Replace Flake8 checks with Ruff (except for flake8-pyi) (#11496)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

.flake8

@@ -1,44 +1,19 @@
-# The following rules come from plugins that are not used by typeshed.
-# Since typeshed stubs them, they can still be expected to be found in a
-# developer's venv for intellisense and reference reasons
-#     A      flake8-builtins
-#     B      flake8-bugbear
-#     D      flake8-docstrings
-#     N8     pep8-naming
-#     SIM    flake8-simplify
-#     RST    flake8-rst-docstrings
-#     TYP    flake8-typing-imports
-
-# The following rules are incompatible with or enforced by Black:
-#     E203   whitespace before ':' -- scripts only
-#     E301   expected 1 blank line
-#     E302   expected 2 blank lines
-#     E305   expected 2 blank lines
-#     E501   line too long
-#     E701   Multiple statements on one line (colon) -- disallows "..." on the same line
-
-# Some rules are considered irrelevant to stub files:
-#     F401   imported but unused -- does not recognize re-exports
-#            https://github.com/PyCQA/pyflakes/issues/474
-
-# Rules that are out of the control of stub authors:
-#     E741   ambiguous variable name
-#     F403   import *' used; unable to detect undefined names
-#     F405   defined from star imports
-
 [flake8]
-extend-ignore = A, B, D, N8, SIM, RST, TYP, E301, E302, E305, E501, E701
+# NQA: Ruff won't warn about redundant `# noqa: Y`
+# Y: Flake8 is only used to run flake8-pyi, everything else is in Ruff
+# F821: Until https://github.com/astral-sh/ruff/issues/3011 is fixed, we need flake8-pyi's monkeypatching
+select = NQA, Y, F821
+# Ignore rules normally excluded by default
+extend-ignore = Y090
 per-file-ignores =
-  *.py: E203
-  *.pyi: E741, F401, F403, F405
-  # Since typing.pyi defines "overload" this is not recognized by Flake8 as typing.overload.
-  # Unfortunately, Flake8 does not allow to "noqa" just a specific error inside the file itself.
-  # https://github.com/PyCQA/flake8/issues/1079
-  #     F811 redefinition of unused '...'
-  stdlib/typing.pyi: E741, F401, F403, F405, F811
-  # Generated protobuf files include docstrings,
-  # and import some things from typing_extensions that could be imported from typing
-  *_pb2.pyi: E741, F401, F403, F405, Y021, Y023, Y026, Y053, Y054
+  # We should only need to noqa Y and F821 codes in .pyi files
+  *.py: NQA
+  # Generated protobuf files:
+  # Y021: Include docstrings
+  # Y023: Alias typing as typing_extensions
+  # Y026: Have implicit type aliases
+  # Y053: have literals >50 characters long
+  *_pb2.pyi: Y021, Y023, Y026, Y053
 
 exclude = .venv*,.git
 noqa_require_code = true

.pre-commit-config.yaml

@@ -25,7 +25,7 @@ repos:
         # Very few rules are useful to run on our test cases;
         # we explicitly enumerate them here:
         name: Run ruff on the test cases
-        args: ["--exit-non-zero-on-fix", "--select=FA,I", "--no-force-exclude", "--unsafe-fixes"]
+        args: ["--exit-non-zero-on-fix", "--select=FA,I,RUF100", "--no-force-exclude", "--unsafe-fixes"]
         files: '.*test_cases/.+\.py$'
   - repo: https://github.com/psf/black-pre-commit-mirror
     rev: 24.1.1 # must match requirements-tests.txt

pyproject.toml

@@ -32,13 +32,21 @@ exclude = [
 # are invoked via separate runs of ruff in pre-commit:
 # see our .pre-commit-config.yaml file for details
 exclude = ["**/test_cases/**/*.py"]
+# We still use flake8-pyi and flake8-noqa to check these (see .flake8 config file);
+# tell ruff not to flag these as e.g. "unused noqa comments"
+external = ["F821", "NQA", "Y"]
 select = [
     "B", # flake8-bugbear
     "FA", # flake8-future-annotations
     "I", # isort
+    "RUF", # Ruff-specific and unused-noqa
     "UP", # pyupgrade
-    # Only enable rules that have safe autofixes:
-    "F401", # Remove unused imports
+    # Flake8 base rules
+    "E", # pycodestyle Error
+    "F", # Pyflakes
+    "W", # pycodestyle Warning
+    # PYI: only enable rules that always autofix, avoids duplicate # noqa with flake8-pyi
+    # See https://github.com/plinss/flake8-noqa/issues/22
     "PYI009", # use `...`, not `pass`, in empty class bodies
     "PYI010", # function bodies must be empty
     "PYI012", # class bodies must not contain `pass`
@@ -51,8 +59,27 @@ select = [
     "PYI058", # use `Iterator` as the return type for `__iter__` methods
 ]
 ignore = [
+    ###
+    # Rules that can conflict with the formatter (Black)
+    # https://docs.astral.sh/ruff/formatter/#conflicting-lint-rules
+    ###
+    "E111", # indentation-with-invalid-multiple
+    "E114", # indentation-with-invalid-multiple-comment
+    "E117", # over-indented
+    "W191", # tab-indentation
+    ###
+    # Rules we don't want or don't agree with
+    ###
     # Slower and more verbose https://github.com/astral-sh/ruff/issues/7871
     "UP038", # Use `X | Y` in `isinstance` call instead of `(X, Y)`
+    # Used for direct, non-subclass type comparison, for example: `type(val) is str`
+    # see https://github.com/astral-sh/ruff/issues/6465
+    "E721", # Do not compare types, use `isinstance()`
+    ###
+    # False-positives, but already checked by type-checkers
+    ###
+    # Ruff doesn't support multi-file analysis yet: https://github.com/astral-sh/ruff/issues/5295
+    "RUF013", # PEP 484 prohibits implicit `Optional`
 ]
 
 [tool.ruff.lint.per-file-ignores]
@@ -60,6 +87,15 @@ ignore = [
     # Most flake8-bugbear rules don't apply for third-party stubs like typeshed.
     # B033 could be slightly useful but Ruff doesn't have per-file select
     "B", # flake8-bugbear
+    # Rules that are out of the control of stub authors:
+    "E501", # Line too long
+    "E741", # ambiguous variable name
+    "F403", # `from . import *` used; unable to detect undefined names
+    # False positives in stubs
+    "F821", # Undefined name: https://github.com/astral-sh/ruff/issues/3011
+    # Stubs can sometimes re-export entire modules.
+    # Issues with using a star-imported name will be caught by type-checkers.
+    "F405", # may be undefined, or defined from star imports
 ]
 
 [tool.ruff.lint.isort]

stdlib/builtins.pyi

@@ -99,7 +99,7 @@ class object:
     @property
     def __class__(self) -> type[Self]: ...
     @__class__.setter
-    def __class__(self, type: type[object], /) -> None: ...  # noqa: F811
+    def __class__(self, type: type[object], /) -> None: ...
     def __init__(self) -> None: ...
     def __new__(cls) -> Self: ...
     # N.B. `object.__setattr__` and `object.__delattr__` are heavily special-cased by type checkers.

stdlib/socket.pyi

@@ -803,7 +803,7 @@ def getfqdn(name: str = "") -> str: ...
 if sys.version_info >= (3, 11):
     def create_connection(
         address: tuple[str | None, int],
-        timeout: float | None = ...,  # noqa: F811
+        timeout: float | None = ...,
         source_address: _Address | None = None,
         *,
         all_errors: bool = False,
@@ -811,7 +811,7 @@ if sys.version_info >= (3, 11):
 
 else:
     def create_connection(
-        address: tuple[str | None, int], timeout: float | None = ..., source_address: _Address | None = None  # noqa: F811
+        address: tuple[str | None, int], timeout: float | None = ..., source_address: _Address | None = None
     ) -> socket: ...
 
 def has_dualstack_ipv6() -> bool: ...

stdlib/typing.pyi

@@ -1,3 +1,5 @@
+# Since this module defines "overload" it is not recognized by Ruff as typing.overload
+# ruff: noqa: F811
 # TODO: The collections import is required, otherwise mypy crashes.
 # https://github.com/python/mypy/issues/16744
 import collections  # noqa: F401  # pyright: ignore

stubs/WebOb/@tests/test_cases/check_wsgify.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from _typeshed.wsgi import StartResponse, WSGIApplication, WSGIEnvironment
-from collections.abc import Iterable  # noqa: F401
+from collections.abc import Iterable
 from typing_extensions import assert_type
 
 from webob.dec import _AnyResponse, wsgify

test_cases/stdlib/typing/check_all.py

@@ -5,10 +5,10 @@ This tests that star imports work when using "all += " syntax.
 from __future__ import annotations
 
 import sys
-from typing import *  # noqa: F403
-from zipfile import *  # noqa: F403
+from typing import *
+from zipfile import *
 
 if sys.version_info >= (3, 9):
-    x: Annotated[int, 42]  # noqa: F405
+    x: Annotated[int, 42]
 
-p: Path  # noqa: F405
+p: Path