E712 fix results in unsafe behavior

[DavidSlayback]

If Ruff is allowed to check for and fix E712 errors, this can result in unexpected behavior with things like pandas DataFrames. Example:

mask = (df["bool_col"] == True) & (df["other_col"].isna())
# If we add noqa, we're ok
mask = (df["bool_col"] == True) & (df["other_col"].isna())  & (df["other_col"].isna()) # noqa: E712
# But if we let ruff fix as part of a pre-commit...
# ruff check . --fix
mask = (df["bool_col"] is True) & (df["other_col"].isna()) 

The original behavior produces a mask for each operand and combines them. The "fix" makes the first operand always return False, which means the whole mask is False.

Ruff version: v0.1.6

I think the desired behavior would be to either consider the fix unsafe or to favor removing == True and != True, but the latter might be difficult (because the correct equivalent to != in Pandas is ~df, not !df or not df

[zanieb]

Please see #4560

This fix should already be marked as unsafe and not applied unless you've opted into unsafe fixes e.g.

❯ ruff check example.py --isolated --no-cache --select E712 --fix
example.py:1:27: E712 Comparison to `True` should be `cond is True` or `if cond:`
Found 1 error.
No fixes available (1 hidden fix can be enabled with the `--unsafe-fixes` option).
❯ ruff check example.py --isolated --no-cache --select E712 --fix --unsafe-fixes
Found 1 error (1 fixed, 0 remaining).

[DavidSlayback]

Hmm...sorry about that, I'll have to figure out how the auto fix got triggered, our pre-commit doesn't specify --unsafe-fixes

[charliermarsh]

Hmm, could you have unsafe-fixes = true set in your pyproject.toml or ruff.toml file?

[DavidSlayback]

No ruff.toml, pyproject.toml doesn't specify anything about the fixes, and .pre-commit-config.yaml section is:

  - repo: https://github.com/astral-sh/ruff-pre-commit
    # Ruff version.
    rev: v0.1.6
    hooks:
      - id: ruff
        name: "Lint and fix code using Ruff"
        args: [ --fix, --exit-non-zero-on-fix ]
        stages: [commit]

Going to assume maybe someone triggered it manually to get it to stop complaining

[zanieb]

@DavidSlayback #9095 will be in our next release so you can disable unsafe fixes entirely to hide that complaint :)