Ignore argument assignments when enforcing RET504

[charliermarsh]

Summary

Right now, we trigger a RET504 (unnecessary-assign) error here:

def str_to_bool(val):
    if isinstance(val, bool):
        return val
    val = val.strip().lower()
    if val in ("1", "true", "yes"):
        return True

    return False

The issue is that we can't find an assignment to val prior to the first return val, so the code as it exists today falls back to assuming that val is defined at the start of the function. Instead, we need to avoid flagging cases in which the return comes before an explicit in-function assignment (like arguments, or returning values defined outside of the function).

Closes #3992.

[github-actions]

PR Check Results

Ecosystem

ℹ️ ecosystem check detected changes. (+0, -1, 0 error(s))

airflow (+0, -1)

- airflow/providers/oracle/hooks/oracle.py:47:16: RET504 Unnecessary variable assignment before `return` statement

Benchmark

Linux

group                                      main                                   pr
-----                                      ----                                   --
linter/all-rules/large/dataset.py          1.02     14.9±0.16ms     2.7 MB/sec    1.00     14.7±0.19ms     2.8 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.01      3.7±0.04ms     4.5 MB/sec    1.00      3.7±0.05ms     4.5 MB/sec
linter/all-rules/numpy/globals.py          1.00    464.6±1.49µs     6.4 MB/sec    1.00    463.4±1.69µs     6.4 MB/sec
linter/all-rules/pydantic/types.py         1.00      6.2±0.09ms     4.1 MB/sec    1.00      6.2±0.09ms     4.1 MB/sec
linter/default-rules/large/dataset.py      1.00      7.2±0.04ms     5.6 MB/sec    1.02      7.4±0.06ms     5.5 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.00   1627.1±3.67µs    10.2 MB/sec    1.02  1654.8±24.34µs    10.1 MB/sec
linter/default-rules/numpy/globals.py      1.00    180.4±2.08µs    16.4 MB/sec    1.01    182.2±0.50µs    16.2 MB/sec
linter/default-rules/pydantic/types.py     1.00      3.3±0.01ms     7.6 MB/sec    1.01      3.4±0.02ms     7.5 MB/sec
parser/large/dataset.py                    1.00      5.8±0.01ms     7.0 MB/sec    1.00      5.8±0.02ms     7.0 MB/sec
parser/numpy/ctypeslib.py                  1.00   1137.9±0.70µs    14.6 MB/sec    1.00   1141.5±5.78µs    14.6 MB/sec
parser/numpy/globals.py                    1.00    112.5±0.24µs    26.2 MB/sec    1.00    112.1±0.19µs    26.3 MB/sec
parser/pydantic/types.py                   1.00      2.5±0.00ms    10.2 MB/sec    1.00      2.5±0.01ms    10.3 MB/sec

Windows

group                                      main                                   pr
-----                                      ----                                   --
linter/all-rules/large/dataset.py          1.01     17.1±0.21ms     2.4 MB/sec    1.00     17.0±0.23ms     2.4 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.00      4.3±0.09ms     3.9 MB/sec    1.00      4.3±0.12ms     3.9 MB/sec
linter/all-rules/numpy/globals.py          1.04    516.0±8.51µs     5.7 MB/sec    1.00    494.4±7.59µs     6.0 MB/sec
linter/all-rules/pydantic/types.py         1.01      7.2±0.12ms     3.5 MB/sec    1.00      7.2±0.13ms     3.5 MB/sec
linter/default-rules/large/dataset.py      1.01      8.5±0.10ms     4.8 MB/sec    1.00      8.4±0.10ms     4.8 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.01  1853.5±26.39µs     9.0 MB/sec    1.00  1832.7±21.69µs     9.1 MB/sec
linter/default-rules/numpy/globals.py      1.03    199.0±5.93µs    14.8 MB/sec    1.00    194.1±6.57µs    15.2 MB/sec
linter/default-rules/pydantic/types.py     1.01      3.9±0.05ms     6.6 MB/sec    1.00      3.8±0.06ms     6.7 MB/sec
parser/large/dataset.py                    1.00      6.6±0.05ms     6.2 MB/sec    1.01      6.7±0.04ms     6.1 MB/sec
parser/numpy/ctypeslib.py                  1.00  1270.6±14.36µs    13.1 MB/sec    1.00  1266.0±24.79µs    13.2 MB/sec
parser/numpy/globals.py                    1.00    125.8±2.36µs    23.5 MB/sec    1.01    126.7±2.96µs    23.3 MB/sec
parser/pydantic/types.py                   1.00      2.9±0.04ms     8.9 MB/sec    1.00      2.9±0.04ms     8.9 MB/sec