[pylint] Implement useless-return (R1711)

[tomecki]

This PR implements https://pylint.pycqa.org/en/latest/user_guide/messages/refactor/useless-return.html , including autofixing.

Impl change from original approach: the check locates the actual useless return statements, in contrast to pylint's implemnentation which flags the functions which have useless return statements.

[tomecki]

Root ticket for pylint coverage: #970

[charliermarsh]

I think the one issue with this rule is that it may conflict with some of the flake8-return rules, e.g. those that require an explicit return None at the end of the function, like RET502 and RET503. I'm hesitant to introduce rules that are in direct conflict. An alternative would be to make the flake8-return rules parameterizable such that they can enforce this behavior if desired, in lieu of enforcing the opposite.

[r3m0t]

Looks like in pylint the rule ignores functions which can return values. https://github.com/PyCQA/pylint/blob/1eef2273aee4c5a2e287f7470d6da3a3ae7d0760/pylint/checkers/refactoring/refactoring_checker.py#L2022

Which makes it the same as/very similar to R501 - https://pypi.org/project/flake8-return/

[charliermarsh]

Oh, in that case, it may actually be different than any existing checks? Since none of those tell you to remove a return entirely, only that the return should be implicit or explicit in various cases. (R501 only tells you to change return None to return if all returns are None, not to drop a return / return None at the end of a method if it's the only return.)

[charliermarsh]

But we need to adjust this such that it only warns if this is the only return in the function.

[github-actions]

PR Check Results

Ecosystem

ℹ️ ecosystem check detected changes. (+18, -0, 0 error(s))

zulip (+2, -0)

+ zerver/lib/streams.py:243:5: PLR1711 [*] Useless `return` statement at end of function
+ zerver/lib/test_helpers.py:122:9: PLR1711 [*] Useless `return` statement at end of function

bokeh (+10, -0)

+ src/bokeh/application/application.py:236:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/application/application.py:249:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/client/connection.py:281:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/contexts.py:301:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/contexts.py:321:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/tornado.py:715:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/views/ws.py:223:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/views/ws.py:262:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/views/ws.py:288:9: PLR1711 [*] Useless `return` statement at end of function
+ src/bokeh/server/views/ws.py:335:9: PLR1711 [*] Useless `return` statement at end of function

airflow (+6, -0)

+ airflow/providers/google/cloud/operators/dataflow.py:1378:9: PLR1711 [*] Useless `return` statement at end of function
+ airflow/providers/microsoft/azure/sensors/data_factory.py:134:9: PLR1711 [*] Useless `return` statement at end of function
+ airflow/utils/db.py:1475:5: PLR1711 [*] Useless `return` statement at end of function
+ dev/check_files.py:223:5: PLR1711 [*] Useless `return` statement at end of function
+ dev/check_files.py:237:5: PLR1711 [*] Useless `return` statement at end of function
+ tests/jobs/test_scheduler_job.py:1924:17: PLR1711 [*] Useless `return` statement at end of function

### Benchmark #### Linux ``` group main pr ----- ---- -- linter/all-rules/large/dataset.py 1.00 18.0±1.03ms 2.3 MB/sec 1.03 18.6±0.89ms 2.2 MB/sec linter/all-rules/numpy/ctypeslib.py 1.00 4.5±0.16ms 3.7 MB/sec 1.05 4.7±0.17ms 3.5 MB/sec linter/all-rules/numpy/globals.py 1.00 637.2±21.11µs 4.6 MB/sec 1.02 652.7±24.48µs 4.5 MB/sec linter/all-rules/pydantic/types.py 1.00 7.9±0.39ms 3.2 MB/sec 1.05 8.3±0.26ms 3.1 MB/sec linter/default-rules/large/dataset.py 1.00 9.9±0.44ms 4.1 MB/sec 1.01 10.0±0.50ms 4.1 MB/sec linter/default-rules/numpy/ctypeslib.py 1.03 2.2±0.11ms 7.6 MB/sec 1.00 2.1±0.10ms 7.8 MB/sec linter/default-rules/numpy/globals.py 1.00 260.4±7.24µs 11.3 MB/sec 1.02 265.4±22.20µs 11.1 MB/sec linter/default-rules/pydantic/types.py 1.00 4.5±0.13ms 5.7 MB/sec 1.04 4.7±0.17ms 5.5 MB/sec ```

Windows

group                                      main                                   pr
-----                                      ----                                   --
linter/all-rules/large/dataset.py          1.00     18.3±0.33ms     2.2 MB/sec    1.02     18.6±0.40ms     2.2 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.01      5.0±0.17ms     3.3 MB/sec    1.00      5.0±0.12ms     3.4 MB/sec
linter/all-rules/numpy/globals.py          1.00   637.8±21.98µs     4.6 MB/sec    1.01   647.3±33.93µs     4.6 MB/sec
linter/all-rules/pydantic/types.py         1.00      8.3±0.28ms     3.1 MB/sec    1.00      8.3±0.19ms     3.1 MB/sec
linter/default-rules/large/dataset.py      1.00     10.2±0.19ms     4.0 MB/sec    1.04     10.6±0.22ms     3.8 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.00      2.2±0.08ms     7.5 MB/sec    1.04      2.3±0.08ms     7.1 MB/sec
linter/default-rules/numpy/globals.py      1.00    248.4±9.31µs    11.9 MB/sec    1.04   257.7±11.80µs    11.5 MB/sec
linter/default-rules/pydantic/types.py     1.00      4.7±0.17ms     5.4 MB/sec    1.01      4.8±0.12ms     5.3 MB/sec