
    """
    Create SNS messages and publish them
    """
    sns_client = boto3.client("sns")
    messages: list[PublishBatchRequestEntryTypeDef] = []

[mbyrnepr2]

No worries - thank you!

[jacobtylerwalls]

Thanks! Per PEP 526, there is a difference in the runtime effect of variable annotations versus function annotations. Given that, the requirement in 3159b17 that both branches of an if TYPE_CHECKING: case define the name is too strict for variable annotations.

[jacobtylerwalls]

Some helpful test cases given in #7773