B023 is emitted when closure is defined inside a loop and uses a variable from the same loop #7847
Description
Code snippet that reproduces the bug
The following snippet emits B023 (function-uses-loop-variable):
def make_squared_list(size: int) -> list[int]:
result = []
for i in range(size):
square = i**2
def _append_to_result() -> None:
# Function definition does not bind loop variable `square` Ruff[B023](https://docs.astral.sh/ruff/rules/function-uses-loop-
# variable)
# (variable) square: int
result.append(square)
_append_to_result()
return resultI have found out that adding a nonlocal <variable> declaration followed by an assignment to itself makes the error go away, i.e. change the closure _append_to_result to this:
def _append_to_result() -> None:
# No longer emits any warnings.
nonlocal square
square = square
result.append(square)Command invoked
$ poetry run ruff ./ruff_bug.pyCurrent ruff settings
Relevant sections from pyproject.toml:
[tool.ruff]
select = [
"F",
"E",
"W",
"I",
"N",
"UP",
"S",
"BLE",
"B",
"A",
"C4",
"SIM",
"PERF",
"RUF"
]
line-length = 88
target-version = "py311"
ignore = [
"S101",
"B011",
]
[tool.ruff.pycodestyle]
ignore-overlong-task-comments = trueCurrent ruff version
$ poetry run ruff --version
ruff 0.0.291