Unexpected TRY400 indicated in unchanged code

[jaraco]

In the feature/compilers-module-redux branch, I'm attempting to refactor the code. When I do, a TRY400 error is indicated even though the code hasn't changed:

__________________________________________________________________ test session ___________________________________________________________________
distutils/compilers/C/msvc.py:163:9: TRY400 Use `logging.exception` instead of `logging.error`
    |
161 |         ).decode('utf-16le', errors='replace')
162 |     except subprocess.CalledProcessError as exc:
163 |         log.error(exc.output)
    |         ^^^^^^^^^^^^^^^^^^^^^ TRY400
164 |         raise DistutilsPlatformError(f"Error executing {exc.cmd}")
    |
    = help: Replace with `exception`

First off, that's a nuisance error. What if what I really wanted was to log just the error message? Ruff shouldn't be griping about legitimate usage of supported interfaces. If logging.error shouldn't ever be used, they should file that as a feature change to CPython to get that functionality deprecated.

Second, why is this error only emitted in the branch (bac29f1), when the same code succeeds just fine in main?

@DimitriPapadopoulos What do you make of this error?

[DimitriPapadopoulos]

My understanding of the purpose of TRY400 is to suggest:

try:
    i = 1 / 0
except ZeroDivisionError as exc:
    logging.exception('"my error message"')

instead of:

try:
    i = 1 / 0
except ZeroDivisionError as exc:
    logging.error(f'"my error message" {exc}')

The output is considered more informative:

ERROR:root:"my error message"
Traceback (most recent call last):
  File "/volatile/home/dp165978/toto.py", line 4, in <module>
    i = 1 / 0
ZeroDivisionError: division by zero

instead of:

ERROR:root:"my error message" division by zero

In any case logging.exception was designed to log exceptions. However, I must admit it doesn't fit all use cases, especially when you just want to log exc.output and not details of exc! I guess TRY400 needs to be disabled globally.

[DimitriPapadopoulos]

I can reproduce the issue with branch feature/compilers-module-redux after removing # noqa: RUF100, TRY400. That's really peculiar!

Files distutils/_msvccompiler.py from main branch and distutils/compilers/C/msvc.py from feature/compilers-module-redux are almost identical. Yet, after removing # noqa: RUF100, TRY400, the latter emits a TRY400 while the former does not. I'll keep looking.

[DimitriPapadopoulos]

The reason is hidden in this change at the top of the file, in imports:

- from ._log import log
+ from ..._log import log

In the former case, log does not seem to be properly identified as logging.getLogger(), thus TRY400 is not emitted. I do see TRY400 emitted if I change:

from ._log import log

into:

import logging
log = logging.getLogger()

That looks like a ruff bug, doesn't it?

[DimitriPapadopoulos]

The bug is triggered by the distutils/__init__.py file:

.
└── distutils
    ├── __init__.py
    ├── _log.py
    └── _msvccompiler.py

Even an empty __init__.py file silences TRY400:

$ ruff check --select=TRY400
All checks passed!
$ 

After removing the empty __init__.py file:

.
└── distutils
    ├── _log.py
    └── _msvccompiler.py

I do see the TRY400 error:

$ ruff check --select=TRY400
distutils/_msvccompiler.py:6:5: TRY400 Use `logging.exception` instead of `logging.error`
  |
4 |     i = 1 / 0
5 | except DivisionByZero as e:
6 |     log.error(f"raised {e}")
  |     ^^^^^^^^^^^^^^^^^^^^^^^^ TRY400
  |
  = help: Replace with `exception`

Found 1 error.
No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).
$ 

[DimitriPapadopoulos]

I created astral-sh/ruff#13225.

[jaraco]

Thanks for the investigation!