Remove B904's lowercase exemption

[charliermarsh]

Summary

It looks like bugbear, from the start, has had an exemption here to exempt raise lower_case_var. I looked at Hypothesis and Trio, which are mentioned in that issue, and Hypothesis has exactly one case of this, and Trio has none, so IMO it doesn't seem worth special-casing.

Closes #5664.

[github-actions]

PR Check Results

Ecosystem

ℹ️ ecosystem check detected changes. (+2, -0, 0 error(s))

bokeh (+1, -0)

+ tests/support/util/filesystem.py:74:17: B904 Within an `except` clause, raise exceptions with `raise ... from err` or `raise ... from None` to distinguish them from errors in exception handling

zulip (+1, -0)

+ zerver/management/commands/register_server.py:127:17: B904 Within an `except` clause, raise exceptions with `raise ... from err` or `raise ... from None` to distinguish them from errors in exception handling

Rules changed: 1

Rule	Changes	Additions	Removals
B904	2	2	0

Benchmark

Linux

group                                      main                                   pr
-----                                      ----                                   --
formatter/large/dataset.py                 1.01      9.5±0.02ms     4.3 MB/sec    1.00      9.4±0.03ms     4.3 MB/sec
formatter/numpy/ctypeslib.py               1.01   1867.3±3.31µs     8.9 MB/sec    1.00   1857.8±2.45µs     9.0 MB/sec
formatter/numpy/globals.py                 1.00    208.1±0.51µs    14.2 MB/sec    1.00    208.6±0.41µs    14.1 MB/sec
formatter/pydantic/types.py                1.01      4.1±0.01ms     6.2 MB/sec    1.00      4.0±0.01ms     6.3 MB/sec
linter/all-rules/large/dataset.py          1.00     13.6±0.02ms     3.0 MB/sec    1.00     13.6±0.03ms     3.0 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.01      3.4±0.01ms     4.8 MB/sec    1.00      3.4±0.00ms     4.9 MB/sec
linter/all-rules/numpy/globals.py          1.03    456.8±3.20µs     6.5 MB/sec    1.00    445.6±0.69µs     6.6 MB/sec
linter/all-rules/pydantic/types.py         1.00      6.1±0.01ms     4.2 MB/sec    1.00      6.1±0.01ms     4.2 MB/sec
linter/default-rules/large/dataset.py      1.00      6.8±0.02ms     6.0 MB/sec    1.00      6.7±0.01ms     6.0 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.02   1488.2±1.49µs    11.2 MB/sec    1.00   1465.5±2.66µs    11.4 MB/sec
linter/default-rules/numpy/globals.py      1.03    170.9±0.24µs    17.3 MB/sec    1.00    165.7±0.17µs    17.8 MB/sec
linter/default-rules/pydantic/types.py     1.01      3.1±0.01ms     8.3 MB/sec    1.00      3.0±0.01ms     8.4 MB/sec

Windows

group                                      main                                   pr
-----                                      ----                                   --
formatter/large/dataset.py                 1.00     12.8±0.34ms     3.2 MB/sec    1.03     13.2±0.25ms     3.1 MB/sec
formatter/numpy/ctypeslib.py               1.00      2.5±0.08ms     6.7 MB/sec    1.04      2.6±0.07ms     6.5 MB/sec
formatter/numpy/globals.py                 1.00   295.5±26.39µs    10.0 MB/sec    1.02   301.3±24.30µs     9.8 MB/sec
formatter/pydantic/types.py                1.00      5.4±0.13ms     4.7 MB/sec    1.04      5.6±0.16ms     4.5 MB/sec
linter/all-rules/large/dataset.py          1.04     19.3±0.44ms     2.1 MB/sec    1.00     18.6±0.35ms     2.2 MB/sec
linter/all-rules/numpy/ctypeslib.py        1.00      4.8±0.14ms     3.5 MB/sec    1.01      4.8±0.11ms     3.4 MB/sec
linter/all-rules/numpy/globals.py          1.03   609.0±24.06µs     4.8 MB/sec    1.00   594.1±18.71µs     5.0 MB/sec
linter/all-rules/pydantic/types.py         1.00      8.6±0.18ms     3.0 MB/sec    1.00      8.6±0.23ms     3.0 MB/sec
linter/default-rules/large/dataset.py      1.01      9.7±0.23ms     4.2 MB/sec    1.00      9.5±0.19ms     4.3 MB/sec
linter/default-rules/numpy/ctypeslib.py    1.00      2.1±0.04ms     8.1 MB/sec    1.02      2.1±0.05ms     7.9 MB/sec
linter/default-rules/numpy/globals.py      1.00    240.4±6.59µs    12.3 MB/sec    1.02    244.1±7.43µs    12.1 MB/sec
linter/default-rules/pydantic/types.py     1.00      4.3±0.13ms     5.9 MB/sec    1.02      4.4±0.08ms     5.8 MB/sec

[zanieb]

Yeah this exclusion doesn't make sense to me? Even if I wanted to use with_traceback you'd need from None to hide the other tracebacks? e.g.

traceback_exc = None
try:
    try:
        raise ValueError()
    except Exception as inner:
        traceback_exc = inner
        raise TypeError() from inner
except Exception:
    raise RuntimeError().with_traceback(traceback_exc.__traceback__) from None

This change does create a new common case though, when an exception is reraised

try:
    raise ValueError()
except ValueError as exc:
    raise exc

Throws

example.py:4:5: B904 Within an `except` clause, raise exceptions with `raise ... from err` or `raise ... from None` to distinguish them from errors in exception handling

but should suggest using just raise to avoid adding an extra traceback frame e.g.

Traceback (most recent call last):
  File "/Users/mz/eng/src/astral-sh/ruff/example.py", line 4, in <module>
    raise exc
  File "/Users/mz/eng/src/astral-sh/ruff/example.py", line 2, in <module>
    raise ValueError()
ValueError

vs

try:
    raise ValueError()
except ValueError:
    raise

Traceback (most recent call last):
  File "/Users/mz/eng/src/astral-sh/ruff/example.py", line 2, in <module>
    raise ValueError()
ValueError

Edit: Charlie pointed out that this is already covered by TRY201 so it probably ought to be excluded entirely here?

[charliermarsh]

Ah interesting, I think these are now false positives whereby in most cases, they're just re-raising the exception. Need to fix.

[charliermarsh]

I'm gonna change the rule to allow those "verbose re-raises", since we have TRY201 to flag them.

[charliermarsh]

(Gonna see how ecosystem CI checks shake out.)

[charliermarsh]

I'm worried this may actually be a dupe of TRY200 now, but I guess this is still fine to fix.

[zanieb]

I still find this message confusing for except e: raise e — both suggestions raise e from None and raise e from e are less correct than raise or raise e.

[charliermarsh]

Hmm, we no longer flag except e: raise e though.

[charliermarsh]

Ah, ok, so we are flagging it for the nested exception in Zulip.

[zanieb]

@charliermarsh Ah I see that's nested — that may be reasonable actually?

As written look like a violation:

try:
    try:
        raise RuntimeError("one") # Raise for traceback
    except Exception as e1:
        raise RuntimeError("two") from e1
except RuntimeError as e2:
    try:
        raise RuntimeError("three")
    except RuntimeError as e3:
        raise e2

Traceback (most recent call last):
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 3, in <module>
    raise RuntimeError("one") # Raise for traceback
    ^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: one

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 10, in <module>
    raise e2
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 5, in <module>
    raise RuntimeError("two") from e1
RuntimeError: two

Suggestions look reasonable:

try:
    try:
        raise RuntimeError("one") # Raise for traceback
    except Exception as e1:
        raise RuntimeError("two") from e1
except RuntimeError as e2:
    try:
        raise RuntimeError("three")
    except RuntimeError as e3:
        raise e2 from e2

Traceback (most recent call last):
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 10, in <module>
    raise e2 from e2
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 5, in <module>
    raise RuntimeError("two") from e1
RuntimeError: two

try:
    try:
        raise RuntimeError("one") # Raise for traceback
    except Exception as e1:
        raise RuntimeError("two") from e1
except RuntimeError as e2:
    try:
        raise RuntimeError("three")
    except RuntimeError as e3:
        raise e2 from None

Traceback (most recent call last):
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 10, in <module>
    raise e2 from None
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 5, in <module>
    raise RuntimeError("two") from e1
RuntimeError: two

try:
    try:
        raise RuntimeError("one") # Raise for traceback
    except Exception as e1:
        raise RuntimeError("two") from e1
except RuntimeError as e2:
    try:
        raise RuntimeError("three")
    except RuntimeError as e3:
        raise e2 from e3

Traceback (most recent call last):
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 8, in <module>
    raise RuntimeError("three")
RuntimeError: three

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 10, in <module>
    raise e2 from e3
  File "/Users/mz/eng/src/RustPython/Parser/example.py", line 5, in <module>
    raise RuntimeError("two") from e1
RuntimeError: two