Description
TC003:
Checks for standard library imports that are only used for type annotations, but aren't defined in a type-checking block.
https://docs.astral.sh/ruff/rules/typing-only-standard-library-import/#typing-only-standard-library-import-tc003
TYPE_CHECKING = False
from __future__ import annotations
TYPE_CHECKING = False
if TYPE_CHECKING:
import os
def thing(locale: os.PathLike[str]) -> None: ...Ruff doesn't allow it:
❯ ruff --version
ruff 0.9.6
❯ ruff check --select TC --isolated 1.py
1.py:5:12: TC003 Move standard library import `os` into a type-checking block
|
3 | TYPE_CHECKING = False
4 | if TYPE_CHECKING:
5 | import os
| ^^ TC003
|
= help: Move into type-checking block
Found 1 error.
But upstream https://pypi.org/project/flake8-type-checking/ does:
❯ flake8 --version
7.1.1 (flake8-2020: 1.8.1, flake8-implicit-str-concat: 0.5.0, flake8-type-checking: 3.0.0, mccabe: 0.7.0, pycodestyle: 2.12.1, pyflakes: 3.2.0) CPython 3.13.2 on Darwin
❯ flake8 1.py
❯
from typing import TYPE_CHECKING
Both are fine with this:
from __future__ import annotations
from typing import TYPE_CHECKING
if TYPE_CHECKING:
import os❯ ruff check --select TC --isolated 1.py
All checks passed!
❯ flake8 1.py --statistics
❯
But the whole point of this typing-only-standard-library-import TC003 check is to avoid imports that are only needed for type checking:
Unused imports add a performance overhead at runtime, and risk creating import cycles. If an import is only used in typing-only contexts, it can instead be imported conditionally under an if TYPE_CHECKING: block to minimize runtime overhead.
See also:
Which look like it should have fixed it in 0.9.5, but I can repro in 0.9.4-0.9.6.
Description
TC003:
https://docs.astral.sh/ruff/rules/typing-only-standard-library-import/#typing-only-standard-library-import-tc003
TYPE_CHECKING = FalseRuff doesn't allow it:
But upstream https://pypi.org/project/flake8-type-checking/ does:
from typing import TYPE_CHECKINGBoth are fine with this:
❯ ruff check --select TC --isolated 1.py All checks passed! ❯ flake8 1.py --statistics ❯But the whole point of this
typing-only-standard-library-importTC003 check is to avoid imports that are only needed for type checking:See also:
TYPE_CHECKINGwith__future__.annotations#15681TYPE_CHECKINGforin_type_checking_block#15719Which look like it should have fixed it in 0.9.5, but I can repro in 0.9.4-0.9.6.