Bump version to 0.0.105

.cargo/config.toml

@@ -0,0 +1,2 @@
+[alias]
+dev = "run --package ruff_dev --bin ruff_dev"

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.103
+    rev: v0.0.105
     hooks:
       - id: ruff
 

CONTRIBUTING.md

@@ -1,17 +1,17 @@
-# Contributing to ruff
+# Contributing to Ruff
 
-Welcome! We're happy to have you here. Thank you in advance for your contribution to ruff.
+Welcome! We're happy to have you here. Thank you in advance for your contribution to Ruff.
 
 ## The basics
 
-ruff welcomes contributions in the form of Pull Requests. For small changes (e.g., bug fixes), feel
+Ruff welcomes contributions in the form of Pull Requests. For small changes (e.g., bug fixes), feel
 free to submit a PR. For larger changes (e.g., new lint rules, new functionality, new configuration
 options), consider submitting an [Issue](https://github.com/charliermarsh/ruff/issues) outlining
 your proposed change.
 
 ### Prerequisites
 
-ruff is written in Rust. You'll need to install the
+Ruff is written in Rust. 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:
@@ -22,7 +22,7 @@ cargo install cargo-insta
 
 ### Development
 
-After cloning the repository, run ruff locally with:
+After cloning the repository, run Ruff locally with:
 
 ```shell
 cargo run resources/test/fixtures --no-cache
@@ -32,9 +32,9 @@ Prior to opening a pull request, ensure that your code has been auto-formatted,
 both the lint and test validation checks:
 
 ```shell
-cargo fmt     # Auto-formatting...
-cargo clippy  # Linting...
-cargo test    # Testing...
+cargo +nightly fmt --all     # Auto-formatting...
+cargo +nightly clippy --all  # Linting...
+cargo +nightly test --all    # Testing...
 ```
 
 These checks will run on GitHub Actions when you open your Pull Request, but running them locally
@@ -45,12 +45,13 @@ prior to merging.
 
 ### Example: Adding a new lint rule
 
-There are three phases to adding a new lint rule:
+There are four phases to adding a new lint rule:
 
 1. Define the rule in `src/checks.rs`.
-2. Define the _logic_ for triggering the rule in `src/check_ast.rs` (for AST-based checks)
-   or `src/check_lines.rs` (for text-based checks).
+2. Define the _logic_ for triggering the rule in `src/check_ast.rs` (for AST-based checks),
+   `src/check_tokens.rs` (for token-based checks), or `src/check_lines.rs` (for text-based checks).
 3. Add a test fixture.
+4. Update the generated files (documentation and generated code).
 
 To define the rule, open up `src/checks.rs`. You'll need to define both a `CheckCode` and
 `CheckKind`. As an example, you can grep for `E402` and `ModuleImportNotAtTopOfFile`, and follow the
@@ -58,37 +59,33 @@ pattern implemented therein.
 
 To trigger the rule, you'll likely want to augment the logic in `src/check_ast.rs`, which defines
 the Python AST visitor, responsible for iterating over the abstract syntax tree and collecting
-lint-rule violations as it goes. Grep for the `Check::new` invocations to understand how other,
-similar rules are implemented.
+lint-rule violations as it goes. If you need to inspect the AST, you can run `cargo dev print-ast`
+with a Python file. Grep for the `Check::new` invocations to understand how other, 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 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:
+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 --no-cache`. Once you're satisfied with the
+output, codify the behavior as a snapshot test by adding a new `testcase` macro to the `mod tests`
+section of `src/linter.rs`, like so:
 
 ```rust
-#[test]
-fn e402() -> Result<()> {
-    let mut checks = check_path(
-        Path::new("./resources/test/fixtures/E402.py"),
-        &settings::Settings::for_rule(CheckCode::E402),
-        &fixer::Mode::Generate,
-    )?;
-    checks.sort_by_key(|check| check.location);
-    insta::assert_yaml_snapshot!(checks);
-    Ok(())
-}
+#[test_case(CheckCode::A001, Path::new("A001.py"); "A001")]
+...
 ```
 
 Then, run `cargo test`. Your test will fail, but you'll be prompted to follow-up with
 `cargo insta review`. Accept the generated snapshot, then commit the snapshot file alongside the
 rest of your changes.
 
+Finally, to update the documentation, run `cargo dev generate-rules-table` from the repo root. To
+update the generated prefix map, run `cargo dev generate-check-code-prefix`. Both of these commands
+should be run whenever a new check is added to the codebase.
+
 ### Example: Adding a new configuration option
 
-ruff's user-facing settings live in two places: first, the command-line options defined with
+Ruff's user-facing settings live in two places: first, the command-line options defined with
 [clap](https://docs.rs/clap/latest/clap/) via the `Cli` struct in `src/main.rs`; and second, the
 `Config` struct defined `src/pyproject.rs`, which is responsible for extracting user-defined
 settings from a `pyproject.toml` file.
@@ -103,9 +100,9 @@ acceptable unused variables (e.g., `_`).
 
 ## Release process
 
-As of now, ruff has an ad hoc release process: releases are cut with high frequency via GitHub
+As of now, Ruff has an ad hoc release process: releases are cut with high frequency via GitHub
 Actions, which automatically generates the appropriate wheels across architectures and publishes
 them to [PyPI](https://pypi.org/project/ruff/).
 
-ruff follows the [semver](https://semver.org/) versioning standard. However, as pre-1.0 software,
+Ruff follows the [semver](https://semver.org/) versioning standard. However, as pre-1.0 software,
 even patch releases may contain [non-backwards-compatible changes](https://semver.org/#spec-item-4).

Cargo.lock

@@ -920,7 +920,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8-to-ruff"
-version = "0.0.103-dev.0"
+version = "0.0.105-dev.0"
 dependencies = [
  "anyhow",
  "clap 4.0.15",
@@ -2221,7 +2221,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.103"
+version = "0.0.105"
 dependencies = [
  "anyhow",
  "assert_cmd",
@@ -2266,7 +2266,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_dev"
-version = "0.0.103"
+version = "0.0.105"
 dependencies = [
  "anyhow",
  "clap 4.0.15",

Cargo.toml

@@ -6,7 +6,7 @@ members = [
 
 [package]
 name = "ruff"
-version = "0.0.103"
+version = "0.0.105"
 edition = "2021"
 
 [lib]

README.md

@@ -52,8 +52,9 @@ Read the [launch blog post](https://notes.crmarsh.com/python-tooling-could-be-mu
    8. [flake8-builtins](#flake8-builtins)
    9. [flake8-print](#flake8-print)
    10. [flake8-quotes](#flake8-quotes)
-   11. [Ruff-specific rules](#ruff-specific-rules)
-   12. [Meta rules](#meta-rules)
+   11. [flake8-annotations](#flake8-annotations)
+   12. [Ruff-specific rules](#ruff-specific-rules)
+   13. [Meta rules](#meta-rules)
 5. [Editor Integrations](#editor-integrations)
 6. [FAQ](#faq)
 7. [Development](#development)
@@ -93,7 +94,7 @@ Ruff also works with [pre-commit](https://pre-commit.com):
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.103
+    rev: v0.0.105
     hooks:
       - id: ruff
 ```
@@ -300,7 +301,7 @@ By default, Ruff enables all `E` and `F` error codes, which correspond to those
 
 The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` command-line option.
 
-<!-- Sections automatically generated by examples/generate_rules_table.rs. -->
+<!-- Sections automatically generated by `cargo dev generate-rules-table`. -->
 <!-- Begin auto-generated sections. -->
 
 ### Pyflakes
@@ -322,7 +323,7 @@ For more, see [Pyflakes](https://pypi.org/project/pyflakes/2.5.0/) on PyPI.
 | 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 `==` and `!=` to compare constant literals |  |
+| 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 |  |
@@ -426,6 +427,7 @@ For more, see [pyupgrade](https://pypi.org/project/pyupgrade/3.2.0/) on PyPI.
 | 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)` | 🛠 |
+| U009 | PEP3120UnnecessaryCodingComment | utf-8 encoding declaration is unnecessary | 🛠 |
 
 ### pep8-naming
 
@@ -522,6 +524,23 @@ For more, see [flake8-quotes](https://pypi.org/project/flake8-quotes/3.3.1/) on
 | Q002 | BadQuotesDocstring | Single quote docstring found but double quotes preferred |  |
 | Q003 | AvoidQuoteEscape | Change outer quotes to avoid escaping inner quotes |  |
 
+### flake8-annotations
+
+For more, see [flake8-annotations](https://pypi.org/project/flake8-annotations/2.9.1/) on PyPI.
+
+| Code | Name | Message | Fix |
+| ---- | ---- | ------- | --- |
+| ANN001 | MissingTypeFunctionArgument | Missing type annotation for function argument |  |
+| ANN002 | MissingTypeArgs | Missing type annotation for `*args` |  |
+| ANN003 | MissingTypeKwargs | Missing type annotation for `**kwargs` |  |
+| ANN101 | MissingTypeSelf | Missing type annotation for `self` in method |  |
+| ANN102 | MissingTypeCls | Missing type annotation for `cls` in classmethod |  |
+| ANN201 | MissingReturnTypePublicFunction | Missing return type annotation for public function |  |
+| ANN202 | MissingReturnTypePrivateFunction | Missing return type annotation for private function |  |
+| ANN204 | MissingReturnTypeMagicMethod | Missing return type annotation for magic method |  |
+| ANN205 | MissingReturnTypeStaticMethod | Missing return type annotation for staticmethod |  |
+| ANN206 | MissingReturnTypeClassMethod | Missing return type annotation for classmethod |  |
+
 ### Ruff-specific rules
 
 | Code | Name | Message | Fix |
@@ -604,9 +623,10 @@ including:
 - [`flake8-super`](https://pypi.org/project/flake8-super/)
 - [`flake8-print`](https://pypi.org/project/flake8-print/)
 - [`flake8-quotes`](https://pypi.org/project/flake8-quotes/)
+- [`flake8-annotations`](https://pypi.org/project/flake8-annotations/)
 - [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
 - [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (15/32)
-- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (10/34)
+- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (11/34)
 - [`autoflake`](https://pypi.org/project/autoflake/) (1/7)
 
 Beyond rule-set parity, Ruff suffers from the following limitations vis-à-vis Flake8:
@@ -626,11 +646,12 @@ Today, Ruff can be used to replace Flake8 when used with any of the following pl
 - [`flake8-super`](https://pypi.org/project/flake8-super/)
 - [`flake8-print`](https://pypi.org/project/flake8-print/)
 - [`flake8-quotes`](https://pypi.org/project/flake8-quotes/)
+- [`flake8-annotations`](https://pypi.org/project/flake8-annotations/)
 - [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
 - [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (15/32)
 
 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/) (10/34).
+and a subset of the rules implemented in [`pyupgrade`](https://pypi.org/project/pyupgrade/) (11/34).
 
 If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, free to file an Issue.
 

flake8_to_ruff/Cargo.lock

@@ -771,7 +771,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8_to_ruff"
-version = "0.0.103"
+version = "0.0.105"
 dependencies = [
  "anyhow",
  "clap",
@@ -1975,7 +1975,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.103"
+version = "0.0.105"
 dependencies = [
  "anyhow",
  "bincode",

flake8_to_ruff/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "flake8-to-ruff"
-version = "0.0.103-dev.0"
+version = "0.0.105-dev.0"
 edition = "2021"
 
 [lib]

flake8_to_ruff/src/converter.rs

@@ -4,7 +4,7 @@ use anyhow::Result;
 use ruff::flake8_quotes::settings::Quote;
 use ruff::settings::options::Options;
 use ruff::settings::pyproject::Pyproject;
-use ruff::{flake8_quotes, pep8_naming};
+use ruff::{flake8_annotations, flake8_quotes, pep8_naming};
 
 use crate::plugin::Plugin;
 use crate::{parser, plugin};
@@ -39,6 +39,7 @@ pub fn convert(
 
     // Parse each supported option.
     let mut options: Options = Default::default();
+    let mut flake8_annotations: flake8_annotations::settings::Options = Default::default();
     let mut flake8_quotes: flake8_quotes::settings::Options = Default::default();
     let mut pep8_naming: pep8_naming::settings::Options = Default::default();
     for (key, value) in flake8 {
@@ -78,6 +79,25 @@ pub fn convert(
                         Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
                     }
                 }
+                // flake8-annotations
+                "suppress-none-returning" | "suppress_none_returning" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.suppress_none_returning = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                "suppress-dummy-args" | "suppress_dummy_args" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.suppress_dummy_args = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                "mypy-init-return" | "mypy_init_return" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.mypy_init_return = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
                 // flake8-quotes
                 "quotes" | "inline-quotes" | "inline_quotes" => match value.trim() {
                     "'" | "single" => flake8_quotes.inline_quotes = Some(Quote::Single),
@@ -94,10 +114,9 @@ pub fn convert(
                     "\"" | "double" => flake8_quotes.docstring_quotes = Some(Quote::Single),
                     _ => eprintln!("Unexpected '{key}' value: {value}"),
                 },
-                "avoid-escape" | "avoid_escape" => match value.trim() {
-                    "true" => flake8_quotes.avoid_escape = Some(true),
-                    "false" => flake8_quotes.avoid_escape = Some(false),
-                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                "avoid-escape" | "avoid_escape" => match parser::parse_bool(value.as_ref()) {
+                    Ok(bool) => flake8_quotes.avoid_escape = Some(bool),
+                    Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
                 },
                 // pep8-naming
                 "ignore-names" | "ignore_names" => {
@@ -166,6 +185,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: None,
             pep8_naming: None,
         });
@@ -195,6 +215,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: None,
             pep8_naming: None,
         });
@@ -224,6 +245,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: None,
             pep8_naming: None,
         });
@@ -253,6 +275,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: None,
             pep8_naming: None,
         });
@@ -282,6 +305,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: Some(flake8_quotes::settings::Options {
                 inline_quotes: Some(flake8_quotes::settings::Quote::Single),
                 multiline_quotes: None,
@@ -354,6 +378,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: None,
             pep8_naming: None,
         });
@@ -384,6 +409,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            flake8_annotations: None,
             flake8_quotes: Some(flake8_quotes::settings::Options {
                 inline_quotes: Some(flake8_quotes::settings::Quote::Single),
                 multiline_quotes: None,

flake8_to_ruff/src/parser.rs

@@ -37,6 +37,15 @@ pub fn parse_strings(value: &str) -> Vec<String> {
         .collect()
 }
 
+/// Parse a boolean.
+pub fn parse_bool(value: &str) -> Result<bool> {
+    match value.trim() {
+        "true" => Ok(true),
+        "false" => Ok(false),
+        _ => Err(anyhow::anyhow!("Unexpected boolean value: {value}")),
+    }
+}
+
 #[derive(Debug)]
 struct Token {
     token_name: TokenType,

flake8_to_ruff/src/plugin.rs

@@ -12,6 +12,7 @@ pub enum Plugin {
     Flake8Docstrings,
     Flake8Print,
     Flake8Quotes,
+    Flake8Annotations,
     PEP8Naming,
     Pyupgrade,
 }
@@ -27,6 +28,7 @@ impl FromStr for Plugin {
             "flake8-docstrings" => Ok(Plugin::Flake8Docstrings),
             "flake8-print" => Ok(Plugin::Flake8Print),
             "flake8-quotes" => Ok(Plugin::Flake8Quotes),
+            "flake8-annotations" => Ok(Plugin::Flake8Annotations),
             "pep8-naming" => Ok(Plugin::PEP8Naming),
             "pyupgrade" => Ok(Plugin::Pyupgrade),
             _ => Err(anyhow!("Unknown plugin: {}", string)),
@@ -58,6 +60,7 @@ impl Plugin {
             }
             Plugin::Flake8Print => vec![CheckCodePrefix::T],
             Plugin::Flake8Quotes => vec![CheckCodePrefix::Q],
+            Plugin::Flake8Annotations => vec![CheckCodePrefix::ANN],
             Plugin::PEP8Naming => vec![CheckCodePrefix::N],
             Plugin::Pyupgrade => vec![CheckCodePrefix::U],
         }
@@ -262,6 +265,31 @@ pub fn infer_plugins(flake8: &HashMap<String, Option<String>>) -> Vec<Plugin> {
             "avoid-escape" | "avoid_escape" => {
                 plugins.insert(Plugin::Flake8Quotes);
             }
+            // flake8-annotations
+            "suppress-none-returning" | "suppress_none_returning" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "suppress-dummy-args" | "suppress_dummy_args" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "allow-untyped-defs" | "allow_untyped_defs" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "allow-untyped-nested" | "allow_untyped_nested" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "mypy-init-return" | "mypy_init_return" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "dispatch-decorators" | "dispatch_decorators" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "overload-decorators" | "overload_decorators" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "allow-star-arg-any" | "allow_star_arg_any" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
             // pep8-naming
             "ignore-names" | "ignore_names" => {
                 plugins.insert(Plugin::PEP8Naming);

resources/test/fixtures/B015.py

@@ -22,3 +22,6 @@ data = [x for x in [1, 2, 3] if x in (1, 2)]
 
 class TestClass:
     1 == 1
+
+
+print(1 == 1)

resources/test/fixtures/F632.py

@@ -3,3 +3,6 @@ if x is "abc":
 
 if 123 is not y:
     pass
+
+if "123" is x < 3:
+    pass

resources/test/fixtures/N803.py

@@ -1,7 +1,7 @@
-def func(a, A):
-    return a, A
+def func(_, a, A):
+    return _, a, A
 
 
 class Class:
-    def method(self, a, A):
-        return a, A
+    def method(self, _, a, A):
+        return _, a, A

resources/test/fixtures/N804.py

@@ -1,19 +1,43 @@
+from abc import ABCMeta
+
+
 class Class:
-    @classmethod
-    def bad_class_method(this):
+    def bad_method(this):
+        pass
+
+    if False:
+
+        def extra_bad_method(this):
+            pass
+
+    def good_method(self):
         pass
 
     @classmethod
-    def good_class_method(cls):
-        pass
-
-    def method(self):
+    def class_method(cls):
         pass
 
     @staticmethod
     def static_method(x):
         return x
 
+    def __init__(self):
+        ...
+
+    def __new__(cls, *args, **kwargs):
+        ...
+
+    def __init_subclass__(self, default_name, **kwargs):
+        ...
+
+
+class MetaClass(ABCMeta):
+    def bad_method(self):
+        pass
+
+    def good_method(cls):
+        pass
+
 
 def func(x):
     return x

resources/test/fixtures/N805.py

@@ -1,11 +1,11 @@
-import random
+from abc import ABCMeta
 
 
 class Class:
     def bad_method(this):
         pass
 
-    if random.random(0, 2) == 0:
+    if False:
 
         def extra_bad_method(this):
             pass
@@ -21,6 +21,23 @@ class Class:
     def static_method(x):
         return x
 
+    def __init__(self):
+        ...
+
+    def __new__(cls, *args, **kwargs):
+        ...
+
+    def __init_subclass__(self, default_name, **kwargs):
+        ...
+
+
+class MetaClass(ABCMeta):
+    def bad_method(self):
+        pass
+
+    def good_method(cls):
+        pass
+
 
 def func(x):
     return x

resources/test/fixtures/U009_0.py

@@ -0,0 +1,3 @@
+# coding=utf8
+
+print('Hello world')

resources/test/fixtures/U009_1.py

@@ -0,0 +1,4 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+print('Hello world')

resources/test/fixtures/U009_2.py

@@ -0,0 +1,5 @@
+#!/usr/bin/python
+# A coding comment is only valid in the first two lines, so this one is not checked.
+# -*- coding: utf-8 -*-
+
+print('Hello world')

resources/test/fixtures/U009_3.py

@@ -0,0 +1,4 @@
+#!/usr/bin/python
+# -*- coding: something-else -*-
+
+print('Hello world')

resources/test/fixtures/flake8_annotations/annotation_presence.py

@@ -0,0 +1,33 @@
+# Error
+def foo(a, b):
+    pass
+
+
+# Error
+def foo(a: int, b):
+    pass
+
+
+# Error
+def foo(a: int, b) -> int:
+    pass
+
+
+# Error
+def foo(a: int, b: int):
+    pass
+
+
+# Error
+def foo():
+    pass
+
+
+# OK
+def foo(a: int, b: int) -> int:
+    pass
+
+
+# OK
+def foo() -> int:
+    pass

resources/test/fixtures/flake8_annotations/mypy_init_return.py

@@ -0,0 +1,41 @@
+"""Test case expected to be run with `mypy_init_return = True`."""
+
+# Error
+class Foo:
+    def __init__(self):
+        ...
+
+
+# Error
+class Foo:
+    def __init__(self, foo):
+        ...
+
+
+# OK
+class Foo:
+    def __init__(self, foo) -> None:
+        ...
+
+
+# OK
+class Foo:
+    def __init__(self) -> None:
+        ...
+
+
+# OK
+class Foo:
+    def __init__(self, foo: int):
+        ...
+
+
+# OK
+class Foo:
+    def __init__(self, foo: int) -> None:
+        ...
+
+
+# Error
+def __init__(self, foo: int):
+    ...

resources/test/fixtures/flake8_annotations/suppress_dummy_args.py

@@ -0,0 +1,26 @@
+"""Test case expected to be run with `suppress_dummy_args = True`."""
+
+# OK
+def foo(_) -> None:
+    ...
+
+
+# OK
+def foo(*_) -> None:
+    ...
+
+
+# OK
+def foo(**_) -> None:
+    ...
+
+
+# OK
+def foo(a: int, _) -> None:
+    ...
+
+
+# OK
+def foo() -> None:
+    def bar(_) -> None:
+        ...

resources/test/fixtures/flake8_annotations/suppress_none_returning.py

@@ -0,0 +1,55 @@
+"""Test case expected to be run with `suppress_none_returning = True`."""
+
+# OK
+def foo():
+    a = 2 + 2
+
+
+# OK
+def foo():
+    return
+
+
+# OK
+def foo():
+    return None
+
+
+# OK
+def foo():
+    a = 2 + 2
+    if a == 4:
+        return
+    else:
+        return
+
+
+# OK
+def foo():
+    a = 2 + 2
+    if a == 4:
+        return None
+    else:
+        return
+
+
+# OK
+def foo():
+    def bar() -> bool:
+        return True
+
+    bar()
+
+
+# Error
+def foo():
+    return True
+
+
+# Error
+def foo():
+    a = 2 + 2
+    if a == 4:
+        return True
+    else:
+        return

ruff_dev/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff_dev"
-version = "0.0.103"
+version = "0.0.105"
 edition = "2021"
 
 [dependencies]

ruff_dev/src/generate_check_code_prefix.rs

@@ -11,7 +11,7 @@ use itertools::Itertools;
 use ruff::checks::CheckCode;
 use strum::IntoEnumIterator;
 
-const FILE: &str = "../src/checks_gen.rs";
+const FILE: &str = "src/checks_gen.rs";
 
 #[derive(Parser)]
 #[command(author, version, about, long_about = None)]

ruff_dev/src/generate_rules_table.rs

@@ -3,13 +3,13 @@
 use std::fs;
 use std::fs::OpenOptions;
 use std::io::Write;
+use std::path::PathBuf;
 
 use anyhow::Result;
 use clap::Args;
 use ruff::checks::{CheckCategory, CheckCode};
 use strum::IntoEnumIterator;
 
-const FILE: &str = "../README.md";
 const BEGIN_PRAGMA: &str = "<!-- Begin auto-generated sections. -->";
 const END_PRAGMA: &str = "<!-- End auto-generated sections. -->";
 
@@ -64,7 +64,11 @@ pub fn main(cli: &Cli) -> Result<()> {
         print!("{}", output);
     } else {
         // Read the existing file.
-        let existing = fs::read_to_string(FILE)?;
+        let file = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+            .parent()
+            .expect("Failed to find root directory")
+            .join("README.md");
+        let existing = fs::read_to_string(&file)?;
 
         // Extract the prefix.
         let index = existing
@@ -79,7 +83,7 @@ pub fn main(cli: &Cli) -> Result<()> {
         let suffix = &existing[index..];
 
         // Write the prefix, new contents, and suffix.
-        let mut f = OpenOptions::new().write(true).truncate(true).open(FILE)?;
+        let mut f = OpenOptions::new().write(true).truncate(true).open(&file)?;
         write!(f, "{}\n\n", prefix)?;
         write!(f, "{}", output)?;
         write!(f, "{}", suffix)?;

src/ast/types.rs

@@ -1,6 +1,7 @@
 use std::collections::BTreeMap;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
+use rustpython_ast::{Expr, Keyword};
 use rustpython_parser::ast::{Located, Location};
 
 fn id() -> usize {
@@ -30,9 +31,17 @@ pub struct FunctionScope {
     pub uses_locals: bool,
 }
 
+#[derive(Clone, Debug, Default)]
+pub struct ClassScope<'a> {
+    pub name: &'a str,
+    pub bases: &'a [Expr],
+    pub keywords: &'a [Keyword],
+    pub decorator_list: &'a [Expr],
+}
+
 #[derive(Clone, Debug)]
-pub enum ScopeKind {
-    Class,
+pub enum ScopeKind<'a> {
+    Class(ClassScope<'a>),
     Function(FunctionScope),
     Generator,
     Module,
@@ -40,15 +49,15 @@ pub enum ScopeKind {
 }
 
 #[derive(Clone, Debug)]
-pub struct Scope {
+pub struct Scope<'a> {
     pub id: usize,
-    pub kind: ScopeKind,
+    pub kind: ScopeKind<'a>,
     pub import_starred: bool,
     pub values: BTreeMap<String, Binding>,
 }
 
-impl Scope {
-    pub fn new(kind: ScopeKind) -> Self {
+impl<'a> Scope<'a> {
+    pub fn new(kind: ScopeKind<'a>) -> Self {
         Scope {
             id: id(),
             kind,
@@ -91,10 +100,6 @@ pub struct Binding {
     pub used: Option<(usize, Range)>,
 }
 
-pub trait CheckLocator {
-    fn locate_check(&self, default: Range) -> Range;
-}
-
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum ImportKind {
     Import,

src/check_lines.rs

@@ -2,6 +2,8 @@
 
 use std::collections::BTreeMap;
 
+use once_cell::sync::Lazy;
+use regex::Regex;
 use rustpython_parser::ast::Location;
 
 use crate::ast::types::Range;
@@ -11,6 +13,10 @@ use crate::noqa;
 use crate::noqa::Directive;
 use crate::settings::Settings;
 
+// Regex from PEP263
+static CODING_COMMENT_REGEX: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r"^[ \t\f]*#.*?coding[:=][ \t]*utf-?8").expect("Invalid regex"));
+
 /// Whether the given line is too long and should be reported.
 fn should_enforce_line_length(line: &str, length: usize, limit: usize) -> bool {
     if length > limit {
@@ -52,6 +58,27 @@ pub fn check_lines(
             .map(|lineno| lineno - 1)
             .unwrap_or(lineno);
 
+        if lineno < 2 {
+            // PEP3120 makes utf-8 the default encoding.
+            if CODING_COMMENT_REGEX.is_match(line) {
+                let line_length = line.len();
+                let mut check = Check::new(
+                    CheckKind::PEP3120UnnecessaryCodingComment,
+                    Range {
+                        location: Location::new(lineno + 1, 0),
+                        end_location: Location::new(lineno + 1, line_length + 1),
+                    },
+                );
+                if autofix.patch() {
+                    check.amend(Fix::deletion(
+                        Location::new(lineno + 1, 0),
+                        Location::new(lineno + 1, line_length + 1),
+                    ));
+                }
+                line_checks.push(check);
+            }
+        }
+
         if enforce_noqa {
             noqa_directives
                 .entry(noqa_lineno)

src/checks.rs

@@ -115,6 +115,17 @@ pub enum CheckCode {
     Q001,
     Q002,
     Q003,
+    // flake8-annotations
+    ANN001,
+    ANN002,
+    ANN003,
+    ANN101,
+    ANN102,
+    ANN201,
+    ANN202,
+    ANN204,
+    ANN205,
+    ANN206,
     // pyupgrade
     U001,
     U002,
@@ -124,6 +135,7 @@ pub enum CheckCode {
     U006,
     U007,
     U008,
+    U009,
     // pydocstyle
     D100,
     D101,
@@ -204,6 +216,7 @@ pub enum CheckCategory {
     Flake8Builtins,
     Flake8Print,
     Flake8Quotes,
+    Flake8Annotations,
     Ruff,
     Meta,
 }
@@ -218,6 +231,7 @@ impl CheckCategory {
             CheckCategory::Flake8Comprehensions => "flake8-comprehensions",
             CheckCategory::Flake8Print => "flake8-print",
             CheckCategory::Flake8Quotes => "flake8-quotes",
+            CheckCategory::Flake8Annotations => "flake8-annotations",
             CheckCategory::Pyupgrade => "pyupgrade",
             CheckCategory::Pydocstyle => "pydocstyle",
             CheckCategory::PEP8Naming => "pep8-naming",
@@ -241,6 +255,9 @@ impl CheckCategory {
             }
             CheckCategory::Flake8Print => Some("https://pypi.org/project/flake8-print/5.0.0/"),
             CheckCategory::Flake8Quotes => Some("https://pypi.org/project/flake8-quotes/3.3.1/"),
+            CheckCategory::Flake8Annotations => {
+                Some("https://pypi.org/project/flake8-annotations/2.9.1/")
+            }
             CheckCategory::Pyupgrade => Some("https://pypi.org/project/pyupgrade/3.2.0/"),
             CheckCategory::Pydocstyle => Some("https://pypi.org/project/pydocstyle/6.1.1/"),
             CheckCategory::PEP8Naming => Some("https://pypi.org/project/pep8-naming/0.13.2/"),
@@ -356,6 +373,17 @@ pub enum CheckKind {
     BadQuotesMultilineString(Quote),
     BadQuotesDocstring(Quote),
     AvoidQuoteEscape,
+    // flake8-annotations
+    MissingTypeFunctionArgument,
+    MissingTypeArgs,
+    MissingTypeKwargs,
+    MissingTypeSelf,
+    MissingTypeCls,
+    MissingReturnTypePublicFunction,
+    MissingReturnTypePrivateFunction,
+    MissingReturnTypeMagicMethod,
+    MissingReturnTypeStaticMethod,
+    MissingReturnTypeClassMethod,
     // pyupgrade
     TypeOfPrimitive(Primitive),
     UnnecessaryAbspath,
@@ -365,6 +393,7 @@ pub enum CheckKind {
     UsePEP585Annotation(String),
     UsePEP604Annotation,
     SuperCallWithParameters,
+    PEP3120UnnecessaryCodingComment,
     // pydocstyle
     BlankLineAfterLastSection(String),
     BlankLineAfterSection(String),
@@ -438,7 +467,9 @@ impl CheckCode {
     /// physical lines).
     pub fn lint_source(&self) -> &'static LintSource {
         match self {
-            CheckCode::E501 | CheckCode::W292 | CheckCode::M001 => &LintSource::Lines,
+            CheckCode::E501 | CheckCode::W292 | CheckCode::M001 | CheckCode::U009 => {
+                &LintSource::Lines
+            }
             CheckCode::Q000
             | CheckCode::Q001
             | CheckCode::Q002
@@ -561,6 +592,17 @@ impl CheckCode {
             CheckCode::Q001 => CheckKind::BadQuotesMultilineString(Quote::Double),
             CheckCode::Q002 => CheckKind::BadQuotesDocstring(Quote::Double),
             CheckCode::Q003 => CheckKind::AvoidQuoteEscape,
+            // flake8-annotations
+            CheckCode::ANN001 => CheckKind::MissingTypeFunctionArgument,
+            CheckCode::ANN002 => CheckKind::MissingTypeArgs,
+            CheckCode::ANN003 => CheckKind::MissingTypeKwargs,
+            CheckCode::ANN101 => CheckKind::MissingTypeSelf,
+            CheckCode::ANN102 => CheckKind::MissingTypeCls,
+            CheckCode::ANN201 => CheckKind::MissingReturnTypePublicFunction,
+            CheckCode::ANN202 => CheckKind::MissingReturnTypePrivateFunction,
+            CheckCode::ANN204 => CheckKind::MissingReturnTypeMagicMethod,
+            CheckCode::ANN205 => CheckKind::MissingReturnTypeStaticMethod,
+            CheckCode::ANN206 => CheckKind::MissingReturnTypeClassMethod,
             // pyupgrade
             CheckCode::U001 => CheckKind::UselessMetaclassType,
             CheckCode::U002 => CheckKind::UnnecessaryAbspath,
@@ -573,6 +615,7 @@ impl CheckCode {
             CheckCode::U006 => CheckKind::UsePEP585Annotation("List".to_string()),
             CheckCode::U007 => CheckKind::UsePEP604Annotation,
             CheckCode::U008 => CheckKind::SuperCallWithParameters,
+            CheckCode::U009 => CheckKind::PEP3120UnnecessaryCodingComment,
             // pydocstyle
             CheckCode::D100 => CheckKind::PublicModule,
             CheckCode::D101 => CheckKind::PublicClass,
@@ -742,6 +785,16 @@ impl CheckCode {
             CheckCode::Q001 => CheckCategory::Flake8Quotes,
             CheckCode::Q002 => CheckCategory::Flake8Quotes,
             CheckCode::Q003 => CheckCategory::Flake8Quotes,
+            CheckCode::ANN001 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN002 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN003 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN101 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN102 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN201 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN202 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN204 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN205 => CheckCategory::Flake8Annotations,
+            CheckCode::ANN206 => CheckCategory::Flake8Annotations,
             CheckCode::U001 => CheckCategory::Pyupgrade,
             CheckCode::U002 => CheckCategory::Pyupgrade,
             CheckCode::U003 => CheckCategory::Pyupgrade,
@@ -750,6 +803,7 @@ impl CheckCode {
             CheckCode::U006 => CheckCategory::Pyupgrade,
             CheckCode::U007 => CheckCategory::Pyupgrade,
             CheckCode::U008 => CheckCategory::Pyupgrade,
+            CheckCode::U009 => CheckCategory::Pyupgrade,
             CheckCode::D100 => CheckCategory::Pydocstyle,
             CheckCode::D101 => CheckCategory::Pydocstyle,
             CheckCode::D102 => CheckCategory::Pydocstyle,
@@ -909,6 +963,17 @@ impl CheckKind {
             CheckKind::BadQuotesMultilineString(_) => &CheckCode::Q001,
             CheckKind::BadQuotesDocstring(_) => &CheckCode::Q002,
             CheckKind::AvoidQuoteEscape => &CheckCode::Q003,
+            // flake8-annotations
+            CheckKind::MissingTypeFunctionArgument => &CheckCode::ANN001,
+            CheckKind::MissingTypeArgs => &CheckCode::ANN002,
+            CheckKind::MissingTypeKwargs => &CheckCode::ANN003,
+            CheckKind::MissingTypeSelf => &CheckCode::ANN101,
+            CheckKind::MissingTypeCls => &CheckCode::ANN102,
+            CheckKind::MissingReturnTypePublicFunction => &CheckCode::ANN201,
+            CheckKind::MissingReturnTypePrivateFunction => &CheckCode::ANN202,
+            CheckKind::MissingReturnTypeMagicMethod => &CheckCode::ANN204,
+            CheckKind::MissingReturnTypeStaticMethod => &CheckCode::ANN205,
+            CheckKind::MissingReturnTypeClassMethod => &CheckCode::ANN206,
             // pyupgrade
             CheckKind::TypeOfPrimitive(_) => &CheckCode::U003,
             CheckKind::UnnecessaryAbspath => &CheckCode::U002,
@@ -918,6 +983,7 @@ impl CheckKind {
             CheckKind::UsePEP604Annotation => &CheckCode::U007,
             CheckKind::UselessObjectInheritance(_) => &CheckCode::U004,
             CheckKind::SuperCallWithParameters => &CheckCode::U008,
+            CheckKind::PEP3120UnnecessaryCodingComment => &CheckCode::U009,
             // pydocstyle
             CheckKind::BlankLineAfterLastSection(_) => &CheckCode::D413,
             CheckKind::BlankLineAfterSection(_) => &CheckCode::D410,
@@ -1293,6 +1359,33 @@ impl CheckKind {
             CheckKind::AvoidQuoteEscape => {
                 "Change outer quotes to avoid escaping inner quotes".to_string()
             }
+            // flake8-annotations
+            CheckKind::MissingTypeFunctionArgument => {
+                "Missing type annotation for function argument".to_string()
+            }
+            CheckKind::MissingTypeArgs => "Missing type annotation for `*args`".to_string(),
+            CheckKind::MissingTypeKwargs => "Missing type annotation for `**kwargs`".to_string(),
+            CheckKind::MissingTypeSelf => {
+                "Missing type annotation for `self` in method".to_string()
+            }
+            CheckKind::MissingTypeCls => {
+                "Missing type annotation for `cls` in classmethod".to_string()
+            }
+            CheckKind::MissingReturnTypePublicFunction => {
+                "Missing return type annotation for public function".to_string()
+            }
+            CheckKind::MissingReturnTypePrivateFunction => {
+                "Missing return type annotation for private function".to_string()
+            }
+            CheckKind::MissingReturnTypeMagicMethod => {
+                "Missing return type annotation for magic method".to_string()
+            }
+            CheckKind::MissingReturnTypeStaticMethod => {
+                "Missing return type annotation for staticmethod".to_string()
+            }
+            CheckKind::MissingReturnTypeClassMethod => {
+                "Missing return type annotation for classmethod".to_string()
+            }
             // pyupgrade
             CheckKind::TypeOfPrimitive(primitive) => {
                 format!("Use `{}` instead of `type(...)`", primitive.builtin())
@@ -1478,6 +1571,9 @@ impl CheckKind {
             CheckKind::ErrorSuffixOnExceptionName(name) => {
                 format!("Exception name `{name}` should be named with an Error suffix")
             }
+            CheckKind::PEP3120UnnecessaryCodingComment => {
+                "utf-8 encoding declaration is unnecessary".to_string()
+            }
             // Ruff
             CheckKind::AmbiguousUnicodeCharacterString(confusable, representant) => {
                 format!(
@@ -1583,6 +1679,8 @@ impl CheckKind {
                 | CheckKind::UsePEP604Annotation
                 | CheckKind::UselessMetaclassType
                 | CheckKind::UselessObjectInheritance(_)
+                | CheckKind::PEP3120UnnecessaryCodingComment
+                | CheckKind::IsLiteral
         )
     }
 }

src/checks_gen.rs

@@ -13,6 +13,23 @@ pub enum CheckCodePrefix {
     A001,
     A002,
     A003,
+    ANN,
+    ANN0,
+    ANN00,
+    ANN001,
+    ANN002,
+    ANN003,
+    ANN1,
+    ANN10,
+    ANN101,
+    ANN102,
+    ANN2,
+    ANN20,
+    ANN201,
+    ANN202,
+    ANN204,
+    ANN205,
+    ANN206,
     B,
     B0,
     B00,
@@ -230,6 +247,7 @@ pub enum CheckCodePrefix {
     U006,
     U007,
     U008,
+    U009,
     W,
     W2,
     W29,
@@ -256,6 +274,46 @@ impl CheckCodePrefix {
             CheckCodePrefix::A001 => vec![CheckCode::A001],
             CheckCodePrefix::A002 => vec![CheckCode::A002],
             CheckCodePrefix::A003 => vec![CheckCode::A003],
+            CheckCodePrefix::ANN => vec![
+                CheckCode::ANN001,
+                CheckCode::ANN002,
+                CheckCode::ANN003,
+                CheckCode::ANN101,
+                CheckCode::ANN102,
+                CheckCode::ANN201,
+                CheckCode::ANN202,
+                CheckCode::ANN204,
+                CheckCode::ANN205,
+                CheckCode::ANN206,
+            ],
+            CheckCodePrefix::ANN0 => vec![CheckCode::ANN001, CheckCode::ANN002, CheckCode::ANN003],
+            CheckCodePrefix::ANN00 => vec![CheckCode::ANN001, CheckCode::ANN002, CheckCode::ANN003],
+            CheckCodePrefix::ANN001 => vec![CheckCode::ANN001],
+            CheckCodePrefix::ANN002 => vec![CheckCode::ANN002],
+            CheckCodePrefix::ANN003 => vec![CheckCode::ANN003],
+            CheckCodePrefix::ANN1 => vec![CheckCode::ANN101, CheckCode::ANN102],
+            CheckCodePrefix::ANN10 => vec![CheckCode::ANN101, CheckCode::ANN102],
+            CheckCodePrefix::ANN101 => vec![CheckCode::ANN101],
+            CheckCodePrefix::ANN102 => vec![CheckCode::ANN102],
+            CheckCodePrefix::ANN2 => vec![
+                CheckCode::ANN201,
+                CheckCode::ANN202,
+                CheckCode::ANN204,
+                CheckCode::ANN205,
+                CheckCode::ANN206,
+            ],
+            CheckCodePrefix::ANN20 => vec![
+                CheckCode::ANN201,
+                CheckCode::ANN202,
+                CheckCode::ANN204,
+                CheckCode::ANN205,
+                CheckCode::ANN206,
+            ],
+            CheckCodePrefix::ANN201 => vec![CheckCode::ANN201],
+            CheckCodePrefix::ANN202 => vec![CheckCode::ANN202],
+            CheckCodePrefix::ANN204 => vec![CheckCode::ANN204],
+            CheckCodePrefix::ANN205 => vec![CheckCode::ANN205],
+            CheckCodePrefix::ANN206 => vec![CheckCode::ANN206],
             CheckCodePrefix::B => vec![
                 CheckCode::B002,
                 CheckCode::B003,
@@ -877,6 +935,7 @@ impl CheckCodePrefix {
                 CheckCode::U006,
                 CheckCode::U007,
                 CheckCode::U008,
+                CheckCode::U009,
             ],
             CheckCodePrefix::U0 => vec![
                 CheckCode::U001,
@@ -887,6 +946,7 @@ impl CheckCodePrefix {
                 CheckCode::U006,
                 CheckCode::U007,
                 CheckCode::U008,
+                CheckCode::U009,
             ],
             CheckCodePrefix::U00 => vec![
                 CheckCode::U001,
@@ -897,6 +957,7 @@ impl CheckCodePrefix {
                 CheckCode::U006,
                 CheckCode::U007,
                 CheckCode::U008,
+                CheckCode::U009,
             ],
             CheckCodePrefix::U001 => vec![CheckCode::U001],
             CheckCodePrefix::U002 => vec![CheckCode::U002],
@@ -906,6 +967,7 @@ impl CheckCodePrefix {
             CheckCodePrefix::U006 => vec![CheckCode::U006],
             CheckCodePrefix::U007 => vec![CheckCode::U007],
             CheckCodePrefix::U008 => vec![CheckCode::U008],
+            CheckCodePrefix::U009 => vec![CheckCode::U009],
             CheckCodePrefix::W => vec![CheckCode::W292, CheckCode::W605],
             CheckCodePrefix::W2 => vec![CheckCode::W292],
             CheckCodePrefix::W29 => vec![CheckCode::W292],
@@ -926,6 +988,23 @@ impl CheckCodePrefix {
             CheckCodePrefix::A001 => PrefixSpecificity::Explicit,
             CheckCodePrefix::A002 => PrefixSpecificity::Explicit,
             CheckCodePrefix::A003 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN => PrefixSpecificity::Category,
+            CheckCodePrefix::ANN0 => PrefixSpecificity::Hundreds,
+            CheckCodePrefix::ANN00 => PrefixSpecificity::Tens,
+            CheckCodePrefix::ANN001 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN002 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN003 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN1 => PrefixSpecificity::Hundreds,
+            CheckCodePrefix::ANN10 => PrefixSpecificity::Tens,
+            CheckCodePrefix::ANN101 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN102 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN2 => PrefixSpecificity::Hundreds,
+            CheckCodePrefix::ANN20 => PrefixSpecificity::Tens,
+            CheckCodePrefix::ANN201 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN202 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN204 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN205 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::ANN206 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B => PrefixSpecificity::Category,
             CheckCodePrefix::B0 => PrefixSpecificity::Hundreds,
             CheckCodePrefix::B00 => PrefixSpecificity::Tens,
@@ -1143,6 +1222,7 @@ impl CheckCodePrefix {
             CheckCodePrefix::U006 => PrefixSpecificity::Explicit,
             CheckCodePrefix::U007 => PrefixSpecificity::Explicit,
             CheckCodePrefix::U008 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::U009 => PrefixSpecificity::Explicit,
             CheckCodePrefix::W => PrefixSpecificity::Category,
             CheckCodePrefix::W2 => PrefixSpecificity::Hundreds,
             CheckCodePrefix::W29 => PrefixSpecificity::Tens,

src/cli.rs

@@ -10,7 +10,7 @@ use crate::checks_gen::CheckCodePrefix;
 use crate::logging::LogLevel;
 use crate::printer::SerializationFormat;
 use crate::settings::configuration::Configuration;
-use crate::settings::types::{PatternPrefixPair, PythonVersion};
+use crate::settings::types::{PatternPrefixPair, PerFileIgnore, PythonVersion};
 
 #[derive(Debug, Parser)]
 #[command(author, about = "ruff: An extremely fast Python linter.")]
@@ -168,7 +168,8 @@ pub fn warn_on(
 /// Collect a list of `PatternPrefixPair` structs as a `BTreeMap`.
 pub fn collect_per_file_ignores(
     pairs: Vec<PatternPrefixPair>,
-) -> BTreeMap<String, Vec<CheckCodePrefix>> {
+    project_root: &Option<PathBuf>,
+) -> Vec<PerFileIgnore> {
     let mut per_file_ignores: BTreeMap<String, Vec<CheckCodePrefix>> = BTreeMap::new();
     for pair in pairs {
         per_file_ignores
@@ -177,4 +178,7 @@ pub fn collect_per_file_ignores(
             .push(pair.prefix);
     }
     per_file_ignores
+        .iter()
+        .map(|(pattern, prefixes)| PerFileIgnore::new(pattern, prefixes, project_root))
+        .collect()
 }

src/cst/matchers.rs

@@ -1,5 +1,5 @@
 use anyhow::Result;
-use libcst_native::Module;
+use libcst_native::{Expr, Module, SmallStatement, Statement};
 
 pub fn match_module(module_text: &str) -> Result<Module> {
     match libcst_native::parse_module(module_text, None) {
@@ -7,3 +7,15 @@ pub fn match_module(module_text: &str) -> Result<Module> {
         Err(_) => Err(anyhow::anyhow!("Failed to extract CST from source.")),
     }
 }
+
+pub fn match_expr<'a, 'b>(module: &'a mut Module<'b>) -> Result<&'a mut Expr<'b>> {
+    if let Some(Statement::Simple(expr)) = module.body.first_mut() {
+        if let Some(SmallStatement::Expr(expr)) = expr.body.first_mut() {
+            Ok(expr)
+        } else {
+            Err(anyhow::anyhow!("Expected node to be: SmallStatement::Expr"))
+        }
+    } else {
+        Err(anyhow::anyhow!("Expected node to be: Statement::Simple"))
+    }
+}

src/flake8_annotations/mod.rs

@@ -0,0 +1,131 @@
+pub mod plugins;
+pub mod settings;
+
+#[cfg(test)]
+mod tests {
+    use std::path::Path;
+
+    use anyhow::Result;
+    use rustpython_parser::lexer::LexResult;
+
+    use crate::autofix::fixer;
+    use crate::checks::{Check, CheckCode};
+    use crate::linter::tokenize;
+    use crate::{flake8_annotations, fs, linter, noqa, Settings, SourceCodeLocator};
+
+    fn check_path(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> Result<Vec<Check>> {
+        let contents = fs::read_file(path)?;
+        let tokens: Vec<LexResult> = tokenize(&contents);
+        let locator = SourceCodeLocator::new(&contents);
+        let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
+        linter::check_path(
+            path,
+            &contents,
+            tokens,
+            &locator,
+            &noqa_line_for,
+            settings,
+            autofix,
+        )
+    }
+
+    #[test]
+    fn defaults() -> Result<()> {
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_annotations/annotation_presence.py"),
+            &Settings {
+                ..Settings::for_rules(vec![
+                    CheckCode::ANN001,
+                    CheckCode::ANN002,
+                    CheckCode::ANN003,
+                    CheckCode::ANN101,
+                    CheckCode::ANN102,
+                    CheckCode::ANN201,
+                    CheckCode::ANN202,
+                    CheckCode::ANN204,
+                    CheckCode::ANN205,
+                    CheckCode::ANN206,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(checks);
+        Ok(())
+    }
+
+    #[test]
+    fn suppress_dummy_args() -> Result<()> {
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_annotations/suppress_dummy_args.py"),
+            &Settings {
+                flake8_annotations: flake8_annotations::settings::Settings {
+                    mypy_init_return: false,
+                    suppress_dummy_args: true,
+                    suppress_none_returning: false,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::ANN001,
+                    CheckCode::ANN002,
+                    CheckCode::ANN003,
+                    CheckCode::ANN101,
+                    CheckCode::ANN102,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(checks);
+        Ok(())
+    }
+
+    #[test]
+    fn mypy_init_return() -> Result<()> {
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_annotations/mypy_init_return.py"),
+            &Settings {
+                flake8_annotations: flake8_annotations::settings::Settings {
+                    mypy_init_return: true,
+                    suppress_dummy_args: false,
+                    suppress_none_returning: false,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::ANN201,
+                    CheckCode::ANN202,
+                    CheckCode::ANN204,
+                    CheckCode::ANN205,
+                    CheckCode::ANN206,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(checks);
+        Ok(())
+    }
+
+    #[test]
+    fn suppress_none_returning() -> Result<()> {
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_annotations/suppress_none_returning.py"),
+            &Settings {
+                flake8_annotations: flake8_annotations::settings::Settings {
+                    mypy_init_return: false,
+                    suppress_dummy_args: false,
+                    suppress_none_returning: true,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::ANN201,
+                    CheckCode::ANN202,
+                    CheckCode::ANN204,
+                    CheckCode::ANN205,
+                    CheckCode::ANN206,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(checks);
+        Ok(())
+    }
+}

src/flake8_annotations/plugins.rs

@@ -0,0 +1,326 @@
+use rustpython_ast::{Arguments, Constant, Expr, ExprKind, Stmt, StmtKind};
+
+use crate::ast::types::Range;
+use crate::ast::visitor;
+use crate::ast::visitor::Visitor;
+use crate::check_ast::Checker;
+use crate::checks::{CheckCode, CheckKind};
+use crate::docstrings::definition::{Definition, DefinitionKind};
+use crate::visibility::Visibility;
+use crate::{visibility, Check};
+
+#[derive(Default)]
+struct ReturnStatementVisitor<'a> {
+    returns: Vec<&'a Option<Box<Expr>>>,
+}
+
+impl<'a, 'b> Visitor<'b> for ReturnStatementVisitor<'a>
+where
+    'b: 'a,
+{
+    fn visit_stmt(&mut self, stmt: &'b Stmt) {
+        match &stmt.node {
+            StmtKind::FunctionDef { .. } | StmtKind::AsyncFunctionDef { .. } => {
+                // No recurse.
+            }
+            StmtKind::Return { value } => self.returns.push(value),
+            _ => visitor::walk_stmt(self, stmt),
+        }
+    }
+}
+
+fn is_none_returning(stmt: &Stmt) -> bool {
+    let mut visitor: ReturnStatementVisitor = Default::default();
+    for stmt in match_body(stmt) {
+        visitor.visit_stmt(stmt);
+    }
+    for expr in visitor.returns.into_iter().flatten() {
+        if !matches!(
+            expr.node,
+            ExprKind::Constant {
+                value: Constant::None,
+                ..
+            }
+        ) {
+            return false;
+        }
+    }
+    true
+}
+
+fn match_args(stmt: &Stmt) -> &Arguments {
+    match &stmt.node {
+        StmtKind::FunctionDef { args, .. } | StmtKind::AsyncFunctionDef { args, .. } => args,
+        _ => panic!("Found non-FunctionDef in match_args"),
+    }
+}
+
+fn match_body(stmt: &Stmt) -> &Vec<Stmt> {
+    match &stmt.node {
+        StmtKind::FunctionDef { body, .. } | StmtKind::AsyncFunctionDef { body, .. } => body,
+        _ => panic!("Found non-FunctionDef in match_body"),
+    }
+}
+
+fn match_returns(stmt: &Stmt) -> &Option<Box<Expr>> {
+    match &stmt.node {
+        StmtKind::FunctionDef { returns, .. } | StmtKind::AsyncFunctionDef { returns, .. } => {
+            returns
+        }
+        _ => panic!("Found non-FunctionDef in match_returns"),
+    }
+}
+
+/// Generate flake8-annotation checks for a given `Definition`.
+pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &Visibility) {
+    match &definition.kind {
+        DefinitionKind::Module => {}
+        DefinitionKind::Package => {}
+        DefinitionKind::Class(_) => {}
+        DefinitionKind::NestedClass(_) => {}
+        DefinitionKind::Function(stmt) | DefinitionKind::NestedFunction(stmt) => {
+            let args = match_args(stmt);
+            let returns = match_returns(stmt);
+
+            // ANN001
+            for arg in args
+                .args
+                .iter()
+                .chain(args.posonlyargs.iter())
+                .chain(args.kwonlyargs.iter())
+            {
+                if arg.node.annotation.is_none() {
+                    if !(checker.settings.flake8_annotations.suppress_dummy_args
+                        && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
+                    {
+                        if checker.settings.enabled.contains(&CheckCode::ANN001) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingTypeFunctionArgument,
+                                Range::from_located(arg),
+                            ));
+                        }
+                    }
+                }
+            }
+
+            // ANN002
+            if let Some(arg) = &args.vararg {
+                if arg.node.annotation.is_none() {
+                    if !(checker.settings.flake8_annotations.suppress_dummy_args
+                        && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
+                    {
+                        if checker.settings.enabled.contains(&CheckCode::ANN002) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingTypeArgs,
+                                Range::from_located(arg),
+                            ));
+                        }
+                    }
+                }
+            }
+
+            // ANN003
+            if let Some(arg) = &args.kwarg {
+                if arg.node.annotation.is_none() {
+                    if !(checker.settings.flake8_annotations.suppress_dummy_args
+                        && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
+                    {
+                        if checker.settings.enabled.contains(&CheckCode::ANN003) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingTypeKwargs,
+                                Range::from_located(arg),
+                            ));
+                        }
+                    }
+                }
+            }
+
+            // ANN201, ANN202
+            if returns.is_none() {
+                // Allow omission of return annotation in `__init__` functions, if the function
+                // only returns `None` (explicitly or implicitly).
+                if checker.settings.flake8_annotations.suppress_none_returning
+                    && is_none_returning(stmt)
+                {
+                    return;
+                }
+
+                match visibility {
+                    Visibility::Public => {
+                        if checker.settings.enabled.contains(&CheckCode::ANN201) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingReturnTypePublicFunction,
+                                Range::from_located(stmt),
+                            ));
+                        }
+                    }
+                    Visibility::Private => {
+                        if checker.settings.enabled.contains(&CheckCode::ANN202) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingReturnTypePrivateFunction,
+                                Range::from_located(stmt),
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+        DefinitionKind::Method(stmt) => {
+            let args = match_args(stmt);
+            let returns = match_returns(stmt);
+            let mut has_any_typed_arg = false;
+
+            // ANN001
+            for arg in args
+                .args
+                .iter()
+                .chain(args.posonlyargs.iter())
+                .chain(args.kwonlyargs.iter())
+                .skip(
+                    // If this is a non-static method, skip `cls` or `self`.
+                    usize::from(!visibility::is_staticmethod(stmt)),
+                )
+            {
+                if arg.node.annotation.is_none() {
+                    if !(checker.settings.flake8_annotations.suppress_dummy_args
+                        && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
+                    {
+                        if checker.settings.enabled.contains(&CheckCode::ANN001) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingTypeFunctionArgument,
+                                Range::from_located(arg),
+                            ));
+                        }
+                    }
+                } else {
+                    has_any_typed_arg = true;
+                }
+            }
+
+            // ANN002
+            if let Some(arg) = &args.vararg {
+                if arg.node.annotation.is_none() {
+                    if !(checker.settings.flake8_annotations.suppress_dummy_args
+                        && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
+                    {
+                        if checker.settings.enabled.contains(&CheckCode::ANN002) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingTypeArgs,
+                                Range::from_located(arg),
+                            ));
+                        }
+                    }
+                } else {
+                    has_any_typed_arg = true;
+                }
+            }
+
+            // ANN003
+            if let Some(arg) = &args.kwarg {
+                if arg.node.annotation.is_none() {
+                    if !(checker.settings.flake8_annotations.suppress_dummy_args
+                        && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
+                    {
+                        if checker.settings.enabled.contains(&CheckCode::ANN003) {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingTypeKwargs,
+                                Range::from_located(arg),
+                            ));
+                        }
+                    }
+                } else {
+                    has_any_typed_arg = true;
+                }
+            }
+
+            // ANN101, ANN102
+            if !visibility::is_staticmethod(stmt) {
+                if let Some(arg) = args.args.first() {
+                    if arg.node.annotation.is_none() {
+                        if visibility::is_classmethod(stmt) {
+                            if checker.settings.enabled.contains(&CheckCode::ANN101) {
+                                checker.add_check(Check::new(
+                                    CheckKind::MissingTypeCls,
+                                    Range::from_located(arg),
+                                ));
+                            }
+                        } else {
+                            if checker.settings.enabled.contains(&CheckCode::ANN102) {
+                                checker.add_check(Check::new(
+                                    CheckKind::MissingTypeSelf,
+                                    Range::from_located(arg),
+                                ));
+                            }
+                        }
+                    }
+                }
+            }
+
+            // ANN201, ANN202
+            if returns.is_none() {
+                // Allow omission of return annotation in `__init__` functions, if the function
+                // only returns `None` (explicitly or implicitly).
+                if checker.settings.flake8_annotations.suppress_none_returning
+                    && is_none_returning(stmt)
+                {
+                    return;
+                }
+
+                if visibility::is_classmethod(stmt) {
+                    if checker.settings.enabled.contains(&CheckCode::ANN206) {
+                        checker.add_check(Check::new(
+                            CheckKind::MissingReturnTypeClassMethod,
+                            Range::from_located(stmt),
+                        ));
+                    }
+                } else if visibility::is_staticmethod(stmt) {
+                    if checker.settings.enabled.contains(&CheckCode::ANN205) {
+                        checker.add_check(Check::new(
+                            CheckKind::MissingReturnTypeStaticMethod,
+                            Range::from_located(stmt),
+                        ));
+                    }
+                } else if visibility::is_magic(stmt) {
+                    if checker.settings.enabled.contains(&CheckCode::ANN204) {
+                        checker.add_check(Check::new(
+                            CheckKind::MissingReturnTypeMagicMethod,
+                            Range::from_located(stmt),
+                        ));
+                    }
+                } else if visibility::is_init(stmt) {
+                    // Allow omission of return annotation in `__init__` functions, as long as at
+                    // least one argument is typed.
+                    if checker.settings.enabled.contains(&CheckCode::ANN204) {
+                        if !(checker.settings.flake8_annotations.mypy_init_return
+                            && has_any_typed_arg)
+                        {
+                            checker.add_check(Check::new(
+                                CheckKind::MissingReturnTypeMagicMethod,
+                                Range::from_located(stmt),
+                            ));
+                        }
+                    }
+                } else {
+                    match visibility {
+                        Visibility::Public => {
+                            if checker.settings.enabled.contains(&CheckCode::ANN201) {
+                                checker.add_check(Check::new(
+                                    CheckKind::MissingReturnTypePublicFunction,
+                                    Range::from_located(stmt),
+                                ));
+                            }
+                        }
+                        Visibility::Private => {
+                            if checker.settings.enabled.contains(&CheckCode::ANN202) {
+                                checker.add_check(Check::new(
+                                    CheckKind::MissingReturnTypePrivateFunction,
+                                    Range::from_located(stmt),
+                                ));
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/flake8_annotations/settings.rs

@@ -0,0 +1,36 @@
+//! Settings for the `flake-annotations` plugin.
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(deny_unknown_fields, rename_all = "kebab-case")]
+pub struct Options {
+    /// Allow omission of a return type hint for `__init__` if at least one
+    /// argument is annotated.
+    pub mypy_init_return: Option<bool>,
+    /// Suppress ANN000-level errors for dummy arguments, like `_`.
+    pub suppress_dummy_args: Option<bool>,
+    /// Suppress ANN200-level errors for functions that meet one of the
+    /// following criteria:
+    /// - Contain no `return` statement
+    /// - Explicit `return` statement(s) all return `None` (explicitly or
+    ///   implicitly).
+    pub suppress_none_returning: Option<bool>,
+}
+
+#[derive(Debug, Hash, Default)]
+pub struct Settings {
+    pub mypy_init_return: bool,
+    pub suppress_dummy_args: bool,
+    pub suppress_none_returning: bool,
+}
+
+impl Settings {
+    pub fn from_options(options: Options) -> Self {
+        Self {
+            mypy_init_return: options.mypy_init_return.unwrap_or_default(),
+            suppress_dummy_args: options.suppress_dummy_args.unwrap_or_default(),
+            suppress_none_returning: options.suppress_none_returning.unwrap_or_default(),
+        }
+    }
+}

src/flake8_annotations/snapshots/ruff__flake8_annotations__tests__defaults.snap

@@ -0,0 +1,69 @@
+---
+source: src/flake8_annotations/mod.rs
+expression: checks
+---
+- kind: MissingReturnTypePublicFunction
+  location:
+    row: 2
+    column: 0
+  end_location:
+    row: 7
+    column: 0
+  fix: ~
+- kind: MissingTypeFunctionArgument
+  location:
+    row: 2
+    column: 8
+  end_location:
+    row: 2
+    column: 9
+  fix: ~
+- kind: MissingTypeFunctionArgument
+  location:
+    row: 2
+    column: 11
+  end_location:
+    row: 2
+    column: 12
+  fix: ~
+- kind: MissingReturnTypePublicFunction
+  location:
+    row: 7
+    column: 0
+  end_location:
+    row: 12
+    column: 0
+  fix: ~
+- kind: MissingTypeFunctionArgument
+  location:
+    row: 7
+    column: 16
+  end_location:
+    row: 7
+    column: 17
+  fix: ~
+- kind: MissingTypeFunctionArgument
+  location:
+    row: 12
+    column: 16
+  end_location:
+    row: 12
+    column: 17
+  fix: ~
+- kind: MissingReturnTypePublicFunction
+  location:
+    row: 17
+    column: 0
+  end_location:
+    row: 22
+    column: 0
+  fix: ~
+- kind: MissingReturnTypePublicFunction
+  location:
+    row: 22
+    column: 0
+  end_location:
+    row: 27
+    column: 0
+  fix: ~
+

src/flake8_annotations/snapshots/ruff__flake8_annotations__tests__mypy_init_return.snap

@@ -0,0 +1,29 @@
+---
+source: src/flake8_annotations/mod.rs
+expression: checks
+---
+- kind: MissingReturnTypeMagicMethod
+  location:
+    row: 5
+    column: 4
+  end_location:
+    row: 10
+    column: 0
+  fix: ~
+- kind: MissingReturnTypeMagicMethod
+  location:
+    row: 11
+    column: 4
+  end_location:
+    row: 16
+    column: 0
+  fix: ~
+- kind: MissingReturnTypePrivateFunction
+  location:
+    row: 40
+    column: 0
+  end_location:
+    row: 42
+    column: 0
+  fix: ~
+

src/flake8_annotations/snapshots/ruff__flake8_annotations__tests__suppress_dummy_args.snap

@@ -0,0 +1,6 @@
+---
+source: src/flake8_annotations/mod.rs
+expression: checks
+---
+[]
+

src/flake8_annotations/snapshots/ruff__flake8_annotations__tests__suppress_none_returning.snap

@@ -0,0 +1,21 @@
+---
+source: src/flake8_annotations/mod.rs
+expression: checks
+---
+- kind: MissingReturnTypePublicFunction
+  location:
+    row: 45
+    column: 0
+  end_location:
+    row: 50
+    column: 0
+  fix: ~
+- kind: MissingReturnTypePublicFunction
+  location:
+    row: 50
+    column: 0
+  end_location:
+    row: 56
+    column: 0
+  fix: ~
+

src/flake8_bugbear/plugins/assert_false.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Stmt, StmtKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::autofix::Fix;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
@@ -42,10 +42,7 @@ pub fn assert_false(checker: &mut Checker, stmt: &Stmt, test: &Expr, msg: &Optio
         ..
     } = &test.node
     {
-        let mut check = Check::new(
-            CheckKind::DoNotAssertFalse,
-            checker.locate_check(Range::from_located(test)),
-        );
+        let mut check = Check::new(CheckKind::DoNotAssertFalse, Range::from_located(test));
         if checker.patch() {
             let mut generator = SourceGenerator::new();
             if let Ok(()) = generator.unparse_stmt(&assertion_error(msg)) {

src/flake8_bugbear/plugins/assert_raises_exception.rs

@@ -1,7 +1,7 @@
 use rustpython_ast::{ExprKind, Stmt, Withitem};
 
 use crate::ast::helpers::match_name_or_attr;
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -17,7 +17,7 @@ pub fn assert_raises_exception(checker: &mut Checker, stmt: &Stmt, items: &[With
             {
                 checker.add_check(Check::new(
                     CheckKind::NoAssertRaisesException,
-                    checker.locate_check(Range::from_located(stmt)),
+                    Range::from_located(stmt),
                 ));
             }
         }

src/flake8_bugbear/plugins/assignment_to_os_environ.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Expr, ExprKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -14,7 +14,7 @@ pub fn assignment_to_os_environ(checker: &mut Checker, targets: &[Expr]) {
                     if id == "os" {
                         checker.add_check(Check::new(
                             CheckKind::AssignmentToOsEnviron,
-                            checker.locate_check(Range::from_located(target)),
+                            Range::from_located(target),
                         ));
                     }
                 }

src/flake8_bugbear/plugins/cannot_raise_literal.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Expr, ExprKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -9,7 +9,7 @@ pub fn cannot_raise_literal(checker: &mut Checker, expr: &Expr) {
     if let ExprKind::Constant { .. } = &expr.node {
         checker.add_check(Check::new(
             CheckKind::CannotRaiseLiteral,
-            checker.locate_check(Range::from_located(expr)),
+            Range::from_located(expr),
         ));
     }
 }

src/flake8_bugbear/plugins/duplicate_exceptions.rs

@@ -4,7 +4,7 @@ use itertools::Itertools;
 use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind, Stmt};
 
 use crate::ast::helpers;
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::autofix::Fix;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckCode, CheckKind};
@@ -47,7 +47,7 @@ pub fn duplicate_handler_exceptions(
                 CheckKind::DuplicateHandlerException(
                     duplicates.into_iter().sorted().collect::<Vec<String>>(),
                 ),
-                checker.locate_check(Range::from_located(expr)),
+                Range::from_located(expr),
             );
             if checker.patch() {
                 // TODO(charlie): If we have a single element, remove the tuple.
@@ -106,7 +106,7 @@ pub fn duplicate_exceptions(checker: &mut Checker, stmt: &Stmt, handlers: &[Exce
         for duplicate in duplicates.into_iter().sorted() {
             checker.add_check(Check::new(
                 CheckKind::DuplicateTryBlockException(duplicate),
-                checker.locate_check(Range::from_located(stmt)),
+                Range::from_located(stmt),
             ));
         }
     }

src/flake8_bugbear/plugins/function_call_argument_default.rs

@@ -1,7 +1,7 @@
 use rustpython_ast::{Arguments, Constant, Expr, ExprKind};
 
 use crate::ast::helpers::compose_call_path;
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::ast::visitor;
 use crate::ast::visitor::Visitor;
 use crate::check_ast::Checker;
@@ -91,6 +91,6 @@ pub fn function_call_argument_default(checker: &mut Checker, arguments: &Argumen
         visitor.visit_expr(expr);
     }
     for (check, range) in visitor.checks {
-        checker.add_check(Check::new(check, checker.locate_check(range)));
+        checker.add_check(Check::new(check, range));
     }
 }

src/flake8_bugbear/plugins/mutable_argument_default.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Arguments, Expr, ExprKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -45,14 +45,14 @@ pub fn mutable_argument_default(checker: &mut Checker, arguments: &Arguments) {
             | ExprKind::SetComp { .. } => {
                 checker.add_check(Check::new(
                     CheckKind::MutableArgumentDefault,
-                    checker.locate_check(Range::from_located(expr)),
+                    Range::from_located(expr),
                 ));
             }
             ExprKind::Call { func, .. } => {
                 if is_mutable_func(func) {
                     checker.add_check(Check::new(
                         CheckKind::MutableArgumentDefault,
-                        checker.locate_check(Range::from_located(expr)),
+                        Range::from_located(expr),
                     ));
                 }
             }

src/flake8_bugbear/plugins/redundant_tuple_in_exception_handler.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Excepthandler, ExcepthandlerKind, ExprKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -13,7 +13,7 @@ pub fn redundant_tuple_in_exception_handler(checker: &mut Checker, handlers: &[E
                 if elts.len() == 1 {
                     checker.add_check(Check::new(
                         CheckKind::RedundantTupleInExceptionHandler(elts[0].to_string()),
-                        checker.locate_check(Range::from_located(type_)),
+                        Range::from_located(type_),
                     ));
                 }
             }

src/flake8_bugbear/plugins/unary_prefix_increment.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Expr, ExprKind, Unaryop};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -11,7 +11,7 @@ pub fn unary_prefix_increment(checker: &mut Checker, expr: &Expr, op: &Unaryop,
             if matches!(op, Unaryop::UAdd) {
                 checker.add_check(Check::new(
                     CheckKind::UnaryPrefixIncrement,
-                    checker.locate_check(Range::from_located(expr)),
+                    Range::from_located(expr),
                 ))
             }
         }

src/flake8_bugbear/plugins/unused_loop_control_variable.rs

@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 
 use rustpython_ast::{Expr, ExprKind, Stmt};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::ast::visitor;
 use crate::ast::visitor::Visitor;
 use crate::autofix::Fix;
@@ -64,7 +64,7 @@ pub fn unused_loop_control_variable(checker: &mut Checker, target: &Expr, body:
 
         let mut check = Check::new(
             CheckKind::UnusedLoopControlVariable(name.to_string()),
-            checker.locate_check(Range::from_located(expr)),
+            Range::from_located(expr),
         );
         if checker.patch() {
             // Prefix the variable name with an underscore.

src/flake8_bugbear/plugins/useless_comparison.rs

@@ -1,14 +1,14 @@
-use rustpython_ast::{Expr, Stmt, StmtKind};
+use rustpython_ast::{Expr, ExprKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
-pub fn useless_comparison(checker: &mut Checker, expr: &Expr, parent: &Stmt) {
-    if let StmtKind::Expr { .. } = &parent.node {
+pub fn useless_comparison(checker: &mut Checker, expr: &Expr) {
+    if let ExprKind::Compare { left, .. } = &expr.node {
         checker.add_check(Check::new(
             CheckKind::UselessComparison,
-            checker.locate_check(Range::from_located(expr)),
+            Range::from_located(left),
         ));
     }
 }

src/flake8_bugbear/plugins/useless_expression.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Constant, ExprKind, Stmt, StmtKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -12,7 +12,7 @@ pub fn useless_expression(checker: &mut Checker, body: &[Stmt]) {
                 ExprKind::List { .. } | ExprKind::Dict { .. } | ExprKind::Set { .. } => {
                     checker.add_check(Check::new(
                         CheckKind::UselessExpression,
-                        checker.locate_check(Range::from_located(value)),
+                        Range::from_located(value),
                     ));
                 }
                 ExprKind::Constant { value: val, .. } => match &val {
@@ -20,7 +20,7 @@ pub fn useless_expression(checker: &mut Checker, body: &[Stmt]) {
                     _ => {
                         checker.add_check(Check::new(
                             CheckKind::UselessExpression,
-                            checker.locate_check(Range::from_located(value)),
+                            Range::from_located(value),
                         ));
                     }
                 },

src/flake8_comprehensions/fixes.rs

@@ -1,28 +1,15 @@
 use anyhow::Result;
 use libcst_native::{
     Arg, Call, Codegen, Dict, DictComp, DictElement, Element, Expr, Expression, LeftCurlyBrace,
-    LeftParen, LeftSquareBracket, List, ListComp, Module, Name, ParenthesizableWhitespace,
-    RightCurlyBrace, RightParen, RightSquareBracket, Set, SetComp, SimpleString, SimpleWhitespace,
-    SmallStatement, Statement, Tuple,
+    LeftParen, LeftSquareBracket, List, ListComp, Name, ParenthesizableWhitespace, RightCurlyBrace,
+    RightParen, RightSquareBracket, Set, SetComp, SimpleString, SimpleWhitespace, Tuple,
 };
 
 use crate::ast::types::Range;
 use crate::autofix::Fix;
-use crate::cst::matchers::match_module;
+use crate::cst::matchers::{match_expr, match_module};
 use crate::source_code_locator::SourceCodeLocator;
 
-fn match_expr<'a, 'b>(module: &'a mut Module<'b>) -> Result<&'a mut Expr<'b>> {
-    if let Some(Statement::Simple(expr)) = module.body.first_mut() {
-        if let Some(SmallStatement::Expr(expr)) = expr.body.first_mut() {
-            Ok(expr)
-        } else {
-            Err(anyhow::anyhow!("Expected node to be: SmallStatement::Expr"))
-        }
-    } else {
-        Err(anyhow::anyhow!("Expected node to be: Statement::Simple"))
-    }
-}
-
 fn match_call<'a, 'b>(expr: &'a mut Expr<'b>) -> Result<&'a mut Call<'b>> {
     if let Expression::Call(call) = &mut expr.value {
         Ok(call)

src/flake8_print/plugins/print_call.rs

@@ -1,7 +1,7 @@
 use log::error;
 use rustpython_ast::{Expr, Stmt, StmtKind};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::autofix::helpers;
 use crate::check_ast::Checker;
 use crate::checks::CheckCode;
@@ -13,7 +13,7 @@ pub fn print_call(checker: &mut Checker, expr: &Expr, func: &Expr) {
         func,
         checker.settings.enabled.contains(&CheckCode::T201),
         checker.settings.enabled.contains(&CheckCode::T203),
-        checker.locate_check(Range::from_located(expr)),
+        Range::from_located(expr),
     ) {
         if checker.patch() {
             let context = checker.binding_context();

src/flake8_quotes/checks.rs

@@ -135,172 +135,3 @@ pub fn quotes(
 
     None
 }
-
-#[cfg(test)]
-mod tests {
-    use std::path::Path;
-
-    use anyhow::Result;
-    use rustpython_parser::lexer::LexResult;
-    use test_case::test_case;
-
-    use crate::autofix::fixer;
-    use crate::checks::{Check, CheckCode};
-    use crate::flake8_quotes::settings::Quote;
-    use crate::linter::tokenize;
-    use crate::{flake8_quotes, fs, linter, noqa, Settings, SourceCodeLocator};
-
-    fn check_path(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> Result<Vec<Check>> {
-        let contents = fs::read_file(path)?;
-        let tokens: Vec<LexResult> = tokenize(&contents);
-        let locator = SourceCodeLocator::new(&contents);
-        let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
-        linter::check_path(
-            path,
-            &contents,
-            tokens,
-            &locator,
-            &noqa_line_for,
-            settings,
-            autofix,
-        )
-    }
-
-    #[test_case(Path::new("doubles.py"))]
-    #[test_case(Path::new("doubles_escaped.py"))]
-    #[test_case(Path::new("doubles_multiline_string.py"))]
-    #[test_case(Path::new("doubles_noqa.py"))]
-    #[test_case(Path::new("doubles_wrapped.py"))]
-    fn doubles(path: &Path) -> Result<()> {
-        let snapshot = format!("doubles_{}", path.to_string_lossy());
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/flake8_quotes")
-                .join(path)
-                .as_path(),
-            &Settings {
-                flake8_quotes: flake8_quotes::settings::Settings {
-                    inline_quotes: Quote::Single,
-                    multiline_quotes: Quote::Single,
-                    docstring_quotes: Quote::Single,
-                    avoid_escape: true,
-                },
-                ..Settings::for_rules(vec![
-                    CheckCode::Q000,
-                    CheckCode::Q001,
-                    CheckCode::Q002,
-                    CheckCode::Q003,
-                ])
-            },
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(snapshot, checks);
-        Ok(())
-    }
-
-    #[test_case(Path::new("singles.py"))]
-    #[test_case(Path::new("singles_escaped.py"))]
-    #[test_case(Path::new("singles_multiline_string.py"))]
-    #[test_case(Path::new("singles_noqa.py"))]
-    #[test_case(Path::new("singles_wrapped.py"))]
-    fn singles(path: &Path) -> Result<()> {
-        let snapshot = format!("singles_{}", path.to_string_lossy());
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/flake8_quotes")
-                .join(path)
-                .as_path(),
-            &Settings {
-                flake8_quotes: flake8_quotes::settings::Settings {
-                    inline_quotes: Quote::Double,
-                    multiline_quotes: Quote::Double,
-                    docstring_quotes: Quote::Double,
-                    avoid_escape: true,
-                },
-                ..Settings::for_rules(vec![
-                    CheckCode::Q000,
-                    CheckCode::Q001,
-                    CheckCode::Q002,
-                    CheckCode::Q003,
-                ])
-            },
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(snapshot, checks);
-        Ok(())
-    }
-
-    #[test_case(Path::new("docstring_doubles.py"))]
-    #[test_case(Path::new("docstring_doubles_module_multiline.py"))]
-    #[test_case(Path::new("docstring_doubles_module_singleline.py"))]
-    #[test_case(Path::new("docstring_doubles_class.py"))]
-    #[test_case(Path::new("docstring_doubles_function.py"))]
-    #[test_case(Path::new("docstring_singles.py"))]
-    #[test_case(Path::new("docstring_singles_module_multiline.py"))]
-    #[test_case(Path::new("docstring_singles_module_singleline.py"))]
-    #[test_case(Path::new("docstring_singles_class.py"))]
-    #[test_case(Path::new("docstring_singles_function.py"))]
-    fn double_docstring(path: &Path) -> Result<()> {
-        let snapshot = format!("double_docstring_{}", path.to_string_lossy());
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/flake8_quotes")
-                .join(path)
-                .as_path(),
-            &Settings {
-                flake8_quotes: flake8_quotes::settings::Settings {
-                    inline_quotes: Quote::Single,
-                    multiline_quotes: Quote::Single,
-                    docstring_quotes: Quote::Double,
-                    avoid_escape: true,
-                },
-                ..Settings::for_rules(vec![
-                    CheckCode::Q000,
-                    CheckCode::Q001,
-                    CheckCode::Q002,
-                    CheckCode::Q003,
-                ])
-            },
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(snapshot, checks);
-        Ok(())
-    }
-
-    #[test_case(Path::new("docstring_doubles.py"))]
-    #[test_case(Path::new("docstring_doubles_module_multiline.py"))]
-    #[test_case(Path::new("docstring_doubles_module_singleline.py"))]
-    #[test_case(Path::new("docstring_doubles_class.py"))]
-    #[test_case(Path::new("docstring_doubles_function.py"))]
-    #[test_case(Path::new("docstring_singles.py"))]
-    #[test_case(Path::new("docstring_singles_module_multiline.py"))]
-    #[test_case(Path::new("docstring_singles_module_singleline.py"))]
-    #[test_case(Path::new("docstring_singles_class.py"))]
-    #[test_case(Path::new("docstring_singles_function.py"))]
-    fn single_docstring(path: &Path) -> Result<()> {
-        let snapshot = format!("single_docstring_{}", path.to_string_lossy());
-        let mut checks = check_path(
-            Path::new("./resources/test/fixtures/flake8_quotes")
-                .join(path)
-                .as_path(),
-            &Settings {
-                flake8_quotes: flake8_quotes::settings::Settings {
-                    inline_quotes: Quote::Single,
-                    multiline_quotes: Quote::Double,
-                    docstring_quotes: Quote::Single,
-                    avoid_escape: true,
-                },
-                ..Settings::for_rules(vec![
-                    CheckCode::Q000,
-                    CheckCode::Q001,
-                    CheckCode::Q002,
-                    CheckCode::Q003,
-                ])
-            },
-            &fixer::Mode::Generate,
-        )?;
-        checks.sort_by_key(|check| check.location);
-        insta::assert_yaml_snapshot!(snapshot, checks);
-        Ok(())
-    }
-}

src/flake8_quotes/mod.rs

@@ -1,2 +1,171 @@
 pub mod checks;
 pub mod settings;
+
+#[cfg(test)]
+mod tests {
+    use std::path::Path;
+
+    use anyhow::Result;
+    use rustpython_parser::lexer::LexResult;
+    use test_case::test_case;
+
+    use crate::autofix::fixer;
+    use crate::checks::{Check, CheckCode};
+    use crate::flake8_quotes::settings::Quote;
+    use crate::linter::tokenize;
+    use crate::{flake8_quotes, fs, linter, noqa, Settings, SourceCodeLocator};
+
+    fn check_path(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> Result<Vec<Check>> {
+        let contents = fs::read_file(path)?;
+        let tokens: Vec<LexResult> = tokenize(&contents);
+        let locator = SourceCodeLocator::new(&contents);
+        let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
+        linter::check_path(
+            path,
+            &contents,
+            tokens,
+            &locator,
+            &noqa_line_for,
+            settings,
+            autofix,
+        )
+    }
+
+    #[test_case(Path::new("doubles.py"))]
+    #[test_case(Path::new("doubles_escaped.py"))]
+    #[test_case(Path::new("doubles_multiline_string.py"))]
+    #[test_case(Path::new("doubles_noqa.py"))]
+    #[test_case(Path::new("doubles_wrapped.py"))]
+    fn doubles(path: &Path) -> Result<()> {
+        let snapshot = format!("doubles_{}", path.to_string_lossy());
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_quotes")
+                .join(path)
+                .as_path(),
+            &Settings {
+                flake8_quotes: flake8_quotes::settings::Settings {
+                    inline_quotes: Quote::Single,
+                    multiline_quotes: Quote::Single,
+                    docstring_quotes: Quote::Single,
+                    avoid_escape: true,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::Q000,
+                    CheckCode::Q001,
+                    CheckCode::Q002,
+                    CheckCode::Q003,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(snapshot, checks);
+        Ok(())
+    }
+
+    #[test_case(Path::new("singles.py"))]
+    #[test_case(Path::new("singles_escaped.py"))]
+    #[test_case(Path::new("singles_multiline_string.py"))]
+    #[test_case(Path::new("singles_noqa.py"))]
+    #[test_case(Path::new("singles_wrapped.py"))]
+    fn singles(path: &Path) -> Result<()> {
+        let snapshot = format!("singles_{}", path.to_string_lossy());
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_quotes")
+                .join(path)
+                .as_path(),
+            &Settings {
+                flake8_quotes: flake8_quotes::settings::Settings {
+                    inline_quotes: Quote::Double,
+                    multiline_quotes: Quote::Double,
+                    docstring_quotes: Quote::Double,
+                    avoid_escape: true,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::Q000,
+                    CheckCode::Q001,
+                    CheckCode::Q002,
+                    CheckCode::Q003,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(snapshot, checks);
+        Ok(())
+    }
+
+    #[test_case(Path::new("docstring_doubles.py"))]
+    #[test_case(Path::new("docstring_doubles_module_multiline.py"))]
+    #[test_case(Path::new("docstring_doubles_module_singleline.py"))]
+    #[test_case(Path::new("docstring_doubles_class.py"))]
+    #[test_case(Path::new("docstring_doubles_function.py"))]
+    #[test_case(Path::new("docstring_singles.py"))]
+    #[test_case(Path::new("docstring_singles_module_multiline.py"))]
+    #[test_case(Path::new("docstring_singles_module_singleline.py"))]
+    #[test_case(Path::new("docstring_singles_class.py"))]
+    #[test_case(Path::new("docstring_singles_function.py"))]
+    fn double_docstring(path: &Path) -> Result<()> {
+        let snapshot = format!("double_docstring_{}", path.to_string_lossy());
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_quotes")
+                .join(path)
+                .as_path(),
+            &Settings {
+                flake8_quotes: flake8_quotes::settings::Settings {
+                    inline_quotes: Quote::Single,
+                    multiline_quotes: Quote::Single,
+                    docstring_quotes: Quote::Double,
+                    avoid_escape: true,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::Q000,
+                    CheckCode::Q001,
+                    CheckCode::Q002,
+                    CheckCode::Q003,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(snapshot, checks);
+        Ok(())
+    }
+
+    #[test_case(Path::new("docstring_doubles.py"))]
+    #[test_case(Path::new("docstring_doubles_module_multiline.py"))]
+    #[test_case(Path::new("docstring_doubles_module_singleline.py"))]
+    #[test_case(Path::new("docstring_doubles_class.py"))]
+    #[test_case(Path::new("docstring_doubles_function.py"))]
+    #[test_case(Path::new("docstring_singles.py"))]
+    #[test_case(Path::new("docstring_singles_module_multiline.py"))]
+    #[test_case(Path::new("docstring_singles_module_singleline.py"))]
+    #[test_case(Path::new("docstring_singles_class.py"))]
+    #[test_case(Path::new("docstring_singles_function.py"))]
+    fn single_docstring(path: &Path) -> Result<()> {
+        let snapshot = format!("single_docstring_{}", path.to_string_lossy());
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/flake8_quotes")
+                .join(path)
+                .as_path(),
+            &Settings {
+                flake8_quotes: flake8_quotes::settings::Settings {
+                    inline_quotes: Quote::Single,
+                    multiline_quotes: Quote::Double,
+                    docstring_quotes: Quote::Single,
+                    avoid_escape: true,
+                },
+                ..Settings::for_rules(vec![
+                    CheckCode::Q000,
+                    CheckCode::Q001,
+                    CheckCode::Q002,
+                    CheckCode::Q003,
+                ])
+            },
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(snapshot, checks);
+        Ok(())
+    }
+}

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_doubles.py.snap

@@ -0,0 +1,50 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 5
+    column: 0
+  end_location:
+    row: 7
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 16
+    column: 4
+  end_location:
+    row: 18
+    column: 7
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 21
+    column: 20
+  end_location:
+    row: 22
+    column: 37
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 30
+    column: 8
+  end_location:
+    row: 32
+    column: 11
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 35
+    column: 12
+  end_location:
+    row: 37
+    column: 15
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_doubles_class.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 3
+    column: 4
+  end_location:
+    row: 3
+    column: 27
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 5
+    column: 22
+  end_location:
+    row: 5
+    column: 43
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_doubles_function.py.snap

@@ -0,0 +1,50 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 3
+    column: 4
+  end_location:
+    row: 3
+    column: 26
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 11
+    column: 4
+  end_location:
+    row: 11
+    column: 26
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 15
+    column: 38
+  end_location:
+    row: 17
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 17
+    column: 4
+  end_location:
+    row: 17
+    column: 19
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 21
+    column: 4
+  end_location:
+    row: 21
+    column: 27
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_doubles_module_multiline.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 4
+    column: 0
+  end_location:
+    row: 6
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 9
+    column: 0
+  end_location:
+    row: 11
+    column: 3
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_doubles_module_singleline.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 2
+    column: 0
+  end_location:
+    row: 2
+    column: 31
+  fix: ~
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 6
+    column: 0
+  end_location:
+    row: 6
+    column: 31
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_singles.py.snap

@@ -0,0 +1,32 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 3
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 14
+    column: 4
+  end_location:
+    row: 16
+    column: 7
+  fix: ~
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 26
+    column: 8
+  end_location:
+    row: 28
+    column: 11
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_singles_class.py.snap

@@ -0,0 +1,32 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 2
+    column: 53
+  fix: ~
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 6
+    column: 8
+  end_location:
+    row: 6
+    column: 57
+  fix: ~
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 9
+    column: 28
+  end_location:
+    row: 9
+    column: 52
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_singles_function.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 2
+    column: 56
+  fix: ~
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 8
+    column: 4
+  end_location:
+    row: 10
+    column: 7
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_singles_module_multiline.py.snap

@@ -0,0 +1,14 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 3
+    column: 3
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__double_docstring_docstring_singles_module_singleline.py.snap

@@ -0,0 +1,14 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: double
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 1
+    column: 49
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__doubles_doubles.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesInlineString: single
+  location:
+    row: 1
+    column: 24
+  end_location:
+    row: 1
+    column: 45
+  fix: ~
+- kind:
+    BadQuotesInlineString: single
+  location:
+    row: 2
+    column: 24
+  end_location:
+    row: 2
+    column: 46
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__doubles_doubles_escaped.py.snap

@@ -0,0 +1,13 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind: AvoidQuoteEscape
+  location:
+    row: 1
+    column: 25
+  end_location:
+    row: 1
+    column: 47
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__doubles_doubles_multiline_string.py.snap

@@ -0,0 +1,14 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: single
+  location:
+    row: 1
+    column: 4
+  end_location:
+    row: 3
+    column: 12
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__doubles_doubles_noqa.py.snap

@@ -0,0 +1,6 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+[]
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__doubles_doubles_wrapped.py.snap

@@ -0,0 +1,6 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+[]
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_doubles.py.snap

@@ -0,0 +1,32 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 3
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 12
+    column: 4
+  end_location:
+    row: 14
+    column: 7
+  fix: ~
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 24
+    column: 8
+  end_location:
+    row: 26
+    column: 11
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_doubles_class.py.snap

@@ -0,0 +1,32 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 2
+    column: 53
+  fix: ~
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 6
+    column: 8
+  end_location:
+    row: 6
+    column: 57
+  fix: ~
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 9
+    column: 28
+  end_location:
+    row: 9
+    column: 52
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_doubles_function.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 2
+    column: 56
+  fix: ~
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 8
+    column: 4
+  end_location:
+    row: 10
+    column: 7
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_doubles_module_multiline.py.snap

@@ -0,0 +1,14 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 3
+    column: 3
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_doubles_module_singleline.py.snap

@@ -0,0 +1,14 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesDocstring: single
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 1
+    column: 49
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_singles.py.snap

@@ -0,0 +1,59 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 5
+    column: 0
+  end_location:
+    row: 7
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 11
+    column: 20
+  end_location:
+    row: 13
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 18
+    column: 4
+  end_location:
+    row: 20
+    column: 7
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 23
+    column: 20
+  end_location:
+    row: 24
+    column: 37
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 32
+    column: 8
+  end_location:
+    row: 34
+    column: 11
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 37
+    column: 12
+  end_location:
+    row: 39
+    column: 15
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_singles_class.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 3
+    column: 4
+  end_location:
+    row: 3
+    column: 27
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 5
+    column: 22
+  end_location:
+    row: 5
+    column: 43
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_singles_function.py.snap

@@ -0,0 +1,50 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 3
+    column: 4
+  end_location:
+    row: 3
+    column: 26
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 11
+    column: 4
+  end_location:
+    row: 11
+    column: 26
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 15
+    column: 38
+  end_location:
+    row: 17
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 17
+    column: 4
+  end_location:
+    row: 17
+    column: 19
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 21
+    column: 4
+  end_location:
+    row: 21
+    column: 27
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_singles_module_multiline.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 4
+    column: 0
+  end_location:
+    row: 6
+    column: 3
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 9
+    column: 0
+  end_location:
+    row: 11
+    column: 3
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__single_docstring_docstring_singles_module_singleline.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 2
+    column: 0
+  end_location:
+    row: 2
+    column: 31
+  fix: ~
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 6
+    column: 0
+  end_location:
+    row: 6
+    column: 31
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__singles_singles.py.snap

@@ -0,0 +1,23 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesInlineString: double
+  location:
+    row: 1
+    column: 24
+  end_location:
+    row: 1
+    column: 45
+  fix: ~
+- kind:
+    BadQuotesInlineString: double
+  location:
+    row: 2
+    column: 24
+  end_location:
+    row: 2
+    column: 46
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__singles_singles_escaped.py.snap

@@ -0,0 +1,13 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind: AvoidQuoteEscape
+  location:
+    row: 1
+    column: 25
+  end_location:
+    row: 1
+    column: 47
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__singles_singles_multiline_string.py.snap

@@ -0,0 +1,14 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+- kind:
+    BadQuotesMultilineString: double
+  location:
+    row: 1
+    column: 4
+  end_location:
+    row: 3
+    column: 12
+  fix: ~
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__singles_singles_noqa.py.snap

@@ -0,0 +1,6 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+[]
+

src/flake8_quotes/snapshots/ruff__flake8_quotes__tests__singles_singles_wrapped.py.snap

@@ -0,0 +1,6 @@
+---
+source: src/flake8_quotes/mod.rs
+expression: checks
+---
+[]
+

src/lib.rs

@@ -25,6 +25,7 @@ pub mod cli;
 pub mod code_gen;
 mod cst;
 mod docstrings;
+pub mod flake8_annotations;
 mod flake8_bugbear;
 mod flake8_builtins;
 mod flake8_comprehensions;

src/linter.rs

@@ -439,6 +439,10 @@ mod tests {
     #[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::U009, Path::new("U009_0.py"); "U009_0")]
+    #[test_case(CheckCode::U009, Path::new("U009_1.py"); "U009_1")]
+    #[test_case(CheckCode::U009, Path::new("U009_2.py"); "U009_2")]
+    #[test_case(CheckCode::U009, Path::new("U009_3.py"); "U009_3")]
     #[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")]

src/main.rs

@@ -1,4 +1,3 @@
-use std::collections::BTreeMap;
 use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 use std::process::ExitCode;
@@ -8,7 +7,6 @@ use std::time::Instant;
 #[cfg(not(target_family = "wasm"))]
 use ::ruff::cache;
 use ::ruff::checks::{CheckCode, CheckKind};
-use ::ruff::checks_gen::CheckCodePrefix;
 use ::ruff::cli::{collect_per_file_ignores, extract_log_level, warn_on, Cli, Warnable};
 use ::ruff::fs::iter_python_files;
 use ::ruff::linter::{add_noqa_to_path, autoformat_path, lint_path, lint_stdin};
@@ -252,8 +250,6 @@ fn inner_main() -> Result<ExitCode> {
         .iter()
         .map(|path| FilePattern::from_user(path, &project_root))
         .collect();
-    let per_file_ignores: BTreeMap<String, Vec<CheckCodePrefix>> =
-        collect_per_file_ignores(cli.per_file_ignores);
 
     let mut configuration = Configuration::from_pyproject(&pyproject, &project_root)?;
     if !exclude.is_empty() {
@@ -262,8 +258,9 @@ fn inner_main() -> Result<ExitCode> {
     if !extend_exclude.is_empty() {
         configuration.extend_exclude = extend_exclude;
     }
-    if !per_file_ignores.is_empty() {
-        configuration.per_file_ignores = per_file_ignores;
+    if !cli.per_file_ignores.is_empty() {
+        configuration.per_file_ignores =
+            collect_per_file_ignores(cli.per_file_ignores, &project_root);
     }
     if !cli.select.is_empty() {
         warn_on(

src/pep8_naming/checks.rs

@@ -1,8 +1,9 @@
-use itertools::Itertools;
 use rustpython_ast::{Arguments, Expr, ExprKind, Stmt};
 
 use crate::ast::types::{FunctionScope, Range, Scope, ScopeKind};
 use crate::checks::{Check, CheckKind};
+use crate::pep8_naming::helpers;
+use crate::pep8_naming::helpers::FunctionType;
 use crate::pep8_naming::settings::Settings;
 
 /// N801
@@ -25,7 +26,7 @@ pub fn invalid_class_name(class_def: &Stmt, name: &str) -> Option<Check> {
 
 /// N802
 pub fn invalid_function_name(func_def: &Stmt, name: &str, settings: &Settings) -> Option<Check> {
-    if !is_lower(name)
+    if name.to_lowercase() != name
         && !settings
             .ignore_names
             .iter()
@@ -40,8 +41,8 @@ pub fn invalid_function_name(func_def: &Stmt, name: &str, settings: &Settings) -
 }
 
 /// N803
-pub fn invalid_argument_name(location: Range, name: &str) -> Option<Check> {
-    if !is_lower(name) {
+pub fn invalid_argument_name(name: &str, location: Range) -> Option<Check> {
+    if name.to_lowercase() != name {
         return Some(Check::new(
             CheckKind::InvalidArgumentName(name.to_string()),
             location,
@@ -53,21 +54,15 @@ pub fn invalid_argument_name(location: Range, name: &str) -> Option<Check> {
 /// N804
 pub fn invalid_first_argument_name_for_class_method(
     scope: &Scope,
+    name: &str,
     decorator_list: &[Expr],
     args: &Arguments,
     settings: &Settings,
 ) -> Option<Check> {
-    if !matches!(scope.kind, ScopeKind::Class) {
-        return None;
-    }
-
-    if decorator_list.iter().any(|decorator| {
-        if let ExprKind::Name { id, .. } = &decorator.node {
-            settings.classmethod_decorators.contains(id)
-        } else {
-            false
-        }
-    }) {
+    if matches!(
+        helpers::function_type(scope, name, decorator_list, settings),
+        FunctionType::ClassMethod
+    ) {
         if let Some(arg) = args.args.first() {
             if arg.node.arg != "cls" {
                 return Some(Check::new(
@@ -83,31 +78,22 @@ pub fn invalid_first_argument_name_for_class_method(
 /// N805
 pub fn invalid_first_argument_name_for_method(
     scope: &Scope,
+    name: &str,
     decorator_list: &[Expr],
     args: &Arguments,
     settings: &Settings,
 ) -> Option<Check> {
-    if !matches!(scope.kind, ScopeKind::Class) {
-        return None;
-    }
-
-    if decorator_list.iter().any(|decorator| {
-        if let ExprKind::Name { id, .. } = &decorator.node {
-            settings.classmethod_decorators.contains(id)
-                || settings.staticmethod_decorators.contains(id)
-        } else {
-            false
-        }
-    }) {
-        return None;
-    }
-
-    if let Some(arg) = args.args.first() {
-        if arg.node.arg != "self" {
-            return Some(Check::new(
-                CheckKind::InvalidFirstArgumentNameForMethod,
-                Range::from_located(arg),
-            ));
+    if matches!(
+        helpers::function_type(scope, name, decorator_list, settings),
+        FunctionType::Method
+    ) {
+        if let Some(arg) = args.args.first() {
+            if arg.node.arg != "self" {
+                return Some(Check::new(
+                    CheckKind::InvalidFirstArgumentNameForMethod,
+                    Range::from_located(arg),
+                ));
+            }
         }
     }
     None
@@ -128,18 +114,16 @@ pub fn non_lowercase_variable_in_function(scope: &Scope, expr: &Expr, name: &str
 }
 
 /// N807
-pub fn dunder_function_name(func_def: &Stmt, scope: &Scope, name: &str) -> Option<Check> {
-    if matches!(scope.kind, ScopeKind::Class) {
+pub fn dunder_function_name(scope: &Scope, stmt: &Stmt, name: &str) -> Option<Check> {
+    if matches!(scope.kind, ScopeKind::Class(_)) {
         return None;
     }
-
     if name.starts_with("__") && name.ends_with("__") {
         return Some(Check::new(
             CheckKind::DunderFunctionName,
-            Range::from_located(func_def),
+            Range::from_located(stmt),
         ));
     }
-
     None
 }
 
@@ -149,7 +133,7 @@ pub fn constant_imported_as_non_constant(
     name: &str,
     asname: &str,
 ) -> Option<Check> {
-    if is_upper(name) && !is_upper(asname) {
+    if helpers::is_upper(name) && !helpers::is_upper(asname) {
         return Some(Check::new(
             CheckKind::ConstantImportedAsNonConstant(name.to_string(), asname.to_string()),
             Range::from_located(import_from),
@@ -164,7 +148,7 @@ pub fn lowercase_imported_as_non_lowercase(
     name: &str,
     asname: &str,
 ) -> Option<Check> {
-    if is_lower(name) && asname.to_lowercase() != asname {
+    if !helpers::is_upper(name) && helpers::is_lower(name) && asname.to_lowercase() != asname {
         return Some(Check::new(
             CheckKind::LowercaseImportedAsNonLowercase(name.to_string(), asname.to_string()),
             Range::from_located(import_from),
@@ -179,7 +163,7 @@ pub fn camelcase_imported_as_lowercase(
     name: &str,
     asname: &str,
 ) -> Option<Check> {
-    if is_camelcase(name) && is_lower(asname) {
+    if helpers::is_camelcase(name) && helpers::is_lower(asname) {
         return Some(Check::new(
             CheckKind::CamelcaseImportedAsLowercase(name.to_string(), asname.to_string()),
             Range::from_located(import_from),
@@ -194,7 +178,11 @@ pub fn camelcase_imported_as_constant(
     name: &str,
     asname: &str,
 ) -> Option<Check> {
-    if is_camelcase(name) && is_upper(asname) && !is_acronym(name, asname) {
+    if helpers::is_camelcase(name)
+        && !helpers::is_lower(asname)
+        && helpers::is_upper(asname)
+        && !helpers::is_acronym(name, asname)
+    {
         return Some(Check::new(
             CheckKind::CamelcaseImportedAsConstant(name.to_string(), asname.to_string()),
             Range::from_located(import_from),
@@ -205,10 +193,10 @@ pub fn camelcase_imported_as_constant(
 
 /// N815
 pub fn mixed_case_variable_in_class_scope(scope: &Scope, expr: &Expr, name: &str) -> Option<Check> {
-    if !matches!(scope.kind, ScopeKind::Class) {
+    if !matches!(scope.kind, ScopeKind::Class(_)) {
         return None;
     }
-    if is_mixed_case(name) {
+    if helpers::is_mixed_case(name) {
         return Some(Check::new(
             CheckKind::MixedCaseVariableInClassScope(name.to_string()),
             Range::from_located(expr),
@@ -226,7 +214,7 @@ pub fn mixed_case_variable_in_global_scope(
     if !matches!(scope.kind, ScopeKind::Module) {
         return None;
     }
-    if is_mixed_case(name) {
+    if helpers::is_mixed_case(name) {
         return Some(Check::new(
             CheckKind::MixedCaseVariableInGlobalScope(name.to_string()),
             Range::from_located(expr),
@@ -241,7 +229,11 @@ pub fn camelcase_imported_as_acronym(
     name: &str,
     asname: &str,
 ) -> Option<Check> {
-    if is_camelcase(name) && is_upper(asname) && is_acronym(name, asname) {
+    if helpers::is_camelcase(name)
+        && !helpers::is_lower(asname)
+        && helpers::is_upper(asname)
+        && helpers::is_acronym(name, asname)
+    {
         return Some(Check::new(
             CheckKind::CamelcaseImportedAsAcronym(name.to_string(), asname.to_string()),
             Range::from_located(import_from),
@@ -272,101 +264,3 @@ pub fn error_suffix_on_exception_name(
     }
     None
 }
-
-fn is_lower(s: &str) -> bool {
-    let mut cased = false;
-    for c in s.chars() {
-        if c.is_uppercase() {
-            return false;
-        } else if !cased && c.is_lowercase() {
-            cased = true;
-        }
-    }
-    cased
-}
-
-fn is_upper(s: &str) -> bool {
-    let mut cased = false;
-    for c in s.chars() {
-        if c.is_lowercase() {
-            return false;
-        } else if (!cased) && c.is_uppercase() {
-            cased = true;
-        }
-    }
-    cased
-}
-
-fn is_camelcase(name: &str) -> bool {
-    !is_lower(name) && !is_upper(name) && !name.contains('_')
-}
-
-fn is_mixed_case(name: &str) -> bool {
-    !is_lower(name)
-        && name
-            .strip_prefix('_')
-            .unwrap_or(name)
-            .chars()
-            .next()
-            .map_or_else(|| false, |c| c.is_lowercase())
-}
-
-fn is_acronym(name: &str, asname: &str) -> bool {
-    name.chars().filter(|c| c.is_uppercase()).join("") == asname
-}
-
-#[cfg(test)]
-mod tests {
-    use super::{is_acronym, is_camelcase, is_lower, is_mixed_case, is_upper};
-
-    #[test]
-    fn test_is_lower() -> () {
-        assert!(is_lower("abc"));
-        assert!(is_lower("a_b_c"));
-        assert!(is_lower("a2c"));
-        assert!(!is_lower("aBc"));
-        assert!(!is_lower("ABC"));
-        assert!(!is_lower(""));
-        assert!(!is_lower("_"));
-    }
-
-    #[test]
-    fn test_is_upper() -> () {
-        assert!(is_upper("ABC"));
-        assert!(is_upper("A_B_C"));
-        assert!(is_upper("A2C"));
-        assert!(!is_upper("aBc"));
-        assert!(!is_upper("abc"));
-        assert!(!is_upper(""));
-        assert!(!is_upper("_"));
-    }
-
-    #[test]
-    fn test_is_camelcase() -> () {
-        assert!(is_camelcase("Camel"));
-        assert!(is_camelcase("CamelCase"));
-        assert!(!is_camelcase("camel"));
-        assert!(!is_camelcase("camel_case"));
-        assert!(!is_camelcase("CAMEL"));
-        assert!(!is_camelcase("CAMEL_CASE"));
-    }
-
-    #[test]
-    fn test_is_mixed_case() -> () {
-        assert!(is_mixed_case("mixedCase"));
-        assert!(is_mixed_case("mixed_Case"));
-        assert!(is_mixed_case("_mixed_Case"));
-        assert!(!is_mixed_case("mixed_case"));
-        assert!(!is_mixed_case("MIXED_CASE"));
-        assert!(!is_mixed_case(""));
-        assert!(!is_mixed_case("_"));
-    }
-
-    #[test]
-    fn test_is_acronym() -> () {
-        assert!(is_acronym("AB", "AB"));
-        assert!(is_acronym("AbcDef", "AD"));
-        assert!(!is_acronym("AbcDef", "Ad"));
-        assert!(!is_acronym("AbcDef", "AB"));
-    }
-}

src/pep8_naming/helpers.rs

@@ -0,0 +1,160 @@
+use itertools::Itertools;
+use rustpython_ast::{Expr, ExprKind};
+
+use crate::ast::helpers::match_name_or_attr;
+use crate::ast::types::{Scope, ScopeKind};
+use crate::pep8_naming::settings::Settings;
+
+const CLASS_METHODS: [&str; 3] = ["__new__", "__init_subclass__", "__class_getitem__"];
+const METACLASS_BASES: [&str; 2] = ["type", "ABCMeta"];
+
+pub enum FunctionType {
+    Function,
+    Method,
+    ClassMethod,
+    StaticMethod,
+}
+
+/// Classify a function based on its scope, name, and decorators.
+pub fn function_type(
+    scope: &Scope,
+    name: &str,
+    decorator_list: &[Expr],
+    settings: &Settings,
+) -> FunctionType {
+    if let ScopeKind::Class(scope) = &scope.kind {
+        // Special-case class method, like `__new__`.
+        if CLASS_METHODS.contains(&name)
+            // The class itself extends a known metaclass, so all methods are class methods.
+            || scope.bases.iter().any(|expr| {
+                METACLASS_BASES
+                    .iter()
+                    .any(|target| match_name_or_attr(expr, target))
+            })
+            // The method is decorated with a class method decorator (like `@classmethod`).
+            || decorator_list.iter().any(|expr| {
+            if let ExprKind::Name { id, .. } = &expr.node {
+                settings.classmethod_decorators.contains(id)
+            } else {
+                false
+            }
+        }) {
+            FunctionType::ClassMethod
+        } else if decorator_list.iter().any(|expr| {
+            if let ExprKind::Name { id, .. } = &expr.node {
+                settings.staticmethod_decorators.contains(id)
+            } else {
+                false
+            }
+        }) {
+            // The method is decorated with a static method decorator (like
+            // `@staticmethod`).
+            FunctionType::StaticMethod
+        } else {
+            // It's an instance method.
+            FunctionType::Method
+        }
+    } else {
+        FunctionType::Function
+    }
+}
+
+pub fn is_lower(s: &str) -> bool {
+    let mut cased = false;
+    for c in s.chars() {
+        if c.is_uppercase() {
+            return false;
+        } else if !cased && c.is_lowercase() {
+            cased = true;
+        }
+    }
+    cased
+}
+
+pub fn is_upper(s: &str) -> bool {
+    let mut cased = false;
+    for c in s.chars() {
+        if c.is_lowercase() {
+            return false;
+        } else if !cased && c.is_uppercase() {
+            cased = true;
+        }
+    }
+    cased
+}
+
+pub fn is_camelcase(name: &str) -> bool {
+    !is_lower(name) && !is_upper(name) && !name.contains('_')
+}
+
+pub fn is_mixed_case(name: &str) -> bool {
+    !is_lower(name)
+        && name
+            .strip_prefix('_')
+            .unwrap_or(name)
+            .chars()
+            .next()
+            .map_or_else(|| false, |c| c.is_lowercase())
+}
+
+pub fn is_acronym(name: &str, asname: &str) -> bool {
+    name.chars().filter(|c| c.is_uppercase()).join("") == asname
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::pep8_naming::helpers::{
+        is_acronym, is_camelcase, is_lower, is_mixed_case, is_upper,
+    };
+
+    #[test]
+    fn test_is_lower() -> () {
+        assert!(is_lower("abc"));
+        assert!(is_lower("a_b_c"));
+        assert!(is_lower("a2c"));
+        assert!(!is_lower("aBc"));
+        assert!(!is_lower("ABC"));
+        assert!(!is_lower(""));
+        assert!(!is_lower("_"));
+    }
+
+    #[test]
+    fn test_is_upper() -> () {
+        assert!(is_upper("ABC"));
+        assert!(is_upper("A_B_C"));
+        assert!(is_upper("A2C"));
+        assert!(!is_upper("aBc"));
+        assert!(!is_upper("abc"));
+        assert!(!is_upper(""));
+        assert!(!is_upper("_"));
+    }
+
+    #[test]
+    fn test_is_camelcase() -> () {
+        assert!(is_camelcase("Camel"));
+        assert!(is_camelcase("CamelCase"));
+        assert!(!is_camelcase("camel"));
+        assert!(!is_camelcase("camel_case"));
+        assert!(!is_camelcase("CAMEL"));
+        assert!(!is_camelcase("CAMEL_CASE"));
+    }
+
+    #[test]
+    fn test_is_mixed_case() -> () {
+        assert!(is_mixed_case("mixedCase"));
+        assert!(is_mixed_case("mixed_Case"));
+        assert!(is_mixed_case("_mixed_Case"));
+        assert!(!is_mixed_case("mixed_case"));
+        assert!(!is_mixed_case("MIXED_CASE"));
+        assert!(!is_mixed_case(""));
+        assert!(!is_mixed_case("_"));
+    }
+
+    #[test]
+    fn test_is_acronym() -> () {
+        assert!(is_acronym("AB", "AB"));
+        assert!(is_acronym("AbcDef", "AD"));
+        assert!(!is_acronym("AbcDef", "Ad"));
+        assert!(!is_acronym("AbcDef", "AB"));
+    }
+}

src/pep8_naming/mod.rs

@@ -1,2 +1,3 @@
 pub mod checks;
+mod helpers;
 pub mod settings;

src/pycodestyle/checks.rs

@@ -2,7 +2,7 @@ use itertools::izip;
 use rustpython_ast::Location;
 use rustpython_parser::ast::{Cmpop, Constant, Expr, ExprKind, Unaryop};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::checks::{Check, CheckKind, RejectedCmpop};
 use crate::source_code_locator::SourceCodeLocator;
 
@@ -61,7 +61,6 @@ pub fn not_tests(
     operand: &Expr,
     check_not_in: bool,
     check_not_is: bool,
-    locator: &dyn CheckLocator,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -73,7 +72,7 @@ pub fn not_tests(
                         if check_not_in {
                             checks.push(Check::new(
                                 CheckKind::NotInTest,
-                                locator.locate_check(Range::from_located(operand)),
+                                Range::from_located(operand),
                             ));
                         }
                     }
@@ -81,7 +80,7 @@ pub fn not_tests(
                         if check_not_is {
                             checks.push(Check::new(
                                 CheckKind::NotIsTest,
-                                locator.locate_check(Range::from_located(operand)),
+                                Range::from_located(operand),
                             ));
                         }
                     }
@@ -101,7 +100,6 @@ pub fn literal_comparisons(
     comparators: &[Expr],
     check_none_comparisons: bool,
     check_true_false_comparisons: bool,
-    locator: &dyn CheckLocator,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -121,13 +119,13 @@ pub fn literal_comparisons(
         if matches!(op, Cmpop::Eq) {
             checks.push(Check::new(
                 CheckKind::NoneComparison(RejectedCmpop::Eq),
-                locator.locate_check(Range::from_located(comparator)),
+                Range::from_located(comparator),
             ));
         }
         if matches!(op, Cmpop::NotEq) {
             checks.push(Check::new(
                 CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                locator.locate_check(Range::from_located(comparator)),
+                Range::from_located(comparator),
             ));
         }
     }
@@ -141,13 +139,13 @@ pub fn literal_comparisons(
             if matches!(op, Cmpop::Eq) {
                 checks.push(Check::new(
                     CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                    locator.locate_check(Range::from_located(comparator)),
+                    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)),
+                    Range::from_located(comparator),
                 ));
             }
         }
@@ -167,13 +165,13 @@ pub fn literal_comparisons(
             if matches!(op, Cmpop::Eq) {
                 checks.push(Check::new(
                     CheckKind::NoneComparison(RejectedCmpop::Eq),
-                    locator.locate_check(Range::from_located(comparator)),
+                    Range::from_located(comparator),
                 ));
             }
             if matches!(op, Cmpop::NotEq) {
                 checks.push(Check::new(
                     CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                    locator.locate_check(Range::from_located(comparator)),
+                    Range::from_located(comparator),
                 ));
             }
         }
@@ -187,13 +185,13 @@ pub fn literal_comparisons(
                 if matches!(op, Cmpop::Eq) {
                     checks.push(Check::new(
                         CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                        locator.locate_check(Range::from_located(comparator)),
+                        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)),
+                        Range::from_located(comparator),
                     ));
                 }
             }

src/pydocstyle/plugins.rs

@@ -13,7 +13,7 @@ use crate::docstrings::definition::{Definition, DefinitionKind};
 use crate::docstrings::helpers;
 use crate::docstrings::sections::{section_contexts, SectionContext};
 use crate::docstrings::styles::SectionStyle;
-use crate::visibility::{is_init, is_magic, is_overload, is_static, Visibility};
+use crate::visibility::{is_init, is_magic, is_overload, is_staticmethod, Visibility};
 
 /// D100, D101, D102, D103, D104, D105, D106, D107
 pub fn not_missing(
@@ -1308,7 +1308,8 @@ fn missing_args(checker: &mut Checker, definition: &Definition, docstrings_args:
                 .skip(
                     // If this is a non-static method, skip `cls` or `self`.
                     usize::from(
-                        matches!(definition.kind, DefinitionKind::Method(_)) && !is_static(parent),
+                        matches!(definition.kind, DefinitionKind::Method(_))
+                            && !is_staticmethod(parent),
                     ),
                 )
                 .collect();

src/pyflakes/checks.rs

@@ -1,13 +1,11 @@
 use std::collections::BTreeSet;
 
-use itertools::izip;
 use regex::Regex;
 use rustpython_parser::ast::{
-    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Stmt,
-    StmtKind,
+    Arg, Arguments, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Stmt, StmtKind,
 };
 
-use crate::ast::types::{BindingKind, CheckLocator, FunctionScope, Range, Scope, ScopeKind};
+use crate::ast::types::{BindingKind, FunctionScope, Range, Scope, ScopeKind};
 use crate::checks::{Check, CheckKind};
 
 /// F631
@@ -30,12 +28,30 @@ pub fn if_tuple(test: &Expr, location: Range) -> Option<Check> {
     None
 }
 
+/// F821
+pub fn undefined_local(scopes: &[&Scope], name: &str) -> Option<Check> {
+    let current = &scopes.last().expect("No current scope found.");
+    if matches!(current.kind, ScopeKind::Function(_)) && !current.values.contains_key(name) {
+        for scope in scopes.iter().rev().skip(1) {
+            if matches!(scope.kind, ScopeKind::Function(_) | ScopeKind::Module) {
+                if let Some(binding) = scope.values.get(name) {
+                    if let Some((scope_id, location)) = binding.used {
+                        if scope_id == current.id {
+                            return Some(Check::new(
+                                CheckKind::UndefinedLocal(name.to_string()),
+                                location,
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
 /// F841
-pub fn unused_variables(
-    scope: &Scope,
-    locator: &dyn CheckLocator,
-    dummy_variable_rgx: &Regex,
-) -> Vec<Check> {
+pub fn unused_variables(scope: &Scope, dummy_variable_rgx: &Regex) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
     if matches!(
@@ -55,7 +71,7 @@ pub fn unused_variables(
         {
             checks.push(Check::new(
                 CheckKind::UnusedVariable(name.to_string()),
-                locator.locate_check(binding.range),
+                binding.range,
             ));
         }
     }
@@ -131,7 +147,6 @@ pub fn repeated_keys(
     keys: &[Expr],
     check_repeated_literals: bool,
     check_repeated_variables: bool,
-    locator: &dyn CheckLocator,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -146,7 +161,7 @@ pub fn repeated_keys(
                     if check_repeated_literals && v1 == v2 {
                         checks.push(Check::new(
                             CheckKind::MultiValueRepeatedKeyLiteral,
-                            locator.locate_check(Range::from_located(k2)),
+                            Range::from_located(k2),
                         ))
                     }
                 }
@@ -154,7 +169,7 @@ pub fn repeated_keys(
                     if check_repeated_variables && v1 == v2 {
                         checks.push(Check::new(
                             CheckKind::MultiValueRepeatedKeyVariable((*v2).to_string()),
-                            locator.locate_check(Range::from_located(k2)),
+                            Range::from_located(k2),
                         ))
                     }
                 }
@@ -166,45 +181,6 @@ pub fn repeated_keys(
     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)
-}
-
-/// F632
-pub fn is_literal(left: &Expr, ops: &[Cmpop], comparators: &[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
-}
-
 /// F621, F622
 pub fn starred_expressions(
     elts: &[Expr],
@@ -236,12 +212,7 @@ pub fn starred_expressions(
 }
 
 /// F701
-pub fn break_outside_loop(
-    stmt: &Stmt,
-    parents: &[&Stmt],
-    parent_stack: &[usize],
-    locator: &dyn CheckLocator,
-) -> Option<Check> {
+pub fn break_outside_loop(stmt: &Stmt, parents: &[&Stmt], parent_stack: &[usize]) -> Option<Check> {
     let mut allowed: bool = false;
     let mut parent = stmt;
     for index in parent_stack.iter().rev() {
@@ -269,7 +240,7 @@ pub fn break_outside_loop(
     if !allowed {
         Some(Check::new(
             CheckKind::BreakOutsideLoop,
-            locator.locate_check(Range::from_located(stmt)),
+            Range::from_located(stmt),
         ))
     } else {
         None
@@ -281,7 +252,6 @@ pub fn continue_outside_loop(
     stmt: &Stmt,
     parents: &[&Stmt],
     parent_stack: &[usize],
-    locator: &dyn CheckLocator,
 ) -> Option<Check> {
     let mut allowed: bool = false;
     let mut parent = stmt;
@@ -310,7 +280,7 @@ pub fn continue_outside_loop(
     if !allowed {
         Some(Check::new(
             CheckKind::ContinueOutsideLoop,
-            locator.locate_check(Range::from_located(stmt)),
+            Range::from_located(stmt),
         ))
     } else {
         None

src/pyflakes/fixes.rs

@@ -1,11 +1,14 @@
 use anyhow::Result;
-use libcst_native::{Codegen, ImportNames, NameOrAttribute, SmallStatement, Statement};
+use libcst_native::{
+    Codegen, CompOp, Comparison, ComparisonTarget, Expr, Expression, ImportNames, NameOrAttribute,
+    SmallStatement, Statement,
+};
 use rustpython_ast::Stmt;
 
 use crate::ast::types::Range;
 use crate::autofix::{helpers, Fix};
 use crate::cst::helpers::compose_module_path;
-use crate::cst::matchers::match_module;
+use crate::cst::matchers::{match_expr, match_module};
 use crate::source_code_locator::SourceCodeLocator;
 
 /// Generate a Fix to remove any unused imports from an `import` statement.
@@ -138,3 +141,66 @@ pub fn remove_unused_import_froms(
         ))
     }
 }
+
+fn match_comparison<'a, 'b>(expr: &'a mut Expr<'b>) -> Result<&'a mut Comparison<'b>> {
+    if let Expression::Comparison(comparison) = &mut expr.value {
+        Ok(comparison)
+    } else {
+        Err(anyhow::anyhow!(
+            "Expected node to be: Expression::Comparison"
+        ))
+    }
+}
+
+/// Generate a Fix to replace invalid is/is not comparisons with equal/not equal
+pub fn fix_invalid_literal_comparison(locator: &SourceCodeLocator, location: Range) -> Result<Fix> {
+    let module_text = locator.slice_source_code_range(&location);
+    let mut tree = match_module(&module_text)?;
+    let mut expr = match_expr(&mut tree)?;
+    let cmp = match_comparison(expr)?;
+    let target = cmp
+        .comparisons
+        .get(0)
+        .ok_or_else(|| anyhow::anyhow!("Expected one ComparisonTarget"))?;
+
+    let new_operator = match &target.operator {
+        CompOp::Is {
+            whitespace_before: b,
+            whitespace_after: a,
+        } => Ok(CompOp::Equal {
+            whitespace_before: b.clone(),
+            whitespace_after: a.clone(),
+        }),
+        CompOp::IsNot {
+            whitespace_before: b,
+            whitespace_after: a,
+            whitespace_between: _,
+        } => Ok(CompOp::NotEqual {
+            whitespace_before: b.clone(),
+            whitespace_after: a.clone(),
+        }),
+        op => Err(anyhow::anyhow!(
+            "Unexpected operator: {:?}. Expected Is or IsNot.",
+            op
+        )),
+    }?;
+
+    expr.value = Expression::Comparison(Box::new(Comparison {
+        left: cmp.left.clone(),
+        comparisons: vec![ComparisonTarget {
+            operator: new_operator,
+            comparator: target.comparator.clone(),
+        }],
+        lpar: cmp.lpar.clone(),
+        rpar: cmp.rpar.clone(),
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        location.location,
+        location.end_location,
+    ))
+}

src/pyflakes/plugins/assert_tuple.rs

@@ -1,13 +1,12 @@
 use rustpython_ast::{Expr, Stmt};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::pyflakes::checks;
 
 /// F631
 pub fn assert_tuple(checker: &mut Checker, stmt: &Stmt, test: &Expr) {
-    if let Some(check) = checks::assert_tuple(test, checker.locate_check(Range::from_located(stmt)))
-    {
+    if let Some(check) = checks::assert_tuple(test, Range::from_located(stmt)) {
         checker.add_check(check);
     }
 }

src/pyflakes/plugins/if_tuple.rs

@@ -1,12 +1,12 @@
 use rustpython_ast::{Expr, Stmt};
 
-use crate::ast::types::{CheckLocator, Range};
+use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::pyflakes::checks;
 
 /// F634
 pub fn if_tuple(checker: &mut Checker, stmt: &Stmt, test: &Expr) {
-    if let Some(check) = checks::if_tuple(test, checker.locate_check(Range::from_located(stmt))) {
+    if let Some(check) = checks::if_tuple(test, Range::from_located(stmt)) {
         checker.add_check(check);
     }
 }

src/pyflakes/plugins/invalid_literal_comparisons.rs

@@ -0,0 +1,62 @@
+use itertools::izip;
+use log::error;
+use rustpython_ast::{Cmpop, Constant, Expr, ExprKind};
+
+use crate::ast::types::Range;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind};
+use crate::pyflakes::fixes::fix_invalid_literal_comparison;
+
+fn is_singleton(expr: &Expr) -> bool {
+    matches!(
+        expr.node,
+        ExprKind::Constant {
+            value: Constant::None | Constant::Bool(_) | Constant::Ellipsis,
+            ..
+        }
+    )
+}
+
+fn is_constant(expr: &Expr) -> bool {
+    match &expr.node {
+        ExprKind::Constant { .. } => true,
+        ExprKind::Tuple { elts, .. } => elts.iter().all(is_constant),
+        _ => false,
+    }
+}
+
+fn is_constant_non_singleton(expr: &Expr) -> bool {
+    is_constant(expr) && !is_singleton(expr)
+}
+
+/// F632
+pub fn invalid_literal_comparison(
+    checker: &mut Checker,
+    left: &Expr,
+    ops: &[Cmpop],
+    comparators: &[Expr],
+    location: Range,
+) {
+    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))
+        {
+            let mut check = Check::new(CheckKind::IsLiteral, location);
+            if checker.patch() {
+                match fix_invalid_literal_comparison(
+                    checker.locator,
+                    Range {
+                        location: left.location,
+                        end_location: right.end_location.unwrap(),
+                    },
+                ) {
+                    Ok(fix) => check.amend(fix),
+                    Err(e) => error!("Failed to fix invalid comparison: {}", e),
+                }
+            }
+            checker.add_check(check);
+        }
+        left = right;
+    }
+}