Adopt the Ruff code linting tool

https://github.com/charliermarsh/ruff

.github/workflows/lint.yml

@@ -28,6 +28,22 @@ jobs:
     - name: Run Tox
       run:  tox -e ${{ matrix.tool }}
 
+  ruff:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Python
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3
+    - name: Install dependencies
+      run:  |
+        python -m pip install --upgrade pip
+        python -m pip install --upgrade ruff
+    - name: Lint with Ruff
+      run:  ruff .  --diff --format github
+
   pre-commit:
     runs-on: ubuntu-latest
     steps:

pyproject.toml

@@ -135,6 +135,54 @@ exclude = [
 [tool.isort]
 line_length = 95
 
+[tool.ruff]
+target-version = "py38"  # Pin Ruff to Python 3.8
+line-length = 95
+exclude = [
+    '.git',
+    '.tox',
+    '.venv',
+    'tests/roots/*',
+    'build/*',
+    'doc/_build/*',
+    'sphinx/search/*',
+    'doc/usage/extensions/example*.py',
+]
+ignore = [
+    # pycodestyle
+    'E741',
+    # flake8-bugbear
+    'B006',
+    'B023',
+    # flake8-bugbear opinionated (disabled by default in flake8)
+    'B904',
+    'B905',
+]
+external = [  # Whitelist for RUF100 unkown code warnings
+    "E704",
+    "W291",
+    "W293",
+]
+select = [
+    "E",   # pycodestyle
+    "F",   # Pyflakes
+    "W",   # pycodestyle
+    # plugins:
+    "B",   # flake8-bugbear
+    "C4",  # flake8-comprehensions
+    "SIM", # flake8-simplify
+    "RUF100"  # yesqa
+]
+
+[tool.ruff.per-file-ignores]
+"tests/*" = ["E501"]
+"sphinx/environment/collectors/toctree.py" = ["B026"]
+"sphinx/environment/adapters/toctree.py" = ["B026"]
+
+# Ruff does not support 'import-order-style = smarkets'
+"sphinx/util/__init__.py" = ["F401"]
+"sphinx/util/inspect.py" = ["F401"]
+
 [tool.mypy]
 check_untyped_defs = true
 disallow_incomplete_defs = true

sphinx/builders/html/__init__.py

@@ -1320,7 +1320,7 @@ def deprecate_html_4(_app: Sphinx, config: Config) -> None:
 # for compatibility
 import sphinxcontrib.serializinghtml  # noqa: E402,F401
 
-import sphinx.builders.dirhtml  # noqa: E402,F401
+import sphinx.builders.dirhtml  # noqa: E402,F401,RUF100
 import sphinx.builders.singlehtml  # noqa: E402,F401
 
 deprecated_alias('sphinx.builders.html',

sphinx/util/__init__.py

@@ -27,7 +27,7 @@ from sphinx.util.nodes import (caption_ref_re, explicit_title_re,  # noqa: F401
                                nested_parse_with_titles, split_explicit_title)
 # import other utilities; partly for backwards compatibility, so don't
 # prune unused ones indiscriminately
-from sphinx.util.osutil import (SEP, copyfile, copytimes, ensuredir,  # noqa: F401,E501
+from sphinx.util.osutil import (SEP, copyfile, copytimes, ensuredir,  # noqa: F401
                                 make_filename, mtimes_of_files, os_path, relative_uri)
 from sphinx.util.typing import PathMatcher
 

tests/test_util_typing.py

@@ -159,7 +159,7 @@ def test_restify_type_hints_alias():
 
 def test_restify_type_ForwardRef():
     from typing import ForwardRef  # type: ignore
-    assert restify(ForwardRef("myint")) == ":py:class:`myint`"
+    assert restify(ForwardRef("myint")) == ":py:class:`myint`"  # NoQA: F821
 
 
 def test_restify_type_Literal():

tox.ini

@@ -43,6 +43,17 @@ extras =
 commands =
     flake8 {posargs}
 
+[testenv:ruff]
+basepython = python3
+description =
+    Run style checks with ruff.
+whitelist_externals =
+    ruff
+extras =
+    lint
+commands =
+    ruff {posargs}
+
 [testenv:isort]
 basepython = python3
 description =