[pylint] Implement import-self (W0406)

[chanman3388]

Implement pylint's W0406

Ideally I'd also want an integration test which tests a package too. I have checked that on this simple example that it emits the same diagnostics that pylint does.

a
├── __init__.py
├── a
│   └── __init__.py
└── a.py

a.a contains

from . import a
import a.a
from a.a import b
from a.a.a import b


def b():
    pass

a.a.a is empty.
Ruff:

/home/chris/projects/pylint_exp/W0604/a/a.py:1:1: PLW0406 import-self
  |
1 | from . import a
  | ^^^^^^^^^^^^^^^ PLW0406
2 | import a.a
3 | from a.a import b
  |

/home/chris/projects/pylint_exp/W0604/a/a.py:2:1: PLW0406 import-self
  |
2 | from . import a
3 | import a.a
  | ^^^^^^^^^^ PLW0406
4 | from a.a import b
5 | from a.a.a import b
  |

/home/chris/projects/pylint_exp/W0604/a/a.py:3:1: PLW0406 import-self
  |
3 | from . import a
4 | import a.a
5 | from a.a import b
  | ^^^^^^^^^^^^^^^^^ PLW0406
6 | from a.a.a import b
  |

Found 3 errors.

Pylint:

a/a.py:1:0: W0406: Module import itself (import-self)
a/a.py:2:0: W0406: Module import itself (import-self)
a/a.py:3:0: W0406: Module import itself (import-self)

[github-actions]

PR Check Results

Ecosystem

✅ ecosystem check detected no changes.

Benchmark

Linux

group                                      main                                   pr
-----                                      ----                                   --
linter/all-rules/large/dataset.py          1.09     16.7±0.10ms     2.4 MB/sec    1.00     15.2±0.34ms     2.7 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.09      4.0±0.02ms     4.2 MB/sec    1.00      3.7±0.07ms     4.5 MB/sec
linter/all-rules/numpy/globals.py          1.09    494.0±6.20µs     6.0 MB/sec    1.00   452.1±16.64µs     6.5 MB/sec
linter/all-rules/pydantic/types.py         1.10      7.1±0.11ms     3.6 MB/sec    1.00      6.4±0.19ms     4.0 MB/sec
linter/default-rules/large/dataset.py      1.10      8.0±0.41ms     5.1 MB/sec    1.00      7.3±0.15ms     5.6 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.00  1604.0±66.20µs    10.4 MB/sec    1.00  1608.8±44.36µs    10.4 MB/sec
linter/default-rules/numpy/globals.py      1.00    183.0±5.74µs    16.1 MB/sec    1.00    182.7±6.00µs    16.1 MB/sec
linter/default-rules/pydantic/types.py     1.02      3.4±0.08ms     7.6 MB/sec    1.00      3.3±0.08ms     7.8 MB/sec
parser/large/dataset.py                    1.02      6.0±0.16ms     6.8 MB/sec    1.00      5.9±0.13ms     6.9 MB/sec
parser/numpy/ctypeslib.py                  1.08  1267.3±11.07µs    13.1 MB/sec    1.00  1169.0±31.84µs    14.2 MB/sec
parser/numpy/globals.py                    1.08    129.2±0.36µs    22.8 MB/sec    1.00    119.8±3.47µs    24.6 MB/sec
parser/pydantic/types.py                   1.09      2.8±0.00ms     9.2 MB/sec    1.00      2.5±0.07ms    10.1 MB/sec

Windows

group                                      main                                   pr
-----                                      ----                                   --
linter/all-rules/large/dataset.py          1.01     17.1±0.13ms     2.4 MB/sec    1.00     16.9±0.12ms     2.4 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.01      4.3±0.03ms     3.9 MB/sec    1.00      4.3±0.03ms     3.9 MB/sec
linter/all-rules/numpy/globals.py          1.00    437.8±7.15µs     6.7 MB/sec    1.00    439.2±7.31µs     6.7 MB/sec
linter/all-rules/pydantic/types.py         1.00      7.2±0.07ms     3.5 MB/sec    1.01      7.2±0.10ms     3.5 MB/sec
linter/default-rules/large/dataset.py      1.00      8.6±0.05ms     4.7 MB/sec    1.00      8.6±0.07ms     4.7 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.00  1816.6±17.43µs     9.2 MB/sec    1.00  1820.4±11.26µs     9.1 MB/sec
linter/default-rules/numpy/globals.py      1.01    194.2±2.01µs    15.2 MB/sec    1.00    191.8±2.90µs    15.4 MB/sec
linter/default-rules/pydantic/types.py     1.00      3.9±0.02ms     6.6 MB/sec    1.00      3.9±0.02ms     6.6 MB/sec
parser/large/dataset.py                    1.01      6.9±0.03ms     5.9 MB/sec    1.00      6.8±0.03ms     6.0 MB/sec
parser/numpy/ctypeslib.py                  1.00  1297.9±10.53µs    12.8 MB/sec    1.00   1292.5±9.67µs    12.9 MB/sec
parser/numpy/globals.py                    1.00    133.3±1.13µs    22.1 MB/sec    1.00    133.0±1.38µs    22.2 MB/sec
parser/pydantic/types.py                   1.00      2.9±0.02ms     8.8 MB/sec    1.00      2.9±0.02ms     8.9 MB/sec

[MichaReiser]

This is looking good. I've a few smaller nit improvements that may help with performance

[chanman3388]

Thanks for all the comments, I believe I'll made all the requested adjustments.