UP036 auto-fixer breaks code at runtime after #5766

[mrcljx]

After #5766 the auto-fixer for UP036 has broken some code for us:

from typing import Any

import cachetools

class MyClass:
    def __init__(self) -> None:
        self._cache: "cachetools.LRUCache[Any, Any]" = cachetools.LRUCache(maxsize=100)

ruff --isolated --select UP --fix ruff_up037.py

ruff_up037.py:7:22: UP037 [*] Remove quotes from type annotation

The auto-fixer strips the quotes. However this is semantically not valid, as LRUCache is not Generic at runtime, only for the pyi files.

$ ruff --version
ruff 0.0.280

[clement-escolano]

I would like to add another example of the rule breaking code at runtime:

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from dependency import MyClass

def my_func():
    result: list["MyClass"] = []
    return result

The quotes around MyClass are removed which breaks at run time.

If this should be in a separate issue, please tell me and I will open one

[charliermarsh]

@clement-escolano -- Hmm, I'm unable to reproduce. This, for example, runs without error for me:

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from dependency import MyClass

def my_func():
    result: list[MyClass] = []
    return result

my_func()

Running python foo.py completes without error.

[clement-escolano]

@charliermarsh
The issue is that dependency is not installed in our production environment (in our project, this is django_stubs_ext which is only used in development for typing). If this is out of scope of this rule, I understand :-)

[charliermarsh]

I don't think the dependency has to be installed in order for the above to work, I don't have a dependency called dependency locally :) Python doesn't evaluate unquoted annotated assignments within function bodies. But perhaps there's another reason that it's failing for you? Or is it just that it's showing up as an error in your editor?

The same is true of the originating comment @mrcljx. This runs fine for me:

from typing import Any

import cachetools

class MyClass:
    def __init__(self) -> None:
        self._cache: cachetools.LRUCache[Any, Any] = cachetools.LRUCache(maxsize=100)

MyClass()

[mrcljx]

@charliermarsh This indeed seems to have been an IDE bug. Very sorry for bothering you with this report, thanks for Ruff!

[charliermarsh]

No worries, I went ahead and reverted any way, it seems like it's going to cause some annoyance for folks.

[zanieb]

@mrcljx Which IDE? Did you open an issue there?

[mrcljx]

PyCharm. That said, it also had that warning earlier (but it became more visually pronounced in ^):