I am reporting strange behaviors since ruff 0.8.5. I have not tried ruff from master branch.

Example 1

Example file test.py:

import collections
import collections.abc
from typing import Callable, Iterable


def test(a: Iterable[str], b: Callable[[str], None]):
    return collections.ChainMap()

Command:

ruff --isolated check --target-version=py39 --select=UP006,UP035 --preview --fix --unsafe-fixes test.py

• File content after ruff 0.8.4 applied:
  (doesn't fix Callable because it's marked as py310+)

  import collections
  import collections.abc
  from typing import Callable
  from collections.abc import Iterable
  
  
  def test(a: Iterable[str], b: Callable[[str], None]):
      return collections.ChainMap()

• File content after ruff 0.8.5 applied:
  (weird!! explicit reference to collections.abc.Callable)

  import collections
  import collections.abc
  from typing import Callable
  from collections.abc import Iterable
  
  
  def test(a: Iterable[str], b: collections.abc.Callable[[str], None]):
      return collections.ChainMap()

Example 2

Example file test.py:

from typing import Callable, Iterable


def test(a: Iterable[str], b: Callable[[str], None]):
    pass

Command:

ruff --isolated check --target-version=py39 --select=UP006,UP035 --preview --fix --unsafe-fixes test.py

• File content after ruff 0.8.4 applied:

  from typing import Callable
  from collections.abc import Iterable
  
  
  def test(a: Iterable[str], b: Callable[[str], None]):
      pass

• File content after ruff 0.8.5 applied:

  Same, but with this additional output:

  error: Failed to create fix for NonPEP585Annotation: Unable to insert `Iterable` into scope due to name conflict
  error: Failed to create fix for NonPEP585Annotation: Unable to insert `Callable` into scope due to name conflict
  error: Failed to create fix for NonPEP585Annotation: Unable to insert `Callable` into scope due to name conflict
  test.py:5:31: UP006 Use `collections.abc.Callable` instead of `Callable` for type annotation
    |
  5 | def test(a: Iterable[str], b: Callable[[str], None]):
    |                               ^^^^^^^^ UP006
  6 |     pass
    |
    = help: Replace with `collections.abc.Callable`
  
  Found 2 errors (1 fixed, 1 remaining).
  

  This was referenced in Errors for attempted autofixes visible to users even without passing --fix and for noqa lines #15229
  but the description of the "fix" for that issue seems to imply that the error messages themselves are the only problem, which I think is not right.
  Ruff should be able to replace from typing import Callable.

Example 3

Example file test.py:

from __future__ import annotations

from typing import Callable, Iterable


def test(a: Iterable[str], b: Callable[[str], None]):
    pass

Command: (note py38 here, unlike all other examples)

ruff --isolated check --target-version=py38 --select=UP006,UP035 --preview --fix --unsafe-fixes test.py

• File content after ruff 0.8.4 applied:

  No change, no errors

• File content after ruff 0.8.5 applied:

  No change, but with this additional output (why does it fail to perform the fixes here??):

  error: Failed to create fix for NonPEP585Annotation: Unable to insert `Iterable` into scope due to name conflict
  error: Failed to create fix for NonPEP585Annotation: Unable to insert `Callable` into scope due to name conflict
  test.py:6:13: UP006 Use `collections.abc.Iterable` instead of `Iterable` for type annotation
    |
  6 | def test(a: Iterable[str], b: Callable[[str], None]):
    |             ^^^^^^^^ UP006
  7 |     return collections.ChainMap()
    |
    = help: Replace with `collections.abc.Iterable`
  
  test.py:6:31: UP006 Use `collections.abc.Callable` instead of `Callable` for type annotation
    |
  6 | def test(a: Iterable[str], b: Callable[[str], None]):
    |                               ^^^^^^^^ UP006
  7 |     return collections.ChainMap()
    |
    = help: Replace with `collections.abc.Callable`
  
  Found 2 errors.
  

Example 4

Example file test.py:

from __future__ import annotations

import collections
import collections.abc
from typing import Callable, Iterable


def test(a: Iterable[str], b: Callable[[str], None]):
    return collections.ChainMap()

Command:

ruff --isolated check --target-version=py39 --select=UP006,UP035 --preview --fix --unsafe-fixes test.py

• File content after ruff 0.8.4 applied:

  from __future__ import annotations
  
  import collections
  import collections.abc
  from typing import Callable
  from collections.abc import Iterable
  
  
  def test(a: Iterable[str], b: Callable[[str], None]):
      return collections.ChainMap()

• File content after ruff 0.8.5 applied:
  (weirdest one yet!!! changes only one of the two imports, and then proceeds to not even use the imports!!)

  from __future__ import annotations
  
  import collections
  import collections.abc
  from typing import Callable
  from collections.abc import Iterable
  
  
  def test(a: collections.abc.Iterable[str], b: collections.abc.Callable[[str], None]):
      return collections.ChainMap()