ruff.toml doesn't work with [tool.ruff] hierarchy

[turnerm]

The ruff documentation states the following:

As an alternative to pyproject.toml, Ruff will also respect a ruff.toml (or .ruff.toml) file, which implements an equivalent schema (though the [tool.ruff] hierarchy can be omitted).

In particular, stating that the [tool.ruff] hierarchy can be omitted implies that it should be possible to use the hierarchy in ruff.toml.

However, I do not find this to be the case. In particular, I've created the following ruff.toml:

[tool.ruff]
line-length = 79

Then with Python 3.11 and ruff 0.0.270 I tried running the command ruff check *, and get the following error:

error: Failed to parse `/home/turnerm/scratch/ruff_test/ruff.toml`: TOML parse error at line 1, column 2
  |
1 | [tool.ruff]
  |  ^^^^
unknown field `tool`, expected one of `allowed-confusables`, `builtins`, `cache-dir`, `dummy-variable-rgx`, `exclude`, `extend`, `extend-exclude`, `extend-include`, `extend-ignore`, `extend-select`, `extend-fixable`, `extend-unfixable`, `external`, `fix`, `fix-only`, `fixable`, `format`, `force-exclude`, `ignore`, `ignore-init-module-imports`, `include`, `line-length`, `tab-size`, `required-version`, `respect-gitignore`, `select`, `show-source`, `show-fixes`, `src`, `namespace-packages`, `target-version`, `task-tags`, `typing-modules`, `unfixable`, `flake8-annotations`, `flake8-bandit`, `flake8-bugbear`, `flake8-builtins`, `flake8-comprehensions`, `flake8-errmsg`, `flake8-quotes`, `flake8-self`, `flake8-tidy-imports`, `flake8-type-checking`, `flake8-gettext`, `flake8-implicit-str-concat`, `flake8-import-conventions`, `flake8-pytest-style`, `flake8-unused-arguments`, `isort`, `mccabe`, `pep8-naming`, `pycodestyle`, `pydocstyle`, `pylint`, `per-file-ignores`, `extend-per-file-ignores`

If I change the name of ruff.toml to pyproject.toml, or remove the [ruff.toml] heading, then ruff runs without error.

[charliermarsh]

The documentation should be clearer on this point: [tool.ruff] has to be omitted for ruff.toml (it's not optional).

[cartok]

People will still land here cause the preset is using it. https://github.com/astral-sh/ruff#configuration.

[phillipjohnston]

People will still land here cause the preset is using it. https://github.com/astral-sh/ruff#configuration.

I did this just now while working through the readme.

[charliermarsh]

I don't think we can put tabs in the README (unlike in the docs). I'll try to clarify it.

[AlexWaygood]

I don't think we can put tabs in the README (unlike in the docs).

Yeah that seems correct :/ github/markup#1552 (comment)