Bump version to 0.0.76

CONTRIBUTING.md

@@ -14,6 +14,12 @@ your proposed change.
 ruff is written in Rust (1.63.0). You'll need to install the
 [Rust toolchain](https://www.rust-lang.org/tools/install) for development.
 
+You'll also need [Insta](https://insta.rs/docs/) to update snapshot tests:
+
+```shell
+cargo install cargo-insta
+```
+
 ### Development
 
 After cloning the repository, run ruff locally with:
@@ -58,7 +64,7 @@ similar rules are implemented.
 To add a test fixture, create a file under `resources/test/fixtures`, named to match the `CheckCode`
 you defined earlier (e.g., `E402.py`). This file should contain a variety of violations and
 non-violations designed to evaluate and demonstrate the behavior of your lint rule. Run ruff locally
-with (e.g.) `cargo run resources/test/fixtures/E402.py`. Once you're satisified with the output,
+with (e.g.) `cargo run resources/test/fixtures/E402.py`. Once you're satisfied with the output,
 codify the behavior as a snapshot test by adding a new function to the `mod tests` section of
 `src/linter.rs`, like so:
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.53"
+version = "0.0.76"
 edition = "2021"
 
 [lib]
@@ -9,10 +9,8 @@ name = "ruff"
 [dependencies]
 anyhow = { version = "1.0.60" }
 bincode = { version = "1.3.3" }
-cacache = { version = "10.0.1" }
 chrono = { version = "0.4.21" }
 clap = { version = "4.0.1", features = ["derive"] }
-clearscreen = { version = "1.0.10" }
 colored = { version = "2.0.0" }
 common-path = { version = "1.0.0" }
 dirs = { version = "4.0.0" }
@@ -23,19 +21,37 @@ itertools = { version = "0.10.5" }
 libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "32a044c127668df44582f85699358e67803b0d73" }
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
+num-bigint = { version = "0.4.3" }
 once_cell = { version = "1.13.1" }
-path-absolutize = { version = "3.0.13", features = ["once_cell_cache"] }
+path-absolutize = { version = "3.0.14", features = ["once_cell_cache", "use_unix_paths_on_wasm"] }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
+rustpython-ast = { features = ["unparse"], git = "https://github.com/charliermarsh/RustPython.git", rev = "778ae2aeb521d0438d2a91bd11238bb5c2bf9d4f" }
+rustpython-common = { git = "https://github.com/charliermarsh/RustPython.git", rev = "778ae2aeb521d0438d2a91bd11238bb5c2bf9d4f" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "778ae2aeb521d0438d2a91bd11238bb5c2bf9d4f" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
+strum = { version = "0.24.1", features = ["strum_macros"] }
+strum_macros = { version = "0.24.3" }
+textwrap = { version = "0.15.1" }
+titlecase = { version = "2.2.1" }
 toml = { version = "0.5.9" }
 update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
 walkdir = { version = "2.3.2" }
 
+[target.'cfg(not(target_family = "wasm"))'.dependencies]
+cacache = { version = "10.0.1" } # uses async-std
+clearscreen = { version = "1.0.10" } # uses which
+
+# https://docs.rs/getrandom/0.2.7/getrandom/#webassembly-support
+# For (future) wasm-pack support
+[target.'cfg(all(target_family = "wasm", target_os = "unknown"))'.dependencies]
+getrandom = { version = "0.2.7", features = ["js"] }
+
 [dev-dependencies]
+assert_cmd = { version = "2.0.4" }
 insta = { version = "1.19.1", features = ["yaml"] }
+test-case = { version = "2.2.2" }
 
 [features]
 default = ["update-informer"]

README.md

@@ -1,4 +1,4 @@
-# ruff
+# Ruff
 
 [![image](https://img.shields.io/pypi/v/ruff.svg)](https://pypi.python.org/pypi/ruff)
 [![image](https://img.shields.io/pypi/l/ruff.svg)](https://pypi.python.org/pypi/ruff)
@@ -20,17 +20,37 @@ An extremely fast Python linter, written in Rust.
 - 🤝 Python 3.10 compatibility
 - 🛠️ `pyproject.toml` support
 - 📦 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired cache support
-- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix)-inspired `--fix` support
-- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` support
-- ⚖️ [Near-complete parity](#Parity-with-Flake8) with the built-in Flake8 rule set
+- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix)-inspired autofix support (e.g., automatically remove unused imports)
+- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` support, for continuous file monitoring
+- ⚖️ [Near-parity](#Parity-with-Flake8) with the built-in Flake8 rule set
+- 🔌 Native re-implementations of popular Flake8 plugins, like [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/) ([`pydocstyle`](https://pypi.org/project/pydocstyle/))
+
+Ruff aims to be orders of magnitude faster than alternative tools while integrating more
+functionality behind a single, common interface. Ruff can be used to replace Flake8 (plus a variety
+of plugins), [`pydocstyle`](https://pypi.org/project/pydocstyle/), [`yesqa`](https://github.com/asottile/yesqa),
+and even a subset of [`pyupgrade`](https://pypi.org/project/pyupgrade/) and [`autoflake`](https://pypi.org/project/autoflake/)
+all while executing tens or hundreds of times faster than any individual tool.
 
 Read the [launch blog post](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
 
-## Installation and usage
+## Table of Contents
+
+1. [Installation and Usage](#installation-and-usage)
+2. [Configuration](#configuration)
+3. [Supported Rules](#supported-rules)
+4. [Editor Integrations](#editor-integrations)
+5. [FAQ](#faq)
+6. [Development](#development)
+7. [Releases](#releases)
+8. [Benchmarks](#benchmarks)
+9. [License](#license)
+10. [Contributing](#contributing)
+
+## Installation and Usage
 
 ### Installation
 
-Available as [ruff](https://pypi.org/project/ruff/) on PyPI:
+Available as [`ruff`](https://pypi.org/project/ruff/) on PyPI:
 
 ```shell
 pip install ruff
@@ -38,7 +58,7 @@ pip install ruff
 
 ### Usage
 
-To run ruff, try any of the following:
+To run Ruff, try any of the following:
 
 ```shell
 ruff path/to/code/to/check.py
@@ -46,27 +66,27 @@ ruff path/to/code/
 ruff path/to/code/*.py
 ```
 
-You can run ruff in `--watch` mode to automatically re-run on-change:
+You can run Ruff in `--watch` mode to automatically re-run on-change:
 
 ```shell
 ruff path/to/code/ --watch
 ```
 
-ruff also works with [pre-commit](https://pre-commit.com):
+Ruff also works with [pre-commit](https://pre-commit.com):
 
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.48
+    rev: v0.0.76
     hooks:
       - id: lint
 ```
 
 ## Configuration
 
-ruff is configurable both via `pyproject.toml` and the command line.
+Ruff is configurable both via `pyproject.toml` and the command line.
 
-For example, you could configure ruff to only enforce a subset of rules with:
+For example, you could configure Ruff to only enforce a subset of rules with:
 
 ```toml
 [tool.ruff]
@@ -94,6 +114,8 @@ Arguments:
   <FILES>...
 
 Options:
+      --config <CONFIG>
+          Path to the `pyproject.toml` file to use for configuration
   -v, --verbose
           Enable verbose logging
   -q, --quiet
@@ -130,6 +152,10 @@ Options:
           Enable automatic additions of noqa directives to failing lines
       --dummy-variable-rgx <DUMMY_VARIABLE_RGX>
           Regular expression matching the name of dummy variables
+      --target-version <TARGET_VERSION>
+          The minimum Python version that should be supported
+      --stdin-filename <STDIN_FILENAME>
+          The name of the file when passing it through stdin
   -h, --help
           Print help information
   -V, --version
@@ -152,7 +178,7 @@ Exclusions are based on globs, and can be either:
 To omit a lint check entirely, add it to the "ignore" list via `--ignore` or `--extend-ignore`,
 either  on the command-line or in your `project.toml` file.
 
-To ignore an error in-line, ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
+To ignore an error in-line, Ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
 To ignore an individual error, add `# noqa: {code}` to the end of the line, like so:
 
 ```python
@@ -176,123 +202,208 @@ Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor i
 """  # noqa: E501
 ```
 
-ruff supports several (experimental) workflows to aid in `noqa` management.
+Ruff supports several workflows to aid in `noqa` management.
 
-First, ruff provides a special error code, `M001`, to enforce that your `noqa` directives are
+First, Ruff provides a special error code, `M001`, to enforce that your `noqa` directives are
 "valid", in that the errors they _say_ they ignore are actually being triggered on that line (and
 thus suppressed). **You can run `ruff /path/to/file.py --extend-select M001` to flag unused `noqa`
 directives.**
 
-Second, ruff can _automatically remove_ unused `noqa` directives via its autofix functionality.
+Second, Ruff can _automatically remove_ unused `noqa` directives via its autofix functionality.
 **You can run `ruff /path/to/file.py --extend-select M001 --fix` to automatically remove unused
 `noqa` directives.**
 
-Third, ruff can _automatically add_ `noqa` directives to all failing lines. This is useful when
-migrating a new codebase to ruff. **You can run `ruff /path/to/file.py --add-noqa` to automatically
+Third, Ruff can _automatically add_ `noqa` directives to all failing lines. This is useful when
+migrating a new codebase to Ruff. **You can run `ruff /path/to/file.py --add-noqa` to automatically
 add `noqa` directives to all failing lines, with the appropriate error codes.**
 
-### Compatibility with Black
+## Supported Rules
 
-ruff is compatible with [Black](https://github.com/psf/black) out-of-the-box, as long as
-the `line-length` setting is consistent between the two.
+By default, Ruff enables all `E`, `W`, and `F` error codes, which correspond to those built-in to
+Flake8.
 
-As a project, ruff is designed to be used alongside Black and, as such, will defer implementing
-stylistic lint rules that are obviated by autoformatting.
-
-### Parity with Flake8
-
-ruff's goal is to achieve feature parity with Flake8 when used (1) without plugins, (2) alongside
-Black, and (3) on Python 3 code.
-
-**Under those conditions, ruff implements 44 out of 60 rules.** (ruff is missing: 14 rules related
-to string `.format` calls, 1 rule related to docstring parsing, and 1 rule related to redefined
-variables.)
-
-ruff also implements some of the most popular Flake8 plugins natively, including:
-
-- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
-- [`flake8-super`](https://pypi.org/project/flake8-super/)
-- [`flake8-print`](https://pypi.org/project/flake8-print/)
-
-Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis Flake8:
-
-1. ruff does not yet support a few Python 3.9 and 3.10 language features, including structural
-   pattern matching and parenthesized context managers.
-2. Flake8 has a plugin architecture and supports writing custom lint rules.
-
-## Rules
+### Pyflakes
 
 | Code | Name | Message |
-| ---- | ----- | ------- |
-| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file |
-| E501 | LineTooLong | Line too long (89 > 88 characters) |
-| E711 | NoneComparison | Comparison to `None` should be `cond is None` |
-| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` |
-| E713 | NotInTest | Test for membership should be `not in` |
-| E714 | NotIsTest | Test for object identity should be `is not` |
-| E721 | TypeComparison | do not compare types, use `isinstance()` |
-| E722 | DoNotUseBareExcept | Do not use bare `except` |
-| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def |
-| E741 | AmbiguousVariableName | ambiguous variable name '...' |
-| E742 | AmbiguousClassName | ambiguous class name '...' |
-| E743 | AmbiguousFunctionName | ambiguous function name '...' |
-| E902 | IOError | ... |
-| E999 | SyntaxError | SyntaxError: ... |
+| ---- | ---- | ------- |
 | F401 | UnusedImport | `...` imported but unused |
-| F402 | ImportShadowedByLoopVar | import '...' from line 1 shadowed by loop variable |
+| F402 | ImportShadowedByLoopVar | Import `...` from line 1 shadowed by loop variable |
 | F403 | ImportStarUsed | `from ... import *` used; unable to detect undefined names |
-| F404 | LateFutureImport | from __future__ imports must occur at the beginning of the file |
-| F405 | ImportStarUsage | '...' may be undefined, or defined from star imports: ... |
+| F404 | LateFutureImport | `from __future__` imports must occur at the beginning of the file |
+| F405 | ImportStarUsage | `...` may be undefined, or defined from star imports: `...` |
 | F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level |
-| F407 | FutureFeatureNotDefined | future feature '...' is not defined |
+| F407 | FutureFeatureNotDefined | Future feature `...` is not defined |
 | F541 | FStringMissingPlaceholders | f-string without any placeholders |
 | F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |
 | F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |
-| F621 | TooManyExpressionsInStarredAssignment | too many expressions in star-unpacking assignment |
-| F622 | TwoStarredExpressions | two starred expressions in assignment |
+| F621 | ExpressionsInStarAssignment | Too many expressions in star-unpacking assignment |
+| F622 | TwoStarredExpressions | Two starred expressions in assignment |
 | F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |
-| F632 | IsLiteral | use ==/!= to compare constant literals |
-| F633 | InvalidPrintSyntax | use of >> is invalid with print function |
+| F632 | IsLiteral | Use `==` and `!=` to compare constant literals |
+| F633 | InvalidPrintSyntax | Use of `>>` is invalid with `print` function |
 | F634 | IfTuple | If test is a tuple, which is always `True` |
 | F701 | BreakOutsideLoop | `break` outside loop |
 | F702 | ContinueOutsideLoop | `continue` not properly in loop |
-| F704 | YieldOutsideFunction | a `yield` or `yield from` statement outside of a function/method |
-| F706 | ReturnOutsideFunction | a `return` statement outside of a function/method |
-| F707 | DefaultExceptNotLast | an `except:` block as not the last exception handler |
-| F722 | ForwardAnnotationSyntaxError | syntax error in forward annotation '...' |
+| F704 | YieldOutsideFunction | `yield` or `yield from` statement outside of a function/method |
+| F706 | ReturnOutsideFunction | `return` statement outside of a function/method |
+| F707 | DefaultExceptNotLast | An `except:` block as not the last exception handler |
+| F722 | ForwardAnnotationSyntaxError | Syntax error in forward annotation: `...` |
 | F821 | UndefinedName | Undefined name `...` |
 | F822 | UndefinedExport | Undefined name `...` in `__all__` |
 | F823 | UndefinedLocal | Local variable `...` referenced before assignment |
 | F831 | DuplicateArgumentName | Duplicate argument name in function definition |
 | F841 | UnusedVariable | Local variable `...` is assigned to but never used |
 | F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` |
+
+### pycodestyle
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
+| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file |
+| E501 | LineTooLong | Line too long (89 > 88 characters) |
+| E711 | NoneComparison | Comparison to `None` should be `cond is None` |
+| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` |
+| E713 | NotInTest | Test for membership should be `not in` |
+| E714 | NotIsTest | Test for object identity should be `is not` |
+| E721 | TypeComparison | Do not compare types, use `isinstance()` |
+| E722 | DoNotUseBareExcept | Do not use bare `except` |
+| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def |
+| E741 | AmbiguousVariableName | Ambiguous variable name: `...` |
+| E742 | AmbiguousClassName | Ambiguous class name: `...` |
+| E743 | AmbiguousFunctionName | Ambiguous function name: `...` |
+| E902 | IOError | IOError: `...` |
+| E999 | SyntaxError | SyntaxError: `...` |
+| W292 | NoNewLineAtEndOfFile | No newline at end of file |
+
+### pydocstyle
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
+| D100 | PublicModule | Missing docstring in public module |
+| D101 | PublicClass | Missing docstring in public class |
+| D102 | PublicMethod | Missing docstring in public method |
+| D103 | PublicFunction | Missing docstring in public function |
+| D104 | PublicPackage | Missing docstring in public package |
+| D105 | MagicMethod | Missing docstring in magic method |
+| D106 | PublicNestedClass | Missing docstring in public nested class |
+| D107 | PublicInit | Missing docstring in `__init__` |
+| D200 | FitsOnOneLine | One-line docstring should fit on one line |
+| D201 | NoBlankLineBeforeFunction | No blank lines allowed before function docstring (found 1) |
+| D202 | NoBlankLineAfterFunction | No blank lines allowed after function docstring (found 1) |
+| D203 | OneBlankLineBeforeClass | 1 blank line required before class docstring |
+| D204 | OneBlankLineAfterClass | 1 blank line required after class docstring |
+| D205 | NoBlankLineAfterSummary | 1 blank line required between summary line and description |
+| D206 | IndentWithSpaces | Docstring should be indented with spaces, not tabs |
+| D207 | NoUnderIndentation | Docstring is under-indented |
+| D208 | NoOverIndentation | Docstring is over-indented |
+| D209 | NewLineAfterLastParagraph | Multi-line docstring closing quotes should be on a separate line |
+| D210 | NoSurroundingWhitespace | No whitespaces allowed surrounding docstring text |
+| D211 | NoBlankLineBeforeClass | No blank lines allowed before class docstring |
+| D212 | MultiLineSummaryFirstLine | Multi-line docstring summary should start at the first line |
+| D213 | MultiLineSummarySecondLine | Multi-line docstring summary should start at the second line |
+| D214 | SectionNotOverIndented | Section is over-indented ("Returns") |
+| D215 | SectionUnderlineNotOverIndented | Section underline is over-indented ("Returns") |
+| D300 | UsesTripleQuotes | Use """triple double quotes""" |
+| D400 | EndsInPeriod | First line should end with a period |
+| D402 | NoSignature | First line should not be the function's 'signature' |
+| D403 | FirstLineCapitalized | First word of the first line should be properly capitalized |
+| D404 | NoThisPrefix | First word of the docstring should not be `This` |
+| D405 | CapitalizeSectionName | Section name should be properly capitalized ("returns") |
+| D406 | NewLineAfterSectionName | Section name should end with a newline ("Returns") |
+| D407 | DashedUnderlineAfterSection | Missing dashed underline after section ("Returns") |
+| D408 | SectionUnderlineAfterName | Section underline should be in the line following the section's name ("Returns") |
+| D409 | SectionUnderlineMatchesSectionLength | Section underline should match the length of its name ("Returns") |
+| D410 | BlankLineAfterSection | Missing blank line after section ("Returns") |
+| D411 | BlankLineBeforeSection | Missing blank line before section ("Returns") |
+| D412 | NoBlankLinesBetweenHeaderAndContent | No blank lines allowed between a section header and its content ("Returns") |
+| D413 | BlankLineAfterLastSection | Missing blank line after last section ("Returns") |
+| D414 | NonEmptySection | Section has no content ("Returns") |
+| D415 | EndsInPunctuation | First line should end with a period, question mark, or exclamation point |
+| D416 | SectionNameEndsInColon | Section name should end with a colon ("Returns") |
+| D417 | DocumentAllArguments | Missing argument descriptions in the docstring: `x`, `y` |
+| D418 | SkipDocstring | Function decorated with @overload shouldn't contain a docstring |
+| D419 | NonEmpty | Docstring is empty |
+
+### pyupgrade
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
+| U001 | UselessMetaclassType | `__metaclass__ = type` is implied |
+| U002 | UnnecessaryAbspath | `abspath(__file__)` is unnecessary in Python 3.9 and later |
+| U003 | TypeOfPrimitive | Use `str` instead of `type(...)` |
+| U004 | UselessObjectInheritance | Class `...` inherits from object |
+| U005 | DeprecatedUnittestAlias | `assertEquals` is deprecated, use `assertEqual` instead |
+| U006 | UsePEP585Annotation | Use `list` instead of `List` for type annotations |
+| U007 | UsePEP604Annotation | Use `X \| Y` for type annotations |
+| U008 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` |
+
+### flake8-comprehensions
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
+| C400 | UnnecessaryGeneratorList | Unnecessary generator - rewrite as a list comprehension |
+| C401 | UnnecessaryGeneratorSet | Unnecessary generator - rewrite as a set comprehension |
+| C402 | UnnecessaryGeneratorDict | Unnecessary generator - rewrite as a dict comprehension |
+| C403 | UnnecessaryListComprehensionSet | Unnecessary list comprehension - rewrite as a set comprehension |
+| C404 | UnnecessaryListComprehensionDict | Unnecessary list comprehension - rewrite as a dict comprehension |
+| C405 | UnnecessaryLiteralSet | Unnecessary <list/tuple> literal - rewrite as a set literal |
+| C406 | UnnecessaryLiteralDict | Unnecessary <list/tuple> literal - rewrite as a dict literal |
+| C408 | UnnecessaryCollectionCall | Unnecessary <dict/list/tuple> call - rewrite as a literal |
+| C409 | UnnecessaryLiteralWithinTupleCall | Unnecessary <list/tuple> literal passed to tuple() - remove the outer call to tuple() |
+| C410 | UnnecessaryLiteralWithinListCall | Unnecessary <list/tuple> literal passed to list() - rewrite as a list literal |
+| C411 | UnnecessaryListCall | Unnecessary list call - remove the outer call to list() |
+| C413 | UnnecessaryCallAroundSorted | Unnecessary <list/reversed> call around sorted() |
+| C414 | UnnecessaryDoubleCastOrProcess | Unnecessary <list/reversed/set/sorted/tuple> call within <list/set/sorted/tuple>(). |
+| C415 | UnnecessarySubscriptReversal | Unnecessary subscript reversal of iterable within <reversed/set/sorted>() |
+| C416 | UnnecessaryComprehension |  Unnecessary <list/set> comprehension - rewrite using <list/set>() |
+| C417 | UnnecessaryMap | Unnecessary map usage - rewrite using a <list/set/dict> comprehension |
+
+### flake8-bugbear
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
+| B011 | DoNotAssertFalse | Do not `assert False` (`python -O` removes these calls), raise `AssertionError()` |
+| B014 | DuplicateHandlerException | Exception handler with duplicate exception: `ValueError` |
+| B025 | DuplicateTryBlockException | try-except block with duplicate exception `Exception` |
+
+### flake8-builtins
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
 | A001 | BuiltinVariableShadowing | Variable `...` is shadowing a python builtin |
 | A002 | BuiltinArgumentShadowing | Argument `...` is shadowing a python builtin |
-| A003 | BuiltinAttributeShadowing | class attribute `...` is shadowing a python builtin |
-| SPR001 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` |
+| A003 | BuiltinAttributeShadowing | Class attribute `...` is shadowing a python builtin |
+
+### flake8-print
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
 | T201 | PrintFound | `print` found |
-| T203 | PPrintFound | `pprint` found` |
-| R001 | UselessObjectInheritance | Class `...` inherits from object |
-| R002 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |
+| T203 | PPrintFound | `pprint` found |
+
+### Meta rules
+
+| Code | Name | Message |
+| ---- | ---- | ------- |
 | M001 | UnusedNOQA | Unused `noqa` directive |
 
-## Integrations
+## Editor Integrations
 
 ### PyCharm
 
-ruff can be installed as an [External Tool](https://www.jetbrains.com/help/pycharm/configuring-third-party-tools.html)
+Ruff can be installed as an [External Tool](https://www.jetbrains.com/help/pycharm/configuring-third-party-tools.html)
 in PyCharm. Open the Preferences pane, then navigate to "Tools", then "External Tools". From there,
 add a new tool with the following configuration:
 
-![Install ruff as an External Tool](https://user-images.githubusercontent.com/1309177/193155720-336e43f0-1a8d-46b4-bc12-e60f9ae01f7e.png)
+![Install Ruff as an External Tool](https://user-images.githubusercontent.com/1309177/193155720-336e43f0-1a8d-46b4-bc12-e60f9ae01f7e.png)
 
-ruff should then appear as a runnable action:
+Ruff should then appear as a runnable action:
 
-![ruff as a runnable action](https://user-images.githubusercontent.com/1309177/193156026-732b0aaf-3dd9-4549-9b4d-2de6d2168a33.png)
+![Ruff as a runnable action](https://user-images.githubusercontent.com/1309177/193156026-732b0aaf-3dd9-4549-9b4d-2de6d2168a33.png)
 
 ### GitHub Actions
 
-GitHub Actions has everything you need to run ruff out-of-the-box:
+GitHub Actions has everything you need to run Ruff out-of-the-box:
 
 ```yaml
 name: CI
@@ -301,22 +412,184 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Install Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: "3.10"
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install ruff
-      - name: Run ruff
+      - name: Run Ruff
         run: ruff .
 ```
 
+## FAQ
+
+### Is Ruff compatible with Black?
+
+Yes. Ruff is compatible with [Black](https://github.com/psf/black) out-of-the-box, as long as
+the `line-length` setting is consistent between the two.
+
+As a project, Ruff is designed to be used alongside Black and, as such, will defer implementing
+stylistic lint rules that are obviated by autoformatting.
+
+### How does Ruff compare to Flake8?
+
+Ruff can be used as a (near) drop-in replacement for Flake8 when used (1) without or with a small
+number of plugins, (2) alongside Black, and (3) on Python 3 code.
+
+Under those conditions Ruff is missing 14 rules related to string `.format` calls, 1 rule related
+to docstring parsing, and 1 rule related to redefined variables.
+
+Ruff re-implements some of the most popular Flake8 plugins and related code quality tools natively,
+including:
+
+- [`pydocstyle`](https://pypi.org/project/pydocstyle/)
+- [`yesqa`](https://github.com/asottile/yesqa)
+- [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/)
+- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
+- [`flake8-super`](https://pypi.org/project/flake8-super/)
+- [`flake8-print`](https://pypi.org/project/flake8-print/)
+- [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
+- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (3/32)
+- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (8/34)
+- [`autoflake`](https://pypi.org/project/autoflake/) (1/7)
+
+Beyond rule-set parity, Ruff suffers from the following limitations vis-à-vis Flake8:
+
+1. Ruff does not yet support a few Python 3.9 and 3.10 language features, including structural
+   pattern matching and parenthesized context managers.
+2. Flake8 has a plugin architecture and supports writing custom lint rules. (To date, popular Flake8
+   plugins have been re-implemented within Ruff directly.)
+
+### Which tools does Ruff replace?
+
+Today, Ruff can be used to replace Flake8 when used with any of the following plugins:
+
+- [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/)
+- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
+- [`flake8-super`](https://pypi.org/project/flake8-super/)
+- [`flake8-print`](https://pypi.org/project/flake8-print/)
+- [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
+- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (3/32)
+
+Ruff also implements the functionality that you get from [`yesqa`](https://github.com/asottile/yesqa),
+and a subset of the rules implemented in [`pyupgrade`](https://pypi.org/project/pyupgrade/) (8/34).
+
+If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, free to file an Issue.
+
+### Do I need to install Rust to use Ruff?
+
+Nope! Ruff is available as [`ruff`](https://pypi.org/project/ruff/) on PyPI:
+
+```shell
+pip install ruff
+```
+
+Ruff ships with wheels for all major platforms, which enables `pip` to install Ruff without relying
+on Rust at all.
+
+### Can I write my own plugins for Ruff?
+
+Ruff does not yet support third-party plugins, though a plugin system is within-scope for the
+project. See [#283](https://github.com/charliermarsh/ruff/issues/2830) for more.
+
+### Does Ruff support NumPy- or Google-style docstrings?
+
+Yes! To enable a specific docstring convention, start by enabling all `pydocstyle` error codes, and
+then selectively disabling based on your [preferred convention](https://www.pydocstyle.org/en/latest/error_codes.html#default-conventions).
+
+For example, if you're coming from `flake8-docstrings`, the following configuration is equivalent to
+`--docstring-convention numpy`:
+
+```toml
+[tool.ruff]
+extend-select = [
+    "D100",
+    "D101",
+    "D102",
+    "D103",
+    "D104",
+    "D105",
+    "D106",
+    "D200",
+    "D201",
+    "D202",
+    "D204",
+    "D205",
+    "D206",
+    "D207",
+    "D208",
+    "D209",
+    "D210",
+    "D211",
+    "D214",
+    "D215",
+    "D300",
+    "D400",
+    "D402",
+    "D403",
+    "D404",
+    "D405",
+    "D406",
+    "D407",
+    "D408",
+    "D409",
+    "D410",
+    "D411",
+    "D412",
+    "D413",
+    "D418",
+    "D419",
+]
+```
+
+Similarly, the following is equivalent to `--docstring-convention google`:
+
+```toml
+[tool.ruff]
+extend-select = [
+    "D100",
+    "D101",
+    "D102",
+    "D103",
+    "D104",
+    "D105",
+    "D106",
+    "D107",
+    "D200",
+    "D201",
+    "D202",
+    "D205",
+    "D206",
+    "D207",
+    "D208",
+    "D209",
+    "D210",
+    "D211",
+    "D212",
+    "D214",
+    "D300",
+    "D402",
+    "D403",
+    "D405",
+    "D410",
+    "D411",
+    "D412",
+    "D414",
+    "D415",
+    "D416",
+    "D417",
+    "D418",
+    "D419",
+]
+```
+
 ## Development
 
-ruff is written in Rust (1.63.0). You'll need to install the [Rust toolchain](https://www.rust-lang.org/tools/install)
+Ruff is written in Rust (1.63.0). You'll need to install the [Rust toolchain](https://www.rust-lang.org/tools/install)
 for development.
 
 Assuming you have `cargo` installed, you can run:
@@ -328,13 +601,13 @@ cargo clippy
 cargo test
 ```
 
-## Deployment
+## Releases
 
-ruff is distributed on [PyPI](https://pypi.org/project/ruff/), and published via [`maturin`](https://github.com/PyO3/maturin).
+Ruff is distributed on [PyPI](https://pypi.org/project/ruff/), and published via [`maturin`](https://github.com/PyO3/maturin).
 
 See: `.github/workflows/release.yaml`.
 
-## Benchmarking
+## Benchmarks
 
 First, clone [CPython](https://github.com/python/cpython). It's a large and diverse Python codebase,
 which makes it a good target for benchmarking.
@@ -411,9 +684,9 @@ hyperfine --ignore-failure --warmup 5 \
 
 In order, these evaluate:
 
-- ruff
+- Ruff
 - Pylint
-- PyFlakes
+- Pyflakes
 - autoflake
 - pycodestyle
 - Flake8
@@ -477,4 +750,4 @@ MIT
 ## Contributing
 
 Contributions are welcome and hugely appreciated. To get started, check out the
-[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTORS.md).
+[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTING.md).

examples/generate_rules_table.rs

@@ -1,19 +1,27 @@
-/// Generate a Markdown-compatible table of supported lint rules.
-use ruff::checks::{CheckCode, ALL_CHECK_CODES};
+//! Generate a Markdown-compatible table of supported lint rules.
+
+use strum::IntoEnumIterator;
+
+use ruff::checks::{CheckCategory, CheckCode};
 
 fn main() {
-    let mut check_codes: Vec<CheckCode> = ALL_CHECK_CODES.to_vec();
-    check_codes.sort();
+    for check_category in CheckCategory::iter() {
+        println!("### {}", check_category.title());
+        println!();
 
-    println!("| Code | Name | Message |");
-    println!("| ---- | ----- | ------- |");
-    for check_code in check_codes {
-        let check_kind = check_code.kind();
-        println!(
-            "| {} | {} | {} |",
-            check_kind.code().as_str(),
-            check_kind.name(),
-            check_kind.body()
-        );
+        println!("| Code | Name | Message |");
+        println!("| ---- | ---- | ------- |");
+        for check_code in CheckCode::iter() {
+            if check_code.category() == check_category {
+                let check_kind = check_code.kind();
+                println!(
+                    "| {} | {} | {} |",
+                    check_kind.code().as_ref(),
+                    check_kind.as_ref(),
+                    check_kind.body().replace("|", r"\|")
+                );
+            }
+        }
+        println!();
     }
 }

examples/generate_source_code.rs

@@ -0,0 +1,26 @@
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::Parser;
+use rustpython_parser::parser;
+
+use ruff::code_gen::SourceGenerator;
+use ruff::fs;
+
+#[derive(Debug, Parser)]
+struct Cli {
+    #[arg(required = true)]
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let contents = fs::read_file(&cli.file)?;
+    let python_ast = parser::parse_program(&contents, &cli.file.to_string_lossy())?;
+    let mut generator = SourceGenerator::new();
+    generator.unparse_suite(&python_ast)?;
+    println!("{}", generator.generate()?);
+
+    Ok(())
+}

examples/print_ast.rs

@@ -1,4 +1,5 @@
-/// Print the AST for a given Python file.
+//! Print the AST for a given Python file.
+
 use std::path::PathBuf;
 
 use anyhow::Result;

examples/print_tokens.rs

@@ -1,4 +1,5 @@
-/// Print the token stream for a given Python file.
+//! Print the token stream for a given Python file.
+
 use std::path::PathBuf;
 
 use anyhow::Result;

resources/test/fixtures/B011.py

@@ -0,0 +1,10 @@
+"""
+Should emit:
+B011 - on line 8
+B011 - on line 10
+"""
+
+assert 1 != 2
+assert False
+assert 1 != 2, "message"
+assert False, "message"

resources/test/fixtures/B014.py

@@ -0,0 +1,76 @@
+"""
+Should emit:
+B014 - on lines 11, 17, 28, 42, 49, 56, and 74.
+"""
+
+import binascii
+import re
+
+try:
+    pass
+except (Exception, TypeError):
+    # TypeError is a subclass of Exception, so it doesn't add anything
+    pass
+
+try:
+    pass
+except (OSError, OSError) as err:
+    # Duplicate exception types are useless
+    pass
+
+
+class MyError(Exception):
+    pass
+
+
+try:
+    pass
+except (MyError, MyError):
+    # Detect duplicate non-builtin errors
+    pass
+
+
+try:
+    pass
+except (MyError, Exception) as e:
+    # Don't assume that we're all subclasses of Exception
+    pass
+
+
+try:
+    pass
+except (MyError, BaseException) as e:
+    # But we *can* assume that everything is a subclass of BaseException
+    pass
+
+
+try:
+    pass
+except (re.error, re.error):
+    # Duplicate exception types as attributes
+    pass
+
+
+try:
+    pass
+except (IOError, EnvironmentError, OSError):
+    # Detect if a primary exception and any its aliases are present.
+    #
+    # Since Python 3.3, IOError, EnvironmentError, WindowsError, mmap.error,
+    # socket.error and select.error are aliases of OSError. See PEP 3151 for
+    # more info.
+    pass
+
+
+try:
+    pass
+except (MyException, NotImplemented):
+    # NotImplemented is not an exception, let's not crash on it.
+    pass
+
+
+try:
+    pass
+except (ValueError, binascii.Error):
+    # binascii.Error is a subclass of ValueError.
+    pass

resources/test/fixtures/B025.py

@@ -0,0 +1,38 @@
+"""
+Should emit:
+B025 - on lines 15, 22, 31
+"""
+
+import pickle
+
+try:
+    a = 1
+except ValueError:
+    a = 2
+finally:
+    a = 3
+
+try:
+    a = 1
+except ValueError:
+    a = 2
+except ValueError:
+    a = 2
+
+try:
+    a = 1
+except pickle.PickleError:
+    a = 2
+except ValueError:
+    a = 2
+except pickle.PickleError:
+    a = 2
+
+try:
+    a = 1
+except (ValueError, TypeError):
+    a = 2
+except ValueError:
+    a = 2
+except (OSError, TypeError):
+    a = 2

resources/test/fixtures/C400.py

@@ -0,0 +1 @@
+x = list(x for x in range(3))

resources/test/fixtures/C401.py

@@ -0,0 +1 @@
+x = set(x for x in range(3))

resources/test/fixtures/C402.py

@@ -0,0 +1 @@
+d = dict((x, x) for x in range(3))

resources/test/fixtures/C403.py

@@ -0,0 +1 @@
+s = set([x for x in range(3)])

resources/test/fixtures/C404.py

@@ -0,0 +1 @@
+d = dict([(i, i) for i in range(3)])

resources/test/fixtures/C405.py

@@ -0,0 +1,5 @@
+s1 = set([1, 2])
+s2 = set((1, 2))
+s3 = set([])
+s4 = set(())
+s5 = set()

resources/test/fixtures/C406.py

@@ -0,0 +1,5 @@
+d1 = dict([(1, 2)])
+d2 = dict(((1, 2),))
+d3 = dict([])
+d4 = dict(())
+d5 = dict()

resources/test/fixtures/C408.py

@@ -0,0 +1,5 @@
+t = tuple()
+l = list()
+d1 = dict()
+d2 = dict(a=1)
+d3 = dict(**d2)

resources/test/fixtures/C409.py

@@ -0,0 +1,3 @@
+t1 = tuple([1, 2])
+t2 = tuple((1, 2))
+t3 = tuple([])

resources/test/fixtures/C410.py

@@ -0,0 +1,4 @@
+l1 = list([1, 2])
+l2 = list((1, 2))
+l3 = list([])
+l4 = list(())

resources/test/fixtures/C411.py

@@ -0,0 +1,2 @@
+x = [1, 2, 3]
+list([i for i in x])

resources/test/fixtures/C413.py

@@ -0,0 +1,4 @@
+x = [2, 3, 1]
+list(sorted(x))
+reversed(sorted(x))
+reversed(sorted(x, reverse=True))

resources/test/fixtures/C414.py

@@ -0,0 +1,14 @@
+x = [1, 2, 3]
+list(list(x))
+list(tuple(x))
+tuple(list(x))
+tuple(tuple(x))
+set(set(x))
+set(list(x))
+set(tuple(x))
+set(sorted(x))
+set(reversed(x))
+sorted(list(x))
+sorted(tuple(x))
+sorted(sorted(x))
+sorted(reversed(x))

resources/test/fixtures/C415.py

@@ -0,0 +1,9 @@
+lst = [2, 1, 3]
+a = set(lst[::-1])
+b = reversed(lst[::-1])
+c = sorted(lst[::-1])
+d = sorted(lst[::-1], reverse=True)
+e = set(lst[2:-1])
+f = set(lst[:1:-1])
+g = set(lst[::1])
+h = set(lst[::-2])

resources/test/fixtures/C416.py

@@ -0,0 +1,6 @@
+x = [1, 2, 3]
+[i for i in x]
+{i for i in x}
+
+[i for i in x if i > 1]
+[i for i in x for j in x]

resources/test/fixtures/C417.py

@@ -0,0 +1,6 @@
+nums = [1, 2, 3]
+map(lambda x: x + 1, nums)
+map(lambda x: str(x), nums)
+list(map(lambda x: x * 2, nums))
+set(map(lambda x: x % 2 == 0, nums))
+dict(map(lambda v: (v, v**2), nums))

resources/test/fixtures/D.py

@@ -0,0 +1,534 @@
+# No docstring, so we can test D100
+from functools import wraps
+import os
+from .expected import Expectation
+from typing import overload
+
+
+expectation = Expectation()
+expect = expectation.expect
+
+expect('class_', 'D101: Missing docstring in public class')
+
+
+class class_:
+
+    expect('meta', 'D419: Docstring is empty')
+
+    class meta:
+        """"""
+
+    @expect('D102: Missing docstring in public method')
+    def method(self=None):
+        pass
+
+    def _ok_since_private(self=None):
+        pass
+
+    @overload
+    def overloaded_method(self, a: int) -> str:
+        ...
+
+    @overload
+    def overloaded_method(self, a: str) -> str:
+        """Foo bar documentation."""
+        ...
+
+    def overloaded_method(a):
+        """Foo bar documentation."""
+        return str(a)
+
+    expect('overloaded_method',
+           "D418: Function/ Method decorated with @overload"
+           " shouldn't contain a docstring")
+
+    @property
+    def foo(self):
+        """The foo of the thing, which isn't in imperitive mood."""
+        return "hello"
+
+    @expect('D102: Missing docstring in public method')
+    def __new__(self=None):
+        pass
+
+    @expect('D107: Missing docstring in __init__')
+    def __init__(self=None):
+        pass
+
+    @expect('D105: Missing docstring in magic method')
+    def __str__(self=None):
+        pass
+
+    @expect('D102: Missing docstring in public method')
+    def __call__(self=None, x=None, y=None, z=None):
+        pass
+
+
+@expect('D419: Docstring is empty')
+def function():
+    """ """
+    def ok_since_nested():
+        pass
+
+    @expect('D419: Docstring is empty')
+    def nested():
+        ''
+
+
+def function_with_nesting():
+    """Foo bar documentation."""
+    @overload
+    def nested_overloaded_func(a: int) -> str:
+        ...
+
+    @overload
+    def nested_overloaded_func(a: str) -> str:
+        """Foo bar documentation."""
+        ...
+
+    def nested_overloaded_func(a):
+        """Foo bar documentation."""
+        return str(a)
+
+
+expect('nested_overloaded_func',
+       "D418: Function/ Method decorated with @overload"
+       " shouldn't contain a docstring")
+
+
+@overload
+def overloaded_func(a: int) -> str:
+    ...
+
+
+@overload
+def overloaded_func(a: str) -> str:
+    """Foo bar documentation."""
+    ...
+
+
+def overloaded_func(a):
+    """Foo bar documentation."""
+    return str(a)
+
+
+expect('overloaded_func',
+       "D418: Function/ Method decorated with @overload"
+       " shouldn't contain a docstring")
+
+
+@expect('D200: One-line docstring should fit on one line with quotes '
+        '(found 3)')
+@expect('D212: Multi-line docstring summary should start at the first line')
+def asdlkfasd():
+    """
+    Wrong.
+    """
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+def leading_space():
+
+    """Leading space."""
+
+
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+def trailing_space():
+    """Leading space."""
+
+    pass
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+def trailing_and_leading_space():
+
+    """Trailing and leading space."""
+
+    pass
+
+
+expect('LeadingSpaceMissing',
+       'D203: 1 blank line required before class docstring (found 0)')
+
+
+class LeadingSpaceMissing:
+    """Leading space missing."""
+
+
+expect('WithLeadingSpace',
+       'D211: No blank lines allowed before class docstring (found 1)')
+
+
+class WithLeadingSpace:
+
+    """With leading space."""
+
+
+expect('TrailingSpace',
+       'D204: 1 blank line required after class docstring (found 0)')
+expect('TrailingSpace',
+       'D211: No blank lines allowed before class docstring (found 1)')
+
+
+class TrailingSpace:
+
+    """TrailingSpace."""
+    pass
+
+
+expect('LeadingAndTrailingSpaceMissing',
+       'D203: 1 blank line required before class docstring (found 0)')
+expect('LeadingAndTrailingSpaceMissing',
+       'D204: 1 blank line required after class docstring (found 0)')
+
+
+class LeadingAndTrailingSpaceMissing:
+    """Leading and trailing space missing."""
+    pass
+
+
+@expect('D205: 1 blank line required between summary line and description '
+        '(found 0)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_zero_separating_blanks():
+    """Summary.
+    Description.
+
+    """
+
+
+@expect('D205: 1 blank line required between summary line and description '
+        '(found 2)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_two_separating_blanks():
+    """Summary.
+
+
+    Description.
+
+    """
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_one_separating_blanks():
+    """Summary.
+
+    Description.
+
+    """
+
+
+@expect('D207: Docstring is under-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdf():
+    """Summary.
+
+Description.
+
+    """
+
+
+@expect('D207: Docstring is under-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdsdfsdffsdf():
+    """Summary.
+
+    Description.
+
+"""
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdsdf24():
+    """Summary.
+
+       Description.
+
+    """
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdsdfsdf24():
+    """Summary.
+
+    Description.
+
+        """
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdfsdsdsdfsdf24():
+    """Summary.
+
+        Description.
+
+    """
+
+
+@expect('D209: Multi-line docstring closing quotes should be on a separate '
+        'line')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfljdf24():
+    """Summary.
+
+    Description."""
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+def endswith():
+    """Whitespace at the end. """
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+def around():
+    """ Whitespace at everywhere. """
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multiline():
+    """ Whitespace at the beginning.
+
+    This is the end.
+    """
+
+
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw():
+    r'''Summary.'''
+
+
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw_uppercase():
+    R'''Summary.'''
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw():
+    r'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw_uppercase():
+    R'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+@expect('D301: Use r""" if any backslashes in a docstring')
+def single_quotes_raw_uppercase_backslash():
+    R'Sum\mary.'
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash():
+    """Sum\\mary."""
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash_uppercase():
+    R"""Sum\\mary."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def exceptions_of_D301():
+    """Exclude some backslashes from D301.
+
+    In particular, line continuations \
+    and unicode literals \u0394 and \N{GREEK CAPITAL LETTER DELTA}.
+    They are considered to be intentionally unescaped.
+    """
+
+
+@expect("D400: First line should end with a period (not 'y')")
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'y')")
+def lwnlkjl():
+    """Summary"""
+
+
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Return', not 'Returns')")
+def liouiwnlkjl():
+    """Returns foo."""
+
+
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'Constructor')")
+def sdgfsdg23245():
+    """Constructor for a foo."""
+
+
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'Constructor')")
+def sdgfsdg23245777():
+    """Constructor."""
+
+
+@expect('D402: First line should not be the function\'s "signature"')
+def foobar():
+    """Signature: foobar()."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def new_209():
+    """First line.
+
+    More lines.
+    """
+    pass
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def old_209():
+    """One liner.
+
+    Multi-line comments. OK to have extra blank line
+
+    """
+
+
+@expect("D103: Missing docstring in public function")
+def oneliner_d102(): return
+
+
+@expect("D400: First line should end with a period (not 'r')")
+@expect("D415: First line should end with a period, question mark,"
+        " or exclamation point (not 'r')")
+def oneliner_withdoc(): """One liner"""
+
+
+def ignored_decorator(func):   # noqa: D400,D401,D415
+    """Runs something"""
+    func()
+    pass
+
+
+def decorator_for_test(func):   # noqa: D400,D401,D415
+    """Runs something"""
+    func()
+    pass
+
+
+@ignored_decorator
+def oneliner_ignored_decorator(): """One liner"""
+
+
+@decorator_for_test
+@expect("D400: First line should end with a period (not 'r')")
+@expect("D415: First line should end with a period, question mark,"
+        " or exclamation point (not 'r')")
+def oneliner_with_decorator_expecting_errors(): """One liner"""
+
+
+@decorator_for_test
+def valid_oneliner_with_decorator(): """One liner."""
+
+
+@expect("D207: Docstring is under-indented")
+@expect('D213: Multi-line docstring summary should start at the second line')
+def docstring_start_in_same_line(): """First Line.
+
+    Second Line
+    """
+
+
+def function_with_lambda_arg(x=lambda y: y):
+    """Wrap the given lambda."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def a_following_valid_function(x=None):
+    """Check for a bug where the previous function caused an assertion.
+
+    The assertion was caused in the next function, so this one is necessary.
+
+    """
+
+
+def outer_function():
+    """Do something."""
+    def inner_function():
+        """Do inner something."""
+        return 0
+
+
+@expect("D400: First line should end with a period (not 'g')")
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Run', not 'Runs')")
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'g')")
+def docstring_bad():
+    """Runs something"""
+    pass
+
+
+def docstring_bad_ignore_all():  # noqa
+    """Runs something"""
+    pass
+
+
+def docstring_bad_ignore_one():  # noqa: D400,D401,D415
+    """Runs something"""
+    pass
+
+
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Run', not 'Runs')")
+def docstring_ignore_some_violations_but_catch_D401():  # noqa: E501,D400,D415
+    """Runs something"""
+    pass
+
+
+@expect(
+    "D401: First line should be in imperative mood "
+    "(perhaps 'Initiate', not 'Initiates')"
+)
+def docstring_initiates():
+    """Initiates the process."""
+
+
+@expect(
+    "D401: First line should be in imperative mood "
+    "(perhaps 'Initialize', not 'Initializes')"
+)
+def docstring_initializes():
+    """Initializes the process."""
+
+
+@wraps(docstring_bad_ignore_one)
+def bad_decorated_function():
+    """Bad (E501) but decorated"""
+    pass
+
+
+def valid_google_string():  # noqa: D400
+    """Test a valid something!"""
+
+
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'g')")
+def bad_google_string():  # noqa: D400
+    """Test a valid something"""
+
+
+# This is reproducing a bug where AttributeError is raised when parsing class
+# parameters as functions for Google / Numpy conventions.
+class Blah:  # noqa: D203,D213
+    """A Blah.
+
+    Parameters
+    ----------
+    x : int
+
+    """
+
+    def __init__(self, x):
+        pass
+
+
+expect(os.path.normcase(__file__ if __file__[-1] != 'c' else __file__[:-1]),
+       'D100: Missing docstring in public module')

resources/test/fixtures/F401_0.py

@@ -65,3 +65,24 @@ b = Union["Nut", None]
 c = cast("Vegetable", b)
 
 Field = lambda default=MISSING: field(default=default)
+
+
+# Test: access a sub-importation via an alias.
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))
+
+
+# Test: referencing an import via TypeAlias.
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_1.py

@@ -0,0 +1,5 @@
+"""Access a sub-importation via an alias."""
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))

resources/test/fixtures/F401_2.py

@@ -0,0 +1,12 @@
+"""Test: referencing an import via TypeAlias."""
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_3.py

@@ -0,0 +1,14 @@
+"""Test: referencing an import via TypeAlias (with future annotations)."""
+from __future__ import annotations
+
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = np.int8 | np.int16

resources/test/fixtures/F401_4.py

@@ -0,0 +1,14 @@
+"""Test: referencing an import via TypeAlias (with future annotations and quotes)."""
+from __future__ import annotations
+
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F404.py

@@ -1,4 +1,3 @@
-from __future__ import print_function
 """Docstring"""
 from __future__ import absolute_import
 

resources/test/fixtures/F821.py

@@ -89,3 +89,45 @@ A = (
     f'B'
     f'{B}'
 )
+
+
+from typing import Annotated, Literal
+
+
+def arbitrary_callable() -> None:
+    ...
+
+
+class PEP593Test:
+    field: Annotated[
+        int,
+        "base64",
+        arbitrary_callable(),
+        123,
+        (1, 2, 3),
+    ]
+    field_with_stringified_type: Annotated[
+        "PEP593Test",
+        123,
+    ]
+    field_with_undefined_stringified_type: Annotated[
+        "PEP593Test123",
+        123,
+    ]
+    field_with_nested_subscript: Annotated[
+        dict[Literal["foo"], str],
+        123,
+    ]
+    field_with_undefined_nested_subscript: Annotated[
+        dict["foo", "bar"],  # Expected to fail as undefined.
+        123,
+    ]
+
+
+def in_ipython_notebook() -> bool:
+    try:
+        # autoimported by notebooks
+        get_ipython()  # type: ignore[name-defined]
+    except NameError:
+        return False  # not in notebook
+    return True

resources/test/fixtures/M001.py

@@ -15,6 +15,9 @@ def f() -> None:
     # Invalid
     d = 1  # noqa: F841, E501
 
+    # Invalid (and unimplemented)
+    d = 1  # noqa: F841, W191
+
 
 # Valid
 _ = """Lorem ipsum dolor sit amet.

resources/test/fixtures/R002.py

@@ -1,3 +0,0 @@
-self.assertEquals (1, 2)
-self.assertEquals(1, 2)
-self.assertEqual(3, 4)

resources/test/fixtures/SPR001.py

@@ -1,22 +0,0 @@
-class Parent:
-    def method(self):
-        pass
-
-    def wrong(self):
-        pass
-
-
-class Child(Parent):
-    def method(self):
-        parent = super()  # ok
-        super().method()  # ok
-        Parent.method(self)  # ok
-        Parent.super(1, 2)  # ok
-
-    def wrong(self):
-        parent = super(Child, self)  # wrong
-        super(Child, self).method  # wrong
-        super(
-            Child,
-            self,
-        ).method()  # wrong

resources/test/fixtures/U001.py

@@ -0,0 +1,13 @@
+class A:
+    __metaclass__ = type
+
+
+class B:
+    __metaclass__ = type
+
+    def __init__(self) -> None:
+        pass
+
+
+class C(metaclass=type):
+    pass

resources/test/fixtures/U002.py

@@ -0,0 +1,15 @@
+from os.path import abspath
+
+x = abspath(__file__)
+
+
+import os
+
+
+y = os.path.abspath(__file__)
+
+
+from os import path
+
+
+z = path.abspath(__file__)

resources/test/fixtures/U003.py

@@ -0,0 +1,5 @@
+type('')
+type(b'')
+type(0)
+type(0.)
+type(0j)

resources/test/fixtures/U005.py

@@ -0,0 +1,10 @@
+import unittest
+
+
+class Suite(unittest.TestCase):
+    def test(self) -> None:
+        self.assertEquals (1, 2)
+        self.assertEquals(1, 2)
+        self.assertEqual(3, 4)
+        self.failUnlessAlmostEqual(1, 1.1)
+        self.assertNotRegexpMatches("a", "b")

resources/test/fixtures/U006.py

@@ -0,0 +1,12 @@
+from typing import List
+
+
+def f(x: List[str]) -> None:
+    ...
+
+
+import typing
+
+
+def f(x: typing.List[str]) -> None:
+    ...

resources/test/fixtures/U007.py

@@ -0,0 +1,40 @@
+from typing import Optional
+
+
+def f(x: Optional[str]) -> None:
+    ...
+
+
+import typing
+
+
+def f(x: typing.Optional[str]) -> None:
+    ...
+
+
+from typing import Union
+
+
+def f(x: Union[str, int, Union[float, bytes]]) -> None:
+    ...
+
+
+import typing
+
+
+def f(x: typing.Union[str, int]) -> None:
+    ...
+
+
+from typing import Union
+
+
+def f(x: "Union[str, int, Union[float, bytes]]") -> None:
+    ...
+
+
+import typing
+
+
+def f(x: "typing.Union[str, int]") -> None:
+    ...

resources/test/fixtures/U008.py

@@ -0,0 +1,65 @@
+class Parent:
+    def method(self):
+        pass
+
+    def wrong(self):
+        pass
+
+
+class Child(Parent):
+    def method(self):
+        parent = super()  # ok
+        super().method()  # ok
+        Parent.method(self)  # ok
+        Parent.super(1, 2)  # ok
+
+    def wrong(self):
+        parent = super(Child, self)  # wrong
+        super(Child, self).method  # wrong
+        super(
+            Child,
+            self,
+        ).method()  # wrong
+
+
+class BaseClass:
+    def f(self):
+        print("f")
+
+
+def defined_outside(self):
+    super(MyClass, self).f()  # CANNOT use super()
+
+
+class MyClass(BaseClass):
+    def normal(self):
+        super(MyClass, self).f()  # can use super()
+        super().f()
+
+    def different_argument(self, other):
+        super(MyClass, other).f()  # CANNOT use super()
+
+    def comprehension_scope(self):
+        [super(MyClass, self).f() for x in [1]]  # CANNOT use super()
+
+    def inner_functions(self):
+        def outer_argument():
+            super(MyClass, self).f()  # CANNOT use super()
+
+        def inner_argument(self):
+            super(MyClass, self).f()  # can use super()
+            super().f()
+
+        outer_argument()
+        inner_argument(self)
+
+    def inner_class(self):
+        class InnerClass:
+            super(MyClass, self).f()  # CANNOT use super()
+
+            def method(inner_self):
+                super(MyClass, self).f()  # CANNOT use super()
+
+        InnerClass().method()
+
+    defined_outside = defined_outside

resources/test/fixtures/W292_0.py

@@ -0,0 +1,2 @@
+def fn() -> None:
+    pass

resources/test/fixtures/W292_1.py

@@ -0,0 +1,2 @@
+def fn() -> None:
+    pass  # noqa: W292

resources/test/fixtures/W292_2.py

@@ -0,0 +1,2 @@
+def fn() -> None:
+    pass

resources/test/fixtures/canonical_google_examples.py

@@ -0,0 +1,108 @@
+"""A one line summary of the module or program, terminated by a period.
+
+Leave one blank line.  The rest of this docstring should contain an
+overall description of the module or program.  Optionally, it may also
+contain a brief description of exported classes and functions and/or usage
+examples.
+
+  Typical usage example:
+
+  foo = ClassFoo()
+  bar = foo.FunctionBar()
+"""
+# above: "2.8.2 Modules" section example
+# https://google.github.io/styleguide/pyguide.html#382-modules
+
+# Examples from the official "Google Python Style Guide" documentation:
+#     * As HTML: https://google.github.io/styleguide/pyguide.html
+#     * Source Markdown:
+#         https://github.com/google/styleguide/blob/gh-pages/pyguide.md
+
+import os
+from .expected import Expectation
+
+expectation = Expectation()
+expect = expectation.expect
+
+# module docstring expected violations:
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D213: Multi-line docstring summary should start at the second line"))
+
+
+# "3.8.3 Functions and Methods" section example
+# https://google.github.io/styleguide/pyguide.html#383-functions-and-methods
+@expect("D213: Multi-line docstring summary should start at the second line",
+        arg_count=3)
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Fetch', not 'Fetches')", arg_count=3)
+@expect("D406: Section name should end with a newline "
+        "('Raises', not 'Raises:')", arg_count=3)
+@expect("D406: Section name should end with a newline "
+        "('Returns', not 'Returns:')", arg_count=3)
+@expect("D407: Missing dashed underline after section ('Raises')", arg_count=3)
+@expect("D407: Missing dashed underline after section ('Returns')",
+        arg_count=3)
+@expect("D413: Missing blank line after last section ('Raises')", arg_count=3)
+def fetch_bigtable_rows(big_table, keys, other_silly_variable=None):
+    """Fetches rows from a Bigtable.
+
+    Retrieves rows pertaining to the given keys from the Table instance
+    represented by big_table.  Silly things may happen if
+    other_silly_variable is not None.
+
+    Args:
+        big_table: An open Bigtable Table instance.
+        keys: A sequence of strings representing the key of each table row
+            to fetch.
+        other_silly_variable: Another optional variable, that has a much
+            longer name than the other args, and which does nothing.
+
+    Returns:
+        A dict mapping keys to the corresponding table row data
+        fetched. Each row is represented as a tuple of strings. For
+        example:
+
+        {'Serak': ('Rigel VII', 'Preparer'),
+         'Zim': ('Irk', 'Invader'),
+         'Lrrr': ('Omicron Persei 8', 'Emperor')}
+
+        If a key from the keys argument is missing from the dictionary,
+        then that row was not found in the table.
+
+    Raises:
+        IOError: An error occurred accessing the bigtable.Table object.
+    """
+
+
+# "3.8.4 Classes" section example
+# https://google.github.io/styleguide/pyguide.html#384-classes
+@expect("D203: 1 blank line required before class docstring (found 0)")
+@expect("D213: Multi-line docstring summary should start at the second line")
+@expect("D406: Section name should end with a newline "
+        "('Attributes', not 'Attributes:')")
+@expect("D407: Missing dashed underline after section ('Attributes')")
+@expect("D413: Missing blank line after last section ('Attributes')")
+class SampleClass:
+    """Summary of class here.
+
+    Longer class information....
+    Longer class information....
+
+    Attributes:
+        likes_spam: A boolean indicating if we like SPAM or not.
+        eggs: An integer count of the eggs we have laid.
+    """
+
+    @expect("D401: First line should be in imperative mood "
+            "(perhaps 'Init', not 'Inits')", arg_count=2)
+    def __init__(self, likes_spam=False):
+        """Inits SampleClass with blah."""
+        if self:  # added to avoid NameError when run via @expect decorator
+            self.likes_spam = likes_spam
+            self.eggs = 0
+
+    @expect("D401: First line should be in imperative mood "
+            "(perhaps 'Perform', not 'Performs')", arg_count=1)
+    def public_method(self):
+        """Performs operation blah."""

resources/test/fixtures/canonical_numpy_examples.py

@@ -0,0 +1,163 @@
+"""This is the docstring for the example.py module.  Modules names should
+have short, all-lowercase names.  The module name may have underscores if
+this improves readability.
+
+Every module should have a docstring at the very top of the file.  The
+module's docstring may extend over multiple lines.  If your docstring does
+extend over multiple lines, the closing three quotation marks must be on
+a line by itself, preferably preceded by a blank line.
+
+"""
+
+# Example source file from the official "numpydoc docstring guide"
+# documentation (with the modification of commenting out all the original
+# ``import`` lines, plus adding this note and ``Expectation`` code):
+#     * As HTML: https://numpydoc.readthedocs.io/en/latest/example.html
+#     * Source Python:
+#         https://github.com/numpy/numpydoc/blob/master/doc/example.py
+
+# from __future__ import division, absolute_import, print_function
+#
+# import os  # standard library imports first
+#
+# Do NOT import using *, e.g. from numpy import *
+#
+# Import the module using
+#
+#   import numpy
+#
+# instead or import individual functions as needed, e.g
+#
+#  from numpy import array, zeros
+#
+# If you prefer the use of abbreviated module names, we suggest the
+# convention used by NumPy itself::
+#
+# import numpy as np
+# import matplotlib as mpl
+# import matplotlib.pyplot as plt
+#
+# These abbreviated names are not to be used in docstrings; users must
+# be able to paste and execute docstrings after importing only the
+# numpy module itself, unabbreviated.
+
+import os
+from .expected import Expectation
+
+expectation = Expectation()
+expect = expectation.expect
+
+# module docstring expected violations:
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D205: 1 blank line required between summary line and description "
+    "(found 0)"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D213: Multi-line docstring summary should start at the second line"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D400: First line should end with a period (not 'd')"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D404: First word of the docstring should not be `This`"))
+expectation.expected.add((
+    os.path.normcase(__file__),
+    "D415: First line should end with a period, question mark, or exclamation "
+    "point (not 'd')"))
+
+
+@expect("D213: Multi-line docstring summary should start at the second line",
+        arg_count=3)
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'A')", arg_count=3)
+@expect("D413: Missing blank line after last section ('Examples')",
+        arg_count=3)
+def foo(var1, var2, long_var_name='hi'):
+    r"""A one-line summary that does not use variable names.
+
+    Several sentences providing an extended description. Refer to
+    variables using back-ticks, e.g. `var`.
+
+    Parameters
+    ----------
+    var1 : array_like
+        Array_like means all those objects -- lists, nested lists, etc. --
+        that can be converted to an array.  We can also refer to
+        variables like `var1`.
+    var2 : int
+        The type above can either refer to an actual Python type
+        (e.g. ``int``), or describe the type of the variable in more
+        detail, e.g. ``(N,) ndarray`` or ``array_like``.
+    long_var_name : {'hi', 'ho'}, optional
+        Choices in brackets, default first when optional.
+
+    Returns
+    -------
+    type
+        Explanation of anonymous return value of type ``type``.
+    describe : type
+        Explanation of return value named `describe`.
+    out : type
+        Explanation of `out`.
+    type_without_description
+
+    Other Parameters
+    ----------------
+    only_seldom_used_keywords : type
+        Explanation
+    common_parameters_listed_above : type
+        Explanation
+
+    Raises
+    ------
+    BadException
+        Because you shouldn't have done that.
+
+    See Also
+    --------
+    numpy.array : Relationship (optional).
+    numpy.ndarray : Relationship (optional), which could be fairly long, in
+                    which case the line wraps here.
+    numpy.dot, numpy.linalg.norm, numpy.eye
+
+    Notes
+    -----
+    Notes about the implementation algorithm (if needed).
+
+    This can have multiple paragraphs.
+
+    You may include some math:
+
+    .. math:: X(e^{j\omega } ) = x(n)e^{ - j\omega n}
+
+    And even use a Greek symbol like :math:`\omega` inline.
+
+    References
+    ----------
+    Cite the relevant literature, e.g. [1]_.  You may also cite these
+    references in the notes section above.
+
+    .. [1] O. McNoleg, "The integration of GIS, remote sensing,
+       expert systems and adaptive co-kriging for environmental habitat
+       modelling of the Highland Haggis using object-oriented, fuzzy-logic
+       and neural-network techniques," Computers & Geosciences, vol. 22,
+       pp. 585-588, 1996.
+
+    Examples
+    --------
+    These are written in doctest format, and should illustrate how to
+    use the function.
+
+    >>> a = [1, 2, 3]
+    >>> print([x + 3 for x in a])
+    [4, 5, 6]
+    >>> print("a\nb")
+    a
+    b
+    """
+    # After closing class docstring, there should be one blank line to
+    # separate following codes (according to PEP257).
+    # But for function, method and module, there should be no blank lines
+    # after closing the docstring.
+    pass

resources/test/fixtures/sections.py

@@ -0,0 +1,497 @@
+"""A valid module docstring."""
+
+from .expected import Expectation
+
+expectation = Expectation()
+expect = expectation.expect
+
+
+_D213 = 'D213: Multi-line docstring summary should start at the second line'
+_D400 = "D400: First line should end with a period (not '!')"
+
+
+@expect(_D213)
+@expect("D405: Section name should be properly capitalized "
+        "('Returns', not 'returns')")
+def not_capitalized():  # noqa: D416
+    """Toggle the gizmo.
+
+    returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D406: Section name should end with a newline "
+        "('Returns', not 'Returns:')")
+def superfluous_suffix():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns:
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D407: Missing dashed underline after section ('Returns')")
+def no_underline():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D407: Missing dashed underline after section ('Returns')")
+@expect("D414: Section has no content ('Returns')")
+def no_underline_and_no_description():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+
+    """
+
+
+@expect(_D213)
+@expect("D410: Missing blank line after section ('Returns')")
+@expect("D414: Section has no content ('Returns')")
+@expect("D411: Missing blank line before section ('Yields')")
+@expect("D414: Section has no content ('Yields')")
+def consecutive_sections():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    -------
+    Yields
+    ------
+
+    Raises
+    ------
+    Questions.
+
+    """
+
+
+@expect(_D213)
+@expect("D408: Section underline should be in the line following the "
+        "section's name ('Returns')")
+def blank_line_before_underline():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D409: Section underline should match the length of its name "
+        "(Expected 7 dashes in section 'Returns', got 2)")
+def bad_underline_length():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    --
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D413: Missing blank line after last section ('Returns')")
+def no_blank_line_after_last_section():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+    -------
+    A value of some sort.
+    """
+
+
+@expect(_D213)
+@expect("D411: Missing blank line before section ('Returns')")
+def no_blank_line_before_section():  # noqa: D416
+    """Toggle the gizmo.
+
+    The function's description.
+    Returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D214: Section is over-indented ('Returns')")
+def section_overindented():  # noqa: D416
+    """Toggle the gizmo.
+
+        Returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D215: Section underline is over-indented (in section 'Returns')")
+def section_underline_overindented():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+        -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D215: Section underline is over-indented (in section 'Returns')")
+@expect("D413: Missing blank line after last section ('Returns')")
+@expect("D414: Section has no content ('Returns')")
+def section_underline_overindented_and_contentless():  # noqa: D416
+    """Toggle the gizmo.
+
+    Returns
+        -------
+    """
+
+
+@expect(_D213)
+def ignore_non_actual_section():  # noqa: D416
+    """Toggle the gizmo.
+
+    This is the function's description, which will also specify what it
+    returns
+
+    """
+
+
+@expect(_D213)
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Return', not 'Returns')")
+@expect("D400: First line should end with a period (not 's')")
+@expect("D415: First line should end with a period, question "
+        "mark, or exclamation point (not 's')")
+@expect("D205: 1 blank line required between summary line and description "
+        "(found 0)")
+def section_name_in_first_line():  # noqa: D416
+    """Returns
+    -------
+    A value of some sort.
+
+    """
+
+
+@expect(_D213)
+@expect("D405: Section name should be properly capitalized "
+        "('Short Summary', not 'Short summary')")
+@expect("D412: No blank lines allowed between a section header and its "
+        "content ('Short Summary')")
+@expect("D409: Section underline should match the length of its name "
+        "(Expected 7 dashes in section 'Returns', got 6)")
+@expect("D410: Missing blank line after section ('Returns')")
+@expect("D411: Missing blank line before section ('Raises')")
+@expect("D406: Section name should end with a newline "
+        "('Raises', not 'Raises:')")
+@expect("D407: Missing dashed underline after section ('Raises')")
+def multiple_sections():  # noqa: D416
+    """Toggle the gizmo.
+
+    Short summary
+    -------------
+
+    This is the function's description, which will also specify what it
+    returns.
+
+    Returns
+    ------
+    Many many wonderful things.
+    Raises:
+    My attention.
+
+    """
+
+
+@expect(_D213)
+def false_positive_section_prefix():  # noqa: D416
+    """Toggle the gizmo.
+
+    Parameters
+    ----------
+    attributes_are_fun: attributes for the function.
+
+    """
+
+
+@expect(_D213)
+def section_names_as_parameter_names():  # noqa: D416
+    """Toggle the gizmo.
+
+    Parameters
+    ----------
+    notes : list
+        A list of wonderful notes.
+    examples: list
+        A list of horrible examples.
+
+    """
+
+
+@expect(_D213)
+@expect("D414: Section has no content ('Returns')")
+def valid_google_style_section():  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Args:
+        note: A random string.
+
+    Returns:
+
+    Raises:
+        RandomError: A random error that occurs randomly.
+
+    """
+
+
+@expect(_D213)
+@expect("D416: Section name should end with a colon "
+        "('Args:', not 'Args')")
+def missing_colon_google_style_section():  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Args
+        note: A random string.
+
+    """
+
+
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'bar' docstring)", func_name="bar")
+def _test_nested_functions():
+    x = 1
+
+    def bar(y=2):  # noqa: D207, D213, D406, D407
+        """Nested function test for docstrings.
+
+        Will this work when referencing x?
+
+        Args:
+            x: Test something
+that is broken.
+
+        """
+        print(x)
+
+
+@expect(_D213)
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'test_missing_google_args' docstring)")
+def test_missing_google_args(x=1, y=2, _private=3):  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Args:
+        x (int): The greatest integer.
+
+    """
+
+
+class TestGoogle:  # noqa: D203
+    """Test class."""
+
+    def test_method(self, test, another_test, _):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            test: A parameter.
+            another_test: Another parameter.
+
+        """
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args' docstring)", arg_count=5)
+    def test_missing_args(self, test, x, y, z=3, _private_arg=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            x: Another parameter.
+
+        """
+
+    @classmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args_class_method' docstring)", arg_count=5)
+    def test_missing_args_class_method(cls, test, x, y, _, z=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            x: Another parameter. The parameter below is missing description.
+            y:
+
+        """
+
+    @staticmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) a, y, z are missing descriptions in "
+            "'test_missing_args_static_method' docstring)", arg_count=4)
+    def test_missing_args_static_method(a, x, y, _test, z=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            x: Another parameter.
+
+        """
+
+    @staticmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) a, b are missing descriptions in "
+            "'test_missing_docstring' docstring)", arg_count=2)
+    def test_missing_docstring(a, b):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Args:
+            a:
+
+        """
+
+    @staticmethod
+    def test_hanging_indent(skip, verbose):  # noqa: D213, D407
+        """Do stuff.
+
+        Args:
+            skip (:attr:`.Skip`):
+                Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+                Etiam at tellus a tellus faucibus maximus. Curabitur tellus
+                mauris, semper id vehicula ac, feugiat ut tortor.
+            verbose (bool):
+                If True, print out as much infromation as possible.
+                If False, print out concise "one-liner" information.
+
+        """
+
+
+@expect(_D213)
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'test_missing_numpy_args' docstring)")
+def test_missing_numpy_args(_private_arg=0, x=1, y=2):  # noqa: D406, D407
+    """Toggle the gizmo.
+
+    Parameters
+    ----------
+    x : int
+        The greatest integer in the history \
+of the entire world.
+
+    """
+
+
+class TestNumpy:  # noqa: D203
+    """Test class."""
+
+    def test_method(self, test, another_test, z, _, x=1, y=2, _private_arg=1):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Some long string with a \
+line continuation.
+
+        Parameters
+        ----------
+        test, another_test
+            Some parameters without type.
+        z : some parameter with a very long type description that requires a \
+line continuation.
+            But no further description.
+        x, y : int
+            Some integer parameters.
+
+        """
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args' docstring)", arg_count=5)
+    def test_missing_args(self, test, x, y, z=3, t=1, _private=0):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Parameters
+        ----------
+        x, t : int
+            Some parameters.
+
+
+        """
+
+    @classmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) test, y, z are missing descriptions in "
+            "'test_missing_args_class_method' docstring)", arg_count=4)
+    def test_missing_args_class_method(cls, test, x, y, z=3):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Parameters
+        ----------
+        z
+        x
+            Another parameter. The parameters y, test below are
+            missing descriptions. The parameter z above is also missing
+            a description.
+        y
+        test
+
+        """
+
+    @staticmethod
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) a, z are missing descriptions in "
+            "'test_missing_args_static_method' docstring)", arg_count=3)
+    def test_missing_args_static_method(a, x, y, z=3, t=1):  # noqa: D213, D407
+        """Test a valid args section.
+
+        Parameters
+        ----------
+        x, y
+            Another parameter.
+        t : int
+            Yet another parameter.
+
+        """
+
+    @staticmethod
+    def test_mixing_numpy_and_google(danger):  # noqa: D213
+        """Repro for #388.
+
+        Parameters
+        ----------
+        danger
+            Zoneeeeee!
+
+        """
+
+
+class TestIncorrectIndent:  # noqa: D203
+    """Test class."""
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) y are missing descriptions in "
+            "'test_incorrect_indent' docstring)", arg_count=3)
+    def test_incorrect_indent(self, x=1, y=2):  # noqa: D207, D213, D407
+        """Reproducing issue #437.
+
+Testing this incorrectly indented docstring.
+
+        Args:
+            x: Test argument.
+
+        """

scripts/.flake8

@@ -0,0 +1,19 @@
+[flake8]
+exclude =
+    # Defaults
+    .svn,
+    CVS,
+    .bzr,
+    .hg,
+    .git,
+    __pycache__,
+    .tox,
+    .idea,
+    .mypy_cache,
+    .venv,
+    node_modules,
+    # Custom
+    _state_machine.py,
+    test_fstring.py,
+    bad_coding2.py,
+    badsyntax_*.py

setup.py

@@ -0,0 +1,23 @@
+import sys
+
+from setuptools import setup
+
+sys.stderr.write(
+    """
+===============================
+Unsupported installation method
+===============================
+ruff no longer supports installation with `python setup.py install`.
+Please use `python -m pip install .` instead.
+"""
+)
+sys.exit(1)
+
+
+# The below code will never execute, however GitHub is particularly
+# picky about where it finds Python packaging metadata.
+# See: https://github.com/github/feedback/discussions/6456
+#
+# To be removed once GitHub catches up.
+
+setup(name="ruff", install_requires=[])

src/ast.rs

@@ -1,4 +1,5 @@
-pub mod checks;
+pub mod checkers;
+pub mod helpers;
 pub mod operations;
 pub mod relocate;
 pub mod types;

src/ast/checks.rs

@@ -1,751 +0,0 @@
-use std::collections::BTreeSet;
-
-use itertools::izip;
-use regex::Regex;
-use rustpython_parser::ast::{
-    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Keyword,
-    Location, Stmt, StmtKind, Unaryop,
-};
-
-use crate::ast::operations::SourceCodeLocator;
-use crate::ast::types::{
-    Binding, BindingKind, CheckLocator, FunctionScope, Range, Scope, ScopeKind,
-};
-use crate::autofix::{fixer, fixes};
-use crate::checks::{Check, CheckKind, Fix, RejectedCmpop};
-use crate::python::builtins::BUILTINS;
-
-/// Check IfTuple compliance.
-pub fn check_if_tuple(test: &Expr, location: Range) -> Option<Check> {
-    if let ExprKind::Tuple { elts, .. } = &test.node {
-        if !elts.is_empty() {
-            return Some(Check::new(CheckKind::IfTuple, location));
-        }
-    }
-    None
-}
-
-/// Check AssertTuple compliance.
-pub fn check_assert_tuple(test: &Expr, location: Range) -> Option<Check> {
-    if let ExprKind::Tuple { elts, .. } = &test.node {
-        if !elts.is_empty() {
-            return Some(Check::new(CheckKind::AssertTuple, location));
-        }
-    }
-    None
-}
-
-/// Check NotInTest and NotIsTest compliance.
-pub fn check_not_tests(
-    op: &Unaryop,
-    operand: &Expr,
-    check_not_in: bool,
-    check_not_is: bool,
-    locator: &dyn CheckLocator,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    if matches!(op, Unaryop::Not) {
-        if let ExprKind::Compare { ops, .. } = &operand.node {
-            for op in ops {
-                match op {
-                    Cmpop::In => {
-                        if check_not_in {
-                            checks.push(Check::new(
-                                CheckKind::NotInTest,
-                                locator.locate_check(Range::from_located(operand)),
-                            ));
-                        }
-                    }
-                    Cmpop::Is => {
-                        if check_not_is {
-                            checks.push(Check::new(
-                                CheckKind::NotIsTest,
-                                locator.locate_check(Range::from_located(operand)),
-                            ));
-                        }
-                    }
-                    _ => {}
-                }
-            }
-        }
-    }
-
-    checks
-}
-
-/// Check UnusedVariable compliance.
-pub fn check_unused_variables(
-    scope: &Scope,
-    locator: &dyn CheckLocator,
-    dummy_variable_rgx: &Regex,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    if matches!(
-        scope.kind,
-        ScopeKind::Function(FunctionScope { uses_locals: true })
-    ) {
-        return checks;
-    }
-
-    for (name, binding) in scope.values.iter() {
-        if binding.used.is_none()
-            && matches!(binding.kind, BindingKind::Assignment)
-            && !dummy_variable_rgx.is_match(name)
-            && name != "__tracebackhide__"
-            && name != "__traceback_info__"
-            && name != "__traceback_supplement__"
-        {
-            checks.push(Check::new(
-                CheckKind::UnusedVariable(name.to_string()),
-                locator.locate_check(binding.range),
-            ));
-        }
-    }
-
-    checks
-}
-
-/// Check DoNotAssignLambda compliance.
-pub fn check_do_not_assign_lambda(value: &Expr, location: Range) -> Option<Check> {
-    if let ExprKind::Lambda { .. } = &value.node {
-        Some(Check::new(CheckKind::DoNotAssignLambda, location))
-    } else {
-        None
-    }
-}
-
-fn is_ambiguous_name(name: &str) -> bool {
-    name == "l" || name == "I" || name == "O"
-}
-
-/// Check AmbiguousVariableName compliance.
-pub fn check_ambiguous_variable_name(name: &str, location: Range) -> Option<Check> {
-    if is_ambiguous_name(name) {
-        Some(Check::new(
-            CheckKind::AmbiguousVariableName(name.to_string()),
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check AmbiguousClassName compliance.
-pub fn check_ambiguous_class_name(name: &str, location: Range) -> Option<Check> {
-    if is_ambiguous_name(name) {
-        Some(Check::new(
-            CheckKind::AmbiguousClassName(name.to_string()),
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check AmbiguousFunctionName compliance.
-pub fn check_ambiguous_function_name(name: &str, location: Range) -> Option<Check> {
-    if is_ambiguous_name(name) {
-        Some(Check::new(
-            CheckKind::AmbiguousFunctionName(name.to_string()),
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check UselessObjectInheritance compliance.
-pub fn check_useless_object_inheritance(
-    stmt: &Stmt,
-    name: &str,
-    bases: &[Expr],
-    keywords: &[Keyword],
-    scope: &Scope,
-    locator: &mut SourceCodeLocator,
-    autofix: &fixer::Mode,
-) -> Option<Check> {
-    for expr in bases {
-        if let ExprKind::Name { id, .. } = &expr.node {
-            if id == "object" {
-                match scope.values.get(id) {
-                    None
-                    | Some(Binding {
-                        kind: BindingKind::Builtin,
-                        ..
-                    }) => {
-                        let mut check = Check::new(
-                            CheckKind::UselessObjectInheritance(name.to_string()),
-                            Range::from_located(expr),
-                        );
-                        if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                            if let Some(fix) = fixes::remove_class_def_base(
-                                locator,
-                                &stmt.location,
-                                expr.location,
-                                bases,
-                                keywords,
-                            ) {
-                                check.amend(fix);
-                            }
-                        }
-                        return Some(check);
-                    }
-                    _ => {}
-                }
-            }
-        }
-    }
-
-    None
-}
-
-/// Check DefaultExceptNotLast compliance.
-pub fn check_default_except_not_last(handlers: &Vec<Excepthandler>) -> Option<Check> {
-    for (idx, handler) in handlers.iter().enumerate() {
-        let ExcepthandlerKind::ExceptHandler { type_, .. } = &handler.node;
-        if type_.is_none() && idx < handlers.len() - 1 {
-            return Some(Check::new(
-                CheckKind::DefaultExceptNotLast,
-                Range::from_located(handler),
-            ));
-        }
-    }
-
-    None
-}
-
-/// Check RaiseNotImplemented compliance.
-pub fn check_raise_not_implemented(expr: &Expr) -> Option<Check> {
-    match &expr.node {
-        ExprKind::Call { func, .. } => {
-            if let ExprKind::Name { id, .. } = &func.node {
-                if id == "NotImplemented" {
-                    return Some(Check::new(
-                        CheckKind::RaiseNotImplemented,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-        }
-        ExprKind::Name { id, .. } => {
-            if id == "NotImplemented" {
-                return Some(Check::new(
-                    CheckKind::RaiseNotImplemented,
-                    Range::from_located(expr),
-                ));
-            }
-        }
-        _ => {}
-    }
-
-    None
-}
-
-/// Check DuplicateArgumentName compliance.
-pub fn check_duplicate_arguments(arguments: &Arguments) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    // Collect all the arguments into a single vector.
-    let mut all_arguments: Vec<&Arg> = arguments
-        .args
-        .iter()
-        .chain(arguments.posonlyargs.iter())
-        .chain(arguments.kwonlyargs.iter())
-        .collect();
-    if let Some(arg) = &arguments.vararg {
-        all_arguments.push(arg);
-    }
-    if let Some(arg) = &arguments.kwarg {
-        all_arguments.push(arg);
-    }
-
-    // Search for duplicates.
-    let mut idents: BTreeSet<&str> = BTreeSet::new();
-    for arg in all_arguments {
-        let ident = &arg.node.arg;
-        if idents.contains(ident.as_str()) {
-            checks.push(Check::new(
-                CheckKind::DuplicateArgumentName,
-                Range::from_located(arg),
-            ));
-        }
-        idents.insert(ident);
-    }
-
-    checks
-}
-
-/// Check AssertEquals compliance.
-pub fn check_assert_equals(expr: &Expr, autofix: &fixer::Mode) -> Option<Check> {
-    if let ExprKind::Attribute { value, attr, .. } = &expr.node {
-        if attr == "assertEquals" {
-            if let ExprKind::Name { id, .. } = &value.node {
-                if id == "self" {
-                    let mut check =
-                        Check::new(CheckKind::NoAssertEquals, Range::from_located(expr));
-                    if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                        check.amend(Fix {
-                            content: "assertEqual".to_string(),
-                            location: Location::new(
-                                expr.location.row(),
-                                expr.location.column() + 1,
-                            ),
-                            end_location: Location::new(
-                                expr.location.row(),
-                                expr.location.column() + 1 + "assertEquals".len(),
-                            ),
-                            applied: false,
-                        });
-                    }
-                    return Some(check);
-                }
-            }
-        }
-    }
-    None
-}
-
-#[derive(Debug, PartialEq)]
-enum DictionaryKey<'a> {
-    Constant(&'a Constant),
-    Variable(&'a String),
-}
-
-fn convert_to_value(expr: &Expr) -> Option<DictionaryKey> {
-    match &expr.node {
-        ExprKind::Constant { value, .. } => Some(DictionaryKey::Constant(value)),
-        ExprKind::Name { id, .. } => Some(DictionaryKey::Variable(id)),
-        _ => None,
-    }
-}
-
-/// Check MultiValueRepeatedKeyLiteral and MultiValueRepeatedKeyVariable compliance.
-pub fn check_repeated_keys(
-    keys: &Vec<Expr>,
-    check_repeated_literals: bool,
-    check_repeated_variables: bool,
-    locator: &dyn CheckLocator,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    let num_keys = keys.len();
-    for i in 0..num_keys {
-        let k1 = &keys[i];
-        let v1 = convert_to_value(k1);
-        for k2 in keys.iter().take(num_keys).skip(i + 1) {
-            let v2 = convert_to_value(k2);
-            match (&v1, &v2) {
-                (Some(DictionaryKey::Constant(v1)), Some(DictionaryKey::Constant(v2))) => {
-                    if check_repeated_literals && v1 == v2 {
-                        checks.push(Check::new(
-                            CheckKind::MultiValueRepeatedKeyLiteral,
-                            locator.locate_check(Range::from_located(k2)),
-                        ))
-                    }
-                }
-                (Some(DictionaryKey::Variable(v1)), Some(DictionaryKey::Variable(v2))) => {
-                    if check_repeated_variables && v1 == v2 {
-                        checks.push(Check::new(
-                            CheckKind::MultiValueRepeatedKeyVariable((*v2).to_string()),
-                            locator.locate_check(Range::from_located(k2)),
-                        ))
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-
-    checks
-}
-
-/// Check TrueFalseComparison and NoneComparison compliance.
-pub fn check_literal_comparisons(
-    left: &Expr,
-    ops: &Vec<Cmpop>,
-    comparators: &Vec<Expr>,
-    check_none_comparisons: bool,
-    check_true_false_comparisons: bool,
-    locator: &dyn CheckLocator,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    let op = ops.first().unwrap();
-    let comparator = left;
-
-    // Check `left`.
-    if check_none_comparisons
-        && matches!(
-            comparator.node,
-            ExprKind::Constant {
-                value: Constant::None,
-                kind: None
-            }
-        )
-    {
-        if matches!(op, Cmpop::Eq) {
-            checks.push(Check::new(
-                CheckKind::NoneComparison(RejectedCmpop::Eq),
-                locator.locate_check(Range::from_located(comparator)),
-            ));
-        }
-        if matches!(op, Cmpop::NotEq) {
-            checks.push(Check::new(
-                CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                locator.locate_check(Range::from_located(comparator)),
-            ));
-        }
-    }
-
-    if check_true_false_comparisons {
-        if let ExprKind::Constant {
-            value: Constant::Bool(value),
-            kind: None,
-        } = comparator.node
-        {
-            if matches!(op, Cmpop::Eq) {
-                checks.push(Check::new(
-                    CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-            if matches!(op, Cmpop::NotEq) {
-                checks.push(Check::new(
-                    CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-        }
-    }
-
-    // Check each comparator in order.
-    for (op, comparator) in izip!(ops, comparators) {
-        if check_none_comparisons
-            && matches!(
-                comparator.node,
-                ExprKind::Constant {
-                    value: Constant::None,
-                    kind: None
-                }
-            )
-        {
-            if matches!(op, Cmpop::Eq) {
-                checks.push(Check::new(
-                    CheckKind::NoneComparison(RejectedCmpop::Eq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-            if matches!(op, Cmpop::NotEq) {
-                checks.push(Check::new(
-                    CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                    locator.locate_check(Range::from_located(comparator)),
-                ));
-            }
-        }
-
-        if check_true_false_comparisons {
-            if let ExprKind::Constant {
-                value: Constant::Bool(value),
-                kind: None,
-            } = comparator.node
-            {
-                if matches!(op, Cmpop::Eq) {
-                    checks.push(Check::new(
-                        CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                        locator.locate_check(Range::from_located(comparator)),
-                    ));
-                }
-                if matches!(op, Cmpop::NotEq) {
-                    checks.push(Check::new(
-                        CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                        locator.locate_check(Range::from_located(comparator)),
-                    ));
-                }
-            }
-        }
-    }
-
-    checks
-}
-
-fn is_constant(expr: &Expr) -> bool {
-    match &expr.node {
-        ExprKind::Constant { .. } => true,
-        ExprKind::Tuple { elts, .. } => elts.iter().all(is_constant),
-        _ => false,
-    }
-}
-
-fn is_singleton(expr: &Expr) -> bool {
-    matches!(
-        expr.node,
-        ExprKind::Constant {
-            value: Constant::None | Constant::Bool(_) | Constant::Ellipsis,
-            ..
-        }
-    )
-}
-
-fn is_constant_non_singleton(expr: &Expr) -> bool {
-    is_constant(expr) && !is_singleton(expr)
-}
-
-/// Check IsLiteral compliance.
-pub fn check_is_literal(
-    left: &Expr,
-    ops: &Vec<Cmpop>,
-    comparators: &Vec<Expr>,
-    location: Range,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    let mut left = left;
-    for (op, right) in izip!(ops, comparators) {
-        if matches!(op, Cmpop::Is | Cmpop::IsNot)
-            && (is_constant_non_singleton(left) || is_constant_non_singleton(right))
-        {
-            checks.push(Check::new(CheckKind::IsLiteral, location));
-        }
-        left = right;
-    }
-
-    checks
-}
-
-/// Check TypeComparison compliance.
-pub fn check_type_comparison(
-    ops: &Vec<Cmpop>,
-    comparators: &Vec<Expr>,
-    location: Range,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
-
-    for (op, right) in izip!(ops, comparators) {
-        if matches!(op, Cmpop::Is | Cmpop::IsNot | Cmpop::Eq | Cmpop::NotEq) {
-            match &right.node {
-                ExprKind::Call { func, args, .. } => {
-                    if let ExprKind::Name { id, .. } = &func.node {
-                        // Ex) type(False)
-                        if id == "type" {
-                            if let Some(arg) = args.first() {
-                                // Allow comparison for types which are not obvious.
-                                if !matches!(arg.node, ExprKind::Name { .. }) {
-                                    checks.push(Check::new(CheckKind::TypeComparison, location));
-                                }
-                            }
-                        }
-                    }
-                }
-                ExprKind::Attribute { value, .. } => {
-                    if let ExprKind::Name { id, .. } = &value.node {
-                        // Ex) types.IntType
-                        if id == "types" {
-                            checks.push(Check::new(CheckKind::TypeComparison, location));
-                        }
-                    }
-                }
-                _ => {}
-            }
-        }
-    }
-
-    checks
-}
-
-/// Check TwoStarredExpressions and TooManyExpressionsInStarredAssignment compliance.
-pub fn check_starred_expressions(
-    elts: &[Expr],
-    check_too_many_expressions: bool,
-    check_two_starred_expressions: bool,
-    location: Range,
-) -> Option<Check> {
-    let mut has_starred: bool = false;
-    let mut starred_index: Option<usize> = None;
-    for (index, elt) in elts.iter().enumerate() {
-        if matches!(elt.node, ExprKind::Starred { .. }) {
-            if has_starred && check_two_starred_expressions {
-                return Some(Check::new(CheckKind::TwoStarredExpressions, location));
-            }
-            has_starred = true;
-            starred_index = Some(index);
-        }
-    }
-
-    if check_too_many_expressions {
-        if let Some(starred_index) = starred_index {
-            if starred_index >= 1 << 8 || elts.len() - starred_index > 1 << 24 {
-                return Some(Check::new(
-                    CheckKind::TooManyExpressionsInStarredAssignment,
-                    location,
-                ));
-            }
-        }
-    }
-
-    None
-}
-
-/// Check BreakOutsideLoop compliance.
-pub fn check_break_outside_loop(
-    stmt: &Stmt,
-    parents: &[&Stmt],
-    parent_stack: &[usize],
-    locator: &dyn CheckLocator,
-) -> Option<Check> {
-    let mut allowed: bool = false;
-    let mut parent = stmt;
-    for index in parent_stack.iter().rev() {
-        let child = parent;
-        parent = parents[*index];
-        match &parent.node {
-            StmtKind::For { orelse, .. }
-            | StmtKind::AsyncFor { orelse, .. }
-            | StmtKind::While { orelse, .. } => {
-                if !orelse.contains(child) {
-                    allowed = true;
-                    break;
-                }
-            }
-
-            StmtKind::FunctionDef { .. }
-            | StmtKind::AsyncFunctionDef { .. }
-            | StmtKind::ClassDef { .. } => {
-                break;
-            }
-            _ => {}
-        }
-    }
-
-    if !allowed {
-        Some(Check::new(
-            CheckKind::BreakOutsideLoop,
-            locator.locate_check(Range::from_located(stmt)),
-        ))
-    } else {
-        None
-    }
-}
-
-/// Check ContinueOutsideLoop compliance.
-pub fn check_continue_outside_loop(
-    stmt: &Stmt,
-    parents: &[&Stmt],
-    parent_stack: &[usize],
-    locator: &dyn CheckLocator,
-) -> Option<Check> {
-    let mut allowed: bool = false;
-    let mut parent = stmt;
-    for index in parent_stack.iter().rev() {
-        let child = parent;
-        parent = parents[*index];
-        match &parent.node {
-            StmtKind::For { orelse, .. }
-            | StmtKind::AsyncFor { orelse, .. }
-            | StmtKind::While { orelse, .. } => {
-                if !orelse.contains(child) {
-                    allowed = true;
-                    break;
-                }
-            }
-
-            StmtKind::FunctionDef { .. }
-            | StmtKind::AsyncFunctionDef { .. }
-            | StmtKind::ClassDef { .. } => {
-                break;
-            }
-            _ => {}
-        }
-    }
-
-    if !allowed {
-        Some(Check::new(
-            CheckKind::ContinueOutsideLoop,
-            locator.locate_check(Range::from_located(stmt)),
-        ))
-    } else {
-        None
-    }
-}
-
-// flake8-builtins
-pub enum ShadowingType {
-    Variable,
-    Argument,
-    Attribute,
-}
-
-/// Check builtin name shadowing
-pub fn check_builtin_shadowing(
-    name: &str,
-    location: Range,
-    node_type: ShadowingType,
-) -> Option<Check> {
-    if BUILTINS.contains(&name) {
-        Some(Check::new(
-            match node_type {
-                ShadowingType::Variable => CheckKind::BuiltinVariableShadowing(name.to_string()),
-                ShadowingType::Argument => CheckKind::BuiltinArgumentShadowing(name.to_string()),
-                ShadowingType::Attribute => CheckKind::BuiltinAttributeShadowing(name.to_string()),
-            },
-            location,
-        ))
-    } else {
-        None
-    }
-}
-
-// flake8-super
-/// Check that `super()` has no args
-pub fn check_super_args(
-    expr: &Expr,
-    func: &Expr,
-    args: &Vec<Expr>,
-    locator: &mut SourceCodeLocator,
-    autofix: &fixer::Mode,
-) -> Option<Check> {
-    if let ExprKind::Name { id, .. } = &func.node {
-        if id == "super" && !args.is_empty() {
-            let mut check = Check::new(
-                CheckKind::SuperCallWithParameters,
-                Range::from_located(expr),
-            );
-            if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                if let Some(fix) = fixes::remove_super_arguments(locator, expr) {
-                    check.amend(fix);
-                }
-            }
-            return Some(check);
-        }
-    }
-    None
-}
-
-// flake8-print
-/// Check whether a function call is a `print` or `pprint` invocation
-pub fn check_print_call(expr: &Expr, func: &Expr) -> Option<Check> {
-    if let ExprKind::Name { id, .. } = &func.node {
-        if id == "print" {
-            return Some(Check::new(CheckKind::PrintFound, Range::from_located(expr)));
-        } else if id == "pprint" {
-            return Some(Check::new(
-                CheckKind::PPrintFound,
-                Range::from_located(expr),
-            ));
-        }
-    }
-
-    if let ExprKind::Attribute { value, attr, .. } = &func.node {
-        if let ExprKind::Name { id, .. } = &value.node {
-            if id == "pprint" && attr == "pprint" {
-                return Some(Check::new(
-                    CheckKind::PPrintFound,
-                    Range::from_located(expr),
-                ));
-            }
-        }
-    }
-
-    None
-}

src/ast/helpers.rs

@@ -0,0 +1,133 @@
+use once_cell::sync::Lazy;
+use regex::Regex;
+use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprKind, StmtKind};
+
+use crate::python::typing;
+
+fn compose_call_path_inner<'a>(expr: &'a Expr, parts: &mut Vec<&'a str>) {
+    match &expr.node {
+        ExprKind::Call { func, .. } => {
+            compose_call_path_inner(func, parts);
+        }
+        ExprKind::Attribute { value, attr, .. } => {
+            compose_call_path_inner(value, parts);
+            parts.push(attr);
+        }
+        ExprKind::Name { id, .. } => {
+            parts.push(id);
+        }
+        _ => {}
+    }
+}
+
+pub fn compose_call_path(expr: &Expr) -> Option<String> {
+    let mut segments = vec![];
+    compose_call_path_inner(expr, &mut segments);
+    if segments.is_empty() {
+        None
+    } else {
+        Some(segments.join("."))
+    }
+}
+
+pub fn match_name_or_attr(expr: &Expr, target: &str) -> bool {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => target == attr,
+        ExprKind::Name { id, .. } => target == id,
+        _ => false,
+    }
+}
+
+pub enum SubscriptKind {
+    AnnotatedSubscript,
+    PEP593AnnotatedSubscript,
+}
+
+pub fn match_annotated_subscript(expr: &Expr) -> Option<SubscriptKind> {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => {
+            if typing::is_annotated_subscript(attr) {
+                Some(SubscriptKind::AnnotatedSubscript)
+            } else if typing::is_pep593_annotated_subscript(attr) {
+                Some(SubscriptKind::PEP593AnnotatedSubscript)
+            } else {
+                None
+            }
+        }
+        ExprKind::Name { id, .. } => {
+            if typing::is_annotated_subscript(id) {
+                Some(SubscriptKind::AnnotatedSubscript)
+            } else if typing::is_pep593_annotated_subscript(id) {
+                Some(SubscriptKind::PEP593AnnotatedSubscript)
+            } else {
+                None
+            }
+        }
+        _ => None,
+    }
+}
+
+static DUNDER_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"__[^\s]+__").unwrap());
+
+pub fn is_assignment_to_a_dunder(node: &StmtKind) -> bool {
+    // Check whether it's an assignment to a dunder, with or without a type annotation.
+    // This is what pycodestyle (as of 2.9.1) does.
+    match node {
+        StmtKind::Assign {
+            targets,
+            value: _,
+            type_comment: _,
+        } => {
+            if targets.len() != 1 {
+                return false;
+            }
+            match &targets[0].node {
+                ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+                _ => false,
+            }
+        }
+        StmtKind::AnnAssign {
+            target,
+            annotation: _,
+            value: _,
+            simple: _,
+        } => match &target.node {
+            ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+            _ => false,
+        },
+        _ => false,
+    }
+}
+
+/// Extract the names of all handled exceptions.
+pub fn extract_handler_names(handlers: &[Excepthandler]) -> Vec<String> {
+    let mut handler_names = vec![];
+    for handler in handlers {
+        match &handler.node {
+            ExcepthandlerKind::ExceptHandler { type_, .. } => {
+                if let Some(type_) = type_ {
+                    if let ExprKind::Tuple { elts, .. } = &type_.node {
+                        for type_ in elts {
+                            if let Some(name) = compose_call_path(type_) {
+                                handler_names.push(name);
+                            }
+                        }
+                    } else if let Some(name) = compose_call_path(type_) {
+                        handler_names.push(name);
+                    }
+                }
+            }
+        }
+    }
+    handler_names
+}
+
+/// Returns `true` if a call is an argumented `super` invocation.
+pub fn is_super_call_with_arguments(func: &Expr, args: &Vec<Expr>) -> bool {
+    // Check: is this a `super` call?
+    if let ExprKind::Name { id, .. } = &func.node {
+        id == "super" && !args.is_empty()
+    } else {
+        false
+    }
+}

src/ast/operations.rs

@@ -121,7 +121,7 @@ pub fn is_unpacking_assignment(stmt: &Stmt) -> bool {
 /// Struct used to efficiently slice source code at (row, column) Locations.
 pub struct SourceCodeLocator<'a> {
     content: &'a str,
-    offsets: Vec<usize>,
+    offsets: Vec<Vec<usize>>,
     initialized: bool,
 }
 
@@ -134,32 +134,52 @@ impl<'a> SourceCodeLocator<'a> {
         }
     }
 
-    pub fn slice_source_code_at(&mut self, location: &Location) -> &'a str {
+    fn init(&mut self) {
         if !self.initialized {
             let mut offset = 0;
-            for i in self.content.lines() {
-                self.offsets.push(offset);
-                offset += i.len();
-                offset += 1;
+            for line in self.content.lines() {
+                let mut newline = 0;
+                let mut line_offsets: Vec<usize> = vec![];
+                for (i, _char) in line.char_indices() {
+                    line_offsets.push(offset + i);
+                    newline = i + 1;
+                }
+                line_offsets.push(offset + newline);
+                self.offsets.push(line_offsets);
+                offset += newline + 1;
             }
+            self.offsets.push(vec![offset]);
             self.initialized = true;
         }
-        let offset = self.offsets[location.row() - 1] + location.column() - 1;
+    }
+
+    pub fn slice_source_code_at(&mut self, location: &Location) -> &'a str {
+        self.init();
+        let offset = self.offsets[location.row() - 1][location.column() - 1];
         &self.content[offset..]
     }
 
     pub fn slice_source_code_range(&mut self, range: &Range) -> &'a str {
-        if !self.initialized {
-            let mut offset = 0;
-            for i in self.content.lines() {
-                self.offsets.push(offset);
-                offset += i.len();
-                offset += 1;
-            }
-            self.initialized = true;
-        }
-        let start = self.offsets[range.location.row() - 1] + range.location.column() - 1;
-        let end = self.offsets[range.end_location.row() - 1] + range.end_location.column() - 1;
+        self.init();
+        let start = self.offsets[range.location.row() - 1][range.location.column() - 1];
+        let end = self.offsets[range.end_location.row() - 1][range.end_location.column() - 1];
         &self.content[start..end]
     }
+
+    pub fn partition_source_code_at(
+        &mut self,
+        outer: &Range,
+        inner: &Range,
+    ) -> (&'a str, &'a str, &'a str) {
+        self.init();
+        let outer_start = self.offsets[outer.location.row() - 1][outer.location.column() - 1];
+        let outer_end = self.offsets[outer.end_location.row() - 1][outer.end_location.column() - 1];
+        let inner_start = self.offsets[inner.location.row() - 1][inner.location.column() - 1];
+        let inner_end = self.offsets[inner.end_location.row() - 1][inner.end_location.column() - 1];
+        (
+            &self.content[outer_start..inner_start],
+            &self.content[inner_start..inner_end],
+            &self.content[inner_end..outer_end],
+        )
+    }
 }

src/ast/types.rs

@@ -74,9 +74,9 @@ pub enum BindingKind {
     Export(Vec<String>),
     FutureImportation,
     StarImportation,
-    Importation(String, BindingContext),
-    FromImportation(String, BindingContext),
-    SubmoduleImportation(String, BindingContext),
+    Importation(String, String, BindingContext),
+    FromImportation(String, String, BindingContext),
+    SubmoduleImportation(String, String, BindingContext),
 }
 
 #[derive(Clone, Debug)]

src/ast/visitor.rs

@@ -4,6 +4,8 @@ use rustpython_parser::ast::{
     PatternKind, Stmt, StmtKind, Unaryop, Withitem,
 };
 
+use crate::ast::helpers::match_name_or_attr;
+
 pub trait Visitor<'a> {
     fn visit_stmt(&mut self, stmt: &'a Stmt) {
         walk_stmt(self, stmt);
@@ -148,7 +150,11 @@ pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
         } => {
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr);
+                if match_name_or_attr(annotation, "TypeAlias") {
+                    visitor.visit_annotation(expr);
+                } else {
+                    visitor.visit_expr(expr);
+                }
             }
             visitor.visit_expr(target);
         }

src/autofix/fixer.rs

@@ -1,7 +1,3 @@
-use std::fs;
-use std::path::Path;
-
-use anyhow::Result;
 use itertools::Itertools;
 use rustpython_parser::ast::Location;
 
@@ -24,17 +20,15 @@ impl From<bool> for Mode {
 }
 
 /// Auto-fix errors in a file, and write the fixed source code to disk.
-pub fn fix_file(checks: &mut [Check], contents: &str, path: &Path) -> Result<()> {
+pub fn fix_file(checks: &mut [Check], contents: &str) -> Option<String> {
     if checks.iter().all(|check| check.fix.is_none()) {
-        return Ok(());
+        return None;
     }
 
-    let output = apply_fixes(
+    Some(apply_fixes(
         checks.iter_mut().filter_map(|check| check.fix.as_mut()),
         contents,
-    );
-
-    fs::write(path, output).map_err(|e| e.into())
+    ))
 }
 
 /// Apply a series of fixes.

src/cache.rs

@@ -1,3 +1,9 @@
+// cacache uses asyncd-std which has no wasm support, so currently no caching support on wasm
+#![cfg_attr(
+    target_family = "wasm",
+    allow(unused_imports, unused_variables, dead_code)
+)]
+
 use std::collections::hash_map::DefaultHasher;
 use std::fs::{create_dir_all, File, Metadata};
 use std::hash::{Hash, Hasher};
@@ -5,6 +11,7 @@ use std::io::Write;
 use std::path::Path;
 
 use anyhow::Result;
+#[cfg(not(target_family = "wasm"))]
 use cacache::Error::EntryNotFound;
 use filetime::FileTime;
 use log::error;
@@ -107,6 +114,7 @@ pub fn get(
         return None;
     };
 
+    #[cfg(not(target_family = "wasm"))] // cacache needs async-std which doesn't support wasm
     match cacache::read_sync(cache_dir(), cache_key(path, settings, autofix)) {
         Ok(encoded) => match bincode::deserialize::<CheckResult>(&encoded[..]) {
             Ok(CheckResult {
@@ -137,12 +145,14 @@ pub fn set(
         return;
     };
 
+    #[cfg(not(target_family = "wasm"))] // modification date not supported on wasm
     let check_result = CheckResultRef {
         metadata: &CacheMetadata {
             mtime: FileTime::from_last_modification_time(metadata).unix_seconds(),
         },
         messages,
     };
+    #[cfg(not(target_family = "wasm"))] // cacache needs async-std which doesn't support wasm
     if let Err(e) = cacache::write_sync(
         cache_dir(),
         cache_key(path, settings, autofix),

src/check_lines.rs

@@ -1,8 +1,8 @@
 use std::collections::BTreeMap;
 
-use crate::ast::types::Range;
 use rustpython_parser::ast::Location;
 
+use crate::ast::types::Range;
 use crate::autofix::fixer;
 use crate::checks::{Check, CheckCode, CheckKind, Fix};
 use crate::noqa;
@@ -32,8 +32,8 @@ pub fn check_lines(
     settings: &Settings,
     autofix: &fixer::Mode,
 ) {
-    let enforce_line_too_long = settings.select.contains(&CheckCode::E501);
-    let enforce_noqa = settings.select.contains(&CheckCode::M001);
+    let enforce_line_too_long = settings.enabled.contains(&CheckCode::E501);
+    let enforce_noqa = settings.enabled.contains(&CheckCode::M001);
 
     let mut noqa_directives: BTreeMap<usize, (Directive, Vec<&str>)> = BTreeMap::new();
 
@@ -66,12 +66,12 @@ pub fn check_lines(
 
                 match noqa {
                     (Directive::All(_, _), matches) => {
-                        matches.push(check.kind.code().as_str());
+                        matches.push(check.kind.code().as_ref());
                         ignored.push(index)
                     }
                     (Directive::Codes(_, _, codes), matches) => {
-                        if codes.contains(&check.kind.code().as_str()) {
-                            matches.push(check.kind.code().as_str());
+                        if codes.contains(&check.kind.code().as_ref()) {
+                            matches.push(check.kind.code().as_ref());
                             ignored.push(index);
                         }
                     }
@@ -98,11 +98,11 @@ pub fn check_lines(
 
                 match noqa {
                     (Directive::All(_, _), matches) => {
-                        matches.push(check.kind.code().as_str());
+                        matches.push(check.kind.code().as_ref());
                     }
                     (Directive::Codes(_, _, codes), matches) => {
-                        if codes.contains(&check.kind.code().as_str()) {
-                            matches.push(check.kind.code().as_str());
+                        if codes.contains(&check.kind.code().as_ref()) {
+                            matches.push(check.kind.code().as_ref());
                         } else {
                             line_checks.push(check);
                         }
@@ -113,6 +113,45 @@ pub fn check_lines(
         }
     }
 
+    // Enforce newlines at end of files.
+    if settings.enabled.contains(&CheckCode::W292) && !contents.ends_with('\n') {
+        // Note: if `lines.last()` is `None`, then `contents` is empty (and so we don't want to
+        // raise W292 anyway).
+        if let Some(line) = lines.last() {
+            let lineno = lines.len() - 1;
+            let noqa_lineno = noqa_line_for
+                .get(lineno)
+                .map(|lineno| lineno - 1)
+                .unwrap_or(lineno);
+
+            let noqa = noqa_directives
+                .entry(noqa_lineno)
+                .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno]), vec![]));
+
+            let check = Check::new(
+                CheckKind::NoNewLineAtEndOfFile,
+                Range {
+                    location: Location::new(lines.len(), line.len() + 1),
+                    end_location: Location::new(lines.len(), line.len() + 1),
+                },
+            );
+
+            match noqa {
+                (Directive::All(_, _), matches) => {
+                    matches.push(check.kind.code().as_ref());
+                }
+                (Directive::Codes(_, _, codes), matches) => {
+                    if codes.contains(&check.kind.code().as_ref()) {
+                        matches.push(check.kind.code().as_ref());
+                    } else {
+                        line_checks.push(check);
+                    }
+                }
+                (Directive::None, _) => line_checks.push(check),
+            }
+        }
+    }
+
     // Enforce that the noqa directive was actually used.
     if enforce_noqa {
         for (row, (directive, matches)) in noqa_directives {
@@ -145,15 +184,15 @@ pub fn check_lines(
                     let mut valid_codes = vec![];
                     for code in codes {
                         if !matches.contains(&code) {
-                            invalid_codes.push(code);
+                            invalid_codes.push(code.to_string());
                         } else {
-                            valid_codes.push(code);
+                            valid_codes.push(code.to_string());
                         }
                     }
 
                     if !invalid_codes.is_empty() {
                         let mut check = Check::new(
-                            CheckKind::UnusedNOQA(Some(invalid_codes.join(", "))),
+                            CheckKind::UnusedNOQA(Some(invalid_codes)),
                             Range {
                                 location: Location::new(row + 1, start + 1),
                                 end_location: Location::new(row + 1, end + 1),

src/cli.rs

@@ -0,0 +1,142 @@
+use std::fmt;
+use std::path::PathBuf;
+
+use clap::{command, Parser};
+use log::warn;
+use regex::Regex;
+
+use crate::checks::CheckCode;
+use crate::printer::SerializationFormat;
+use crate::pyproject::StrCheckCodePair;
+use crate::settings::PythonVersion;
+use crate::RawSettings;
+
+#[derive(Debug, Parser)]
+#[command(author, about = "ruff: An extremely fast Python linter.")]
+#[command(version)]
+pub struct Cli {
+    #[arg(required = true)]
+    pub files: Vec<PathBuf>,
+    /// Path to the `pyproject.toml` file to use for configuration.
+    #[arg(long)]
+    pub config: Option<PathBuf>,
+    /// Enable verbose logging.
+    #[arg(short, long)]
+    pub verbose: bool,
+    /// Disable all logging (but still exit with status code "1" upon detecting errors).
+    #[arg(short, long)]
+    pub quiet: bool,
+    /// Exit with status code "0", even upon detecting errors.
+    #[arg(short, long)]
+    pub exit_zero: bool,
+    /// Run in watch mode by re-running whenever files change.
+    #[arg(short, long)]
+    pub watch: bool,
+    /// Attempt to automatically fix lint errors.
+    #[arg(short, long)]
+    pub fix: bool,
+    /// Disable cache reads.
+    #[arg(short, long)]
+    pub no_cache: bool,
+    /// List of error codes to enable.
+    #[arg(long, value_delimiter = ',')]
+    pub select: Vec<CheckCode>,
+    /// Like --select, but adds additional error codes on top of the selected ones.
+    #[arg(long, value_delimiter = ',')]
+    pub extend_select: Vec<CheckCode>,
+    /// List of error codes to ignore.
+    #[arg(long, value_delimiter = ',')]
+    pub ignore: Vec<CheckCode>,
+    /// Like --ignore, but adds additional error codes on top of the ignored ones.
+    #[arg(long, value_delimiter = ',')]
+    pub extend_ignore: Vec<CheckCode>,
+    /// List of paths, used to exclude files and/or directories from checks.
+    #[arg(long, value_delimiter = ',')]
+    pub exclude: Vec<String>,
+    /// Like --exclude, but adds additional files and directories on top of the excluded ones.
+    #[arg(long, value_delimiter = ',')]
+    pub extend_exclude: Vec<String>,
+    /// List of mappings from file pattern to code to exclude
+    #[arg(long, value_delimiter = ',')]
+    pub per_file_ignores: Vec<StrCheckCodePair>,
+    /// Output serialization format for error messages.
+    #[arg(long, value_enum, default_value_t=SerializationFormat::Text)]
+    pub format: SerializationFormat,
+    /// See the files ruff will be run against with the current settings.
+    #[arg(long)]
+    pub show_files: bool,
+    /// See ruff's settings.
+    #[arg(long)]
+    pub show_settings: bool,
+    /// Enable automatic additions of noqa directives to failing lines.
+    #[arg(long)]
+    pub add_noqa: bool,
+    /// Regular expression matching the name of dummy variables.
+    #[arg(long)]
+    pub dummy_variable_rgx: Option<Regex>,
+    /// The minimum Python version that should be supported.
+    #[arg(long)]
+    pub target_version: Option<PythonVersion>,
+    /// Round-trip auto-formatting.
+    // TODO(charlie): This should be a sub-command.
+    #[arg(long, hide = true)]
+    pub autoformat: bool,
+    /// The name of the file when passing it through stdin.
+    #[arg(long)]
+    pub stdin_filename: Option<String>,
+}
+
+pub enum Warnable {
+    Select,
+    ExtendSelect,
+}
+
+impl fmt::Display for Warnable {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Warnable::Select => fmt.write_str("--select"),
+            Warnable::ExtendSelect => fmt.write_str("--extend-select"),
+        }
+    }
+}
+
+/// Warn the user if they attempt to enable a code that won't be respected.
+pub fn warn_on(
+    flag: Warnable,
+    codes: &Vec<CheckCode>,
+    cli_ignore: &Vec<CheckCode>,
+    cli_extend_ignore: &Vec<CheckCode>,
+    pyproject_settings: &RawSettings,
+    pyproject_path: &Option<PathBuf>,
+) {
+    for code in codes {
+        if !cli_ignore.is_empty() {
+            if cli_ignore.contains(code) {
+                warn!("{code:?} was passed to {flag}, but ignored via --ignore")
+            }
+        } else if pyproject_settings.ignore.contains(code) {
+            if let Some(path) = pyproject_path {
+                warn!(
+                    "{code:?} was passed to {flag}, but ignored by the `ignore` field in {}",
+                    path.to_string_lossy()
+                )
+            } else {
+                warn!("{code:?} was passed to {flag}, but ignored by the default `ignore` field",)
+            }
+        }
+        if !cli_extend_ignore.is_empty() {
+            if cli_extend_ignore.contains(code) {
+                warn!("{code:?} was passed to {flag}, but ignored via --extend-ignore")
+            }
+        } else if pyproject_settings.extend_ignore.contains(code) {
+            if let Some(path) = pyproject_path {
+                warn!(
+                    "{code:?} was passed to {flag}, but ignored by the `extend_ignore` field in {}",
+                    path.to_string_lossy()
+                )
+            } else {
+                warn!("{code:?} was passed to {flag}, but ignored by the default `extend_ignore` field")
+            }
+        }
+    }
+}

src/docstrings.rs

@@ -0,0 +1,8 @@
+pub mod docstring_plugins;
+pub mod extraction;
+mod google;
+mod helpers;
+mod numpy;
+pub mod sections;
+mod styles;
+pub mod types;

src/docstrings/docstring_plugins.rs

@@ -0,0 +1,707 @@
+//! Abstractions for tracking and validating docstrings in Python code.
+
+use once_cell::sync::Lazy;
+use regex::Regex;
+use rustpython_ast::{Constant, ExprKind, Location, StmtKind};
+
+use crate::ast::types::Range;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind};
+use crate::docstrings::google::check_google_section;
+use crate::docstrings::helpers;
+use crate::docstrings::helpers::{indentation, leading_space};
+use crate::docstrings::numpy::check_numpy_section;
+use crate::docstrings::sections::section_contexts;
+use crate::docstrings::styles::SectionStyle;
+use crate::docstrings::types::{Definition, DefinitionKind};
+use crate::visibility::{is_init, is_magic, is_overload, Visibility};
+
+/// D100, D101, D102, D103, D104, D105, D106, D107
+pub fn not_missing(
+    checker: &mut Checker,
+    definition: &Definition,
+    visibility: &Visibility,
+) -> bool {
+    if matches!(visibility, Visibility::Private) {
+        return true;
+    }
+
+    if definition.docstring.is_some() {
+        return true;
+    }
+
+    match definition.kind {
+        DefinitionKind::Module => {
+            if checker.settings.enabled.contains(&CheckCode::D100) {
+                checker.add_check(Check::new(
+                    CheckKind::PublicModule,
+                    Range {
+                        location: Location::new(1, 1),
+                        end_location: Location::new(1, 1),
+                    },
+                ));
+            }
+            false
+        }
+        DefinitionKind::Package => {
+            if checker.settings.enabled.contains(&CheckCode::D104) {
+                checker.add_check(Check::new(
+                    CheckKind::PublicPackage,
+                    Range {
+                        location: Location::new(1, 1),
+                        end_location: Location::new(1, 1),
+                    },
+                ));
+            }
+            false
+        }
+        DefinitionKind::Class(stmt) => {
+            if checker.settings.enabled.contains(&CheckCode::D101) {
+                checker.add_check(Check::new(
+                    CheckKind::PublicClass,
+                    Range::from_located(stmt),
+                ));
+            }
+            false
+        }
+        DefinitionKind::NestedClass(stmt) => {
+            if checker.settings.enabled.contains(&CheckCode::D106) {
+                checker.add_check(Check::new(
+                    CheckKind::PublicNestedClass,
+                    Range::from_located(stmt),
+                ));
+            }
+            false
+        }
+        DefinitionKind::Function(stmt) | DefinitionKind::NestedFunction(stmt) => {
+            if is_overload(stmt) {
+                true
+            } else {
+                if checker.settings.enabled.contains(&CheckCode::D103) {
+                    checker.add_check(Check::new(
+                        CheckKind::PublicFunction,
+                        Range::from_located(stmt),
+                    ));
+                }
+                false
+            }
+        }
+        DefinitionKind::Method(stmt) => {
+            if is_overload(stmt) {
+                true
+            } else if is_magic(stmt) {
+                if checker.settings.enabled.contains(&CheckCode::D105) {
+                    checker.add_check(Check::new(
+                        CheckKind::MagicMethod,
+                        Range::from_located(stmt),
+                    ));
+                }
+                true
+            } else if is_init(stmt) {
+                if checker.settings.enabled.contains(&CheckCode::D107) {
+                    checker.add_check(Check::new(CheckKind::PublicInit, Range::from_located(stmt)));
+                }
+                true
+            } else {
+                if checker.settings.enabled.contains(&CheckCode::D102) {
+                    checker.add_check(Check::new(
+                        CheckKind::PublicMethod,
+                        Range::from_located(stmt),
+                    ));
+                }
+                true
+            }
+        }
+    }
+}
+
+/// D200
+pub fn one_liner(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = &definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let mut line_count = 0;
+            let mut non_empty_line_count = 0;
+            for line in string.lines() {
+                line_count += 1;
+                if !line.trim().is_empty() {
+                    non_empty_line_count += 1;
+                }
+                if non_empty_line_count > 1 {
+                    break;
+                }
+            }
+
+            if non_empty_line_count == 1 && line_count > 1 {
+                checker.add_check(Check::new(
+                    CheckKind::FitsOnOneLine,
+                    helpers::range_for(docstring),
+                ));
+            }
+        }
+    }
+}
+
+static COMMENT_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"^\s*#").unwrap());
+
+static INNER_FUNCTION_OR_CLASS_REGEX: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r"^\s+(?:(?:class|def|async def)\s|@)").unwrap());
+
+/// D201, D202
+pub fn blank_before_after_function(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let DefinitionKind::Function(parent)
+        | DefinitionKind::NestedFunction(parent)
+        | DefinitionKind::Method(parent) = &definition.kind
+        {
+            if let ExprKind::Constant {
+                value: Constant::Str(_),
+                ..
+            } = &docstring.node
+            {
+                let (before, _, after) = checker.locator.partition_source_code_at(
+                    &Range::from_located(parent),
+                    &helpers::range_for(docstring),
+                );
+
+                if checker.settings.enabled.contains(&CheckCode::D201) {
+                    let blank_lines_before = before
+                        .lines()
+                        .rev()
+                        .skip(1)
+                        .take_while(|line| line.trim().is_empty())
+                        .count();
+                    if blank_lines_before != 0 {
+                        checker.add_check(Check::new(
+                            CheckKind::NoBlankLineBeforeFunction(blank_lines_before),
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                }
+
+                if checker.settings.enabled.contains(&CheckCode::D202) {
+                    let blank_lines_after = after
+                        .lines()
+                        .skip(1)
+                        .take_while(|line| line.trim().is_empty())
+                        .count();
+                    let all_blank_after = after
+                        .lines()
+                        .skip(1)
+                        .all(|line| line.trim().is_empty() || COMMENT_REGEX.is_match(line));
+                    // Report a D202 violation if the docstring is followed by a blank line
+                    // and the blank line is not itself followed by an inner function or
+                    // class.
+                    if !all_blank_after
+                        && blank_lines_after != 0
+                        && !(blank_lines_after == 1
+                            && INNER_FUNCTION_OR_CLASS_REGEX.is_match(after))
+                    {
+                        checker.add_check(Check::new(
+                            CheckKind::NoBlankLineAfterFunction(blank_lines_after),
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// D203, D204, D211
+pub fn blank_before_after_class(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = &definition.docstring {
+        if let DefinitionKind::Class(parent) | DefinitionKind::NestedClass(parent) =
+            &definition.kind
+        {
+            if let ExprKind::Constant {
+                value: Constant::Str(_),
+                ..
+            } = &docstring.node
+            {
+                let (before, _, after) = checker.locator.partition_source_code_at(
+                    &Range::from_located(parent),
+                    &helpers::range_for(docstring),
+                );
+
+                if checker.settings.enabled.contains(&CheckCode::D203)
+                    || checker.settings.enabled.contains(&CheckCode::D211)
+                {
+                    let blank_lines_before = before
+                        .lines()
+                        .rev()
+                        .skip(1)
+                        .take_while(|line| line.trim().is_empty())
+                        .count();
+                    if blank_lines_before != 0
+                        && checker.settings.enabled.contains(&CheckCode::D211)
+                    {
+                        checker.add_check(Check::new(
+                            CheckKind::NoBlankLineBeforeClass(blank_lines_before),
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                    if blank_lines_before != 1
+                        && checker.settings.enabled.contains(&CheckCode::D203)
+                    {
+                        checker.add_check(Check::new(
+                            CheckKind::OneBlankLineBeforeClass(blank_lines_before),
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                }
+
+                if checker.settings.enabled.contains(&CheckCode::D204) {
+                    let blank_lines_after = after
+                        .lines()
+                        .skip(1)
+                        .take_while(|line| line.trim().is_empty())
+                        .count();
+                    let all_blank_after = after
+                        .lines()
+                        .skip(1)
+                        .all(|line| line.trim().is_empty() || COMMENT_REGEX.is_match(line));
+                    if !all_blank_after && blank_lines_after != 1 {
+                        checker.add_check(Check::new(
+                            CheckKind::OneBlankLineAfterClass(blank_lines_after),
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// D205
+pub fn blank_after_summary(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let mut lines_count = 1;
+            let mut blanks_count = 0;
+            for line in string.trim().lines().skip(1) {
+                lines_count += 1;
+                if line.trim().is_empty() {
+                    blanks_count += 1;
+                } else {
+                    break;
+                }
+            }
+            if lines_count > 1 && blanks_count != 1 {
+                checker.add_check(Check::new(
+                    CheckKind::NoBlankLineAfterSummary,
+                    helpers::range_for(docstring),
+                ));
+            }
+        }
+    }
+}
+
+/// D206, D207, D208
+pub fn indent(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let lines: Vec<&str> = string.lines().collect();
+            if lines.len() <= 1 {
+                return;
+            }
+
+            let mut has_seen_tab = false;
+            let mut has_seen_over_indent = false;
+            let mut has_seen_under_indent = false;
+
+            let docstring_indent = indentation(checker, docstring).to_string();
+            if !has_seen_tab {
+                if docstring_indent.contains('\t') {
+                    if checker.settings.enabled.contains(&CheckCode::D206) {
+                        checker.add_check(Check::new(
+                            CheckKind::IndentWithSpaces,
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                    has_seen_tab = true;
+                }
+            }
+
+            for i in 0..lines.len() {
+                // First lines and continuations doesn't need any indentation.
+                if i == 0 || lines[i - 1].ends_with('\\') {
+                    continue;
+                }
+
+                // Omit empty lines, except for the last line, which is non-empty by way of
+                // containing the closing quotation marks.
+                if i < lines.len() - 1 && lines[i].trim().is_empty() {
+                    continue;
+                }
+
+                let line_indent = leading_space(lines[i]);
+                if !has_seen_tab {
+                    if line_indent.contains('\t') {
+                        if checker.settings.enabled.contains(&CheckCode::D206) {
+                            checker.add_check(Check::new(
+                                CheckKind::IndentWithSpaces,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                        has_seen_tab = true;
+                    }
+                }
+
+                if !has_seen_over_indent {
+                    if line_indent.len() > docstring_indent.len() {
+                        if checker.settings.enabled.contains(&CheckCode::D208) {
+                            checker.add_check(Check::new(
+                                CheckKind::NoOverIndentation,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                        has_seen_over_indent = true;
+                    }
+                }
+
+                if !has_seen_under_indent {
+                    if line_indent.len() < docstring_indent.len() {
+                        if checker.settings.enabled.contains(&CheckCode::D207) {
+                            checker.add_check(Check::new(
+                                CheckKind::NoUnderIndentation,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                        has_seen_under_indent = true;
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// D209
+pub fn newline_after_last_paragraph(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let mut line_count = 0;
+            for line in string.lines() {
+                if !line.trim().is_empty() {
+                    line_count += 1;
+                }
+                if line_count > 1 {
+                    let content = checker
+                        .locator
+                        .slice_source_code_range(&helpers::range_for(docstring));
+                    if let Some(line) = content.lines().last() {
+                        let line = line.trim();
+                        if line != "\"\"\"" && line != "'''" {
+                            checker.add_check(Check::new(
+                                CheckKind::NewLineAfterLastParagraph,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                    }
+                    return;
+                }
+            }
+        }
+    }
+}
+
+/// D210
+pub fn no_surrounding_whitespace(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let mut lines = string.lines();
+            if let Some(line) = lines.next() {
+                if line.trim().is_empty() {
+                    return;
+                }
+                if line.starts_with(' ') || (matches!(lines.next(), None) && line.ends_with(' ')) {
+                    checker.add_check(Check::new(
+                        CheckKind::NoSurroundingWhitespace,
+                        helpers::range_for(docstring),
+                    ));
+                }
+            }
+        }
+    }
+}
+
+/// D212, D213
+pub fn multi_line_summary_start(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            if string.lines().nth(1).is_some() {
+                let content = checker
+                    .locator
+                    .slice_source_code_range(&helpers::range_for(docstring));
+                if let Some(first_line) = content.lines().next() {
+                    let first_line = first_line.trim();
+                    if first_line == "\"\"\"" || first_line == "'''" {
+                        if checker.settings.enabled.contains(&CheckCode::D212) {
+                            checker.add_check(Check::new(
+                                CheckKind::MultiLineSummaryFirstLine,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                    } else {
+                        if checker.settings.enabled.contains(&CheckCode::D213) {
+                            checker.add_check(Check::new(
+                                CheckKind::MultiLineSummarySecondLine,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// D300
+pub fn triple_quotes(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let content = checker
+                .locator
+                .slice_source_code_range(&helpers::range_for(docstring));
+            if string.contains("\"\"\"") {
+                if !content.starts_with("'''") {
+                    checker.add_check(Check::new(
+                        CheckKind::UsesTripleQuotes,
+                        helpers::range_for(docstring),
+                    ));
+                }
+            } else if !content.starts_with("\"\"\"") {
+                checker.add_check(Check::new(
+                    CheckKind::UsesTripleQuotes,
+                    helpers::range_for(docstring),
+                ));
+            }
+        }
+    }
+}
+
+/// D400
+pub fn ends_with_period(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            if let Some(string) = string.lines().next() {
+                if !string.ends_with('.') {
+                    checker.add_check(Check::new(
+                        CheckKind::EndsInPeriod,
+                        helpers::range_for(docstring),
+                    ));
+                }
+            }
+        }
+    }
+}
+
+/// D402
+pub fn no_signature(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let DefinitionKind::Function(parent)
+        | DefinitionKind::NestedFunction(parent)
+        | DefinitionKind::Method(parent) = definition.kind
+        {
+            if let StmtKind::FunctionDef { name, .. } = &parent.node {
+                if let ExprKind::Constant {
+                    value: Constant::Str(string),
+                    ..
+                } = &docstring.node
+                {
+                    if let Some(first_line) = string.lines().next() {
+                        if first_line.contains(&format!("{name}(")) {
+                            checker.add_check(Check::new(
+                                CheckKind::NoSignature,
+                                helpers::range_for(docstring),
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// D403
+pub fn capitalized(checker: &mut Checker, definition: &Definition) {
+    if !matches!(definition.kind, DefinitionKind::Function(_)) {
+        return;
+    }
+
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            if let Some(first_word) = string.split(' ').next() {
+                if first_word == first_word.to_uppercase() {
+                    return;
+                }
+                for char in first_word.chars() {
+                    if !char.is_ascii_alphabetic() && char != '\'' {
+                        return;
+                    }
+                }
+                if let Some(first_char) = first_word.chars().next() {
+                    if !first_char.is_uppercase() {
+                        checker.add_check(Check::new(
+                            CheckKind::FirstLineCapitalized,
+                            helpers::range_for(docstring),
+                        ));
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// D404
+pub fn starts_with_this(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let trimmed = string.trim();
+            if trimmed.is_empty() {
+                return;
+            }
+
+            if let Some(first_word) = string.split(' ').next() {
+                if first_word
+                    .replace(|c: char| !c.is_alphanumeric(), "")
+                    .to_lowercase()
+                    == "this"
+                {
+                    checker.add_check(Check::new(
+                        CheckKind::NoThisPrefix,
+                        helpers::range_for(docstring),
+                    ));
+                }
+            }
+        }
+    }
+}
+
+/// D415
+pub fn ends_with_punctuation(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            if let Some(string) = string.lines().next() {
+                if !(string.ends_with('.') || string.ends_with('!') || string.ends_with('?')) {
+                    checker.add_check(Check::new(
+                        CheckKind::EndsInPunctuation,
+                        helpers::range_for(docstring),
+                    ));
+                }
+            }
+        }
+    }
+}
+
+/// D418
+pub fn if_needed(checker: &mut Checker, definition: &Definition) {
+    if definition.docstring.is_some() {
+        if let DefinitionKind::Function(stmt)
+        | DefinitionKind::NestedFunction(stmt)
+        | DefinitionKind::Method(stmt) = definition.kind
+        {
+            if is_overload(stmt) {
+                checker.add_check(Check::new(
+                    CheckKind::SkipDocstring,
+                    Range::from_located(stmt),
+                ));
+            }
+        }
+    }
+}
+
+/// D419
+pub fn not_empty(checker: &mut Checker, definition: &Definition) -> bool {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            if string.trim().is_empty() {
+                if checker.settings.enabled.contains(&CheckCode::D419) {
+                    checker.add_check(Check::new(
+                        CheckKind::NonEmpty,
+                        helpers::range_for(docstring),
+                    ));
+                }
+                return false;
+            }
+        }
+    }
+    true
+}
+
+/// D212, D214, D215, D405, D406, D407, D408, D409, D410, D411, D412, D413, D414, D416, D417
+pub fn sections(checker: &mut Checker, definition: &Definition) {
+    if let Some(docstring) = definition.docstring {
+        if let ExprKind::Constant {
+            value: Constant::Str(string),
+            ..
+        } = &docstring.node
+        {
+            let lines: Vec<&str> = string.lines().collect();
+            if lines.len() < 2 {
+                return;
+            }
+
+            // First, interpret as NumPy-style sections.
+            let mut found_numpy_section = false;
+            for context in &section_contexts(&lines, &SectionStyle::NumPy) {
+                found_numpy_section = true;
+                check_numpy_section(checker, definition, context);
+            }
+
+            // If no such sections were identified, interpret as Google-style sections.
+            if !found_numpy_section {
+                for context in &section_contexts(&lines, &SectionStyle::Google) {
+                    check_google_section(checker, definition, context);
+                }
+            }
+        }
+    }
+}

src/docstrings/extraction.rs

@@ -0,0 +1,82 @@
+//! Extract docstrings from an AST.
+
+use rustpython_ast::{Constant, Expr, ExprKind, Stmt, StmtKind};
+
+use crate::docstrings::types::{Definition, DefinitionKind, Documentable};
+use crate::visibility::{Modifier, VisibleScope};
+
+/// Extract a docstring from a function or class body.
+pub fn docstring_from(suite: &[Stmt]) -> Option<&Expr> {
+    if let Some(stmt) = suite.first() {
+        if let StmtKind::Expr { value } = &stmt.node {
+            if matches!(
+                &value.node,
+                ExprKind::Constant {
+                    value: Constant::Str(_),
+                    ..
+                }
+            ) {
+                return Some(value);
+            }
+        }
+    }
+    None
+}
+
+/// Extract a `Definition` from the AST node defined by a `Stmt`.
+pub fn extract<'a>(
+    scope: &VisibleScope,
+    stmt: &'a Stmt,
+    body: &'a [Stmt],
+    kind: &Documentable,
+) -> Definition<'a> {
+    let expr = docstring_from(body);
+    match kind {
+        Documentable::Function => match scope {
+            VisibleScope {
+                modifier: Modifier::Module,
+                ..
+            } => Definition {
+                kind: DefinitionKind::Function(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Class,
+                ..
+            } => Definition {
+                kind: DefinitionKind::Method(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Function,
+                ..
+            } => Definition {
+                kind: DefinitionKind::NestedFunction(stmt),
+                docstring: expr,
+            },
+        },
+        Documentable::Class => match scope {
+            VisibleScope {
+                modifier: Modifier::Module,
+                ..
+            } => Definition {
+                kind: DefinitionKind::Class(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Class,
+                ..
+            } => Definition {
+                kind: DefinitionKind::NestedClass(stmt),
+                docstring: expr,
+            },
+            VisibleScope {
+                modifier: Modifier::Function,
+                ..
+            } => Definition {
+                kind: DefinitionKind::NestedClass(stmt),
+                docstring: expr,
+            },
+        },
+    }
+}

src/docstrings/google.rs

@@ -0,0 +1,150 @@
+//! Abstractions for Google-style docstrings.
+
+use std::collections::BTreeSet;
+
+use once_cell::sync::Lazy;
+use regex::Regex;
+
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind};
+use crate::docstrings::helpers::range_for;
+use crate::docstrings::sections;
+use crate::docstrings::sections::SectionContext;
+use crate::docstrings::styles::SectionStyle;
+use crate::docstrings::types::Definition;
+
+pub(crate) static GOOGLE_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "Args",
+        "Arguments",
+        "Attention",
+        "Attributes",
+        "Caution",
+        "Danger",
+        "Error",
+        "Example",
+        "Examples",
+        "Hint",
+        "Important",
+        "Keyword Args",
+        "Keyword Arguments",
+        "Methods",
+        "Note",
+        "Notes",
+        "Return",
+        "Returns",
+        "Raises",
+        "References",
+        "See Also",
+        "Tip",
+        "Todo",
+        "Warning",
+        "Warnings",
+        "Warns",
+        "Yield",
+        "Yields",
+    ])
+});
+
+pub(crate) static LOWERCASE_GOOGLE_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "args",
+        "arguments",
+        "attention",
+        "attributes",
+        "caution",
+        "danger",
+        "error",
+        "example",
+        "examples",
+        "hint",
+        "important",
+        "keyword args",
+        "keyword arguments",
+        "methods",
+        "note",
+        "notes",
+        "return",
+        "returns",
+        "raises",
+        "references",
+        "see also",
+        "tip",
+        "todo",
+        "warning",
+        "warnings",
+        "warns",
+        "yield",
+        "yields",
+    ])
+});
+
+// See: `GOOGLE_ARGS_REGEX` in `pydocstyle/checker.py`.
+static GOOGLE_ARGS_REGEX: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r"^\s*(\w+)\s*(\(.*?\))?\s*:\n?\s*.+").expect("Invalid regex"));
+
+fn check_args_section(checker: &mut Checker, definition: &Definition, context: &SectionContext) {
+    let mut args_sections: Vec<String> = vec![];
+    for line in textwrap::dedent(&context.following_lines.join("\n")).lines() {
+        if line
+            .chars()
+            .next()
+            .map(|char| char.is_whitespace())
+            .unwrap_or(true)
+        {
+            // This is a continuation of documentation for the last
+            // parameter because it does start with whitespace.
+            if let Some(current) = args_sections.last_mut() {
+                current.push_str(line);
+            }
+        } else {
+            // This line is the start of documentation for the next
+            // parameter because it doesn't start with any whitespace.
+            args_sections.push(line.to_string());
+        }
+    }
+
+    sections::check_missing_args(
+        checker,
+        definition,
+        // Collect the list of arguments documented in the docstring.
+        &BTreeSet::from_iter(args_sections.iter().filter_map(|section| {
+            match GOOGLE_ARGS_REGEX.captures(section.as_str()) {
+                Some(caps) => caps.get(1).map(|arg_name| arg_name.as_str()),
+                None => None,
+            }
+        })),
+    )
+}
+
+pub(crate) fn check_google_section(
+    checker: &mut Checker,
+    definition: &Definition,
+    context: &SectionContext,
+) {
+    sections::check_common_section(checker, definition, context, &SectionStyle::Google);
+
+    if checker.settings.enabled.contains(&CheckCode::D416) {
+        let suffix = context
+            .line
+            .trim()
+            .strip_prefix(&context.section_name)
+            .unwrap();
+        if suffix != ":" {
+            let docstring = definition
+                .docstring
+                .expect("Sections are only available for docstrings.");
+            checker.add_check(Check::new(
+                CheckKind::SectionNameEndsInColon(context.section_name.to_string()),
+                range_for(docstring),
+            ))
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::D417) {
+        let capitalized_section_name = titlecase::titlecase(&context.section_name);
+        if capitalized_section_name == "Args" || capitalized_section_name == "Arguments" {
+            check_args_section(checker, definition, context);
+        }
+    }
+}

src/docstrings/helpers.rs

@@ -0,0 +1,37 @@
+use rustpython_ast::{Expr, Location};
+
+use crate::ast::types::Range;
+use crate::check_ast::Checker;
+
+/// Extract the leading words from a line of text.
+pub fn leading_words(line: &str) -> String {
+    line.trim()
+        .chars()
+        .take_while(|char| char.is_alphanumeric() || char.is_whitespace())
+        .collect()
+}
+
+/// Extract the leading whitespace from a line of text.
+pub fn leading_space(line: &str) -> String {
+    line.chars()
+        .take_while(|char| char.is_whitespace())
+        .collect()
+}
+
+/// Extract the leading indentation from a docstring.
+pub fn indentation<'a>(checker: &'a mut Checker, docstring: &Expr) -> &'a str {
+    let range = range_for(docstring);
+    checker.locator.slice_source_code_range(&Range {
+        location: Location::new(range.location.row(), 1),
+        end_location: Location::new(range.location.row(), range.location.column()),
+    })
+}
+
+/// Extract the source code range for a docstring.
+pub fn range_for(docstring: &Expr) -> Range {
+    // RustPython currently omits the first quotation mark in a string, so offset the location.
+    Range {
+        location: Location::new(docstring.location.row(), docstring.location.column() - 1),
+        end_location: docstring.end_location,
+    }
+}

src/docstrings/numpy.rs

@@ -0,0 +1,114 @@
+//! Abstractions for NumPy-style docstrings.
+
+use std::collections::BTreeSet;
+
+use once_cell::sync::Lazy;
+
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind};
+use crate::docstrings::helpers::range_for;
+use crate::docstrings::sections::SectionContext;
+use crate::docstrings::styles::SectionStyle;
+use crate::docstrings::types::Definition;
+use crate::docstrings::{helpers, sections};
+
+pub(crate) static LOWERCASE_NUMPY_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "short summary",
+        "extended summary",
+        "parameters",
+        "returns",
+        "yields",
+        "other parameters",
+        "raises",
+        "see also",
+        "notes",
+        "references",
+        "examples",
+        "attributes",
+        "methods",
+    ])
+});
+
+pub(crate) static NUMPY_SECTION_NAMES: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
+    BTreeSet::from([
+        "Short Summary",
+        "Extended Summary",
+        "Parameters",
+        "Returns",
+        "Yields",
+        "Other Parameters",
+        "Raises",
+        "See Also",
+        "Notes",
+        "References",
+        "Examples",
+        "Attributes",
+        "Methods",
+    ])
+});
+
+fn check_parameters_section(
+    checker: &mut Checker,
+    definition: &Definition,
+    context: &SectionContext,
+) {
+    // Collect the list of arguments documented in the docstring.
+    let mut docstring_args: BTreeSet<&str> = Default::default();
+    let section_level_indent = helpers::leading_space(context.line);
+    for i in 1..context.following_lines.len() {
+        let current_line = context.following_lines[i - 1];
+        let current_leading_space = helpers::leading_space(current_line);
+        let next_line = context.following_lines[i];
+        if current_leading_space == section_level_indent
+            && (helpers::leading_space(next_line).len() > current_leading_space.len())
+            && !next_line.trim().is_empty()
+        {
+            let parameters = if let Some(semi_index) = current_line.find(':') {
+                // If the parameter has a type annotation, exclude it.
+                &current_line[..semi_index]
+            } else {
+                // Otherwise, it's just a list of parameters on the current line.
+                current_line.trim()
+            };
+            // Notably, NumPy lets you put multiple parameters of the same type on the same line.
+            for parameter in parameters.split(',') {
+                docstring_args.insert(parameter.trim());
+            }
+        }
+    }
+    // Validate that all arguments were documented.
+    sections::check_missing_args(checker, definition, &docstring_args);
+}
+
+pub(crate) fn check_numpy_section(
+    checker: &mut Checker,
+    definition: &Definition,
+    context: &SectionContext,
+) {
+    sections::check_common_section(checker, definition, context, &SectionStyle::NumPy);
+
+    if checker.settings.enabled.contains(&CheckCode::D406) {
+        let suffix = context
+            .line
+            .trim()
+            .strip_prefix(&context.section_name)
+            .unwrap();
+        if !suffix.is_empty() {
+            let docstring = definition
+                .docstring
+                .expect("Sections are only available for docstrings.");
+            checker.add_check(Check::new(
+                CheckKind::NewLineAfterSectionName(context.section_name.to_string()),
+                range_for(docstring),
+            ))
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::D417) {
+        let capitalized_section_name = titlecase::titlecase(&context.section_name);
+        if capitalized_section_name == "Parameters" {
+            check_parameters_section(checker, definition, context);
+        }
+    }
+}

src/docstrings/sections.rs

@@ -0,0 +1,377 @@
+use std::collections::BTreeSet;
+
+use itertools::Itertools;
+use rustpython_ast::{Arg, StmtKind};
+use titlecase::titlecase;
+
+use crate::ast::types::Range;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind};
+use crate::docstrings::helpers;
+use crate::docstrings::helpers::range_for;
+use crate::docstrings::styles::SectionStyle;
+use crate::docstrings::types::{Definition, DefinitionKind};
+use crate::visibility::is_static;
+
+#[derive(Debug)]
+pub(crate) struct SectionContext<'a> {
+    pub(crate) section_name: String,
+    pub(crate) previous_line: &'a str,
+    pub(crate) line: &'a str,
+    pub(crate) following_lines: &'a [&'a str],
+    pub(crate) is_last_section: bool,
+    original_index: usize,
+}
+
+fn suspected_as_section(line: &str, style: &SectionStyle) -> bool {
+    style
+        .lowercase_section_names()
+        .contains(&helpers::leading_words(line).to_lowercase().as_str())
+}
+
+/// Check if the suspected context is really a section header.
+fn is_docstring_section(context: &SectionContext) -> bool {
+    let section_name_suffix = context
+        .line
+        .trim()
+        .strip_prefix(&context.section_name)
+        .unwrap()
+        .trim();
+    let this_looks_like_a_section_name =
+        section_name_suffix == ":" || section_name_suffix.is_empty();
+    if !this_looks_like_a_section_name {
+        return false;
+    }
+
+    let prev_line = context.previous_line.trim();
+    let prev_line_ends_with_punctuation = [',', ';', '.', '-', '\\', '/', ']', '}', ')']
+        .into_iter()
+        .any(|char| prev_line.ends_with(char));
+    let prev_line_looks_like_end_of_paragraph =
+        prev_line_ends_with_punctuation || prev_line.is_empty();
+    if !prev_line_looks_like_end_of_paragraph {
+        return false;
+    }
+
+    true
+}
+
+/// Extract all `SectionContext` values from a docstring.
+pub(crate) fn section_contexts<'a>(
+    lines: &'a [&'a str],
+    style: &SectionStyle,
+) -> Vec<SectionContext<'a>> {
+    let suspected_section_indices: Vec<usize> = lines
+        .iter()
+        .enumerate()
+        .filter_map(|(lineno, line)| {
+            if lineno > 0 && suspected_as_section(line, style) {
+                Some(lineno)
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    let mut contexts = vec![];
+    for lineno in suspected_section_indices {
+        let context = SectionContext {
+            section_name: helpers::leading_words(lines[lineno]),
+            previous_line: lines[lineno - 1],
+            line: lines[lineno],
+            following_lines: &lines[lineno + 1..],
+            original_index: lineno,
+            is_last_section: false,
+        };
+        if is_docstring_section(&context) {
+            contexts.push(context);
+        }
+    }
+
+    let mut truncated_contexts = vec![];
+    let mut end: Option<usize> = None;
+    for context in contexts.into_iter().rev() {
+        let next_end = context.original_index;
+        truncated_contexts.push(SectionContext {
+            section_name: context.section_name,
+            previous_line: context.previous_line,
+            line: context.line,
+            following_lines: if let Some(end) = end {
+                &lines[context.original_index + 1..end]
+            } else {
+                context.following_lines
+            },
+            original_index: context.original_index,
+            is_last_section: end.is_none(),
+        });
+        end = Some(next_end);
+    }
+    truncated_contexts.reverse();
+    truncated_contexts
+}
+
+fn check_blanks_and_section_underline(
+    checker: &mut Checker,
+    definition: &Definition,
+    context: &SectionContext,
+) {
+    let docstring = definition
+        .docstring
+        .expect("Sections are only available for docstrings.");
+
+    let mut blank_lines_after_header = 0;
+    for line in context.following_lines {
+        if !line.trim().is_empty() {
+            break;
+        }
+        blank_lines_after_header += 1;
+    }
+
+    // Nothing but blank lines after the section header.
+    if blank_lines_after_header == context.following_lines.len() {
+        if checker.settings.enabled.contains(&CheckCode::D407) {
+            checker.add_check(Check::new(
+                CheckKind::DashedUnderlineAfterSection(context.section_name.to_string()),
+                range_for(docstring),
+            ));
+        }
+        if checker.settings.enabled.contains(&CheckCode::D414) {
+            checker.add_check(Check::new(
+                CheckKind::NonEmptySection(context.section_name.to_string()),
+                range_for(docstring),
+            ));
+        }
+        return;
+    }
+
+    let non_empty_line = context.following_lines[blank_lines_after_header];
+    let dash_line_found = non_empty_line
+        .chars()
+        .all(|char| char.is_whitespace() || char == '-');
+
+    if !dash_line_found {
+        if checker.settings.enabled.contains(&CheckCode::D407) {
+            checker.add_check(Check::new(
+                CheckKind::DashedUnderlineAfterSection(context.section_name.to_string()),
+                range_for(docstring),
+            ));
+        }
+        if blank_lines_after_header > 0 {
+            if checker.settings.enabled.contains(&CheckCode::D212) {
+                checker.add_check(Check::new(
+                    CheckKind::NoBlankLinesBetweenHeaderAndContent(
+                        context.section_name.to_string(),
+                    ),
+                    range_for(docstring),
+                ));
+            }
+        }
+    } else {
+        if blank_lines_after_header > 0 {
+            if checker.settings.enabled.contains(&CheckCode::D408) {
+                checker.add_check(Check::new(
+                    CheckKind::SectionUnderlineAfterName(context.section_name.to_string()),
+                    range_for(docstring),
+                ));
+            }
+        }
+
+        if non_empty_line
+            .trim()
+            .chars()
+            .filter(|char| *char == '-')
+            .count()
+            != context.section_name.len()
+        {
+            if checker.settings.enabled.contains(&CheckCode::D409) {
+                checker.add_check(Check::new(
+                    CheckKind::SectionUnderlineMatchesSectionLength(
+                        context.section_name.to_string(),
+                    ),
+                    range_for(docstring),
+                ));
+            }
+        }
+
+        if checker.settings.enabled.contains(&CheckCode::D215) {
+            if helpers::leading_space(non_empty_line).len()
+                > helpers::indentation(checker, docstring).len()
+            {
+                checker.add_check(Check::new(
+                    CheckKind::SectionUnderlineNotOverIndented(context.section_name.to_string()),
+                    range_for(docstring),
+                ));
+            }
+        }
+
+        let line_after_dashes_index = blank_lines_after_header + 1;
+
+        if line_after_dashes_index < context.following_lines.len() {
+            let line_after_dashes = context.following_lines[line_after_dashes_index];
+            if line_after_dashes.trim().is_empty() {
+                let rest_of_lines = &context.following_lines[line_after_dashes_index..];
+                if rest_of_lines.iter().all(|line| line.trim().is_empty()) {
+                    if checker.settings.enabled.contains(&CheckCode::D414) {
+                        checker.add_check(Check::new(
+                            CheckKind::NonEmptySection(context.section_name.to_string()),
+                            range_for(docstring),
+                        ));
+                    }
+                } else {
+                    if checker.settings.enabled.contains(&CheckCode::D412) {
+                        checker.add_check(Check::new(
+                            CheckKind::NoBlankLinesBetweenHeaderAndContent(
+                                context.section_name.to_string(),
+                            ),
+                            range_for(docstring),
+                        ));
+                    }
+                }
+            }
+        } else {
+            if checker.settings.enabled.contains(&CheckCode::D414) {
+                checker.add_check(Check::new(
+                    CheckKind::NonEmptySection(context.section_name.to_string()),
+                    range_for(docstring),
+                ));
+            }
+        }
+    }
+}
+
+pub(crate) fn check_common_section(
+    checker: &mut Checker,
+    definition: &Definition,
+    context: &SectionContext,
+    style: &SectionStyle,
+) {
+    let docstring = definition
+        .docstring
+        .expect("Sections are only available for docstrings.");
+
+    if checker.settings.enabled.contains(&CheckCode::D405) {
+        if !style
+            .section_names()
+            .contains(&context.section_name.as_str())
+            && style
+                .section_names()
+                .contains(titlecase(&context.section_name).as_str())
+        {
+            checker.add_check(Check::new(
+                CheckKind::CapitalizeSectionName(context.section_name.to_string()),
+                range_for(docstring),
+            ))
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::D214) {
+        if helpers::leading_space(context.line).len()
+            > helpers::indentation(checker, docstring).len()
+        {
+            checker.add_check(Check::new(
+                CheckKind::SectionNotOverIndented(context.section_name.to_string()),
+                range_for(docstring),
+            ))
+        }
+    }
+
+    if context
+        .following_lines
+        .last()
+        .map(|line| !line.trim().is_empty())
+        .unwrap_or(true)
+    {
+        if context.is_last_section {
+            if checker.settings.enabled.contains(&CheckCode::D413) {
+                checker.add_check(Check::new(
+                    CheckKind::BlankLineAfterLastSection(context.section_name.to_string()),
+                    range_for(docstring),
+                ))
+            }
+        } else {
+            if checker.settings.enabled.contains(&CheckCode::D410) {
+                checker.add_check(Check::new(
+                    CheckKind::BlankLineAfterSection(context.section_name.to_string()),
+                    range_for(docstring),
+                ))
+            }
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::D411) {
+        if !context.previous_line.is_empty() {
+            checker.add_check(Check::new(
+                CheckKind::BlankLineBeforeSection(context.section_name.to_string()),
+                range_for(docstring),
+            ))
+        }
+    }
+
+    check_blanks_and_section_underline(checker, definition, context);
+}
+
+pub(crate) fn check_missing_args(
+    checker: &mut Checker,
+    definition: &Definition,
+    docstrings_args: &BTreeSet<&str>,
+) {
+    if let DefinitionKind::Function(parent)
+    | DefinitionKind::NestedFunction(parent)
+    | DefinitionKind::Method(parent) = definition.kind
+    {
+        if let StmtKind::FunctionDef {
+            args: arguments, ..
+        }
+        | StmtKind::AsyncFunctionDef {
+            args: arguments, ..
+        } = &parent.node
+        {
+            // Collect all the arguments into a single vector.
+            let mut all_arguments: Vec<&Arg> = arguments
+                .args
+                .iter()
+                .chain(arguments.posonlyargs.iter())
+                .chain(arguments.kwonlyargs.iter())
+                .skip(
+                    // If this is a non-static method, skip `cls` or `self`.
+                    if matches!(definition.kind, DefinitionKind::Method(_)) && !is_static(parent) {
+                        1
+                    } else {
+                        0
+                    },
+                )
+                .collect();
+            if let Some(arg) = &arguments.vararg {
+                all_arguments.push(arg);
+            }
+            if let Some(arg) = &arguments.kwarg {
+                all_arguments.push(arg);
+            }
+
+            // Look for arguments that weren't included in the docstring.
+            let mut missing_args: BTreeSet<&str> = Default::default();
+            for arg in all_arguments {
+                let arg_name = arg.node.arg.as_str();
+                if arg_name.starts_with('_') {
+                    continue;
+                }
+                if docstrings_args.contains(&arg_name) {
+                    continue;
+                }
+                missing_args.insert(arg_name);
+            }
+
+            if !missing_args.is_empty() {
+                let names = missing_args
+                    .into_iter()
+                    .map(String::from)
+                    .sorted()
+                    .collect();
+                checker.add_check(Check::new(
+                    CheckKind::DocumentAllArguments(names),
+                    Range::from_located(parent),
+                ));
+            }
+        }
+    }
+}

src/docstrings/styles.rs

@@ -0,0 +1,27 @@
+use std::collections::BTreeSet;
+
+use once_cell::sync::Lazy;
+
+use crate::docstrings::google::{GOOGLE_SECTION_NAMES, LOWERCASE_GOOGLE_SECTION_NAMES};
+use crate::docstrings::numpy::{LOWERCASE_NUMPY_SECTION_NAMES, NUMPY_SECTION_NAMES};
+
+pub(crate) enum SectionStyle {
+    NumPy,
+    Google,
+}
+
+impl SectionStyle {
+    pub(crate) fn section_names(&self) -> &Lazy<BTreeSet<&'static str>> {
+        match self {
+            SectionStyle::NumPy => &NUMPY_SECTION_NAMES,
+            SectionStyle::Google => &GOOGLE_SECTION_NAMES,
+        }
+    }
+
+    pub(crate) fn lowercase_section_names(&self) -> &Lazy<BTreeSet<&'static str>> {
+        match self {
+            SectionStyle::NumPy => &LOWERCASE_NUMPY_SECTION_NAMES,
+            SectionStyle::Google => &LOWERCASE_GOOGLE_SECTION_NAMES,
+        }
+    }
+}

src/docstrings/types.rs

@@ -0,0 +1,23 @@
+use rustpython_ast::{Expr, Stmt};
+
+#[derive(Debug)]
+pub enum DefinitionKind<'a> {
+    Module,
+    Package,
+    Class(&'a Stmt),
+    NestedClass(&'a Stmt),
+    Function(&'a Stmt),
+    NestedFunction(&'a Stmt),
+    Method(&'a Stmt),
+}
+
+#[derive(Debug)]
+pub struct Definition<'a> {
+    pub kind: DefinitionKind<'a>,
+    pub docstring: Option<&'a Expr>,
+}
+
+pub enum Documentable {
+    Class,
+    Function,
+}

src/lib.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::collapsible_if, clippy::collapsible_else_if)]
+
 use std::path::Path;
 
 use anyhow::Result;
@@ -7,7 +9,7 @@ use rustpython_parser::lexer::LexResult;
 use crate::autofix::fixer::Mode;
 use crate::linter::{check_path, tokenize};
 use crate::message::Message;
-use crate::settings::Settings;
+use crate::settings::{RawSettings, Settings};
 
 mod ast;
 mod autofix;
@@ -15,15 +17,20 @@ pub mod cache;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;
+pub mod cli;
+pub mod code_gen;
+mod docstrings;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
 mod noqa;
+mod plugins;
 pub mod printer;
 pub mod pyproject;
 mod python;
 pub mod settings;
+pub mod visibility;
 
 /// Run ruff over Python source code directly.
 pub fn check(path: &Path, contents: &str) -> Result<Vec<Message>> {
@@ -39,7 +46,7 @@ pub fn check(path: &Path, contents: &str) -> Result<Vec<Message>> {
         None => debug!("Unable to find pyproject.toml; using default settings..."),
     };
 
-    let settings = Settings::from_pyproject(pyproject, project_root)?;
+    let settings = Settings::from_raw(RawSettings::from_pyproject(&pyproject, &project_root)?);
 
     // Tokenize once.
     let tokens: Vec<LexResult> = tokenize(contents);

src/linter.rs

@@ -1,6 +1,10 @@
+use std::fs::write;
+use std::io;
+use std::io::Write;
 use std::path::Path;
 
 use anyhow::Result;
+#[cfg(not(target_family = "wasm"))]
 use log::debug;
 use rustpython_parser::lexer::LexResult;
 use rustpython_parser::{lexer, parser};
@@ -11,6 +15,7 @@ use crate::autofix::fixer::fix_file;
 use crate::check_ast::check_ast;
 use crate::check_lines::check_lines;
 use crate::checks::{Check, CheckCode, CheckKind, LintSource};
+use crate::code_gen::SourceGenerator;
 use crate::message::Message;
 use crate::noqa::add_noqa;
 use crate::settings::Settings;
@@ -42,7 +47,7 @@ pub(crate) fn check_path(
 
     // Run the AST-based checks.
     if settings
-        .select
+        .enabled
         .iter()
         .any(|check_code| matches!(check_code.lint_source(), LintSource::AST))
     {
@@ -51,7 +56,7 @@ pub(crate) fn check_path(
                 checks.extend(check_ast(&python_ast, contents, settings, autofix, path))
             }
             Err(parse_error) => {
-                if settings.select.contains(&CheckCode::E999) {
+                if settings.enabled.contains(&CheckCode::E999) {
                     checks.push(Check::new(
                         CheckKind::SyntaxError(parse_error.error.to_string()),
                         Range {
@@ -81,6 +86,44 @@ pub(crate) fn check_path(
     Ok(checks)
 }
 
+pub fn lint_stdin(
+    path: &Path,
+    stdin: &str,
+    settings: &Settings,
+    autofix: &fixer::Mode,
+) -> Result<Vec<Message>> {
+    // Tokenize once.
+    let tokens: Vec<LexResult> = tokenize(stdin);
+
+    // Determine the noqa line for every line in the source.
+    let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
+
+    // Generate checks.
+    let mut checks = check_path(path, stdin, tokens, &noqa_line_for, settings, autofix)?;
+
+    // Apply autofix, write results to stdout.
+    if matches!(autofix, fixer::Mode::Apply) {
+        let output = match fix_file(&mut checks, stdin) {
+            None => stdin.to_string(),
+            Some(content) => content,
+        };
+        io::stdout().write_all(output.as_bytes())?;
+    }
+
+    // Convert to messages.
+    Ok(checks
+        .into_iter()
+        .map(|check| Message {
+            kind: check.kind,
+            fixed: check.fix.map(|fix| fix.applied).unwrap_or_default(),
+            location: check.location,
+            end_location: check.end_location,
+            filename: path.to_string_lossy().to_string(),
+        })
+        .collect())
+}
+
+#[cfg_attr(target_family = "wasm", allow(unused_variables))]
 pub fn lint_path(
     path: &Path,
     settings: &Settings,
@@ -90,6 +133,7 @@ pub fn lint_path(
     let metadata = path.metadata()?;
 
     // Check the cache.
+    #[cfg(not(target_family = "wasm"))]
     if let Some(messages) = cache::get(path, &metadata, settings, autofix, mode) {
         debug!("Cache hit for: {}", path.to_string_lossy());
         return Ok(messages);
@@ -109,7 +153,9 @@ pub fn lint_path(
 
     // Apply autofix.
     if matches!(autofix, fixer::Mode::Apply) {
-        fix_file(&mut checks, &contents, path)?;
+        if let Some(fixed_contents) = fix_file(&mut checks, &contents) {
+            write(path, fixed_contents)?;
+        }
     };
 
     // Convert to messages.
@@ -123,6 +169,7 @@ pub fn lint_path(
             filename: path.to_string_lossy().to_string(),
         })
         .collect();
+    #[cfg(not(target_family = "wasm"))]
     cache::set(path, &metadata, settings, autofix, &messages, mode);
 
     Ok(messages)
@@ -151,13 +198,31 @@ pub fn add_noqa_to_path(path: &Path, settings: &Settings) -> Result<usize> {
     add_noqa(&checks, &contents, &noqa_line_for, path)
 }
 
+pub fn autoformat_path(path: &Path) -> Result<()> {
+    // Read the file from disk.
+    let contents = fs::read_file(path)?;
+
+    // Tokenize once.
+    let tokens: Vec<LexResult> = tokenize(&contents);
+
+    // Generate the AST.
+    let python_ast = parser::parse_program_tokens(tokens, "<filename>")?;
+    let mut generator: SourceGenerator = Default::default();
+    generator.unparse_suite(&python_ast)?;
+    write(path, generator.generate()?)?;
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
+    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
     use regex::Regex;
     use rustpython_parser::lexer::LexResult;
+    use test_case::test_case;
 
     use crate::autofix::fixer;
     use crate::checks::{Check, CheckCode};
@@ -177,459 +242,139 @@ mod tests {
         linter::check_path(path, &contents, tokens, &noqa_line_for, settings, autofix)
     }
 
-    #[test]
-    fn e402() -> Result<()> {
+    #[test_case(CheckCode::A001, Path::new("A001.py"); "A001")]
+    #[test_case(CheckCode::A002, Path::new("A002.py"); "A002")]
+    #[test_case(CheckCode::A003, Path::new("A003.py"); "A003")]
+    #[test_case(CheckCode::B011, Path::new("B011.py"); "B011")]
+    #[test_case(CheckCode::B014, Path::new("B014.py"); "B014")]
+    #[test_case(CheckCode::B025, Path::new("B025.py"); "B025")]
+    #[test_case(CheckCode::C400, Path::new("C400.py"); "C400")]
+    #[test_case(CheckCode::C401, Path::new("C401.py"); "C401")]
+    #[test_case(CheckCode::C402, Path::new("C402.py"); "C402")]
+    #[test_case(CheckCode::C403, Path::new("C403.py"); "C403")]
+    #[test_case(CheckCode::C404, Path::new("C404.py"); "C404")]
+    #[test_case(CheckCode::C405, Path::new("C405.py"); "C405")]
+    #[test_case(CheckCode::C406, Path::new("C406.py"); "C406")]
+    #[test_case(CheckCode::C408, Path::new("C408.py"); "C408")]
+    #[test_case(CheckCode::C409, Path::new("C409.py"); "C409")]
+    #[test_case(CheckCode::C410, Path::new("C410.py"); "C410")]
+    #[test_case(CheckCode::C411, Path::new("C411.py"); "C411")]
+    #[test_case(CheckCode::C413, Path::new("C413.py"); "C413")]
+    #[test_case(CheckCode::C414, Path::new("C414.py"); "C414")]
+    #[test_case(CheckCode::C415, Path::new("C415.py"); "C415")]
+    #[test_case(CheckCode::C416, Path::new("C416.py"); "C416")]
+    #[test_case(CheckCode::C417, Path::new("C417.py"); "C417")]
+    #[test_case(CheckCode::D100, Path::new("D.py"); "D100")]
+    #[test_case(CheckCode::D101, Path::new("D.py"); "D101")]
+    #[test_case(CheckCode::D102, Path::new("D.py"); "D102")]
+    #[test_case(CheckCode::D103, Path::new("D.py"); "D103")]
+    #[test_case(CheckCode::D104, Path::new("D.py"); "D104")]
+    #[test_case(CheckCode::D105, Path::new("D.py"); "D105")]
+    #[test_case(CheckCode::D106, Path::new("D.py"); "D106")]
+    #[test_case(CheckCode::D107, Path::new("D.py"); "D107")]
+    #[test_case(CheckCode::D201, Path::new("D.py"); "D201")]
+    #[test_case(CheckCode::D202, Path::new("D.py"); "D202")]
+    #[test_case(CheckCode::D203, Path::new("D.py"); "D203")]
+    #[test_case(CheckCode::D204, Path::new("D.py"); "D204")]
+    #[test_case(CheckCode::D205, Path::new("D.py"); "D205")]
+    #[test_case(CheckCode::D206, Path::new("D.py"); "D206")]
+    #[test_case(CheckCode::D207, Path::new("D.py"); "D207")]
+    #[test_case(CheckCode::D208, Path::new("D.py"); "D208")]
+    #[test_case(CheckCode::D209, Path::new("D.py"); "D209")]
+    #[test_case(CheckCode::D210, Path::new("D.py"); "D210")]
+    #[test_case(CheckCode::D211, Path::new("D.py"); "D211")]
+    #[test_case(CheckCode::D212, Path::new("D.py"); "D212")]
+    #[test_case(CheckCode::D213, Path::new("D.py"); "D213")]
+    #[test_case(CheckCode::D214, Path::new("sections.py"); "D214")]
+    #[test_case(CheckCode::D215, Path::new("sections.py"); "D215")]
+    #[test_case(CheckCode::D300, Path::new("D.py"); "D300")]
+    #[test_case(CheckCode::D400, Path::new("D.py"); "D400")]
+    #[test_case(CheckCode::D402, Path::new("D.py"); "D402")]
+    #[test_case(CheckCode::D403, Path::new("D.py"); "D403")]
+    #[test_case(CheckCode::D404, Path::new("D.py"); "D404")]
+    #[test_case(CheckCode::D405, Path::new("sections.py"); "D405")]
+    #[test_case(CheckCode::D406, Path::new("sections.py"); "D406")]
+    #[test_case(CheckCode::D407, Path::new("sections.py"); "D407")]
+    #[test_case(CheckCode::D408, Path::new("sections.py"); "D408")]
+    #[test_case(CheckCode::D409, Path::new("sections.py"); "D409")]
+    #[test_case(CheckCode::D410, Path::new("sections.py"); "D410")]
+    #[test_case(CheckCode::D411, Path::new("sections.py"); "D411")]
+    #[test_case(CheckCode::D412, Path::new("sections.py"); "D412")]
+    #[test_case(CheckCode::D413, Path::new("sections.py"); "D413")]
+    #[test_case(CheckCode::D414, Path::new("sections.py"); "D414")]
+    #[test_case(CheckCode::D415, Path::new("D.py"); "D415")]
+    #[test_case(CheckCode::D416, Path::new("D.py"); "D416")]
+    #[test_case(CheckCode::D417, Path::new("sections.py"); "D417_0")]
+    #[test_case(CheckCode::D417, Path::new("canonical_numpy_examples.py"); "D417_1")]
+    #[test_case(CheckCode::D417, Path::new("canonical_google_examples.py"); "D417_2")]
+    #[test_case(CheckCode::D418, Path::new("D.py"); "D418")]
+    #[test_case(CheckCode::D419, Path::new("D.py"); "D419")]
+    #[test_case(CheckCode::E402, Path::new("E402.py"); "E402")]
+    #[test_case(CheckCode::E501, Path::new("E501.py"); "E501")]
+    #[test_case(CheckCode::E711, Path::new("E711.py"); "E711")]
+    #[test_case(CheckCode::E712, Path::new("E712.py"); "E712")]
+    #[test_case(CheckCode::E713, Path::new("E713.py"); "E713")]
+    #[test_case(CheckCode::E714, Path::new("E714.py"); "E714")]
+    #[test_case(CheckCode::E721, Path::new("E721.py"); "E721")]
+    #[test_case(CheckCode::E722, Path::new("E722.py"); "E722")]
+    #[test_case(CheckCode::E731, Path::new("E731.py"); "E731")]
+    #[test_case(CheckCode::E741, Path::new("E741.py"); "E741")]
+    #[test_case(CheckCode::E742, Path::new("E742.py"); "E742")]
+    #[test_case(CheckCode::E743, Path::new("E743.py"); "E743")]
+    #[test_case(CheckCode::E999, Path::new("E999.py"); "E999")]
+    #[test_case(CheckCode::F401, Path::new("F401_0.py"); "F401_0")]
+    #[test_case(CheckCode::F401, Path::new("F401_1.py"); "F401_1")]
+    #[test_case(CheckCode::F401, Path::new("F401_2.py"); "F401_2")]
+    #[test_case(CheckCode::F401, Path::new("F401_3.py"); "F401_3")]
+    #[test_case(CheckCode::F401, Path::new("F401_4.py"); "F401_4")]
+    #[test_case(CheckCode::F402, Path::new("F402.py"); "F402")]
+    #[test_case(CheckCode::F403, Path::new("F403.py"); "F403")]
+    #[test_case(CheckCode::F404, Path::new("F404.py"); "F404")]
+    #[test_case(CheckCode::F405, Path::new("F405.py"); "F405")]
+    #[test_case(CheckCode::F406, Path::new("F406.py"); "F406")]
+    #[test_case(CheckCode::F407, Path::new("F407.py"); "F407")]
+    #[test_case(CheckCode::F541, Path::new("F541.py"); "F541")]
+    #[test_case(CheckCode::F601, Path::new("F601.py"); "F601")]
+    #[test_case(CheckCode::F602, Path::new("F602.py"); "F602")]
+    #[test_case(CheckCode::F622, Path::new("F622.py"); "F622")]
+    #[test_case(CheckCode::F631, Path::new("F631.py"); "F631")]
+    #[test_case(CheckCode::F632, Path::new("F632.py"); "F632")]
+    #[test_case(CheckCode::F633, Path::new("F633.py"); "F633")]
+    #[test_case(CheckCode::F634, Path::new("F634.py"); "F634")]
+    #[test_case(CheckCode::F701, Path::new("F701.py"); "F701")]
+    #[test_case(CheckCode::F702, Path::new("F702.py"); "F702")]
+    #[test_case(CheckCode::F704, Path::new("F704.py"); "F704")]
+    #[test_case(CheckCode::F706, Path::new("F706.py"); "F706")]
+    #[test_case(CheckCode::F707, Path::new("F707.py"); "F707")]
+    #[test_case(CheckCode::F722, Path::new("F722.py"); "F722")]
+    #[test_case(CheckCode::F821, Path::new("F821.py"); "F821")]
+    #[test_case(CheckCode::F822, Path::new("F822.py"); "F822")]
+    #[test_case(CheckCode::F823, Path::new("F823.py"); "F823")]
+    #[test_case(CheckCode::F831, Path::new("F831.py"); "F831")]
+    #[test_case(CheckCode::F841, Path::new("F841.py"); "F841")]
+    #[test_case(CheckCode::F901, Path::new("F901.py"); "F901")]
+    #[test_case(CheckCode::T201, Path::new("T201.py"); "T201")]
+    #[test_case(CheckCode::T203, Path::new("T203.py"); "T203")]
+    #[test_case(CheckCode::U001, Path::new("U001.py"); "U001")]
+    #[test_case(CheckCode::U002, Path::new("U002.py"); "U002")]
+    #[test_case(CheckCode::U003, Path::new("U003.py"); "U003")]
+    #[test_case(CheckCode::U004, Path::new("U004.py"); "U004")]
+    #[test_case(CheckCode::U005, Path::new("U005.py"); "U005")]
+    #[test_case(CheckCode::U006, Path::new("U006.py"); "U006")]
+    #[test_case(CheckCode::U007, Path::new("U007.py"); "U007")]
+    #[test_case(CheckCode::U008, Path::new("U008.py"); "U008")]
+    #[test_case(CheckCode::W292, Path::new("W292_0.py"); "W292_0")]
+    #[test_case(CheckCode::W292, Path::new("W292_1.py"); "W292_1")]
+    #[test_case(CheckCode::W292, Path::new("W292_2.py"); "W292_2")]
+    fn checks(check_code: CheckCode, path: &Path) -> Result<()> {
+        let snapshot = format!("{}_{}", check_code.as_ref(), path.to_string_lossy());
         let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E402.py"),
-            &settings::Settings::for_rule(CheckCode::E402),
+            Path::new("./resources/test/fixtures").join(path).as_path(),
+            &settings::Settings::for_rule(check_code.clone()),
             &fixer::Mode::Generate,
         )?;
         checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e501() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E501.py"),
-            &settings::Settings::for_rule(CheckCode::E501),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e711() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E711.py"),
-            &settings::Settings::for_rule(CheckCode::E711),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e712() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E712.py"),
-            &settings::Settings::for_rule(CheckCode::E712),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e713() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E713.py"),
-            &settings::Settings::for_rule(CheckCode::E713),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e721() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E721.py"),
-            &settings::Settings::for_rule(CheckCode::E721),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e722() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E722.py"),
-            &settings::Settings::for_rule(CheckCode::E722),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e714() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E714.py"),
-            &settings::Settings::for_rule(CheckCode::E714),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e731() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E731.py"),
-            &settings::Settings::for_rule(CheckCode::E731),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e741() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E741.py"),
-            &settings::Settings::for_rule(CheckCode::E741),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e742() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E742.py"),
-            &settings::Settings::for_rule(CheckCode::E742),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn e743() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E743.py"),
-            &settings::Settings::for_rule(CheckCode::E743),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f401() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F401.py"),
-            &settings::Settings::for_rule(CheckCode::F401),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f402() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F402.py"),
-            &settings::Settings::for_rule(CheckCode::F402),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f403() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F403.py"),
-            &settings::Settings::for_rule(CheckCode::F403),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f404() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F404.py"),
-            &settings::Settings::for_rule(CheckCode::F404),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f405() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F405.py"),
-            &settings::Settings::for_rule(CheckCode::F405),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f406() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F406.py"),
-            &settings::Settings::for_rule(CheckCode::F406),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f407() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F407.py"),
-            &settings::Settings::for_rule(CheckCode::F407),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f541() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F541.py"),
-            &settings::Settings::for_rule(CheckCode::F541),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f601() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F601.py"),
-            &settings::Settings::for_rule(CheckCode::F601),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f602() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F602.py"),
-            &settings::Settings::for_rule(CheckCode::F602),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f622() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F622.py"),
-            &settings::Settings::for_rule(CheckCode::F622),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f631() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F631.py"),
-            &settings::Settings::for_rule(CheckCode::F631),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f632() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F632.py"),
-            &settings::Settings::for_rule(CheckCode::F632),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f633() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F633.py"),
-            &settings::Settings::for_rule(CheckCode::F633),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f634() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F634.py"),
-            &settings::Settings::for_rule(CheckCode::F634),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f701() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F701.py"),
-            &settings::Settings::for_rule(CheckCode::F701),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f702() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F702.py"),
-            &settings::Settings::for_rule(CheckCode::F702),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f704() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F704.py"),
-            &settings::Settings::for_rule(CheckCode::F704),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f706() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F706.py"),
-            &settings::Settings::for_rule(CheckCode::F706),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f707() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F707.py"),
-            &settings::Settings::for_rule(CheckCode::F707),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f722() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F722.py"),
-            &settings::Settings::for_rule(CheckCode::F722),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f821() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F821.py"),
-            &settings::Settings::for_rule(CheckCode::F821),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f822() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F822.py"),
-            &settings::Settings::for_rule(CheckCode::F822),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f823() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F823.py"),
-            &settings::Settings::for_rule(CheckCode::F823),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f831() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F831.py"),
-            &settings::Settings::for_rule(CheckCode::F831),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn f841() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F841.py"),
-            &settings::Settings::for_rule(CheckCode::F841),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(snapshot, checks);
         Ok(())
     }
 
@@ -648,18 +393,6 @@ mod tests {
         Ok(())
     }
 
-    #[test]
-    fn f901() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/F901.py"),
-            &settings::Settings::for_rule(CheckCode::F901),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
     #[test]
     fn m001() -> Result<()> {
         let mut checks = check_path(
@@ -672,30 +405,6 @@ mod tests {
         Ok(())
     }
 
-    #[test]
-    fn r001() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/R001.py"),
-            &settings::Settings::for_rule(CheckCode::R001),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn r002() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/R002.py"),
-            &settings::Settings::for_rule(CheckCode::R002),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
     #[test]
     fn init() -> Result<()> {
         let mut checks = check_path(
@@ -719,88 +428,4 @@ mod tests {
         insta::assert_yaml_snapshot!(checks);
         Ok(())
     }
-
-    #[test]
-    fn e999() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/E999.py"),
-            &settings::Settings::for_rule(CheckCode::E999),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn a001() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/A001.py"),
-            &settings::Settings::for_rule(CheckCode::A001),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn a002() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/A002.py"),
-            &settings::Settings::for_rule(CheckCode::A002),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn a003() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/A003.py"),
-            &settings::Settings::for_rule(CheckCode::A003),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn spr001() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/SPR001.py"),
-            &settings::Settings::for_rule(CheckCode::SPR001),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn t201() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/T201.py"),
-            &settings::Settings::for_rule(CheckCode::T201),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
-
-    #[test]
-    fn t203() -> Result<()> {
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/T203.py"),
-            &settings::Settings::for_rule(CheckCode::T203),
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(checks);
-        Ok(())
-    }
 }

src/main.rs

@@ -1,95 +1,52 @@
-use std::io;
+use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 use std::process::ExitCode;
 use std::sync::mpsc::channel;
 use std::time::Instant;
 
 use anyhow::Result;
-use clap::{command, Parser};
+use clap::Parser;
 use colored::Colorize;
 use log::{debug, error};
 use notify::{raw_watcher, RecursiveMode, Watcher};
+#[cfg(not(target_family = "wasm"))]
 use rayon::prelude::*;
-use regex::Regex;
 use walkdir::DirEntry;
 
-use ::ruff::cache;
-use ::ruff::checks::CheckCode;
-use ::ruff::checks::CheckKind;
-use ::ruff::fs::iter_python_files;
-use ::ruff::linter::add_noqa_to_path;
-use ::ruff::linter::lint_path;
-use ::ruff::logging::set_up_logging;
-use ::ruff::message::Message;
-use ::ruff::printer::{Printer, SerializationFormat};
-use ::ruff::pyproject::{self, StrCheckCodePair};
-use ::ruff::settings::CurrentSettings;
-use ::ruff::settings::{FilePattern, PerFileIgnore, Settings};
-use ::ruff::tell_user;
+#[cfg(not(target_family = "wasm"))]
+use ruff::cache;
+use ruff::checks::CheckCode;
+use ruff::checks::CheckKind;
+use ruff::cli::{warn_on, Cli, Warnable};
+use ruff::fs::iter_python_files;
+use ruff::linter::add_noqa_to_path;
+use ruff::linter::autoformat_path;
+use ruff::linter::{lint_path, lint_stdin};
+use ruff::logging::set_up_logging;
+use ruff::message::Message;
+use ruff::printer::{Printer, SerializationFormat};
+use ruff::pyproject::{self};
+use ruff::settings::CurrentSettings;
+use ruff::settings::RawSettings;
+use ruff::settings::{FilePattern, PerFileIgnore, Settings};
+use ruff::tell_user;
 
+#[cfg(feature = "update-informer")]
 const CARGO_PKG_NAME: &str = env!("CARGO_PKG_NAME");
+#[cfg(feature = "update-informer")]
 const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
 
-#[derive(Debug, Parser)]
-#[command(author, about = "ruff: An extremely fast Python linter.")]
-#[command(version)]
-struct Cli {
-    #[arg(required = true)]
-    files: Vec<PathBuf>,
-    /// Enable verbose logging.
-    #[arg(short, long)]
-    verbose: bool,
-    /// Disable all logging (but still exit with status code "1" upon detecting errors).
-    #[arg(short, long)]
-    quiet: bool,
-    /// Exit with status code "0", even upon detecting errors.
-    #[arg(short, long)]
-    exit_zero: bool,
-    /// Run in watch mode by re-running whenever files change.
-    #[arg(short, long)]
-    watch: bool,
-    /// Attempt to automatically fix lint errors.
-    #[arg(short, long)]
-    fix: bool,
-    /// Disable cache reads.
-    #[arg(short, long)]
-    no_cache: bool,
-    /// List of error codes to enable.
-    #[arg(long, value_delimiter = ',')]
-    select: Vec<CheckCode>,
-    /// Like --select, but adds additional error codes on top of the selected ones.
-    #[arg(long, value_delimiter = ',')]
-    extend_select: Vec<CheckCode>,
-    /// List of error codes to ignore.
-    #[arg(long, value_delimiter = ',')]
-    ignore: Vec<CheckCode>,
-    /// Like --ignore, but adds additional error codes on top of the ignored ones.
-    #[arg(long, value_delimiter = ',')]
-    extend_ignore: Vec<CheckCode>,
-    /// List of paths, used to exclude files and/or directories from checks.
-    #[arg(long, value_delimiter = ',')]
-    exclude: Vec<String>,
-    /// Like --exclude, but adds additional files and directories on top of the excluded ones.
-    #[arg(long, value_delimiter = ',')]
-    extend_exclude: Vec<String>,
-    /// List of mappings from file pattern to code to exclude
-    #[arg(long, value_delimiter = ',')]
-    per_file_ignores: Vec<StrCheckCodePair>,
-    /// Output serialization format for error messages.
-    #[arg(long, value_enum, default_value_t=SerializationFormat::Text)]
-    format: SerializationFormat,
-    /// See the files ruff will be run against with the current settings.
-    #[arg(long)]
-    show_files: bool,
-    /// See ruff's settings.
-    #[arg(long)]
-    show_settings: bool,
-    /// Enable automatic additions of noqa directives to failing lines.
-    #[arg(long)]
-    add_noqa: bool,
-    /// Regular expression matching the name of dummy variables.
-    #[arg(long)]
-    dummy_variable_rgx: Option<Regex>,
+/// Shim that calls par_iter except for wasm because there's no wasm support in rayon yet
+/// (there is a shim to be used for the web, but it requires js cooperation)
+/// Unfortunately, ParallelIterator does not implement Iterator so the signatures diverge
+#[cfg(not(target_family = "wasm"))]
+fn par_iter<T: Sync>(iterable: &Vec<T>) -> impl ParallelIterator<Item = &T> {
+    iterable.par_iter()
+}
+
+#[cfg(target_family = "wasm")]
+fn par_iter<T: Sync>(iterable: &Vec<T>) -> impl Iterator<Item = &T> {
+    iterable.iter()
 }
 
 #[cfg(feature = "update-informer")]
@@ -116,8 +73,11 @@ fn check_for_updates() {
     }
 }
 
-fn show_settings(settings: Settings) {
-    println!("{:#?}", CurrentSettings::from_settings(settings));
+fn show_settings(settings: RawSettings, project_root: Option<PathBuf>, pyproject: Option<PathBuf>) {
+    println!(
+        "{:#?}",
+        CurrentSettings::from_settings(settings, project_root, pyproject)
+    );
 }
 
 fn show_files(files: &[PathBuf], settings: &Settings) {
@@ -132,6 +92,19 @@ fn show_files(files: &[PathBuf], settings: &Settings) {
     }
 }
 
+fn read_from_stdin() -> Result<String> {
+    let mut buffer = String::new();
+    io::stdin().lock().read_to_string(&mut buffer)?;
+    Ok(buffer)
+}
+
+fn run_once_stdin(settings: &Settings, filename: &Path, autofix: bool) -> Result<Vec<Message>> {
+    let stdin = read_from_stdin()?;
+    let mut messages = lint_stdin(filename, &stdin, settings, &autofix.into())?;
+    messages.sort_unstable();
+    Ok(messages)
+}
+
 fn run_once(
     files: &[PathBuf],
     settings: &Settings,
@@ -148,8 +121,7 @@ fn run_once(
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let mut messages: Vec<Message> = paths
-        .par_iter()
+    let mut messages: Vec<Message> = par_iter(&paths)
         .map(|entry| {
             match entry {
                 Ok(entry) => {
@@ -165,7 +137,7 @@ fn run_once(
             }
             .unwrap_or_else(|(path, message)| {
                 if let Some(path) = path {
-                    if settings.select.contains(&CheckCode::E902) {
+                    if settings.enabled.contains(&CheckCode::E902) {
                         vec![Message {
                             kind: CheckKind::IOError(message),
                             fixed: false,
@@ -204,8 +176,7 @@ fn add_noqa(files: &[PathBuf], settings: &Settings) -> Result<usize> {
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let modifications: usize = paths
-        .par_iter()
+    let modifications: usize = par_iter(&paths)
         .map(|entry| match entry {
             Ok(entry) => {
                 let path = entry.path();
@@ -222,6 +193,32 @@ fn add_noqa(files: &[PathBuf], settings: &Settings) -> Result<usize> {
     Ok(modifications)
 }
 
+fn autoformat(files: &[PathBuf], settings: &Settings) -> Result<usize> {
+    // Collect all the files to format.
+    let start = Instant::now();
+    let paths: Vec<DirEntry> = files
+        .iter()
+        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
+        .flatten()
+        .collect();
+    let duration = start.elapsed();
+    debug!("Identified files to lint in: {:?}", duration);
+
+    let start = Instant::now();
+    let modifications = par_iter(&paths)
+        .map(|entry| {
+            let path = entry.path();
+            autoformat_path(path)
+        })
+        .flatten()
+        .count();
+
+    let duration = start.elapsed();
+    debug!("Auto-formatted files in: {:?}", duration);
+
+    Ok(modifications)
+}
+
 fn inner_main() -> Result<ExitCode> {
     let cli = Cli::parse();
 
@@ -233,7 +230,9 @@ fn inner_main() -> Result<ExitCode> {
         Some(path) => debug!("Found project root at: {:?}", path),
         None => debug!("Unable to identify project root; assuming current directory..."),
     };
-    let pyproject = pyproject::find_pyproject_toml(&project_root);
+    let pyproject = cli
+        .config
+        .or_else(|| pyproject::find_pyproject_toml(&project_root));
     match &pyproject {
         Some(path) => debug!("Found pyproject.toml at: {:?}", path),
         None => debug!("Unable to find pyproject.toml; using default settings..."),
@@ -256,7 +255,7 @@ fn inner_main() -> Result<ExitCode> {
         .map(|pair| PerFileIgnore::new(pair, &project_root))
         .collect();
 
-    let mut settings = Settings::from_pyproject(pyproject, project_root)?;
+    let mut settings = RawSettings::from_pyproject(&pyproject, &project_root)?;
     if !exclude.is_empty() {
         settings.exclude = exclude;
     }
@@ -267,17 +266,35 @@ fn inner_main() -> Result<ExitCode> {
         settings.per_file_ignores = per_file_ignores;
     }
     if !cli.select.is_empty() {
-        settings.clear();
-        settings.select(cli.select);
+        warn_on(
+            Warnable::Select,
+            &cli.select,
+            &cli.ignore,
+            &cli.extend_ignore,
+            &settings,
+            &pyproject,
+        );
+        settings.select = cli.select;
     }
     if !cli.extend_select.is_empty() {
-        settings.select(cli.extend_select);
+        warn_on(
+            Warnable::ExtendSelect,
+            &cli.extend_select,
+            &cli.ignore,
+            &cli.extend_ignore,
+            &settings,
+            &pyproject,
+        );
+        settings.extend_select = cli.extend_select;
     }
     if !cli.ignore.is_empty() {
-        settings.ignore(&cli.ignore);
+        settings.ignore = cli.ignore;
     }
     if !cli.extend_ignore.is_empty() {
-        settings.ignore(&cli.extend_ignore);
+        settings.extend_ignore = cli.extend_ignore;
+    }
+    if let Some(target_version) = cli.target_version {
+        settings.target_version = target_version;
     }
     if let Some(dummy_variable_rgx) = cli.dummy_variable_rgx {
         settings.dummy_variable_rgx = dummy_variable_rgx;
@@ -287,15 +304,19 @@ fn inner_main() -> Result<ExitCode> {
         eprintln!("Error: specify --show-settings or show-files (not both).");
         return Ok(ExitCode::FAILURE);
     }
+    if cli.show_settings {
+        show_settings(settings, project_root, pyproject);
+        return Ok(ExitCode::SUCCESS);
+    }
+
+    let settings = Settings::from_raw(settings);
+
     if cli.show_files {
         show_files(&cli.files, &settings);
         return Ok(ExitCode::SUCCESS);
     }
-    if cli.show_settings {
-        show_settings(settings);
-        return Ok(ExitCode::SUCCESS);
-    }
 
+    #[cfg(not(target_family = "wasm"))]
     cache::init()?;
 
     let mut printer = Printer::new(cli.format, cli.verbose);
@@ -308,6 +329,10 @@ fn inner_main() -> Result<ExitCode> {
             eprintln!("Warning: --no-qa is not enabled in watch mode.");
         }
 
+        if cli.autoformat {
+            eprintln!("Warning: --autoformat is not enabled in watch mode.");
+        }
+
         if cli.format != SerializationFormat::Text {
             eprintln!("Warning: --format 'text' is used in watch mode.");
         }
@@ -351,16 +376,38 @@ fn inner_main() -> Result<ExitCode> {
         if modifications > 0 {
             println!("Added {modifications} noqa directives.");
         }
+    } else if cli.autoformat {
+        let modifications = autoformat(&cli.files, &settings)?;
+        if modifications > 0 {
+            println!("Formatted {modifications} files.");
+        }
     } else {
-        let messages = run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?;
-        if !cli.quiet {
+        let (messages, should_print_messages, should_check_updates) =
+            if cli.files == vec![PathBuf::from("-")] {
+                let filename = cli.stdin_filename.unwrap_or_else(|| "-".to_string());
+                let path = Path::new(&filename);
+                (
+                    run_once_stdin(&settings, path, cli.fix)?,
+                    !cli.quiet && !cli.fix,
+                    false,
+                )
+            } else {
+                (
+                    run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?,
+                    !cli.quiet,
+                    !cli.quiet,
+                )
+            };
+        if should_print_messages {
             printer.write_once(&messages)?;
         }
 
         #[cfg(feature = "update-informer")]
-        check_for_updates();
+        if should_check_updates {
+            check_for_updates();
+        }
 
-        if !messages.is_empty() && !cli.exit_zero {
+        if messages.iter().any(|message| !message.fixed) && !cli.exit_zero {
             return Ok(ExitCode::FAILURE);
         }
     }

src/message.rs

@@ -45,7 +45,7 @@ impl fmt::Display for Message {
             ":".cyan(),
             self.location.column(),
             ":".cyan(),
-            self.kind.code().as_str().red().bold(),
+            self.kind.code().as_ref().red().bold(),
             self.kind.body()
         )
     }

src/noqa.rs

@@ -104,9 +104,7 @@ fn add_noqa_inner(
             .unwrap_or(lineno);
 
         if !codes.is_empty() {
-            let matches = matches_by_line
-                .entry(noqa_lineno)
-                .or_insert_with(BTreeSet::new);
+            let matches = matches_by_line.entry(noqa_lineno).or_default();
             matches.append(&mut codes);
         }
     }
@@ -127,7 +125,7 @@ fn add_noqa_inner(
                     Directive::All(start, _) => output.push_str(&line[..start]),
                     Directive::Codes(start, _, _) => output.push_str(&line[..start]),
                 };
-                let codes: Vec<&str> = codes.iter().map(|code| code.as_str()).collect();
+                let codes: Vec<&str> = codes.iter().map(|code| code.as_ref()).collect();
                 output.push_str("  # noqa: ");
                 output.push_str(&codes.join(", "));
                 output.push('\n');
@@ -152,12 +150,12 @@ pub fn add_noqa(
 
 #[cfg(test)]
 mod tests {
-    use crate::ast::types::Range;
     use anyhow::Result;
     use rustpython_parser::ast::Location;
     use rustpython_parser::lexer;
     use rustpython_parser::lexer::LexResult;
 
+    use crate::ast::types::Range;
     use crate::checks::{Check, CheckKind};
     use crate::noqa::{add_noqa_inner, extract_noqa_line_for};
 

src/plugins.rs

@@ -0,0 +1,29 @@
+pub use assert_false::assert_false;
+pub use assert_tuple::assert_tuple;
+pub use deprecated_unittest_alias::deprecated_unittest_alias;
+pub use duplicate_exceptions::duplicate_exceptions;
+pub use if_tuple::if_tuple;
+pub use invalid_print_syntax::invalid_print_syntax;
+pub use print_call::print_call;
+pub use super_call_with_parameters::super_call_with_parameters;
+pub use type_of_primitive::type_of_primitive;
+pub use unnecessary_abspath::unnecessary_abspath;
+pub use use_pep585_annotation::use_pep585_annotation;
+pub use use_pep604_annotation::use_pep604_annotation;
+pub use useless_metaclass_type::useless_metaclass_type;
+pub use useless_object_inheritance::useless_object_inheritance;
+
+mod assert_false;
+mod assert_tuple;
+mod deprecated_unittest_alias;
+mod duplicate_exceptions;
+mod if_tuple;
+mod invalid_print_syntax;
+mod print_call;
+mod super_call_with_parameters;
+mod type_of_primitive;
+mod unnecessary_abspath;
+mod use_pep585_annotation;
+mod use_pep604_annotation;
+mod useless_metaclass_type;
+mod useless_object_inheritance;

src/plugins/assert_false.rs

@@ -0,0 +1,61 @@
+use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Stmt, StmtKind};
+
+use crate::ast::types::Range;
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind, Fix};
+use crate::code_gen::SourceGenerator;
+
+fn assertion_error(msg: &Option<Box<Expr>>) -> Stmt {
+    Stmt::new(
+        Default::default(),
+        Default::default(),
+        StmtKind::Raise {
+            exc: Some(Box::new(Expr::new(
+                Default::default(),
+                Default::default(),
+                ExprKind::Call {
+                    func: Box::new(Expr::new(
+                        Default::default(),
+                        Default::default(),
+                        ExprKind::Name {
+                            id: "AssertionError".to_string(),
+                            ctx: ExprContext::Load,
+                        },
+                    )),
+                    args: if let Some(msg) = msg {
+                        vec![*msg.clone()]
+                    } else {
+                        vec![]
+                    },
+                    keywords: vec![],
+                },
+            ))),
+            cause: None,
+        },
+    )
+}
+
+pub fn assert_false(checker: &mut Checker, stmt: &Stmt, test: &Expr, msg: &Option<Box<Expr>>) {
+    if let ExprKind::Constant {
+        value: Constant::Bool(false),
+        ..
+    } = &test.node
+    {
+        let mut check = Check::new(CheckKind::DoNotAssertFalse, Range::from_located(test));
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            let mut generator = SourceGenerator::new();
+            if let Ok(()) = generator.unparse_stmt(&assertion_error(msg)) {
+                if let Ok(content) = generator.generate() {
+                    check.amend(Fix {
+                        content,
+                        location: stmt.location,
+                        end_location: stmt.end_location,
+                        applied: false,
+                    })
+                }
+            }
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/assert_tuple.rs

@@ -0,0 +1,13 @@
+use rustpython_ast::{Expr, Stmt};
+
+use crate::ast::checkers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::check_ast::Checker;
+
+pub fn assert_tuple(checker: &mut Checker, stmt: &Stmt, test: &Expr) {
+    if let Some(check) =
+        checkers::assert_tuple(test, checker.locate_check(Range::from_located(stmt)))
+    {
+        checker.add_check(check);
+    }
+}

src/plugins/deprecated_unittest_alias.rs

@@ -0,0 +1,56 @@
+use std::collections::BTreeMap;
+
+use once_cell::sync::Lazy;
+use rustpython_ast::{Expr, ExprKind, Location};
+
+use crate::ast::types::Range;
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind, Fix};
+
+static DEPRECATED_ALIASES: Lazy<BTreeMap<&'static str, &'static str>> = Lazy::new(|| {
+    BTreeMap::from([
+        ("failUnlessEqual", "assertEqual"),
+        ("assertEquals", "assertEqual"),
+        ("failIfEqual", "assertNotEqual"),
+        ("assertNotEquals", "assertNotEqual"),
+        ("failUnless", "assertTrue"),
+        ("assert_", "assertTrue"),
+        ("failIf", "assertFalse"),
+        ("failUnlessRaises", "assertRaises"),
+        ("failUnlessAlmostEqual", "assertAlmostEqual"),
+        ("assertAlmostEquals", "assertAlmostEqual"),
+        ("failIfAlmostEqual", "assertNotAlmostEqual"),
+        ("assertNotAlmostEquals", "assertNotAlmostEqual"),
+        ("assertRegexpMatches", "assertRegex"),
+        ("assertNotRegexpMatches", "assertNotRegex"),
+        ("assertRaisesRegexp", "assertRaisesRegex"),
+    ])
+});
+
+pub fn deprecated_unittest_alias(checker: &mut Checker, expr: &Expr) {
+    if let ExprKind::Attribute { value, attr, .. } = &expr.node {
+        if let Some(target) = DEPRECATED_ALIASES.get(attr.as_str()) {
+            if let ExprKind::Name { id, .. } = &value.node {
+                if id == "self" {
+                    let mut check = Check::new(
+                        CheckKind::DeprecatedUnittestAlias(attr.to_string(), target.to_string()),
+                        Range::from_located(expr),
+                    );
+                    if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                        check.amend(Fix {
+                            content: format!("self.{}", target),
+                            location: Location::new(expr.location.row(), expr.location.column()),
+                            end_location: Location::new(
+                                expr.end_location.row(),
+                                expr.end_location.column(),
+                            ),
+                            applied: false,
+                        });
+                    }
+                    checker.add_check(check);
+                }
+            }
+        }
+    }
+}

src/plugins/duplicate_exceptions.rs

@@ -0,0 +1,114 @@
+use std::collections::BTreeSet;
+
+use itertools::Itertools;
+use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind, Stmt};
+
+use crate::ast::helpers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckCode, CheckKind, Fix};
+use crate::code_gen::SourceGenerator;
+
+fn type_pattern(elts: Vec<&Expr>) -> Expr {
+    Expr::new(
+        Default::default(),
+        Default::default(),
+        ExprKind::Tuple {
+            elts: elts.into_iter().cloned().collect(),
+            ctx: ExprContext::Load,
+        },
+    )
+}
+
+pub fn duplicate_handler_exceptions(
+    checker: &mut Checker,
+    expr: &Expr,
+    elts: &Vec<Expr>,
+) -> BTreeSet<String> {
+    let mut seen: BTreeSet<String> = Default::default();
+    let mut duplicates: BTreeSet<String> = Default::default();
+    let mut unique_elts: Vec<&Expr> = Default::default();
+    for type_ in elts {
+        if let Some(name) = helpers::compose_call_path(type_) {
+            if seen.contains(&name) {
+                duplicates.insert(name);
+            } else {
+                seen.insert(name);
+                unique_elts.push(type_);
+            }
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::B014) {
+        // TODO(charlie): Handle "BaseException" and redundant exception aliases.
+        if !duplicates.is_empty() {
+            let mut check = Check::new(
+                CheckKind::DuplicateHandlerException(
+                    duplicates.into_iter().sorted().collect::<Vec<String>>(),
+                ),
+                checker.locate_check(Range::from_located(expr)),
+            );
+            if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                // TODO(charlie): If we have a single element, remove the tuple.
+                let mut generator = SourceGenerator::new();
+                if let Ok(()) = generator.unparse_expr(&type_pattern(unique_elts), 0) {
+                    if let Ok(content) = generator.generate() {
+                        check.amend(Fix {
+                            content,
+                            location: expr.location,
+                            end_location: expr.end_location,
+                            applied: false,
+                        })
+                    }
+                }
+            }
+            checker.add_check(check);
+        }
+    }
+
+    seen
+}
+
+pub fn duplicate_exceptions(checker: &mut Checker, stmt: &Stmt, handlers: &[Excepthandler]) {
+    let mut seen: BTreeSet<String> = Default::default();
+    let mut duplicates: BTreeSet<String> = Default::default();
+    for handler in handlers {
+        match &handler.node {
+            ExcepthandlerKind::ExceptHandler { type_, .. } => {
+                if let Some(type_) = type_ {
+                    match &type_.node {
+                        ExprKind::Attribute { .. } | ExprKind::Name { .. } => {
+                            if let Some(name) = helpers::compose_call_path(type_) {
+                                if seen.contains(&name) {
+                                    duplicates.insert(name);
+                                } else {
+                                    seen.insert(name);
+                                }
+                            }
+                        }
+                        ExprKind::Tuple { elts, .. } => {
+                            for name in duplicate_handler_exceptions(checker, type_, elts) {
+                                if seen.contains(&name) {
+                                    duplicates.insert(name);
+                                } else {
+                                    seen.insert(name);
+                                }
+                            }
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+    }
+
+    if checker.settings.enabled.contains(&CheckCode::B025) {
+        for duplicate in duplicates.into_iter().sorted() {
+            checker.add_check(Check::new(
+                CheckKind::DuplicateTryBlockException(duplicate),
+                checker.locate_check(Range::from_located(stmt)),
+            ));
+        }
+    }
+}

src/plugins/if_tuple.rs

@@ -0,0 +1,11 @@
+use rustpython_ast::{Expr, Stmt};
+
+use crate::ast::checkers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::check_ast::Checker;
+
+pub fn if_tuple(checker: &mut Checker, stmt: &Stmt, test: &Expr) {
+    if let Some(check) = checkers::if_tuple(test, checker.locate_check(Range::from_located(stmt))) {
+        checker.add_check(check);
+    }
+}

src/plugins/invalid_print_syntax.rs

@@ -0,0 +1,23 @@
+use rustpython_ast::{Expr, ExprKind};
+
+use crate::ast::types::{Binding, BindingKind, Range};
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind};
+
+pub fn invalid_print_syntax(checker: &mut Checker, left: &Expr) {
+    if let ExprKind::Name { id, .. } = &left.node {
+        if id == "print" {
+            let scope = checker.current_scope();
+            if let Some(Binding {
+                kind: BindingKind::Builtin,
+                ..
+            }) = scope.values.get("print")
+            {
+                checker.add_check(Check::new(
+                    CheckKind::InvalidPrintSyntax,
+                    Range::from_located(left),
+                ));
+            }
+        }
+    }
+}

src/plugins/print_call.rs

@@ -0,0 +1,46 @@
+use log::error;
+use rustpython_ast::{Expr, Stmt, StmtKind};
+
+use crate::ast::checkers;
+use crate::autofix::{fixer, fixes};
+use crate::check_ast::Checker;
+use crate::checks::CheckCode;
+
+pub fn print_call(checker: &mut Checker, expr: &Expr, func: &Expr) {
+    if let Some(mut check) = checkers::print_call(
+        expr,
+        func,
+        checker.settings.enabled.contains(&CheckCode::T201),
+        checker.settings.enabled.contains(&CheckCode::T203),
+    ) {
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            let context = checker.binding_context();
+            if matches!(
+                checker.parents[context.defined_by].node,
+                StmtKind::Expr { .. }
+            ) {
+                let deleted: Vec<&Stmt> = checker
+                    .deletions
+                    .iter()
+                    .map(|index| checker.parents[*index])
+                    .collect();
+
+                match fixes::remove_stmt(
+                    checker.parents[context.defined_by],
+                    context.defined_in.map(|index| checker.parents[index]),
+                    &deleted,
+                ) {
+                    Ok(fix) => {
+                        if fix.content.is_empty() || fix.content == "pass" {
+                            checker.deletions.insert(context.defined_by);
+                        }
+                        check.amend(fix)
+                    }
+                    Err(e) => error!("Failed to fix unused imports: {}", e),
+                }
+            }
+        }
+
+        checker.add_check(check);
+    }
+}

src/plugins/super_call_with_parameters.rs

@@ -0,0 +1,31 @@
+use rustpython_ast::{Expr, Stmt};
+
+use crate::ast::{checkers, helpers};
+use crate::autofix::{fixer, fixes};
+use crate::check_ast::Checker;
+
+pub fn super_call_with_parameters(
+    checker: &mut Checker,
+    expr: &Expr,
+    func: &Expr,
+    args: &Vec<Expr>,
+) {
+    // Only bother going through the super check at all if we're in a `super` call.
+    // (We check this in `check_super_args` too, so this is just an optimization.)
+    if helpers::is_super_call_with_arguments(func, args) {
+        let scope = checker.current_scope();
+        let parents: Vec<&Stmt> = checker
+            .parent_stack
+            .iter()
+            .map(|index| checker.parents[*index])
+            .collect();
+        if let Some(mut check) = checkers::super_args(scope, &parents, expr, func, args) {
+            if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                if let Some(fix) = fixes::remove_super_arguments(&mut checker.locator, expr) {
+                    check.amend(fix);
+                }
+            }
+            checker.add_check(check)
+        }
+    }
+}

src/plugins/type_of_primitive.rs

@@ -0,0 +1,25 @@
+use rustpython_ast::Expr;
+
+use crate::ast::checkers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::{CheckKind, Fix};
+
+pub fn type_of_primitive(checker: &mut Checker, expr: &Expr, func: &Expr, args: &Vec<Expr>) {
+    if let Some(mut check) =
+        checkers::type_of_primitive(func, args, checker.locate_check(Range::from_located(expr)))
+    {
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            if let CheckKind::TypeOfPrimitive(primitive) = &check.kind {
+                check.amend(Fix {
+                    content: primitive.builtin(),
+                    location: expr.location,
+                    end_location: expr.end_location,
+                    applied: false,
+                });
+            }
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/unnecessary_abspath.rs

@@ -0,0 +1,23 @@
+use rustpython_ast::Expr;
+
+use crate::ast::checkers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::Fix;
+
+pub fn unnecessary_abspath(checker: &mut Checker, expr: &Expr, func: &Expr, args: &Vec<Expr>) {
+    if let Some(mut check) =
+        checkers::unnecessary_abspath(func, args, checker.locate_check(Range::from_located(expr)))
+    {
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            check.amend(Fix {
+                content: "__file__".to_string(),
+                location: expr.location,
+                end_location: expr.end_location,
+                applied: false,
+            });
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/use_pep585_annotation.rs

@@ -0,0 +1,26 @@
+use rustpython_ast::Expr;
+
+use crate::ast::types::Range;
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind, Fix};
+use crate::python::typing;
+
+pub fn use_pep585_annotation(checker: &mut Checker, expr: &Expr, id: &str) {
+    // TODO(charlie): Verify that the builtin is imported from the `typing` module.
+    if typing::is_pep585_builtin(id) {
+        let mut check = Check::new(
+            CheckKind::UsePEP585Annotation(id.to_string()),
+            Range::from_located(expr),
+        );
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            check.amend(Fix {
+                content: id.to_lowercase(),
+                location: expr.location,
+                end_location: expr.end_location,
+                applied: false,
+            })
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/use_pep604_annotation.rs

@@ -0,0 +1,100 @@
+use rustpython_ast::{Constant, Expr, ExprKind, Operator};
+
+use crate::ast::helpers::match_name_or_attr;
+use crate::ast::types::Range;
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind, Fix};
+use crate::code_gen::SourceGenerator;
+
+fn optional(expr: &Expr) -> Expr {
+    Expr::new(
+        Default::default(),
+        Default::default(),
+        ExprKind::BinOp {
+            left: Box::new(expr.clone()),
+            op: Operator::BitOr,
+            right: Box::new(Expr::new(
+                Default::default(),
+                Default::default(),
+                ExprKind::Constant {
+                    value: Constant::None,
+                    kind: None,
+                },
+            )),
+        },
+    )
+}
+
+fn union(elts: &[Expr]) -> Expr {
+    if elts.len() == 1 {
+        elts[0].clone()
+    } else {
+        Expr::new(
+            Default::default(),
+            Default::default(),
+            ExprKind::BinOp {
+                left: Box::new(union(&elts[..elts.len() - 1])),
+                op: Operator::BitOr,
+                right: Box::new(elts[elts.len() - 1].clone()),
+            },
+        )
+    }
+}
+
+pub fn use_pep604_annotation(checker: &mut Checker, expr: &Expr, value: &Expr, slice: &Expr) {
+    if match_name_or_attr(value, "Optional") {
+        let mut check = Check::new(CheckKind::UsePEP604Annotation, Range::from_located(expr));
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            let mut generator = SourceGenerator::new();
+            if let Ok(()) = generator.unparse_expr(&optional(slice), 0) {
+                if let Ok(content) = generator.generate() {
+                    check.amend(Fix {
+                        content,
+                        location: expr.location,
+                        end_location: expr.end_location,
+                        applied: false,
+                    })
+                }
+            }
+        }
+        checker.add_check(check);
+    } else if match_name_or_attr(value, "Union") {
+        let mut check = Check::new(CheckKind::UsePEP604Annotation, Range::from_located(expr));
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            match &slice.node {
+                ExprKind::Slice { .. } => {
+                    // Invalid type annotation.
+                }
+                ExprKind::Tuple { elts, .. } => {
+                    let mut generator = SourceGenerator::new();
+                    if let Ok(()) = generator.unparse_expr(&union(elts), 0) {
+                        if let Ok(content) = generator.generate() {
+                            check.amend(Fix {
+                                content,
+                                location: expr.location,
+                                end_location: expr.end_location,
+                                applied: false,
+                            })
+                        }
+                    }
+                }
+                _ => {
+                    // Single argument.
+                    let mut generator = SourceGenerator::new();
+                    if let Ok(()) = generator.unparse_expr(slice, 0) {
+                        if let Ok(content) = generator.generate() {
+                            check.amend(Fix {
+                                content,
+                                location: expr.location,
+                                end_location: expr.end_location,
+                                applied: false,
+                            });
+                        }
+                    }
+                }
+            }
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/useless_metaclass_type.rs

@@ -0,0 +1,44 @@
+use log::error;
+use rustpython_ast::{Expr, Stmt};
+
+use crate::ast::checkers;
+use crate::ast::types::{CheckLocator, Range};
+use crate::autofix::{fixer, fixes};
+use crate::check_ast::Checker;
+
+pub fn useless_metaclass_type(
+    checker: &mut Checker,
+    stmt: &Stmt,
+    value: &Expr,
+    targets: &Vec<Expr>,
+) {
+    if let Some(mut check) = checkers::useless_metaclass_type(
+        targets,
+        value,
+        checker.locate_check(Range::from_located(stmt)),
+    ) {
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            let context = checker.binding_context();
+            let deleted: Vec<&Stmt> = checker
+                .deletions
+                .iter()
+                .map(|index| checker.parents[*index])
+                .collect();
+
+            match fixes::remove_stmt(
+                checker.parents[context.defined_by],
+                context.defined_in.map(|index| checker.parents[index]),
+                &deleted,
+            ) {
+                Ok(fix) => {
+                    if fix.content.is_empty() || fix.content == "pass" {
+                        checker.deletions.insert(context.defined_by);
+                    }
+                    check.amend(fix)
+                }
+                Err(e) => error!("Failed to fix unused imports: {}", e),
+            }
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/useless_object_inheritance.rs

@@ -0,0 +1,29 @@
+use rustpython_ast::{Expr, Keyword, Stmt};
+
+use crate::ast::checkers;
+use crate::autofix::{fixer, fixes};
+use crate::check_ast::Checker;
+
+pub fn useless_object_inheritance(
+    checker: &mut Checker,
+    stmt: &Stmt,
+    name: &str,
+    bases: &[Expr],
+    keywords: &[Keyword],
+) {
+    let scope = checker.current_scope();
+    if let Some(mut check) = checkers::useless_object_inheritance(name, bases, scope) {
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            if let Some(fix) = fixes::remove_class_def_base(
+                &mut checker.locator,
+                &stmt.location,
+                check.location,
+                bases,
+                keywords,
+            ) {
+                check.amend(fix);
+            }
+        }
+        checker.add_check(check);
+    }
+}

src/printer.rs

@@ -104,6 +104,7 @@ impl Printer {
     }
 
     pub fn clear_screen(&mut self) -> Result<()> {
+        #[cfg(not(target_family = "wasm"))]
         clearscreen::clear()?;
         Ok(())
     }

src/pyproject.rs

@@ -9,6 +9,7 @@ use serde::{Deserialize, Deserializer};
 
 use crate::checks::CheckCode;
 use crate::fs;
+use crate::settings::PythonVersion;
 
 pub fn load_config(pyproject: &Option<PathBuf>) -> Result<Config> {
     match pyproject {
@@ -29,11 +30,19 @@ pub fn load_config(pyproject: &Option<PathBuf>) -> Result<Config> {
 pub struct Config {
     pub line_length: Option<usize>,
     pub exclude: Option<Vec<String>>,
-    pub extend_exclude: Option<Vec<String>>,
+    #[serde(default)]
+    pub extend_exclude: Vec<String>,
     pub select: Option<Vec<CheckCode>>,
-    pub ignore: Option<Vec<CheckCode>>,
-    pub per_file_ignores: Option<Vec<StrCheckCodePair>>,
+    #[serde(default)]
+    pub extend_select: Vec<CheckCode>,
+    #[serde(default)]
+    pub ignore: Vec<CheckCode>,
+    #[serde(default)]
+    pub extend_ignore: Vec<CheckCode>,
+    #[serde(default)]
+    pub per_file_ignores: Vec<StrCheckCodePair>,
     pub dummy_variable_rgx: Option<String>,
+    pub target_version: Option<PythonVersion>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -145,12 +154,13 @@ mod tests {
 
     use anyhow::Result;
 
-    use super::StrCheckCodePair;
     use crate::checks::CheckCode;
     use crate::pyproject::{
         find_project_root, find_pyproject_toml, parse_pyproject_toml, Config, PyProject, Tools,
     };
 
+    use super::StrCheckCodePair;
+
     #[test]
     fn deserialize() -> Result<()> {
         let pyproject: PyProject = toml::from_str(r#""#)?;
@@ -175,11 +185,14 @@ mod tests {
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -197,11 +210,14 @@ line-length = 79
                 ruff: Some(Config {
                     line_length: Some(79),
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -219,11 +235,14 @@ exclude = ["foo.py"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: Some(vec!["foo.py".to_string()]),
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -241,11 +260,14 @@ select = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: Some(vec![CheckCode::E501]),
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -254,6 +276,7 @@ select = ["E501"]
             r#"
 [tool.black]
 [tool.ruff]
+extend-select = ["M001"]
 ignore = ["E501"]
 "#,
         )?;
@@ -263,11 +286,14 @@ ignore = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: Some(vec![CheckCode::E501]),
-                    per_file_ignores: None,
+                    extend_select: vec![CheckCode::M001],
+                    ignore: vec![CheckCode::E501],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -325,15 +351,18 @@ other-attribute = 1
             Config {
                 line_length: Some(88),
                 exclude: None,
-                extend_exclude: Some(vec![
+                extend_exclude: vec![
                     "excluded.py".to_string(),
                     "migrations".to_string(),
                     "directory/also_excluded.py".to_string(),
-                ]),
+                ],
                 select: None,
-                ignore: None,
-                per_file_ignores: None,
+                extend_select: vec![],
+                ignore: vec![],
+                extend_ignore: vec![],
+                per_file_ignores: vec![],
                 dummy_variable_rgx: None,
+                target_version: None,
             }
         );
 

src/python/typing.rs

@@ -7,6 +7,7 @@ static ANNOTATED_SUBSCRIPTS: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
         "AbstractAsyncContextManager",
         "AbstractContextManager",
         "AbstractSet",
+        // "Annotated",
         "AsyncContextManager",
         "AsyncGenerator",
         "AsyncIterable",
@@ -87,3 +88,14 @@ static ANNOTATED_SUBSCRIPTS: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
 pub fn is_annotated_subscript(name: &str) -> bool {
     ANNOTATED_SUBSCRIPTS.contains(name)
 }
+
+pub fn is_pep593_annotated_subscript(name: &str) -> bool {
+    name == "Annotated"
+}
+
+static PEP_585_BUILTINS: Lazy<BTreeSet<&'static str>> =
+    Lazy::new(|| BTreeSet::from(["Dict", "FrozenSet", "List", "Set", "Tuple", "Type"]));
+
+pub fn is_pep585_builtin(name: &str) -> bool {
+    PEP_585_BUILTINS.contains(name)
+}