UP007 should leave type aliases alone

[aberres]

Given the following snippet, ruff should not throw an error. At least this is the behavior of pyupgrade.

There are cases where one still needs an explicit Optional. See fastapi/typer#348 / fastapi/typer#348 (comment) for an example.

Code

from __future__ import annotations

from typing import Optional

StrOrNone = Optional[str]

Output

up007.py:6:13: UP007 [*] Use `X | Y` for type annotations
Found 1 error.

[charliermarsh]

Ah that's interesting. I think we used to not change this (following pyupgrade), but I didn't see a good reason not to, and changed it. We can revert.

Note that pyupgrade will fix these cases:

from __future__ import annotations

from typing import List

StrOrNone = List[str]

[twoertwein]

might be wrong: I think this was just a limitation of mypy<1.0

[aberres]

To have some more context, the use case for me is like this:

Without the indirection pyupgrade modernizes the code as expected, and typer fails.

[charliermarsh]

Yeah that makes sense.

Is there any sense for when fastapi/typer#522 would be merged?