Request: More autofixes for redundant-none-literal/PYI061

[Avasam]

• A minimal code snippet that reproduces the bug.
  https://docs.astral.sh/ruff/rules/redundant-none-literal mentions that the rule is sometimes autofixable, but I landed on the following cases which are not autofixed and I believe should:

def get_rotation(rotation: float | Literal[None, "horizontal", "vertical"]) -> float: ...

def spy(
    Z,
    precision: float | Literal["present"] = ...,
    marker=...,
    markersize=...,
    aspect: Literal["equal", "auto", None] | float = ...,
    origin: Literal["upper", "lower"] = ...,
    **kwargs,
) -> tuple[AxesImage, Line2D]: ...

class Axes(_AxesBase):
    def spy(
        self,
        Z,
        precision: float | Literal["present"] = 0,
        marker=...,
        markersize=...,
        aspect: Literal["equal", "auto", None] | float = "equal",
        origin: Literal["upper", "lower"] = ...,
        **kwargs,
    ) -> AxesImage | Line2D: ...

• The command you invoked
  ruff check --fix --preview --select=PYI061 --isolated

• The current Ruff version (ruff --version).
  ruff 0.8.0

[kiran-4444]

I’d like to take this up.

[kiran-4444]

So, if I understand this correctly the rule PYI061 is working for snippets like this:

from typing import Literal

a: Literal[None]
b: Literal[1, 2, 3, "foo", 5, None]

which gets auto-fixed to:

from typing import Literal

a: None
b: Literal[1, 2, 3, "foo", 5, None]

Here, I can see that the second statement isn't getting fixed. Is this the issue about? To fix things like this adhering to PYI061?

[Avasam]

@kiran-4444 Exactly. Even the error message alludes to this being possible to autofix, just not implemented:

PYI061 `Literal[None, ...]` can be replaced with `Literal[...] | None`
  |
3 | a: None
4 | b: Literal[1, 2, 3, "foo", 5, None]
  |                               ^^^^ PYI061
  |
  = help: Replace with `Literal[...] | None`

[InSyncWithFoo]

This seems to have been resolved by #14872.

[Avasam]

Yep, Looks like this is closed by #14872 !

[Avasam]

Hmmm, I'm on 0.9.3 and all three of my example cases don't yet autofix:
ruff check --fix --unsafe-fixes --preview

stubs\matplotlib\axes\_axes.pyi:577:42: PYI061 `Literal[None, ...]` can be replaced with `Literal[...] | None`
    |
575 |         marker=...,
576 |         markersize=...,
577 |         aspect: Literal["equal", "auto", None] | float = "equal",
    |                                          ^^^^ PYI061
578 |         origin: Literal["upper", "lower"] = ...,
579 |         **kwargs,
    |
    = help: Replace with `Literal[...] | None`

stubs\matplotlib\pyplot.pyi:715:38: PYI061 `Literal[None, ...]` can be replaced with `Literal[...] | None`
    |
713 |     marker=...,
714 |     markersize=...,
715 |     aspect: Literal["equal", "auto", None] | float = ...,
    |                                      ^^^^ PYI061
716 |     origin: Literal["upper", "lower"] = ...,
717 |     **kwargs,
    |
    = help: Replace with `Literal[...] | None`

stubs\matplotlib\text.pyi:16:44: PYI061 `Literal[None, ...]` can be replaced with `Literal[...] | None`
   |
14 | from .transforms import Bbox, Transform
15 |
16 | def get_rotation(rotation: float | Literal[None, "horizontal", "vertical"]) -> float: ...
   |                                            ^^^^ PYI061
17 |
18 | class Text(Artist):
   |
   = help: Replace with `Literal[...] | None`

Found 3 errors.

[charliermarsh]

Fixes just fine for me in the playground: https://play.ruff.rs/fd2b0091-14e2-44e2-9208-983d8e9c1862

[Avasam]

I get it: on Python 3.9 the fix isn't offered at all rather than being "unsafe" (or using Union). I must've tested on 3.10 when I marked the issue as closed.
#14872 (review)

We can't safely offer the fix with the | syntax on Python <=3.9, as the | syntax for unions was added in Python 3.10. Possibly we could in the future use typing.Union for the fix and offer it even on older versions of Python, but I think we can leave that to another PR :-)

So I guess the fix being marked as unsafe but available was also left aside in that PR. I'll open a different issue for that specific use-case !

Done here: #15795