Bump version to 0.0.65

.editorconfig

@@ -0,0 +1,14 @@
+# Check http://editorconfig.org for more information
+# This is the main config file for this project:
+root = true
+
+[*]
+charset = utf-8
+trim_trailing_whitespace = true
+end_of_line = lf
+indent_style = space
+insert_final_newline = true
+indent_size = 2
+
+[*.{rs,py}]
+indent_size = 4

.pre-commit-config.yaml

@@ -3,3 +3,8 @@ repos:
     rev: v0.0.40
     hooks:
       - id: lint
+
+  - repo: https://github.com/abravalheri/validate-pyproject
+    rev: v0.10.1
+    hooks:
+      - id: validate-pyproject

CODE_OF_CONDUCT.md

@@ -0,0 +1,128 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, religion, or sexual identity
+and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the
+  overall community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or
+  advances of any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email
+  address, without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official e-mail address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+charlie.r.marsh@gmail.com.
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series
+of actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or
+permanent ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior,  harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within
+the community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.0, available at
+https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
+
+Community Impact Guidelines were inspired by [Mozilla's code of conduct
+enforcement ladder](https://github.com/mozilla/diversity).
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see the FAQ at
+https://www.contributor-covenant.org/faq. Translations are available at
+https://www.contributor-covenant.org/translations.

CONTRIBUTING.md

@@ -0,0 +1,111 @@
+# Contributing 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
+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 (1.63.0). You'll need to install the
+[Rust toolchain](https://www.rust-lang.org/tools/install) for development.
+
+You'll also need [Insta](https://insta.rs/docs/) to update snapshot tests:
+
+```shell
+cargo install cargo-insta
+```
+
+### Development
+
+After cloning the repository, run ruff locally with:
+
+```shell
+cargo run resources/test/fixtures --no-cache
+```
+
+Prior to opening a pull request, ensure that your code has been auto-formatted, and that it passes
+both the lint and test validation checks:
+
+```shell
+cargo fmt     # Auto-formatting...
+cargo clippy  # Linting...
+cargo test    # Testing...
+```
+
+These checks will run on GitHub Actions when you open your Pull Request, but running them locally
+will save you time and expedite the merge process.
+
+Your Pull Request will be reviewed by a maintainer, which may involve a few rounds of iteration
+prior to merging.
+
+### Example: Adding a new lint rule
+
+There are three 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).
+3. Add a test fixture.
+
+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
+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.
+
+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:
+
+```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(())
+}
+```
+
+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.
+
+### Example: Adding a new configuration option
+
+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.
+
+Ultimately, these two sources of configuration are merged into the `Settings` struct defined
+in `src/settings.rs`, which is then threaded through the codebase.
+
+To add a new configuration option, you'll likely want to _both_ add a CLI option to `src/main.rs`
+_and_ a `pyproject.toml` parameter to `src/pyproject.rs`. If you want to pattern-match against an
+existing example, grep for `dummy_variable_rgx`, which defines a regular expression to match against
+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
+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,
+even patch releases may contain [non-backwards-compatible changes](https://semver.org/#spec-item-4).

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.40"
+version = "0.0.65"
 edition = "2021"
 
 [lib]
@@ -11,27 +11,33 @@ anyhow = { version = "1.0.60" }
 bincode = { version = "1.3.3" }
 cacache = { version = "10.0.1" }
 chrono = { version = "0.4.21" }
-clap = { version = "3.2.16", features = ["derive"] }
+clap = { version = "4.0.1", features = ["derive"] }
 clearscreen = { version = "1.0.10" }
 colored = { version = "2.0.0" }
 common-path = { version = "1.0.0" }
 dirs = { version = "4.0.0" }
 fern = { version = "0.6.1" }
 filetime = { version = "0.2.17" }
-glob = "0.3.0"
-itertools = "0.10.3"
+glob = { version = "0.3.0" }
+itertools = { version = "0.10.5" }
+libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "32a044c127668df44582f85699358e67803b0d73" }
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
 once_cell = { version = "1.13.1" }
 path-absolutize = { version = "3.0.13", features = ["once_cell_cache"] }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "7d21c6923a506e79cc041708d83cef925efd33f4" }
+rustpython-ast = { features = ["unparse"], git = "https://github.com/charliermarsh/RustPython.git", rev = "778ae2aeb521d0438d2a91bd11238bb5c2bf9d4f" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "778ae2aeb521d0438d2a91bd11238bb5c2bf9d4f" }
+rustpython-common = { git = "https://github.com/charliermarsh/RustPython.git", rev = "778ae2aeb521d0438d2a91bd11238bb5c2bf9d4f" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }
 update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
 walkdir = { version = "2.3.2" }
+strum = { version = "0.24.1", features = ["strum_macros"] }
+strum_macros = "0.24.3"
+num-bigint = "0.4.3"
 
 [dev-dependencies]
 insta = { version = "1.19.1", features = ["yaml"] }

README.md

@@ -20,11 +20,9 @@ An extremely fast Python linter, written in Rust.
 - 🤝 Python 3.10 compatibility
 - 🛠️ `pyproject.toml` support
 - 📦 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired cache support
-- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired `--fix` support
+- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix)-inspired `--fix` support
 - 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` support
-
-_ruff is a proof-of-concept and not yet intended for production use. It supports only a small subset
-of the Flake8 rules, and may crash on your codebase._
+- ⚖️ [Near-complete parity](#Parity-with-Flake8) with the built-in Flake8 rule set
 
 Read the [launch blog post](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
 
@@ -59,7 +57,7 @@ ruff also works with [pre-commit](https://pre-commit.com):
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.40
+    rev: v0.0.48
     hooks:
       - id: lint
 ```
@@ -82,51 +80,66 @@ select = [
 Alternatively, on the command-line:
 
 ```shell
-ruff path/to/code/ --select F401 F403
+ruff path/to/code/ --select F401 --select F403
 ```
 
 See `ruff --help` for more:
 
 ```shell
-ruff (v0.0.40)
-An extremely fast Python linter.
+ruff: An extremely fast Python linter.
 
-USAGE:
-    ruff [OPTIONS] <FILES>...
+Usage: ruff [OPTIONS] <FILES>...
 
-ARGS:
-    <FILES>...
+Arguments:
+  <FILES>...
 
-OPTIONS:
-    -e, --exit-zero
-            Exit with status code "0", even upon detecting errors
-        --exclude <EXCLUDE>...
-            List of paths, used to exclude files and/or directories from checks
-        --extend-exclude <EXTEND_EXCLUDE>...
-            Like --exclude, but adds additional files and directories on top of the excluded ones
-    -f, --fix
-            Attempt to automatically fix lint errors
-        --format <FORMAT>
-            Output serialization format for error messages [default: text] [possible values: text,
-            json]
-    -h, --help
-            Print help information
-        --ignore <IGNORE>...
-            List of error codes to ignore
-    -n, --no-cache
-            Disable cache reads
-    -q, --quiet
-            Disable all logging (but still exit with status code "1" upon detecting errors)
-        --select <SELECT>...
-            List of error codes to enable
-    -v, --verbose
-            Enable verbose logging
-    -V, --version
-            Print version information
-    -w, --watch
-            Run in watch mode by re-running whenever files change
+Options:
+  -v, --verbose
+          Enable verbose logging
+  -q, --quiet
+          Disable all logging (but still exit with status code "1" upon detecting errors)
+  -e, --exit-zero
+          Exit with status code "0", even upon detecting errors
+  -w, --watch
+          Run in watch mode by re-running whenever files change
+  -f, --fix
+          Attempt to automatically fix lint errors
+  -n, --no-cache
+          Disable cache reads
+      --select <SELECT>
+          List of error codes to enable
+      --extend-select <EXTEND_SELECT>
+          Like --select, but adds additional error codes on top of the selected ones
+      --ignore <IGNORE>
+          List of error codes to ignore
+      --extend-ignore <EXTEND_IGNORE>
+          Like --ignore, but adds additional error codes on top of the ignored ones
+      --exclude <EXCLUDE>
+          List of paths, used to exclude files and/or directories from checks
+      --extend-exclude <EXTEND_EXCLUDE>
+          Like --exclude, but adds additional files and directories on top of the excluded ones
+      --per-file-ignores <PER_FILE_IGNORES>
+          List of mappings from file pattern to code to exclude
+      --format <FORMAT>
+          Output serialization format for error messages [default: text] [possible values: text, json]
+      --show-files
+          See the files ruff will be run against with the current settings
+      --show-settings
+          See ruff's settings
+      --add-noqa
+          Enable automatic additions of noqa directives to failing lines
+      --dummy-variable-rgx <DUMMY_VARIABLE_RGX>
+          Regular expression matching the name of dummy variables
+      --target-version <TARGET_VERSION>
+          The minimum Python version that should be supported
+  -h, --help
+          Print help information
+  -V, --version
+          Print version information
 ```
 
+### Excluding files
+
 Exclusions are based on globs, and can be either:
 
 - Single-path patterns, like `.mypy_cache` (to exclude any directory named `.mypy_cache` in the
@@ -136,82 +149,193 @@ Exclusions are based on globs, and can be either:
   (to exclude any Python files in `directory`). Note that these paths are relative to the
   project root (e.g., the directory containing your `pyproject.toml`).
 
+### Ignoring errors
+
+To omit a lint check entirely, add it to the "ignore" list via `--ignore` or `--extend-ignore`,
+either  on the command-line or in your `project.toml` file.
+
+To ignore an error in-line, ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
+To ignore an individual error, add `# noqa: {code}` to the end of the line, like so:
+
+```python
+# Ignore F841.
+x = 1  # noqa: F841
+
+# Ignore E741 and F841.
+i = 1  # noqa: E741, F841
+
+# Ignore _all_ errors.
+x = 1  # noqa
+```
+
+Note that, for multi-line strings, the `noqa` directive should come at the end of the string, and
+will apply to the entire body, like so:
+
+```python
+"""Lorem ipsum dolor sit amet.
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+"""  # noqa: E501
+```
+
+ruff supports several (experimental) workflows to aid in `noqa` management.
+
+First, ruff provides a special error code, `M001`, to enforce that your `noqa` directives are
+"valid", in that the errors they _say_ they ignore are actually being triggered on that line (and
+thus suppressed). **You can run `ruff /path/to/file.py --extend-select M001` to flag unused `noqa`
+directives.**
+
+Second, ruff can _automatically remove_ unused `noqa` directives via its autofix functionality.
+**You can run `ruff /path/to/file.py --extend-select M001 --fix` to automatically remove unused
+`noqa` directives.**
+
+Third, ruff can _automatically add_ `noqa` directives to all failing lines. This is useful when
+migrating a new codebase to ruff. **You can run `ruff /path/to/file.py --add-noqa` to automatically
+add `noqa` directives to all failing lines, with the appropriate error codes.**
+
 ### Compatibility with Black
 
-ruff is intended to be compatible with [Black](https://github.com/psf/black), and should be
-compatible out-of-the-box as long as the `line-length` setting is consistent between the two.
+ruff is compatible with [Black](https://github.com/psf/black) out-of-the-box, as long as
+the `line-length` setting is consistent between the two.
 
 As a project, ruff is designed to be used alongside Black and, as such, will defer implementing
-lint rules that are obviated by Black (e.g., stylistic rules).
+stylistic lint rules that are obviated by autoformatting.
 
 ### Parity with Flake8
 
-ruff's goal is to achieve feature-parity with Flake8 when used (1) without any plugins,
-(2) alongside Black, and (3) on Python 3 code. (Using Black obviates the need for many of Flake8's
-stylistic checks; limiting to Python 3 obviates the need for certain compatibility checks.)
+ruff's goal is to achieve feature parity with Flake8 when used (1) without plugins, (2) alongside
+Black, and (3) on Python 3 code.
 
-Under those conditions, Flake8 implements about 60 rules, give or take. At time of writing, ruff
-implements 42 rules. (Note that these 42 rules likely cover a disproportionate share of errors:
-unused imports, undefined variables, etc.)
+**Under those conditions, ruff implements 44 out of 60 rules.** (ruff is missing: 14 rules related
+to string `.format` calls, 1 rule related to docstring parsing, and 1 rule related to redefined
+variables.)
 
-The unimplemented rules are tracked in #170, and include:
+ruff also implements some of the most popular Flake8 plugins natively, including:
 
-- 14 rules related to string `.format` calls.
-- 4 logical rules.
-- 1 rule related to parsing.
+- [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
+- [`flake8-super`](https://pypi.org/project/flake8-super/)
+- [`flake8-print`](https://pypi.org/project/flake8-print/)
+- [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/) (partial)
+- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (partial)
 
 Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis Flake8:
 
-1. Flake8 supports a wider range of `noqa` patterns, such as per-file ignores defined in `.flake8`.
+1. ruff does not yet support a few Python 3.9 and 3.10 language features, including structural
+   pattern matching and parenthesized context managers.
 2. Flake8 has a plugin architecture and supports writing custom lint rules.
-3. ruff does not yet support parenthesized context managers.
 
 ## Rules
 
-| Code | Name | Message |
-| ---- | ----- | ------- |
-| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file |
-| E501 | LineTooLong | Line too long (89 > 88 characters) |
-| E711 | NoneComparison | Comparison to `None` should be `cond is None` |
-| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` |
-| E713 | NotInTest | Test for membership should be `not in` |
-| E714 | NotIsTest | Test for object identity should be `is not` |
-| E721 | TypeComparison | do not compare types, use `isinstance()` |
-| E722 | DoNotUseBareExcept | Do not use bare `except` |
-| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def |
-| E741 | AmbiguousVariableName | ambiguous variable name '...' |
-| E742 | AmbiguousClassName | ambiguous class name '...' |
-| E743 | AmbiguousFunctionName | ambiguous function name '...' |
-| E902 | IOError | No such file or directory: `...` |
-| E999 | SyntaxError | SyntaxError: ... |
-| F401 | UnusedImport | `...` imported but unused |
-| F403 | ImportStarUsage | `from ... import *` used; unable to detect undefined names |
-| F404 | LateFutureImport | from __future__ imports must occur at the beginning of the file |
-| F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level |
-| F407 | FutureFeatureNotDefined | future feature '...' is not defined |
-| F541 | FStringMissingPlaceholders | f-string without any placeholders |
-| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |
-| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |
-| F621 | TooManyExpressionsInStarredAssignment | too many expressions in star-unpacking assignment |
-| F622 | TwoStarredExpressions | two starred expressions in assignment |
-| F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |
-| F632 | IsLiteral | use ==/!= to compare constant literals |
-| F633 | InvalidPrintSyntax | use of >> is invalid with print function |
-| F634 | IfTuple | If test is a tuple, which is always `True` |
-| F701 | BreakOutsideLoop | `break` outside loop |
-| F702 | ContinueOutsideLoop | `continue` not properly in loop |
-| F704 | YieldOutsideFunction | a `yield` or `yield from` statement outside of a function/method |
-| F706 | ReturnOutsideFunction | a `return` statement outside of a function/method |
-| F707 | DefaultExceptNotLast | an `except:` block as not the last exception handler |
-| F722 | ForwardAnnotationSyntaxError | syntax error in forward annotation '...' |
-| F821 | UndefinedName | Undefined name `...` |
-| F822 | UndefinedExport | Undefined name `...` in `__all__` |
-| F823 | UndefinedLocal | Local variable `...` referenced before assignment |
-| F831 | DuplicateArgumentName | Duplicate argument name in function definition |
-| F841 | UnusedVariable | Local variable `...` is assigned to but never used |
-| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` |
-| R001 | UselessObjectInheritance | Class `...` inherits from object |
-| R002 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |
+The ✅ emoji indicates a rule is enabled by default.
+
+The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` command-line option.
+
+| Code | Name | Message |     |     |
+| ---- | ---- | ------- | --- | --- |
+| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file | ✅ |  |
+| E501 | LineTooLong | Line too long (89 > 88 characters) | ✅ |  |
+| E711 | NoneComparison | Comparison to `None` should be `cond is None` | ✅ |  |
+| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` | ✅ |  |
+| E713 | NotInTest | Test for membership should be `not in` | ✅ |  |
+| E714 | NotIsTest | Test for object identity should be `is not` | ✅ |  |
+| E721 | TypeComparison | Do not compare types, use `isinstance()` | ✅ |  |
+| E722 | DoNotUseBareExcept | Do not use bare `except` | ✅ |  |
+| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def | ✅ |  |
+| E741 | AmbiguousVariableName | Ambiguous variable name: `...` | ✅ |  |
+| E742 | AmbiguousClassName | Ambiguous class name: `...` | ✅ |  |
+| E743 | AmbiguousFunctionName | Ambiguous function name: `...` | ✅ |  |
+| E902 | IOError | IOError: `...` | ✅ |  |
+| E999 | SyntaxError | SyntaxError: `...` | ✅ |  |
+| W292 | NoNewLineAtEndOfFile | No newline at end of file | ✅ |  |
+| F401 | UnusedImport | `...` imported but unused | ✅ | 🛠 |
+| F402 | ImportShadowedByLoopVar | Import `...` from line 1 shadowed by loop variable | ✅ |  |
+| F403 | ImportStarUsed | `from ... import *` used; unable to detect undefined names | ✅ |  |
+| F404 | LateFutureImport | `from __future__` imports must occur at the beginning of the file | ✅ |  |
+| F405 | ImportStarUsage | `...` may be undefined, or defined from star imports: `...` | ✅ |  |
+| F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level | ✅ |  |
+| F407 | FutureFeatureNotDefined | Future feature `...` is not defined | ✅ |  |
+| F541 | FStringMissingPlaceholders | f-string without any placeholders | ✅ |  |
+| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated | ✅ |  |
+| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated | ✅ |  |
+| F621 | 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 | ✅ |  |
+| F633 | InvalidPrintSyntax | Use of `>>` is invalid with `print` function | ✅ |  |
+| F634 | IfTuple | If test is a tuple, which is always `True` | ✅ |  |
+| F701 | BreakOutsideLoop | `break` outside loop | ✅ |  |
+| F702 | ContinueOutsideLoop | `continue` not properly in loop | ✅ |  |
+| F704 | YieldOutsideFunction | `yield` or `yield from` statement outside of a function/method | ✅ |  |
+| F706 | ReturnOutsideFunction | `return` statement outside of a function/method | ✅ |  |
+| F707 | DefaultExceptNotLast | An `except:` block as not the last exception handler | ✅ |  |
+| F722 | ForwardAnnotationSyntaxError | Syntax error in forward annotation: `...` | ✅ |  |
+| F821 | UndefinedName | Undefined name `...` | ✅ |  |
+| F822 | UndefinedExport | Undefined name `...` in `__all__` | ✅ |  |
+| F823 | UndefinedLocal | Local variable `...` referenced before assignment | ✅ |  |
+| F831 | DuplicateArgumentName | Duplicate argument name in function definition | ✅ |  |
+| F841 | UnusedVariable | Local variable `...` is assigned to but never used | ✅ |  |
+| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` | ✅ |  |
+| A001 | BuiltinVariableShadowing | Variable `...` is shadowing a python builtin |  |  |
+| A002 | BuiltinArgumentShadowing | Argument `...` is shadowing a python builtin |  |  |
+| A003 | BuiltinAttributeShadowing | Class attribute `...` is shadowing a python builtin |  |  |
+| C400 | UnnecessaryGeneratorList | Unnecessary generator - rewrite as a list comprehension |  |  |
+| C401 | UnnecessaryGeneratorSet | Unnecessary generator - rewrite as a set comprehension |  |  |
+| C402 | UnnecessaryGeneratorDict | Unnecessary generator - rewrite as a dict comprehension |  |  |
+| C403 | UnnecessaryListComprehensionSet | Unnecessary list comprehension - rewrite as a set comprehension |  |  |
+| C404 | UnnecessaryListComprehensionDict | Unnecessary list comprehension - rewrite as a dict comprehension |  |  |
+| C405 | UnnecessaryLiteralSet | Unnecessary <list/tuple> literal - rewrite as a set literal |  |  |
+| C406 | UnnecessaryLiteralDict | Unnecessary <list/tuple> literal - rewrite as a dict literal |  |  |
+| C408 | UnnecessaryCollectionCall | Unnecessary <dict/list/tuple> call - rewrite as a literal |  |  |
+| C415 | UnnecessarySubscriptReversal | Unnecessary subscript reversal of iterable within <reversed/set/sorted>() |  |  |
+| T201 | PrintFound | `print` found |  | 🛠 |
+| T203 | PPrintFound | `pprint` found |  | 🛠 |
+| U001 | UselessMetaclassType | `__metaclass__ = type` is implied |  | 🛠 |
+| U002 | UnnecessaryAbspath | `abspath(__file__)` is unnecessary in Python 3.9 and later |  | 🛠 |
+| U003 | TypeOfPrimitive | Use `str` instead of `type(...)` |  | 🛠 |
+| U004 | UselessObjectInheritance | Class `...` inherits from object |  | 🛠 |
+| U005 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |  | 🛠 |
+| U006 | UsePEP585Annotation | Use `list` instead of `List` for type annotations |  | 🛠 |
+| U007 | UsePEP604Annotation | Use `X \| Y` for type annotations |  | 🛠 |
+| U008 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` |  | 🛠 |
+| M001 | UnusedNOQA | Unused `noqa` directive |  | 🛠 |
+
+## Integrations
+
+### PyCharm
+
+ruff can be installed as an [External Tool](https://www.jetbrains.com/help/pycharm/configuring-third-party-tools.html)
+in PyCharm. Open the Preferences pane, then navigate to "Tools", then "External Tools". From there,
+add a new tool with the following configuration:
+
+![Install ruff as an External Tool](https://user-images.githubusercontent.com/1309177/193155720-336e43f0-1a8d-46b4-bc12-e60f9ae01f7e.png)
+
+ruff should then appear as a runnable action:
+
+![ruff as a runnable action](https://user-images.githubusercontent.com/1309177/193156026-732b0aaf-3dd9-4549-9b4d-2de6d2168a33.png)
+
+### GitHub Actions
+
+GitHub Actions has everything you need to run ruff out-of-the-box:
+
+```yaml
+name: CI
+on: push
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.10"
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install ruff
+      - name: Run ruff
+        run: ruff .
+```
 
 ## Development
 
@@ -247,29 +371,29 @@ Add this `pyproject.toml` to the CPython directory:
 ```toml
 [tool.ruff]
 line-length = 88
-exclude = [
-    "./resources/test/cpython/Lib/lib2to3/tests/data/bom.py",
-    "./resources/test/cpython/Lib/lib2to3/tests/data/crlf.py",
-    "./resources/test/cpython/Lib/lib2to3/tests/data/different_encoding.py",
-    "./resources/test/cpython/Lib/lib2to3/tests/data/false_encoding.py",
-    "./resources/test/cpython/Lib/lib2to3/tests/data/py2_test_grammar.py",
-    "./resources/test/cpython/Lib/test/bad_coding2.py",
-    "./resources/test/cpython/Lib/test/badsyntax_3131.py",
-    "./resources/test/cpython/Lib/test/badsyntax_pep3120.py",
-    "./resources/test/cpython/Lib/test/encoded_modules/module_iso_8859_1.py",
-    "./resources/test/cpython/Lib/test/encoded_modules/module_koi8_r.py",
-    "./resources/test/cpython/Lib/test/test_fstring.py",
-    "./resources/test/cpython/Lib/test/test_grammar.py",
-    "./resources/test/cpython/Lib/test/test_importlib/test_util.py",
-    "./resources/test/cpython/Lib/test/test_named_expressions.py",
-    "./resources/test/cpython/Lib/test/test_patma.py",
-    "./resources/test/cpython/Lib/test/test_source_encoding.py",
-    "./resources/test/cpython/Tools/c-analyzer/c_parser/parser/_delim.py",
-    "./resources/test/cpython/Tools/i18n/pygettext.py",
-    "./resources/test/cpython/Tools/test2to3/maintest.py",
-    "./resources/test/cpython/Tools/test2to3/setup.py",
-    "./resources/test/cpython/Tools/test2to3/test/test_foo.py",
-    "./resources/test/cpython/Tools/test2to3/test2to3/hello.py",
+extend-exclude = [
+    "Lib/lib2to3/tests/data/bom.py",
+    "Lib/lib2to3/tests/data/crlf.py",
+    "Lib/lib2to3/tests/data/different_encoding.py",
+    "Lib/lib2to3/tests/data/false_encoding.py",
+    "Lib/lib2to3/tests/data/py2_test_grammar.py",
+    "Lib/test/bad_coding2.py",
+    "Lib/test/badsyntax_3131.py",
+    "Lib/test/badsyntax_pep3120.py",
+    "Lib/test/encoded_modules/module_iso_8859_1.py",
+    "Lib/test/encoded_modules/module_koi8_r.py",
+    "Lib/test/test_fstring.py",
+    "Lib/test/test_grammar.py",
+    "Lib/test/test_importlib/test_util.py",
+    "Lib/test/test_named_expressions.py",
+    "Lib/test/test_patma.py",
+    "Lib/test/test_source_encoding.py",
+    "Tools/c-analyzer/c_parser/parser/_delim.py",
+    "Tools/i18n/pygettext.py",
+    "Tools/test2to3/maintest.py",
+    "Tools/test2to3/setup.py",
+    "Tools/test2to3/test/test_foo.py",
+    "Tools/test2to3/test2to3/hello.py",
 ]
 ```
 
@@ -278,17 +402,21 @@ Next, to benchmark the release build:
 ```shell
 cargo build --release
 
-hyperfine --ignore-failure --warmup 1 \
+hyperfine --ignore-failure --warmup 10 --runs 100 \
   "./target/release/ruff ./resources/test/cpython/ --no-cache" \
   "./target/release/ruff ./resources/test/cpython/"
 
 Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
-  Time (mean ± σ):     353.6 ms ±   7.6 ms    [User: 2868.8 ms, System: 171.5 ms]
-  Range (min … max):   344.4 ms … 367.3 ms    10 runs
+  Time (mean ± σ):     297.4 ms ±   4.9 ms    [User: 2460.0 ms, System: 67.2 ms]
+  Range (min … max):   287.7 ms … 312.1 ms    100 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 2: ./target/release/ruff ./resources/test/cpython/
-  Time (mean ± σ):      59.6 ms ±   2.5 ms    [User: 36.4 ms, System: 345.6 ms]
-  Range (min … max):    55.9 ms …  67.0 ms    48 runs
+  Time (mean ± σ):      79.6 ms ±   7.3 ms    [User: 59.7 ms, System: 356.1 ms]
+  Range (min … max):    62.4 ms … 111.2 ms    100 runs
+
+  Warning: Ignoring non-zero exit code.
 ```
 
 To benchmark against the ecosystem's existing tools:
@@ -300,11 +428,8 @@ hyperfine --ignore-failure --warmup 5 \
   "pyflakes resources/test/cpython" \
   "autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython" \
   "pycodestyle resources/test/cpython" \
-  "pycodestyle --select E501 resources/test/cpython" \
   "flake8 resources/test/cpython" \
-  "flake8 --select=F831,F541,F634,F403,F706,F901,E501 resources/test/cpython" \
-  "python -m scripts.run_flake8 resources/test/cpython" \
-  "python -m scripts.run_flake8 resources/test/cpython --select=F831,F541,F634,F403,F706,F901,E501"
+  "python -m scripts.run_flake8 resources/test/cpython"
 ```
 
 In order, these evaluate:
@@ -314,68 +439,65 @@ In order, these evaluate:
 - PyFlakes
 - autoflake
 - pycodestyle
-- pycodestyle, limited to the checks supported by ruff
 - Flake8
-- Flake8, limited to the checks supported by ruff
 - Flake8, with a hack to enable multiprocessing on macOS
-- Flake8, with a hack to enable multiprocessing on macOS, limited to the checks supported by ruff
 
 (You can `poetry install` from `./scripts` to create a working environment for the above.)
 
 ```shell
 Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
-  Time (mean ± σ):     469.3 ms ±  16.3 ms    [User: 2663.0 ms, System: 972.5 ms]
-  Range (min … max):   445.2 ms … 494.8 ms    10 runs
+  Time (mean ± σ):     297.9 ms ±   7.0 ms    [User: 2436.6 ms, System: 65.9 ms]
+  Range (min … max):   289.9 ms … 314.6 ms    10 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 2: pylint --recursive=y resources/test/cpython/
-  Time (mean ± σ):     27.211 s ±  0.097 s    [User: 26.405 s, System: 0.799 s]
-  Range (min … max):   27.056 s … 27.349 s    10 runs
+  Time (mean ± σ):     37.634 s ±  0.225 s    [User: 36.728 s, System: 0.853 s]
+  Range (min … max):   37.201 s … 38.106 s    10 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 3: pyflakes resources/test/cpython
-  Time (mean ± σ):     27.309 s ±  0.033 s    [User: 27.137 s, System: 0.169 s]
-  Range (min … max):   27.267 s … 27.372 s    10 runs
+  Time (mean ± σ):     40.950 s ±  0.449 s    [User: 40.688 s, System: 0.229 s]
+  Range (min … max):   40.348 s … 41.671 s    10 runs
+
+  Warning: Ignoring non-zero exit code.
 
 Benchmark 4: autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython
-  Time (mean ± σ):      8.027 s ±  0.024 s    [User: 74.255 s, System: 0.953 s]
-  Range (min … max):    7.969 s …  8.052 s    10 runs
+  Time (mean ± σ):     11.562 s ±  0.160 s    [User: 107.022 s, System: 1.143 s]
+  Range (min … max):   11.417 s … 11.917 s    10 runs
 
 Benchmark 5: pycodestyle resources/test/cpython
-  Time (mean ± σ):     41.666 s ±  0.266 s    [User: 41.531 s, System: 0.132 s]
-  Range (min … max):   41.295 s … 41.980 s    10 runs
+  Time (mean ± σ):     67.428 s ±  0.985 s    [User: 67.199 s, System: 0.203 s]
+  Range (min … max):   65.313 s … 68.496 s    10 runs
 
-Benchmark 6: pycodestyle --select E501 resources/test/cpython
-  Time (mean ± σ):     14.547 s ±  0.077 s    [User: 14.466 s, System: 0.079 s]
-  Range (min … max):   14.429 s … 14.695 s    10 runs
+  Warning: Ignoring non-zero exit code.
 
-Benchmark 7: flake8 resources/test/cpython
-  Time (mean ± σ):     75.700 s ±  0.152 s    [User: 75.254 s, System: 0.440 s]
-  Range (min … max):   75.513 s … 76.014 s    10 runs
+Benchmark 6: flake8 resources/test/cpython
+  Time (mean ± σ):     116.099 s ±  1.178 s    [User: 115.217 s, System: 0.845 s]
+  Range (min … max):   114.180 s … 117.724 s    10 runs
 
-Benchmark 8: flake8 --select=F831,F541,F634,F403,F706,F901,E501 resources/test/cpython
-  Time (mean ± σ):     75.122 s ±  0.532 s    [User: 74.677 s, System: 0.440 s]
-  Range (min … max):   74.130 s … 75.606 s    10 runs
+  Warning: Ignoring non-zero exit code.
 
-Benchmark 9: python -m scripts.run_flake8 resources/test/cpython
-  Time (mean ± σ):     12.794 s ±  0.147 s    [User: 90.792 s, System: 0.738 s]
-  Range (min … max):   12.606 s … 13.030 s    10 runs
-
-Benchmark 10: python -m scripts.run_flake8 resources/test/cpython --select=F831,F541,F634,F403,F706,F901,E501
-  Time (mean ± σ):     12.487 s ±  0.118 s    [User: 90.052 s, System: 0.714 s]
-  Range (min … max):   12.265 s … 12.665 s    10 runs
+Benchmark 7: python -m scripts.run_flake8 resources/test/cpython
+  Time (mean ± σ):     20.477 s ±  0.349 s    [User: 142.372 s, System: 1.504 s]
+  Range (min … max):   20.107 s … 21.183 s    10 runs
 
 Summary
   './target/release/ruff ./resources/test/cpython/ --no-cache' ran
-   17.10 ± 0.60 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
-   26.60 ± 0.96 times faster than 'python -m scripts.run_flake8 resources/test/cpython --select=F831,F541,F634,F403,F706,F901,E501'
-   27.26 ± 1.00 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
-   30.99 ± 1.09 times faster than 'pycodestyle --select E501 resources/test/cpython'
-   57.98 ± 2.03 times faster than 'pylint --recursive=y resources/test/cpython/'
-   58.19 ± 2.02 times faster than 'pyflakes resources/test/cpython'
-   88.77 ± 3.14 times faster than 'pycodestyle resources/test/cpython'
-  160.06 ± 5.68 times faster than 'flake8 --select=F831,F541,F634,F403,F706,F901,E501 resources/test/cpython'
-  161.29 ± 5.61 times faster than 'flake8 resources/test/cpython'
+   38.81 ± 1.05 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
+   68.74 ± 1.99 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
+  126.33 ± 3.05 times faster than 'pylint --recursive=y resources/test/cpython/'
+  137.46 ± 3.55 times faster than 'pyflakes resources/test/cpython'
+  226.35 ± 6.23 times faster than 'pycodestyle resources/test/cpython'
+  389.73 ± 9.92 times faster than 'flake8 resources/test/cpython'
 ```
 
 ## License
 
 MIT
+
+## Contributing
+
+Contributions are welcome and hugely appreciated. To get started, check out the
+[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTING.md).

examples/generate_rules_table.rs

@@ -1,19 +1,26 @@
 /// Generate a Markdown-compatible table of supported lint rules.
-use ruff::checks::{CheckCode, ALL_CHECK_CODES};
+use strum::IntoEnumIterator;
+
+use ruff::checks::{CheckCode, DEFAULT_CHECK_CODES};
 
 fn main() {
-    let mut check_codes: Vec<CheckCode> = ALL_CHECK_CODES.to_vec();
-    check_codes.sort();
-
-    println!("| Code | Name | Message |");
-    println!("| ---- | ----- | ------- |");
-    for check_code in check_codes {
+    println!("| Code | Name | Message |     |     |");
+    println!("| ---- | ---- | ------- | --- | --- |");
+    for check_code in CheckCode::iter() {
         let check_kind = check_code.kind();
+        let default_token = if DEFAULT_CHECK_CODES.contains(&check_code) {
+            "✅"
+        } else {
+            ""
+        };
+        let fix_token = if check_kind.fixable() { "🛠" } else { "" };
         println!(
-            "| {} | {} | {} |",
-            check_kind.code().as_str(),
-            check_kind.name(),
-            check_kind.body()
+            "| {} | {} | {} | {} | {} |",
+            check_kind.code().as_ref(),
+            check_kind.as_ref(),
+            check_kind.body().replace("|", r"\|"),
+            default_token,
+            fix_token
         );
     }
 }

examples/generate_source_code.rs

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

examples/print_ast.rs

@@ -2,14 +2,14 @@
 use std::path::PathBuf;
 
 use anyhow::Result;
-use clap::{Parser, ValueHint};
+use clap::Parser;
 use rustpython_parser::parser;
 
 use ruff::fs;
 
 #[derive(Debug, Parser)]
 struct Cli {
-    #[clap(parse(from_os_str), value_hint = ValueHint::FilePath, required = true)]
+    #[arg(required = true)]
     file: PathBuf,
 }
 

examples/print_tokens.rs

@@ -2,14 +2,14 @@
 use std::path::PathBuf;
 
 use anyhow::Result;
-use clap::{Parser, ValueHint};
+use clap::Parser;
 use rustpython_parser::lexer;
 
 use ruff::fs;
 
 #[derive(Debug, Parser)]
 struct Cli {
-    #[clap(parse(from_os_str), value_hint = ValueHint::FilePath, required = true)]
+    #[arg(required = true)]
     file: PathBuf,
 }
 

pyproject.toml

@@ -8,7 +8,6 @@ classifiers = [
     "License :: OSI Approved :: MIT License",
     "Operating System :: OS Independent",
     "Programming Language :: Python",
-    "Programming Language :: Python :: 3.6",
     "Programming Language :: Python :: 3.7",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",

resources/test/fixtures/A001.py

@@ -0,0 +1,27 @@
+import some as sum
+from some import other as int
+
+print = 1
+copyright: 'annotation' = 2
+(complex := 3)
+float = object = 4
+min, max = 5, 6
+
+def bytes():
+    pass
+
+class slice:
+    pass
+
+try:
+    ...
+except ImportError as ValueError:
+    ...
+
+for memoryview, *bytearray in []:
+    pass
+
+with open('file') as str, open('file2') as (all, any):
+    pass
+
+[0 for sum in ()]

resources/test/fixtures/A002.py

@@ -0,0 +1,9 @@
+def func1(str, /, type, *complex, Exception, **getattr):
+    pass
+
+
+async def func2(bytes):
+    pass
+
+
+map([], lambda float: ...)

resources/test/fixtures/A003.py

@@ -0,0 +1,8 @@
+class MyClass:
+    ImportError = 4
+
+    def __init__(self):
+        self.float = 5  # is fine
+
+    def str(self):
+        pass

resources/test/fixtures/C400.py

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

resources/test/fixtures/C401.py

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

resources/test/fixtures/C402.py

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

resources/test/fixtures/C403.py

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

resources/test/fixtures/C404.py

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

resources/test/fixtures/C405.py

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

resources/test/fixtures/C406.py

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

resources/test/fixtures/C408.py

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

resources/test/fixtures/C415.py

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

resources/test/fixtures/E402.py

@@ -1,4 +1,8 @@
 """Top-level docstring."""
+
+__all__ = ["y"]
+__version__: str = "0.1.0"
+
 import a
 
 try:

resources/test/fixtures/E501.py

@@ -5,5 +5,12 @@
 Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
 """
 
+_ = """Lorem ipsum dolor sit amet.
+
+    https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+"""  # noqa: E501
+
 _ = "---------------------------------------------------------------------------AAAAAAA"
 _ = "---------------------------------------------------------------------------亜亜亜亜亜亜亜"

resources/test/fixtures/F401.py

@@ -1,41 +0,0 @@
-from __future__ import all_feature_names
-import os
-import functools
-from datetime import datetime
-from collections import (
-    Counter,
-    OrderedDict,
-    namedtuple,
-)
-import multiprocessing.pool
-import multiprocessing.process
-import logging.config
-import logging.handlers
-from typing import TYPING_CHECK, NamedTuple, Dict, Type, TypeVar, List, Set, Union, cast
-
-from blah import ClassA, ClassB, ClassC
-
-if TYPING_CHECK:
-    from models import Fruit, Nut, Vegetable
-
-
-class X:
-    datetime: datetime
-    foo: Type["NamedTuple"]
-
-    def a(self) -> "namedtuple":
-        x = os.environ["1"]
-        y = Counter()
-        z = multiprocessing.pool.ThreadPool()
-
-
-__all__ = ["ClassA"] + ["ClassB"]
-__all__ += ["ClassC"]
-
-X = TypeVar("X")
-Y = TypeVar("Y", bound="Dict")
-Z = TypeVar("Z", "List", "Set")
-
-a = list["Fruit"]
-b = Union["Nut", None]
-c = cast("Vegetable", b)

resources/test/fixtures/F401_0.py

@@ -0,0 +1,88 @@
+from __future__ import all_feature_names
+import functools, os
+from datetime import datetime
+from collections import (
+    Counter,
+    OrderedDict,
+    namedtuple,
+)
+import multiprocessing.pool
+import multiprocessing.process
+import logging.config
+import logging.handlers
+from typing import (
+    TYPE_CHECKING,
+    NamedTuple,
+    Dict,
+    Type,
+    TypeVar,
+    List,
+    Set,
+    Union,
+    cast,
+)
+from dataclasses import MISSING, field
+
+from blah import ClassA, ClassB, ClassC
+
+if TYPE_CHECKING:
+    from models import Fruit, Nut, Vegetable
+
+
+if TYPE_CHECKING:
+    import shelve
+    import importlib
+
+if TYPE_CHECKING:
+    """Hello, world!"""
+    import pathlib
+
+    z = 1
+
+
+class X:
+    datetime: datetime
+    foo: Type["NamedTuple"]
+
+    def a(self) -> "namedtuple":
+        x = os.environ["1"]
+        y = Counter()
+        z = multiprocessing.pool.ThreadPool()
+
+    def b(self) -> None:
+        import pickle
+
+
+__all__ = ["ClassA"] + ["ClassB"]
+__all__ += ["ClassC"]
+
+X = TypeVar("X")
+Y = TypeVar("Y", bound="Dict")
+Z = TypeVar("Z", "List", "Set")
+
+a = list["Fruit"]
+b = Union["Nut", None]
+c = cast("Vegetable", b)
+
+Field = lambda default=MISSING: field(default=default)
+
+
+# Test: access a sub-importation via an alias.
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))
+
+
+# Test: referencing an import via TypeAlias.
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_1.py

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

resources/test/fixtures/F401_2.py

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

resources/test/fixtures/F401_3.py

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

resources/test/fixtures/F401_4.py

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

resources/test/fixtures/F402.py

@@ -0,0 +1,9 @@
+import os
+import os.path as path
+
+
+for os in range(3):
+    pass
+
+for path in range(3):
+    pass

resources/test/fixtures/F405.py

@@ -0,0 +1,11 @@
+from mymodule import *
+
+
+def print_name():
+    print(name)
+
+
+def print_name(name):
+    print(name)
+
+__all__ = ['a']

resources/test/fixtures/F821.py

@@ -82,3 +82,43 @@ class Ticket:
 def update_tomato():
     print(TOMATO)
     TOMATO = "cherry tomato"
+
+
+A = f'{B}'
+A = (
+    f'B'
+    f'{B}'
+)
+
+
+from typing import Annotated, Literal
+
+
+def arbitrary_callable() -> None:
+    ...
+
+
+class PEP593Test:
+    field: Annotated[
+        int,
+        "base64",
+        arbitrary_callable(),
+        123,
+        (1, 2, 3),
+    ]
+    field_with_stringified_type: Annotated[
+        "PEP593Test",
+        123,
+    ]
+    field_with_undefined_stringified_type: Annotated[
+        "PEP593Test123",
+        123,
+    ]
+    field_with_nested_subscript: Annotated[
+        dict[Literal["foo"], str],
+        123,
+    ]
+    field_with_undefined_nested_subscript: Annotated[
+        dict["foo", "bar"],  # Expected to fail as undefined.
+        123,
+    ]

resources/test/fixtures/F841.py

@@ -10,13 +10,13 @@ except ValueError as e:
     print(e)
 
 
-def f():
+def f1():
     x = 1
     y = 2
     z = x + y
 
 
-def g():
+def f2():
     foo = (1, 2)
     (a, b) = (1, 2)
 
@@ -26,6 +26,12 @@ def g():
     (x, y) = baz = bar
 
 
-def h():
+def f3():
     locals()
     x = 1
+
+
+def f4():
+    _ = 1
+    __ = 1
+    _discarded = 1

resources/test/fixtures/M001.py

@@ -0,0 +1,57 @@
+def f() -> None:
+    # Valid
+    a = 1  # noqa
+
+    # Valid
+    b = 2  # noqa: F841
+
+    # Invalid
+    c = 1  # noqa
+    print(c)
+
+    # Invalid
+    d = 1  # noqa: E501
+
+    # Invalid
+    d = 1  # noqa: F841, E501
+
+
+# Valid
+_ = """Lorem ipsum dolor sit amet.
+
+    https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+"""  # noqa: E501
+
+# Valid
+_ = """Lorem ipsum dolor sit amet.
+
+    https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+"""  # noqa
+
+# Invalid
+_ = """Lorem ipsum dolor sit amet.
+
+    https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+"""  # noqa: E501, F841
+
+# Invalid
+_ = """Lorem ipsum dolor sit amet.
+
+    https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor.
+"""  # noqa: E501
+
+# Invalid
+_ = """Lorem ipsum dolor sit amet.
+
+    https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor.
+"""  # noqa

resources/test/fixtures/R002.py

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

resources/test/fixtures/T201.py

@@ -0,0 +1 @@
+print("Hello, world!")  # T201

resources/test/fixtures/T203.py

@@ -0,0 +1,10 @@
+from pprint import pprint
+
+pprint("Hello, world!")  # T203
+
+
+import pprint
+
+pprint.pprint("Hello, world!")  # T203
+
+pprint.pformat("Hello, world!")

resources/test/fixtures/U001.py

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

resources/test/fixtures/U002.py

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

resources/test/fixtures/U003.py

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

resources/test/fixtures/U005.py

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

resources/test/fixtures/U006.py

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

resources/test/fixtures/U007.py

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

resources/test/fixtures/U008.py

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

resources/test/fixtures/W292_0.py

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

resources/test/fixtures/W292_1.py

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

resources/test/fixtures/W292_2.py

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

resources/test/fixtures/future_annotations.py

@@ -2,7 +2,10 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 
-from models import Fruit, Nut
+from models import (
+    Fruit,
+    Nut,
+)
 
 
 @dataclass

src/ast.rs

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

src/ast/checks.rs

@@ -1,18 +1,22 @@
 use std::collections::BTreeSet;
 
 use itertools::izip;
+use num_bigint::BigInt;
+use regex::Regex;
 use rustpython_parser::ast::{
-    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Keyword,
-    Location, Stmt, StmtKind, Unaryop,
+    Arg, ArgData, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind,
+    KeywordData, Located, Stmt, StmtKind, Unaryop,
 };
+use serde::{Deserialize, Serialize};
 
-use crate::ast::operations::SourceCodeLocator;
-use crate::ast::types::{Binding, BindingKind, FunctionScope, Scope, ScopeKind};
-use crate::autofix::{fixer, fixes};
-use crate::checks::{Check, CheckKind, Fix, RejectedCmpop};
+use crate::ast::types::{
+    Binding, BindingKind, CheckLocator, FunctionScope, Range, Scope, ScopeKind,
+};
+use crate::checks::{Check, CheckKind, RejectedCmpop};
+use crate::python::builtins::BUILTINS;
 
 /// Check IfTuple compliance.
-pub fn check_if_tuple(test: &Expr, location: Location) -> Option<Check> {
+pub fn check_if_tuple(test: &Expr, location: Range) -> Option<Check> {
     if let ExprKind::Tuple { elts, .. } = &test.node {
         if !elts.is_empty() {
             return Some(Check::new(CheckKind::IfTuple, location));
@@ -22,7 +26,7 @@ pub fn check_if_tuple(test: &Expr, location: Location) -> Option<Check> {
 }
 
 /// Check AssertTuple compliance.
-pub fn check_assert_tuple(test: &Expr, location: Location) -> Option<Check> {
+pub fn check_assert_tuple(test: &Expr, location: Range) -> Option<Check> {
     if let ExprKind::Tuple { elts, .. } = &test.node {
         if !elts.is_empty() {
             return Some(Check::new(CheckKind::AssertTuple, location));
@@ -37,6 +41,7 @@ pub fn check_not_tests(
     operand: &Expr,
     check_not_in: bool,
     check_not_is: bool,
+    locator: &dyn CheckLocator,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -46,12 +51,18 @@ pub fn check_not_tests(
                 match op {
                     Cmpop::In => {
                         if check_not_in {
-                            checks.push(Check::new(CheckKind::NotInTest, operand.location));
+                            checks.push(Check::new(
+                                CheckKind::NotInTest,
+                                locator.locate_check(Range::from_located(operand)),
+                            ));
                         }
                     }
                     Cmpop::Is => {
                         if check_not_is {
-                            checks.push(Check::new(CheckKind::NotIsTest, operand.location));
+                            checks.push(Check::new(
+                                CheckKind::NotIsTest,
+                                locator.locate_check(Range::from_located(operand)),
+                            ));
                         }
                     }
                     _ => {}
@@ -64,7 +75,11 @@ pub fn check_not_tests(
 }
 
 /// Check UnusedVariable compliance.
-pub fn check_unused_variables(scope: &Scope) -> Vec<Check> {
+pub fn check_unused_variables(
+    scope: &Scope,
+    locator: &dyn CheckLocator,
+    dummy_variable_rgx: &Regex,
+) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
     if matches!(
@@ -75,17 +90,16 @@ pub fn check_unused_variables(scope: &Scope) -> Vec<Check> {
     }
 
     for (name, binding) in scope.values.iter() {
-        // TODO(charlie): Ignore if using `locals`.
         if binding.used.is_none()
-            && name != "_"
+            && matches!(binding.kind, BindingKind::Assignment)
+            && !dummy_variable_rgx.is_match(name)
             && name != "__tracebackhide__"
             && name != "__traceback_info__"
             && name != "__traceback_supplement__"
-            && matches!(binding.kind, BindingKind::Assignment)
         {
             checks.push(Check::new(
                 CheckKind::UnusedVariable(name.to_string()),
-                binding.location,
+                locator.locate_check(binding.range),
             ));
         }
     }
@@ -94,7 +108,7 @@ pub fn check_unused_variables(scope: &Scope) -> Vec<Check> {
 }
 
 /// Check DoNotAssignLambda compliance.
-pub fn check_do_not_assign_lambda(value: &Expr, location: Location) -> Option<Check> {
+pub fn check_do_not_assign_lambda(value: &Expr, location: Range) -> Option<Check> {
     if let ExprKind::Lambda { .. } = &value.node {
         Some(Check::new(CheckKind::DoNotAssignLambda, location))
     } else {
@@ -102,12 +116,112 @@ pub fn check_do_not_assign_lambda(value: &Expr, location: Location) -> Option<Ch
     }
 }
 
+/// Check UselessMetaclassType compliance.
+pub fn check_useless_metaclass_type(
+    targets: &Vec<Expr>,
+    value: &Expr,
+    location: Range,
+) -> Option<Check> {
+    if targets.len() == 1 {
+        if let ExprKind::Name { id, .. } = targets.first().map(|expr| &expr.node).unwrap() {
+            if id == "__metaclass__" {
+                if let ExprKind::Name { id, .. } = &value.node {
+                    if id == "type" {
+                        return Some(Check::new(CheckKind::UselessMetaclassType, location));
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check UnnecessaryAbspath compliance.
+pub fn check_unnecessary_abspath(func: &Expr, args: &Vec<Expr>, location: Range) -> Option<Check> {
+    // Validate the arguments.
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &args[0].node {
+            if id == "__file__" {
+                match &func.node {
+                    ExprKind::Attribute { attr: id, .. } | ExprKind::Name { id, .. } => {
+                        if id == "abspath" {
+                            return Some(Check::new(CheckKind::UnnecessaryAbspath, location));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    None
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Primitive {
+    Bool,
+    Str,
+    Bytes,
+    Int,
+    Float,
+    Complex,
+}
+
+impl Primitive {
+    fn from_constant(constant: &Constant) -> Option<Self> {
+        match constant {
+            Constant::Bool(_) => Some(Primitive::Bool),
+            Constant::Str(_) => Some(Primitive::Str),
+            Constant::Bytes(_) => Some(Primitive::Bytes),
+            Constant::Int(_) => Some(Primitive::Int),
+            Constant::Float(_) => Some(Primitive::Float),
+            Constant::Complex { .. } => Some(Primitive::Complex),
+            _ => None,
+        }
+    }
+
+    pub fn builtin(&self) -> String {
+        match self {
+            Primitive::Bool => "bool".to_string(),
+            Primitive::Str => "str".to_string(),
+            Primitive::Bytes => "bytes".to_string(),
+            Primitive::Int => "int".to_string(),
+            Primitive::Float => "float".to_string(),
+            Primitive::Complex => "complex".to_string(),
+        }
+    }
+}
+
+/// Check TypeOfPrimitive compliance.
+pub fn check_type_of_primitive(func: &Expr, args: &Vec<Expr>, location: Range) -> Option<Check> {
+    // Validate the arguments.
+    if args.len() == 1 {
+        match &func.node {
+            ExprKind::Attribute { attr: id, .. } | ExprKind::Name { id, .. } => {
+                if id == "type" {
+                    if let ExprKind::Constant { value, .. } = &args[0].node {
+                        if let Some(primitive) = Primitive::from_constant(value) {
+                            return Some(Check::new(
+                                CheckKind::TypeOfPrimitive(primitive),
+                                location,
+                            ));
+                        }
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+
+    None
+}
+
 fn is_ambiguous_name(name: &str) -> bool {
     name == "l" || name == "I" || name == "O"
 }
 
 /// Check AmbiguousVariableName compliance.
-pub fn check_ambiguous_variable_name(name: &str, location: Location) -> Option<Check> {
+pub fn check_ambiguous_variable_name(name: &str, location: Range) -> Option<Check> {
     if is_ambiguous_name(name) {
         Some(Check::new(
             CheckKind::AmbiguousVariableName(name.to_string()),
@@ -119,7 +233,7 @@ pub fn check_ambiguous_variable_name(name: &str, location: Location) -> Option<C
 }
 
 /// Check AmbiguousClassName compliance.
-pub fn check_ambiguous_class_name(name: &str, location: Location) -> Option<Check> {
+pub fn check_ambiguous_class_name(name: &str, location: Range) -> Option<Check> {
     if is_ambiguous_name(name) {
         Some(Check::new(
             CheckKind::AmbiguousClassName(name.to_string()),
@@ -131,7 +245,7 @@ pub fn check_ambiguous_class_name(name: &str, location: Location) -> Option<Chec
 }
 
 /// Check AmbiguousFunctionName compliance.
-pub fn check_ambiguous_function_name(name: &str, location: Location) -> Option<Check> {
+pub fn check_ambiguous_function_name(name: &str, location: Range) -> Option<Check> {
     if is_ambiguous_name(name) {
         Some(Check::new(
             CheckKind::AmbiguousFunctionName(name.to_string()),
@@ -144,13 +258,9 @@ pub fn check_ambiguous_function_name(name: &str, location: Location) -> Option<C
 
 /// Check UselessObjectInheritance compliance.
 pub fn check_useless_object_inheritance(
-    stmt: &Stmt,
     name: &str,
     bases: &[Expr],
-    keywords: &[Keyword],
     scope: &Scope,
-    locator: &mut SourceCodeLocator,
-    autofix: &fixer::Mode,
 ) -> Option<Check> {
     for expr in bases {
         if let ExprKind::Name { id, .. } = &expr.node {
@@ -161,22 +271,10 @@ pub fn check_useless_object_inheritance(
                         kind: BindingKind::Builtin,
                         ..
                     }) => {
-                        let mut check = Check::new(
+                        return Some(Check::new(
                             CheckKind::UselessObjectInheritance(name.to_string()),
-                            expr.location,
-                        );
-                        if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                            if let Some(fix) = fixes::remove_class_def_base(
-                                locator,
-                                &stmt.location,
-                                expr.location,
-                                bases,
-                                keywords,
-                            ) {
-                                check.amend(fix);
-                            }
-                        }
-                        return Some(check);
+                            Range::from_located(expr),
+                        ));
                     }
                     _ => {}
                 }
@@ -194,7 +292,7 @@ pub fn check_default_except_not_last(handlers: &Vec<Excepthandler>) -> Option<Ch
         if type_.is_none() && idx < handlers.len() - 1 {
             return Some(Check::new(
                 CheckKind::DefaultExceptNotLast,
-                handler.location,
+                Range::from_located(handler),
             ));
         }
     }
@@ -208,13 +306,19 @@ pub fn check_raise_not_implemented(expr: &Expr) -> Option<Check> {
         ExprKind::Call { func, .. } => {
             if let ExprKind::Name { id, .. } = &func.node {
                 if id == "NotImplemented" {
-                    return Some(Check::new(CheckKind::RaiseNotImplemented, expr.location));
+                    return Some(Check::new(
+                        CheckKind::RaiseNotImplemented,
+                        Range::from_located(expr),
+                    ));
                 }
             }
         }
         ExprKind::Name { id, .. } => {
             if id == "NotImplemented" {
-                return Some(Check::new(CheckKind::RaiseNotImplemented, expr.location));
+                return Some(Check::new(
+                    CheckKind::RaiseNotImplemented,
+                    Range::from_located(expr),
+                ));
             }
         }
         _ => {}
@@ -246,7 +350,10 @@ pub fn check_duplicate_arguments(arguments: &Arguments) -> Vec<Check> {
     for arg in all_arguments {
         let ident = &arg.node.arg;
         if idents.contains(ident.as_str()) {
-            checks.push(Check::new(CheckKind::DuplicateArgumentName, arg.location));
+            checks.push(Check::new(
+                CheckKind::DuplicateArgumentName,
+                Range::from_located(arg),
+            ));
         }
         idents.insert(ident);
     }
@@ -254,32 +361,6 @@ pub fn check_duplicate_arguments(arguments: &Arguments) -> Vec<Check> {
     checks
 }
 
-/// Check AssertEquals compliance.
-pub fn check_assert_equals(expr: &Expr, autofix: &fixer::Mode) -> Option<Check> {
-    if let ExprKind::Attribute { value, attr, .. } = &expr.node {
-        if attr == "assertEquals" {
-            if let ExprKind::Name { id, .. } = &value.node {
-                if id == "self" {
-                    let mut check = Check::new(CheckKind::NoAssertEquals, expr.location);
-                    if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                        check.amend(Fix {
-                            content: "assertEqual".to_string(),
-                            start: Location::new(expr.location.row(), expr.location.column() + 1),
-                            end: Location::new(
-                                expr.location.row(),
-                                expr.location.column() + 1 + "assertEquals".len(),
-                            ),
-                            applied: false,
-                        });
-                    }
-                    return Some(check);
-                }
-            }
-        }
-    }
-    None
-}
-
 #[derive(Debug, PartialEq)]
 enum DictionaryKey<'a> {
     Constant(&'a Constant),
@@ -299,6 +380,7 @@ pub fn check_repeated_keys(
     keys: &Vec<Expr>,
     check_repeated_literals: bool,
     check_repeated_variables: bool,
+    locator: &dyn CheckLocator,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -313,7 +395,7 @@ pub fn check_repeated_keys(
                     if check_repeated_literals && v1 == v2 {
                         checks.push(Check::new(
                             CheckKind::MultiValueRepeatedKeyLiteral,
-                            k2.location,
+                            locator.locate_check(Range::from_located(k2)),
                         ))
                     }
                 }
@@ -321,7 +403,7 @@ pub fn check_repeated_keys(
                     if check_repeated_variables && v1 == v2 {
                         checks.push(Check::new(
                             CheckKind::MultiValueRepeatedKeyVariable((*v2).to_string()),
-                            k2.location,
+                            locator.locate_check(Range::from_located(k2)),
                         ))
                     }
                 }
@@ -340,6 +422,7 @@ pub fn check_literal_comparisons(
     comparators: &Vec<Expr>,
     check_none_comparisons: bool,
     check_true_false_comparisons: bool,
+    locator: &dyn CheckLocator,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -359,13 +442,13 @@ pub fn check_literal_comparisons(
         if matches!(op, Cmpop::Eq) {
             checks.push(Check::new(
                 CheckKind::NoneComparison(RejectedCmpop::Eq),
-                comparator.location,
+                locator.locate_check(Range::from_located(comparator)),
             ));
         }
         if matches!(op, Cmpop::NotEq) {
             checks.push(Check::new(
                 CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                comparator.location,
+                locator.locate_check(Range::from_located(comparator)),
             ));
         }
     }
@@ -379,13 +462,13 @@ pub fn check_literal_comparisons(
             if matches!(op, Cmpop::Eq) {
                 checks.push(Check::new(
                     CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                    comparator.location,
+                    locator.locate_check(Range::from_located(comparator)),
                 ));
             }
             if matches!(op, Cmpop::NotEq) {
                 checks.push(Check::new(
                     CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                    comparator.location,
+                    locator.locate_check(Range::from_located(comparator)),
                 ));
             }
         }
@@ -405,13 +488,13 @@ pub fn check_literal_comparisons(
             if matches!(op, Cmpop::Eq) {
                 checks.push(Check::new(
                     CheckKind::NoneComparison(RejectedCmpop::Eq),
-                    comparator.location,
+                    locator.locate_check(Range::from_located(comparator)),
                 ));
             }
             if matches!(op, Cmpop::NotEq) {
                 checks.push(Check::new(
                     CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                    comparator.location,
+                    locator.locate_check(Range::from_located(comparator)),
                 ));
             }
         }
@@ -425,13 +508,13 @@ pub fn check_literal_comparisons(
                 if matches!(op, Cmpop::Eq) {
                     checks.push(Check::new(
                         CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                        comparator.location,
+                        locator.locate_check(Range::from_located(comparator)),
                     ));
                 }
                 if matches!(op, Cmpop::NotEq) {
                     checks.push(Check::new(
                         CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                        comparator.location,
+                        locator.locate_check(Range::from_located(comparator)),
                     ));
                 }
             }
@@ -468,7 +551,7 @@ pub fn check_is_literal(
     left: &Expr,
     ops: &Vec<Cmpop>,
     comparators: &Vec<Expr>,
-    location: Location,
+    location: Range,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -489,7 +572,7 @@ pub fn check_is_literal(
 pub fn check_type_comparison(
     ops: &Vec<Cmpop>,
     comparators: &Vec<Expr>,
-    location: Location,
+    location: Range,
 ) -> Vec<Check> {
     let mut checks: Vec<Check> = vec![];
 
@@ -528,9 +611,9 @@ pub fn check_type_comparison(
 /// Check TwoStarredExpressions and TooManyExpressionsInStarredAssignment compliance.
 pub fn check_starred_expressions(
     elts: &[Expr],
-    location: Location,
     check_too_many_expressions: bool,
     check_two_starred_expressions: bool,
+    location: Range,
 ) -> Option<Check> {
     let mut has_starred: bool = false;
     let mut starred_index: Option<usize> = None;
@@ -547,10 +630,7 @@ pub fn check_starred_expressions(
     if check_too_many_expressions {
         if let Some(starred_index) = starred_index {
             if starred_index >= 1 << 8 || elts.len() - starred_index > 1 << 24 {
-                return Some(Check::new(
-                    CheckKind::TooManyExpressionsInStarredAssignment,
-                    location,
-                ));
+                return Some(Check::new(CheckKind::ExpressionsInStarAssignment, location));
             }
         }
     }
@@ -563,6 +643,7 @@ pub fn check_break_outside_loop(
     stmt: &Stmt,
     parents: &[&Stmt],
     parent_stack: &[usize],
+    locator: &dyn CheckLocator,
 ) -> Option<Check> {
     let mut allowed: bool = false;
     let mut parent = stmt;
@@ -589,7 +670,10 @@ pub fn check_break_outside_loop(
     }
 
     if !allowed {
-        Some(Check::new(CheckKind::BreakOutsideLoop, stmt.location))
+        Some(Check::new(
+            CheckKind::BreakOutsideLoop,
+            locator.locate_check(Range::from_located(stmt)),
+        ))
     } else {
         None
     }
@@ -600,6 +684,7 @@ pub fn check_continue_outside_loop(
     stmt: &Stmt,
     parents: &[&Stmt],
     parent_stack: &[usize],
+    locator: &dyn CheckLocator,
 ) -> Option<Check> {
     let mut allowed: bool = false;
     let mut parent = stmt;
@@ -626,8 +711,397 @@ pub fn check_continue_outside_loop(
     }
 
     if !allowed {
-        Some(Check::new(CheckKind::ContinueOutsideLoop, stmt.location))
+        Some(Check::new(
+            CheckKind::ContinueOutsideLoop,
+            locator.locate_check(Range::from_located(stmt)),
+        ))
     } else {
         None
     }
 }
+
+// flake8-builtins
+pub enum ShadowingType {
+    Variable,
+    Argument,
+    Attribute,
+}
+
+/// Check builtin name shadowing
+pub fn check_builtin_shadowing(
+    name: &str,
+    location: Range,
+    node_type: ShadowingType,
+) -> Option<Check> {
+    if BUILTINS.contains(&name) {
+        Some(Check::new(
+            match node_type {
+                ShadowingType::Variable => CheckKind::BuiltinVariableShadowing(name.to_string()),
+                ShadowingType::Argument => CheckKind::BuiltinArgumentShadowing(name.to_string()),
+                ShadowingType::Attribute => CheckKind::BuiltinAttributeShadowing(name.to_string()),
+            },
+            location,
+        ))
+    } else {
+        None
+    }
+}
+
+/// Returns `true` if a call is an argumented `super` invocation.
+pub fn is_super_call_with_arguments(func: &Expr, args: &Vec<Expr>) -> bool {
+    // Check: is this a `super` call?
+    if let ExprKind::Name { id, .. } = &func.node {
+        id == "super" && !args.is_empty()
+    } else {
+        false
+    }
+}
+
+// flakes8-comprehensions
+/// Check `list(generator)` compliance.
+pub fn unnecessary_generator_list(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "list" {
+                if let ExprKind::GeneratorExp { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryGeneratorList,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `set(generator)` compliance.
+pub fn unnecessary_generator_set(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" {
+                if let ExprKind::GeneratorExp { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryGeneratorList,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `dict((x, y) for x, y in iterable)` compliance.
+pub fn unnecessary_generator_dict(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "dict" {
+                if let ExprKind::GeneratorExp { elt, .. } = &args[0].node {
+                    match &elt.node {
+                        ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryListComprehensionDict,
+                                Range::from_located(expr),
+                            ));
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `set([...])` compliance.
+pub fn unnecessary_list_comprehension_set(
+    expr: &Expr,
+    func: &Expr,
+    args: &Vec<Expr>,
+) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" {
+                if let ExprKind::ListComp { .. } = &args[0].node {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryListComprehensionSet,
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `dict([...])` compliance.
+pub fn unnecessary_list_comprehension_dict(
+    expr: &Expr,
+    func: &Expr,
+    args: &Vec<Expr>,
+) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "dict" {
+                if let ExprKind::ListComp { elt, .. } = &args[0].node {
+                    match &elt.node {
+                        ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryListComprehensionDict,
+                                Range::from_located(expr),
+                            ));
+                        }
+                        _ => {}
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `set([1, 2])` compliance.
+pub fn unnecessary_literal_set(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" {
+                match &args[0].node {
+                    ExprKind::List { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralSet("list".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    ExprKind::Tuple { .. } => {
+                        return Some(Check::new(
+                            CheckKind::UnnecessaryLiteralSet("tuple".to_string()),
+                            Range::from_located(expr),
+                        ));
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+    None
+}
+
+/// Check `dict([(1, 2)])` compliance.
+pub fn unnecessary_literal_dict(expr: &Expr, func: &Expr, args: &Vec<Expr>) -> Option<Check> {
+    if args.len() == 1 {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "dict" {
+                match &args[0].node {
+                    ExprKind::Tuple { elts, .. } => {
+                        if let Some(elt) = elts.first() {
+                            match &elt.node {
+                                // dict((1, 2), ...))
+                                ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                                    return Some(Check::new(
+                                        CheckKind::UnnecessaryLiteralDict("tuple".to_string()),
+                                        Range::from_located(expr),
+                                    ));
+                                }
+                                _ => {}
+                            }
+                        } else {
+                            // dict(())
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryLiteralDict("tuple".to_string()),
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                    ExprKind::List { elts, .. } => {
+                        if let Some(elt) = elts.first() {
+                            match &elt.node {
+                                // dict([(1, 2), ...])
+                                ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
+                                    return Some(Check::new(
+                                        CheckKind::UnnecessaryLiteralDict("list".to_string()),
+                                        Range::from_located(expr),
+                                    ));
+                                }
+                                _ => {}
+                            }
+                        } else {
+                            // dict([])
+                            return Some(Check::new(
+                                CheckKind::UnnecessaryLiteralDict("list".to_string()),
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_collection_call(
+    expr: &Expr,
+    func: &Expr,
+    args: &Vec<Expr>,
+    keywords: &Vec<Located<KeywordData>>,
+) -> Option<Check> {
+    if args.is_empty() {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "list" || id == "tuple" {
+                // list() or tuple()
+                return Some(Check::new(
+                    CheckKind::UnnecessaryCollectionCall(id.to_string()),
+                    Range::from_located(expr),
+                ));
+            } else if id == "dict" {
+                // dict() or dict(a=1)
+                if keywords.is_empty() || keywords.iter().all(|kw| kw.node.arg.is_some()) {
+                    return Some(Check::new(
+                        CheckKind::UnnecessaryCollectionCall(id.to_string()),
+                        Range::from_located(expr),
+                    ));
+                }
+            }
+        }
+    }
+    None
+}
+
+pub fn unnecessary_subscript_reversal(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+    if let Some(first_arg) = args.first() {
+        if let ExprKind::Name { id, .. } = &func.node {
+            if id == "set" || id == "sorted" || id == "reversed" {
+                if let ExprKind::Subscript { slice, .. } = &first_arg.node {
+                    if let ExprKind::Slice { lower, upper, step } = &slice.node {
+                        if lower.is_none() && upper.is_none() {
+                            if let Some(step) = step {
+                                if let ExprKind::UnaryOp {
+                                    op: Unaryop::USub,
+                                    operand,
+                                } = &step.node
+                                {
+                                    if let ExprKind::Constant {
+                                        value: Constant::Int(val),
+                                        ..
+                                    } = &operand.node
+                                    {
+                                        if *val == BigInt::from(1) {
+                                            return Some(Check::new(
+                                                CheckKind::UnnecessarySubscriptReversal(
+                                                    id.to_string(),
+                                                ),
+                                                Range::from_located(expr),
+                                            ));
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
+// flake8-super
+/// Check that `super()` has no args
+pub fn check_super_args(
+    scope: &Scope,
+    parents: &[&Stmt],
+    expr: &Expr,
+    func: &Expr,
+    args: &Vec<Expr>,
+) -> Option<Check> {
+    if !is_super_call_with_arguments(func, args) {
+        return None;
+    }
+
+    // Check: are we in a Function scope?
+    if !matches!(scope.kind, ScopeKind::Function { .. }) {
+        return None;
+    }
+
+    let mut parents = parents.iter().rev();
+
+    // For a `super` invocation to be unnecessary, the first argument needs to match the enclosing
+    // class, and the second argument needs to match the first argument to the enclosing function.
+    if let [first_arg, second_arg] = args.as_slice() {
+        // Find the enclosing function definition (if any).
+        if let Some(StmtKind::FunctionDef {
+            args: parent_args, ..
+        }) = parents
+            .find(|stmt| matches!(stmt.node, StmtKind::FunctionDef { .. }))
+            .map(|stmt| &stmt.node)
+        {
+            // Extract the name of the first argument to the enclosing function.
+            if let Some(ArgData {
+                arg: parent_arg, ..
+            }) = parent_args.args.first().map(|expr| &expr.node)
+            {
+                // Find the enclosing class definition (if any).
+                if let Some(StmtKind::ClassDef {
+                    name: parent_name, ..
+                }) = parents
+                    .find(|stmt| matches!(stmt.node, StmtKind::ClassDef { .. }))
+                    .map(|stmt| &stmt.node)
+                {
+                    if let (
+                        ExprKind::Name {
+                            id: first_arg_id, ..
+                        },
+                        ExprKind::Name {
+                            id: second_arg_id, ..
+                        },
+                    ) = (&first_arg.node, &second_arg.node)
+                    {
+                        if first_arg_id == parent_name && second_arg_id == parent_arg {
+                            return Some(Check::new(
+                                CheckKind::SuperCallWithParameters,
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    None
+}
+
+// flake8-print
+/// Check whether a function call is a `print` or `pprint` invocation
+pub fn check_print_call(
+    expr: &Expr,
+    func: &Expr,
+    check_print: bool,
+    check_pprint: bool,
+) -> Option<Check> {
+    if let ExprKind::Name { id, .. } = &func.node {
+        if check_print && id == "print" {
+            return Some(Check::new(CheckKind::PrintFound, Range::from_located(expr)));
+        } else if check_pprint && id == "pprint" {
+            return Some(Check::new(
+                CheckKind::PPrintFound,
+                Range::from_located(expr),
+            ));
+        }
+    }
+
+    if let ExprKind::Attribute { value, attr, .. } = &func.node {
+        if let ExprKind::Name { id, .. } = &value.node {
+            if check_pprint && id == "pprint" && attr == "pprint" {
+                return Some(Check::new(
+                    CheckKind::PPrintFound,
+                    Range::from_located(expr),
+                ));
+            }
+        }
+    }
+
+    None
+}

src/ast/helpers.rs

@@ -0,0 +1,74 @@
+use once_cell::sync::Lazy;
+use regex::Regex;
+use rustpython_ast::{Expr, ExprKind, StmtKind};
+
+use crate::python::typing;
+
+static DUNDER_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"__[^\s]+__").unwrap());
+
+pub enum SubscriptKind {
+    AnnotatedSubscript,
+    PEP593AnnotatedSubscript,
+}
+
+pub fn match_annotated_subscript(expr: &Expr) -> Option<SubscriptKind> {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => {
+            if typing::is_annotated_subscript(attr) {
+                Some(SubscriptKind::AnnotatedSubscript)
+            } else if typing::is_pep593_annotated_subscript(attr) {
+                Some(SubscriptKind::PEP593AnnotatedSubscript)
+            } else {
+                None
+            }
+        }
+        ExprKind::Name { id, .. } => {
+            if typing::is_annotated_subscript(id) {
+                Some(SubscriptKind::AnnotatedSubscript)
+            } else if typing::is_pep593_annotated_subscript(id) {
+                Some(SubscriptKind::PEP593AnnotatedSubscript)
+            } else {
+                None
+            }
+        }
+        _ => None,
+    }
+}
+
+pub fn is_assignment_to_a_dunder(node: &StmtKind) -> bool {
+    // Check whether it's an assignment to a dunder, with or without a type annotation.
+    // This is what pycodestyle (as of 2.9.1) does.
+    match node {
+        StmtKind::Assign {
+            targets,
+            value: _,
+            type_comment: _,
+        } => {
+            if targets.len() != 1 {
+                return false;
+            }
+            match &targets[0].node {
+                ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+                _ => false,
+            }
+        }
+        StmtKind::AnnAssign {
+            target,
+            annotation: _,
+            value: _,
+            simple: _,
+        } => match &target.node {
+            ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+            _ => false,
+        },
+        _ => false,
+    }
+}
+
+pub fn match_name_or_attr(expr: &Expr, target: &str) -> bool {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => target == attr,
+        ExprKind::Name { id, .. } => target == id,
+        _ => false,
+    }
+}

src/ast/operations.rs

@@ -1,6 +1,6 @@
 use rustpython_parser::ast::{Constant, Expr, ExprKind, Location, Stmt, StmtKind};
 
-use crate::ast::types::{BindingKind, Scope};
+use crate::ast::types::{BindingKind, Range, Scope};
 
 /// Extract the names bound to a given __all__ assignment.
 pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
@@ -134,7 +134,7 @@ impl<'a> SourceCodeLocator<'a> {
         }
     }
 
-    pub fn slice_source_code(&mut self, location: &Location) -> &'a str {
+    pub fn slice_source_code_at(&mut self, location: &Location) -> &'a str {
         if !self.initialized {
             let mut offset = 0;
             for i in self.content.lines() {
@@ -147,4 +147,19 @@ impl<'a> SourceCodeLocator<'a> {
         let offset = self.offsets[location.row() - 1] + location.column() - 1;
         &self.content[offset..]
     }
+
+    pub fn slice_source_code_range(&mut self, range: &Range) -> &'a str {
+        if !self.initialized {
+            let mut offset = 0;
+            for i in self.content.lines() {
+                self.offsets.push(offset);
+                offset += i.len();
+                offset += 1;
+            }
+            self.initialized = true;
+        }
+        let start = self.offsets[range.location.row() - 1] + range.location.column() - 1;
+        let end = self.offsets[range.end_location.row() - 1] + range.end_location.column() - 1;
+        &self.content[start..end]
+    }
 }

src/ast/relocate.rs

@@ -1,13 +1,17 @@
-use rustpython_parser::ast::{Expr, ExprKind, Keyword, Location};
+use rustpython_parser::ast::{Expr, ExprKind, Keyword};
 
-fn relocate_keyword(keyword: &mut Keyword, location: Location) {
-    keyword.location = location;
+use crate::ast::types::Range;
+
+fn relocate_keyword(keyword: &mut Keyword, location: Range) {
+    keyword.location = location.location;
+    keyword.end_location = location.end_location;
     relocate_expr(&mut keyword.node.value, location);
 }
 
 /// Change an expression's location (recursively) to match a desired, fixed location.
-pub fn relocate_expr(expr: &mut Expr, location: Location) {
-    expr.location = location;
+pub fn relocate_expr(expr: &mut Expr, location: Range) {
+    expr.location = location.location;
+    expr.end_location = location.end_location;
     match &mut expr.node {
         ExprKind::BoolOp { values, .. } => {
             for expr in values {

src/ast/types.rs

@@ -1,13 +1,28 @@
 use std::collections::BTreeMap;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
-use rustpython_parser::ast::Location;
+use rustpython_parser::ast::{Located, Location};
 
 fn id() -> usize {
     static COUNTER: AtomicUsize = AtomicUsize::new(1);
     COUNTER.fetch_add(1, Ordering::Relaxed)
 }
 
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Range {
+    pub location: Location,
+    pub end_location: Location,
+}
+
+impl Range {
+    pub fn from_located<T>(located: &Located<T>) -> Self {
+        Range {
+            location: located.location,
+            end_location: located.end_location,
+        }
+    }
+}
+
 #[derive(Clone, Debug, Default)]
 pub struct FunctionScope {
     pub uses_locals: bool,
@@ -25,6 +40,7 @@ pub enum ScopeKind {
 pub struct Scope {
     pub id: usize,
     pub kind: ScopeKind,
+    pub import_starred: bool,
     pub values: BTreeMap<String, Binding>,
 }
 
@@ -33,32 +49,51 @@ impl Scope {
         Scope {
             id: id(),
             kind,
+            import_starred: false,
             values: BTreeMap::new(),
         }
     }
 }
 
+#[derive(Clone, Debug)]
+pub struct BindingContext {
+    pub defined_by: usize,
+    pub defined_in: Option<usize>,
+}
+
 #[derive(Clone, Debug)]
 pub enum BindingKind {
     Annotation,
     Argument,
     Assignment,
     Binding,
+    LoopVar,
     Builtin,
     ClassDefinition,
     Definition,
     Export(Vec<String>),
     FutureImportation,
-    Importation(String),
     StarImportation,
-    SubmoduleImportation(String),
+    Importation(String, String, BindingContext),
+    FromImportation(String, String, BindingContext),
+    SubmoduleImportation(String, String, BindingContext),
 }
 
 #[derive(Clone, Debug)]
 pub struct Binding {
     pub kind: BindingKind,
-    pub location: Location,
-    /// Tuple of (scope index, location) indicating the scope and location at which the binding was
+    pub range: Range,
+    /// Tuple of (scope index, range) indicating the scope and range at which the binding was
     /// last used.
-    pub used: Option<(usize, Location)>,
+    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,
+    ImportFrom,
 }

src/ast/visitor.rs

@@ -1,3 +1,4 @@
+use crate::ast::helpers::match_name_or_attr;
 use rustpython_parser::ast::{
     Alias, Arg, Arguments, Boolop, Cmpop, Comprehension, Constant, Excepthandler,
     ExcepthandlerKind, Expr, ExprContext, ExprKind, Keyword, MatchCase, Operator, Pattern,
@@ -148,7 +149,11 @@ pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
         } => {
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr);
+                if match_name_or_attr(annotation, "TypeAlias") {
+                    visitor.visit_annotation(expr);
+                } else {
+                    visitor.visit_expr(expr);
+                }
             }
             visitor.visit_expr(target);
         }

src/autofix/fixer.rs

@@ -2,6 +2,7 @@ use std::fs;
 use std::path::Path;
 
 use anyhow::Result;
+use itertools::Itertools;
 use rustpython_parser::ast::Location;
 
 use crate::checks::{Check, Fix};
@@ -43,41 +44,46 @@ fn apply_fixes<'a>(fixes: impl Iterator<Item = &'a mut Fix>, contents: &str) ->
     let mut output = "".to_string();
     let mut last_pos: Location = Location::new(0, 0);
 
-    for fix in fixes {
+    for fix in fixes.sorted_by_key(|fix| fix.location) {
         // Best-effort approach: if this fix overlaps with a fix we've already applied, skip it.
-        if last_pos > fix.start {
+        if last_pos > fix.location {
             continue;
         }
 
-        if fix.start.row() > last_pos.row() {
+        if fix.location.row() > last_pos.row() {
             if last_pos.row() > 0 || last_pos.column() > 0 {
                 output.push_str(&lines[last_pos.row() - 1][last_pos.column() - 1..]);
                 output.push('\n');
             }
-            for line in &lines[last_pos.row()..fix.start.row() - 1] {
+            for line in &lines[last_pos.row()..fix.location.row() - 1] {
                 output.push_str(line);
                 output.push('\n');
             }
-            output.push_str(&lines[fix.start.row() - 1][..fix.start.column() - 1]);
+            output.push_str(&lines[fix.location.row() - 1][..fix.location.column() - 1]);
             output.push_str(&fix.content);
         } else {
             output.push_str(
-                &lines[last_pos.row() - 1][last_pos.column() - 1..fix.start.column() - 1],
+                &lines[last_pos.row() - 1][last_pos.column() - 1..fix.location.column() - 1],
             );
             output.push_str(&fix.content);
         }
 
-        last_pos = fix.end;
+        last_pos = fix.end_location;
         fix.applied = true;
     }
 
-    if last_pos.row() > 0 || last_pos.column() > 0 {
+    if last_pos.row() > 0
+        && (last_pos.row() - 1) < lines.len()
+        && (last_pos.row() > 0 || last_pos.column() > 0)
+    {
         output.push_str(&lines[last_pos.row() - 1][last_pos.column() - 1..]);
         output.push('\n');
     }
-    for line in &lines[last_pos.row()..] {
-        output.push_str(line);
-        output.push('\n');
+    if last_pos.row() < lines.len() {
+        for line in &lines[last_pos.row()..] {
+            output.push_str(line);
+            output.push('\n');
+        }
     }
 
     output
@@ -106,8 +112,8 @@ mod tests {
     fn apply_single_replacement() -> Result<()> {
         let mut fixes = vec![Fix {
             content: "Bar".to_string(),
-            start: Location::new(1, 9),
-            end: Location::new(1, 15),
+            location: Location::new(1, 9),
+            end_location: Location::new(1, 15),
             applied: false,
         }];
         let actual = apply_fixes(
@@ -130,8 +136,8 @@ mod tests {
     fn apply_single_removal() -> Result<()> {
         let mut fixes = vec![Fix {
             content: "".to_string(),
-            start: Location::new(1, 8),
-            end: Location::new(1, 16),
+            location: Location::new(1, 8),
+            end_location: Location::new(1, 16),
             applied: false,
         }];
         let actual = apply_fixes(
@@ -155,14 +161,14 @@ mod tests {
         let mut fixes = vec![
             Fix {
                 content: "".to_string(),
-                start: Location::new(1, 8),
-                end: Location::new(1, 17),
+                location: Location::new(1, 8),
+                end_location: Location::new(1, 17),
                 applied: false,
             },
             Fix {
                 content: "".to_string(),
-                start: Location::new(1, 17),
-                end: Location::new(1, 24),
+                location: Location::new(1, 17),
+                end_location: Location::new(1, 24),
                 applied: false,
             },
         ];
@@ -187,14 +193,14 @@ mod tests {
         let mut fixes = vec![
             Fix {
                 content: "".to_string(),
-                start: Location::new(1, 8),
-                end: Location::new(1, 16),
+                location: Location::new(1, 8),
+                end_location: Location::new(1, 16),
                 applied: false,
             },
             Fix {
                 content: "ignored".to_string(),
-                start: Location::new(1, 10),
-                end: Location::new(1, 12),
+                location: Location::new(1, 10),
+                end_location: Location::new(1, 12),
                 applied: false,
             },
         ];

src/autofix/fixes.rs

@@ -1,8 +1,14 @@
-use rustpython_parser::ast::{Expr, Keyword, Location};
+use anyhow::Result;
+use itertools::Itertools;
+use libcst_native::ImportNames::Aliases;
+use libcst_native::NameOrAttribute::N;
+use libcst_native::{Codegen, Expression, SmallStatement, Statement};
+use rustpython_parser::ast::{ExcepthandlerKind, Expr, Keyword, Location, Stmt, StmtKind};
 use rustpython_parser::lexer;
 use rustpython_parser::token::Tok;
 
 use crate::ast::operations::SourceCodeLocator;
+use crate::ast::types::Range;
 use crate::checks::Fix;
 
 /// Convert a location within a file (relative to `base`) to an absolute position.
@@ -25,7 +31,7 @@ pub fn remove_class_def_base(
     bases: &[Expr],
     keywords: &[Keyword],
 ) -> Option<Fix> {
-    let content = locator.slice_source_code(stmt_at);
+    let content = locator.slice_source_code_at(stmt_at);
 
     // Case 1: `object` is the only base.
     if bases.len() == 1 && keywords.is_empty() {
@@ -52,8 +58,8 @@ pub fn remove_class_def_base(
         return match (fix_start, fix_end) {
             (Some(start), Some(end)) => Some(Fix {
                 content: "".to_string(),
-                start,
-                end,
+                location: start,
+                end_location: end,
                 applied: false,
             }),
             _ => None,
@@ -91,8 +97,8 @@ pub fn remove_class_def_base(
         match (fix_start, fix_end) {
             (Some(start), Some(end)) => Some(Fix {
                 content: "".to_string(),
-                start,
-                end,
+                location: start,
+                end_location: end,
                 applied: false,
             }),
             _ => None,
@@ -116,11 +122,271 @@ pub fn remove_class_def_base(
         match (fix_start, fix_end) {
             (Some(start), Some(end)) => Some(Fix {
                 content: "".to_string(),
-                start,
-                end,
+                location: start,
+                end_location: end,
                 applied: false,
             }),
             _ => None,
         }
     }
 }
+
+pub fn remove_super_arguments(locator: &mut SourceCodeLocator, expr: &Expr) -> Option<Fix> {
+    let range = Range::from_located(expr);
+    let contents = locator.slice_source_code_range(&range);
+
+    let mut tree = match libcst_native::parse_module(contents, None) {
+        Ok(m) => m,
+        Err(_) => return None,
+    };
+
+    if let Some(Statement::Simple(body)) = tree.body.first_mut() {
+        if let Some(SmallStatement::Expr(body)) = body.body.first_mut() {
+            if let Expression::Call(body) = &mut body.value {
+                body.args = vec![];
+                body.whitespace_before_args = Default::default();
+                body.whitespace_after_func = Default::default();
+
+                let mut state = Default::default();
+                tree.codegen(&mut state);
+
+                return Some(Fix {
+                    content: state.to_string(),
+                    location: range.location,
+                    end_location: range.end_location,
+                    applied: false,
+                });
+            }
+        }
+    }
+
+    None
+}
+
+/// Determine if a body contains only a single statement, taking into account deleted.
+fn has_single_child(body: &[Stmt], deleted: &[&Stmt]) -> bool {
+    body.iter().filter(|child| !deleted.contains(child)).count() == 1
+}
+
+/// Determine if a child is the only statement in its body.
+fn is_lone_child(child: &Stmt, parent: &Stmt, deleted: &[&Stmt]) -> Result<bool> {
+    match &parent.node {
+        StmtKind::FunctionDef { body, .. }
+        | StmtKind::AsyncFunctionDef { body, .. }
+        | StmtKind::ClassDef { body, .. }
+        | StmtKind::With { body, .. }
+        | StmtKind::AsyncWith { body, .. } => {
+            if body.iter().contains(child) {
+                Ok(has_single_child(body, deleted))
+            } else {
+                Err(anyhow::anyhow!("Unable to find child in parent body."))
+            }
+        }
+        StmtKind::For { body, orelse, .. }
+        | StmtKind::AsyncFor { body, orelse, .. }
+        | StmtKind::While { body, orelse, .. }
+        | StmtKind::If { body, orelse, .. } => {
+            if body.iter().contains(child) {
+                Ok(has_single_child(body, deleted))
+            } else if orelse.iter().contains(child) {
+                Ok(has_single_child(orelse, deleted))
+            } else {
+                Err(anyhow::anyhow!("Unable to find child in parent body."))
+            }
+        }
+        StmtKind::Try {
+            body,
+            handlers,
+            orelse,
+            finalbody,
+        } => {
+            if body.iter().contains(child) {
+                Ok(has_single_child(body, deleted))
+            } else if orelse.iter().contains(child) {
+                Ok(has_single_child(orelse, deleted))
+            } else if finalbody.iter().contains(child) {
+                Ok(has_single_child(finalbody, deleted))
+            } else if let Some(body) = handlers.iter().find_map(|handler| match &handler.node {
+                ExcepthandlerKind::ExceptHandler { body, .. } => {
+                    if body.iter().contains(child) {
+                        Some(body)
+                    } else {
+                        None
+                    }
+                }
+            }) {
+                Ok(has_single_child(body, deleted))
+            } else {
+                Err(anyhow::anyhow!("Unable to find child in parent body."))
+            }
+        }
+        _ => Err(anyhow::anyhow!("Unable to find child in parent body.")),
+    }
+}
+
+pub fn remove_stmt(stmt: &Stmt, parent: Option<&Stmt>, deleted: &[&Stmt]) -> Result<Fix> {
+    if parent
+        .map(|parent| is_lone_child(stmt, parent, deleted))
+        .map_or(Ok(None), |v| v.map(Some))?
+        .unwrap_or_default()
+    {
+        // If removing this node would lead to an invalid syntax tree, replace
+        // it with a `pass`.
+        Ok(Fix {
+            location: stmt.location,
+            end_location: stmt.end_location,
+            content: "pass".to_string(),
+            applied: false,
+        })
+    } else {
+        // Otherwise, nuke the entire line.
+        // TODO(charlie): This logic assumes that there are no multi-statement physical lines.
+        Ok(Fix {
+            location: Location::new(stmt.location.row(), 1),
+            end_location: Location::new(stmt.end_location.row() + 1, 1),
+            content: "".to_string(),
+            applied: false,
+        })
+    }
+}
+
+/// Generate a Fix to remove any unused imports from an `import` statement.
+pub fn remove_unused_imports(
+    locator: &mut SourceCodeLocator,
+    full_names: &[&str],
+    stmt: &Stmt,
+    parent: Option<&Stmt>,
+    deleted: &[&Stmt],
+) -> Result<Fix> {
+    let mut tree = match libcst_native::parse_module(
+        locator.slice_source_code_range(&Range::from_located(stmt)),
+        None,
+    ) {
+        Ok(m) => m,
+        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
+    };
+
+    let body = if let Some(Statement::Simple(body)) = tree.body.first_mut() {
+        body
+    } else {
+        return Err(anyhow::anyhow!("Expected node to be: Statement::Simple."));
+    };
+    let body = if let Some(SmallStatement::Import(body)) = body.body.first_mut() {
+        body
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected node to be: SmallStatement::ImportFrom."
+        ));
+    };
+    let aliases = &mut body.names;
+
+    // Preserve the trailing comma (or not) from the last entry.
+    let trailing_comma = aliases.last().and_then(|alias| alias.comma.clone());
+
+    // Identify unused imports from within the `import from`.
+    let mut removable = vec![];
+    for (index, alias) in aliases.iter().enumerate() {
+        if let N(import_name) = &alias.name {
+            if full_names.contains(&import_name.value) {
+                removable.push(index);
+            }
+        }
+    }
+    // TODO(charlie): This is quadratic.
+    for index in removable.iter().rev() {
+        aliases.remove(*index);
+    }
+
+    if let Some(alias) = aliases.last_mut() {
+        alias.comma = trailing_comma;
+    }
+
+    if aliases.is_empty() {
+        remove_stmt(stmt, parent, deleted)
+    } else {
+        let mut state = Default::default();
+        tree.codegen(&mut state);
+
+        Ok(Fix {
+            content: state.to_string(),
+            location: stmt.location,
+            end_location: stmt.end_location,
+            applied: false,
+        })
+    }
+}
+
+/// Generate a Fix to remove any unused imports from an `import from` statement.
+pub fn remove_unused_import_froms(
+    locator: &mut SourceCodeLocator,
+    full_names: &[&str],
+    stmt: &Stmt,
+    parent: Option<&Stmt>,
+    deleted: &[&Stmt],
+) -> Result<Fix> {
+    let mut tree = match libcst_native::parse_module(
+        locator.slice_source_code_range(&Range::from_located(stmt)),
+        None,
+    ) {
+        Ok(m) => m,
+        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
+    };
+
+    let body = if let Some(Statement::Simple(body)) = tree.body.first_mut() {
+        body
+    } else {
+        return Err(anyhow::anyhow!("Expected node to be: Statement::Simple."));
+    };
+    let body = if let Some(SmallStatement::ImportFrom(body)) = body.body.first_mut() {
+        body
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected node to be: SmallStatement::ImportFrom."
+        ));
+    };
+    let aliases = if let Aliases(aliases) = &mut body.names {
+        aliases
+    } else {
+        return Err(anyhow::anyhow!("Expected node to be: Aliases."));
+    };
+
+    // Preserve the trailing comma (or not) from the last entry.
+    let trailing_comma = aliases.last().and_then(|alias| alias.comma.clone());
+
+    // Identify unused imports from within the `import from`.
+    let mut removable = vec![];
+    for (index, alias) in aliases.iter().enumerate() {
+        if let N(name) = &alias.name {
+            let import_name = if let Some(N(module_name)) = &body.module {
+                format!("{}.{}", module_name.value, name.value)
+            } else {
+                name.value.to_string()
+            };
+            if full_names.contains(&import_name.as_str()) {
+                removable.push(index);
+            }
+        }
+    }
+    // TODO(charlie): This is quadratic.
+    for index in removable.iter().rev() {
+        aliases.remove(*index);
+    }
+
+    if let Some(alias) = aliases.last_mut() {
+        alias.comma = trailing_comma;
+    }
+
+    if aliases.is_empty() {
+        remove_stmt(stmt, parent, deleted)
+    } else {
+        let mut state = Default::default();
+        tree.codegen(&mut state);
+
+        Ok(Fix {
+            content: state.to_string(),
+            location: stmt.location,
+            end_location: stmt.end_location,
+            applied: false,
+        })
+    }
+}

src/check_lines.rs

@@ -1,6 +1,12 @@
+use std::collections::BTreeMap;
+
 use rustpython_parser::ast::Location;
 
-use crate::checks::{Check, CheckCode, CheckKind};
+use crate::ast::types::Range;
+use crate::autofix::fixer;
+use crate::checks::{Check, CheckCode, CheckKind, Fix};
+use crate::noqa;
+use crate::noqa::Directive;
 use crate::settings::Settings;
 
 /// Whether the given line is too long and should be reported.
@@ -19,17 +25,58 @@ fn should_enforce_line_length(line: &str, length: usize, limit: usize) -> bool {
     }
 }
 
-pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings) {
-    let enforce_line_too_long = settings.select.contains(&CheckCode::E501);
+pub fn check_lines(
+    checks: &mut Vec<Check>,
+    contents: &str,
+    noqa_line_for: &[usize],
+    settings: &Settings,
+    autofix: &fixer::Mode,
+) {
+    let enforce_line_too_long = settings.enabled.contains(&CheckCode::E501);
+    let enforce_noqa = settings.enabled.contains(&CheckCode::M001);
+
+    let mut noqa_directives: BTreeMap<usize, (Directive, Vec<&str>)> = BTreeMap::new();
 
     let mut line_checks = vec![];
     let mut ignored = vec![];
-    for (row, line) in contents.lines().enumerate() {
+
+    let lines: Vec<&str> = contents.lines().collect();
+    for (lineno, line) in lines.iter().enumerate() {
+        // Grab the noqa (logical) line number for the current (physical) line.
+        // If there are newlines at the end of the file, they won't be represented in
+        // `noqa_line_for`, so fallback to the current line.
+        let noqa_lineno = noqa_line_for
+            .get(lineno)
+            .map(|lineno| lineno - 1)
+            .unwrap_or(lineno);
+
+        if enforce_noqa {
+            noqa_directives
+                .entry(noqa_lineno)
+                .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno]), vec![]));
+        }
+
         // Remove any ignored checks.
         // TODO(charlie): Only validate checks for the current line.
         for (index, check) in checks.iter().enumerate() {
-            if check.location.row() == row + 1 && check.is_inline_ignored(line) {
-                ignored.push(index);
+            if check.location.row() == lineno + 1 {
+                let noqa = noqa_directives
+                    .entry(noqa_lineno)
+                    .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno]), vec![]));
+
+                match noqa {
+                    (Directive::All(_, _), matches) => {
+                        matches.push(check.kind.code().as_ref());
+                        ignored.push(index)
+                    }
+                    (Directive::Codes(_, _, codes), matches) => {
+                        if codes.contains(&check.kind.code().as_ref()) {
+                            matches.push(check.kind.code().as_ref());
+                            ignored.push(index);
+                        }
+                    }
+                    (Directive::None, _) => {}
+                }
             }
         }
 
@@ -37,16 +84,151 @@ pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings)
         if enforce_line_too_long {
             let line_length = line.chars().count();
             if should_enforce_line_length(line, line_length, settings.line_length) {
+                let noqa = noqa_directives
+                    .entry(noqa_lineno)
+                    .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno]), vec![]));
+
                 let check = Check::new(
                     CheckKind::LineTooLong(line_length, settings.line_length),
-                    Location::new(row + 1, settings.line_length + 1),
+                    Range {
+                        location: Location::new(lineno + 1, 1),
+                        end_location: Location::new(lineno + 1, line_length + 1),
+                    },
                 );
-                if !check.is_inline_ignored(line) {
-                    line_checks.push(check);
+
+                match noqa {
+                    (Directive::All(_, _), matches) => {
+                        matches.push(check.kind.code().as_ref());
+                    }
+                    (Directive::Codes(_, _, codes), matches) => {
+                        if codes.contains(&check.kind.code().as_ref()) {
+                            matches.push(check.kind.code().as_ref());
+                        } else {
+                            line_checks.push(check);
+                        }
+                    }
+                    (Directive::None, _) => line_checks.push(check),
                 }
             }
         }
     }
+
+    // Enforce newlines at end of files.
+    if settings.enabled.contains(&CheckCode::W292) && !contents.ends_with('\n') {
+        // Note: if `lines.last()` is `None`, then `contents` is empty (and so we don't want to
+        // raise W292 anyway).
+        if let Some(line) = lines.last() {
+            let lineno = lines.len() - 1;
+            let noqa_lineno = noqa_line_for
+                .get(lineno)
+                .map(|lineno| lineno - 1)
+                .unwrap_or(lineno);
+
+            let noqa = noqa_directives
+                .entry(noqa_lineno)
+                .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno]), vec![]));
+
+            let check = Check::new(
+                CheckKind::NoNewLineAtEndOfFile,
+                Range {
+                    location: Location::new(lines.len(), line.len() + 1),
+                    end_location: Location::new(lines.len(), line.len() + 1),
+                },
+            );
+
+            match noqa {
+                (Directive::All(_, _), matches) => {
+                    matches.push(check.kind.code().as_ref());
+                }
+                (Directive::Codes(_, _, codes), matches) => {
+                    if codes.contains(&check.kind.code().as_ref()) {
+                        matches.push(check.kind.code().as_ref());
+                    } else {
+                        line_checks.push(check);
+                    }
+                }
+                (Directive::None, _) => line_checks.push(check),
+            }
+        }
+    }
+
+    // Enforce that the noqa directive was actually used.
+    if enforce_noqa {
+        for (row, (directive, matches)) in noqa_directives {
+            match directive {
+                Directive::All(start, end) => {
+                    if matches.is_empty() {
+                        let mut check = Check::new(
+                            CheckKind::UnusedNOQA(None),
+                            Range {
+                                location: Location::new(row + 1, start + 1),
+                                end_location: Location::new(row + 1, end + 1),
+                            },
+                        );
+                        if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                            check.amend(Fix {
+                                content: "".to_string(),
+                                location: Location::new(row + 1, start + 1),
+                                end_location: Location::new(
+                                    row + 1,
+                                    lines[row].chars().count() + 1,
+                                ),
+                                applied: false,
+                            });
+                        }
+                        line_checks.push(check);
+                    }
+                }
+                Directive::Codes(start, end, codes) => {
+                    let mut invalid_codes = vec![];
+                    let mut valid_codes = vec![];
+                    for code in codes {
+                        if !matches.contains(&code) {
+                            invalid_codes.push(code);
+                        } else {
+                            valid_codes.push(code);
+                        }
+                    }
+
+                    if !invalid_codes.is_empty() {
+                        let mut check = Check::new(
+                            CheckKind::UnusedNOQA(Some(invalid_codes.join(", "))),
+                            Range {
+                                location: Location::new(row + 1, start + 1),
+                                end_location: Location::new(row + 1, end + 1),
+                            },
+                        );
+                        if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+                            if valid_codes.is_empty() {
+                                check.amend(Fix {
+                                    content: "".to_string(),
+                                    location: Location::new(row + 1, start + 1),
+                                    end_location: Location::new(
+                                        row + 1,
+                                        lines[row].chars().count() + 1,
+                                    ),
+                                    applied: false,
+                                });
+                            } else {
+                                check.amend(Fix {
+                                    content: format!("  # noqa: {}", valid_codes.join(", ")),
+                                    location: Location::new(row + 1, start + 1),
+                                    end_location: Location::new(
+                                        row + 1,
+                                        lines[row].chars().count() + 1,
+                                    ),
+                                    applied: false,
+                                });
+                            }
+                        }
+                        line_checks.push(check);
+                    }
+                }
+                Directive::None => {}
+            }
+        }
+    }
+
     ignored.sort();
     for index in ignored.iter().rev() {
         checks.swap_remove(*index);
@@ -56,22 +238,28 @@ pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings)
 
 #[cfg(test)]
 mod tests {
+    use crate::autofix::fixer;
+    use crate::checks::{Check, CheckCode};
+    use crate::settings;
+
     use super::check_lines;
-    use super::*;
-    use std::collections::BTreeSet;
 
     #[test]
     fn e501_non_ascii_char() {
         let line = "'\u{4e9c}' * 2"; // 7 in UTF-32, 9 in UTF-8.
+        let noqa_line_for: Vec<usize> = vec![1];
         let check_with_max_line_length = |line_length: usize| {
             let mut checks: Vec<Check> = vec![];
-            let settings = Settings {
-                line_length,
-                exclude: vec![],
-                extend_exclude: vec![],
-                select: BTreeSet::from_iter(vec![CheckCode::E501]),
-            };
-            check_lines(&mut checks, line, &settings);
+            check_lines(
+                &mut checks,
+                line,
+                &noqa_line_for,
+                &settings::Settings {
+                    line_length,
+                    ..settings::Settings::for_rule(CheckCode::E501)
+                },
+                &fixer::Mode::Generate,
+            );
             return checks;
         };
         assert!(!check_with_max_line_length(6).is_empty());

src/checks.rs

@@ -1,12 +1,13 @@
-use std::str::FromStr;
-
-use anyhow::Result;
-use once_cell::sync::Lazy;
-use regex::Regex;
+use itertools::Itertools;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
+use strum_macros::{AsRefStr, EnumIter, EnumString};
 
-pub const ALL_CHECK_CODES: [CheckCode; 42] = [
+use crate::ast::checks::Primitive;
+use crate::ast::types::Range;
+
+pub const DEFAULT_CHECK_CODES: [CheckCode; 43] = [
+    // pycodestyle errors
     CheckCode::E402,
     CheckCode::E501,
     CheckCode::E711,
@@ -21,9 +22,14 @@ pub const ALL_CHECK_CODES: [CheckCode; 42] = [
     CheckCode::E743,
     CheckCode::E902,
     CheckCode::E999,
+    // pycodestyle warnings
+    CheckCode::W292,
+    // pyflakes
     CheckCode::F401,
+    CheckCode::F402,
     CheckCode::F403,
     CheckCode::F404,
+    CheckCode::F405,
     CheckCode::F406,
     CheckCode::F407,
     CheckCode::F541,
@@ -47,12 +53,24 @@ pub const ALL_CHECK_CODES: [CheckCode; 42] = [
     CheckCode::F831,
     CheckCode::F841,
     CheckCode::F901,
-    CheckCode::R001,
-    CheckCode::R002,
 ];
 
-#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize, Hash, PartialOrd, Ord)]
+#[derive(
+    AsRefStr,
+    EnumIter,
+    EnumString,
+    Debug,
+    PartialEq,
+    Eq,
+    Clone,
+    Serialize,
+    Deserialize,
+    Hash,
+    PartialOrd,
+    Ord,
+)]
 pub enum CheckCode {
+    // pycodestyle errors
     E402,
     E501,
     E711,
@@ -67,9 +85,14 @@ pub enum CheckCode {
     E743,
     E902,
     E999,
+    // pycodestyle warnings
+    W292,
+    // pyflakes
     F401,
+    F402,
     F403,
     F404,
+    F405,
     F406,
     F407,
     F541,
@@ -93,166 +116,34 @@ pub enum CheckCode {
     F831,
     F841,
     F901,
-    R001,
-    R002,
-}
-
-impl FromStr for CheckCode {
-    type Err = anyhow::Error;
-
-    fn from_str(s: &str) -> Result<Self> {
-        match s {
-            "E402" => Ok(CheckCode::E402),
-            "E501" => Ok(CheckCode::E501),
-            "E711" => Ok(CheckCode::E711),
-            "E712" => Ok(CheckCode::E712),
-            "E713" => Ok(CheckCode::E713),
-            "E714" => Ok(CheckCode::E714),
-            "E721" => Ok(CheckCode::E721),
-            "E722" => Ok(CheckCode::E722),
-            "E731" => Ok(CheckCode::E731),
-            "E741" => Ok(CheckCode::E741),
-            "E742" => Ok(CheckCode::E742),
-            "E743" => Ok(CheckCode::E743),
-            "E902" => Ok(CheckCode::E902),
-            "E999" => Ok(CheckCode::E999),
-            "F401" => Ok(CheckCode::F401),
-            "F403" => Ok(CheckCode::F403),
-            "F404" => Ok(CheckCode::F404),
-            "F406" => Ok(CheckCode::F406),
-            "F407" => Ok(CheckCode::F407),
-            "F541" => Ok(CheckCode::F541),
-            "F601" => Ok(CheckCode::F601),
-            "F602" => Ok(CheckCode::F602),
-            "F621" => Ok(CheckCode::F621),
-            "F622" => Ok(CheckCode::F622),
-            "F631" => Ok(CheckCode::F631),
-            "F632" => Ok(CheckCode::F632),
-            "F633" => Ok(CheckCode::F633),
-            "F634" => Ok(CheckCode::F634),
-            "F701" => Ok(CheckCode::F701),
-            "F702" => Ok(CheckCode::F702),
-            "F704" => Ok(CheckCode::F704),
-            "F706" => Ok(CheckCode::F706),
-            "F707" => Ok(CheckCode::F707),
-            "F722" => Ok(CheckCode::F722),
-            "F821" => Ok(CheckCode::F821),
-            "F822" => Ok(CheckCode::F822),
-            "F823" => Ok(CheckCode::F823),
-            "F831" => Ok(CheckCode::F831),
-            "F841" => Ok(CheckCode::F841),
-            "F901" => Ok(CheckCode::F901),
-            "R001" => Ok(CheckCode::R001),
-            "R002" => Ok(CheckCode::R002),
-            _ => Err(anyhow::anyhow!("Unknown check code: {s}")),
-        }
-    }
-}
-
-impl CheckCode {
-    pub fn as_str(&self) -> &str {
-        match self {
-            CheckCode::E402 => "E402",
-            CheckCode::E501 => "E501",
-            CheckCode::E711 => "E711",
-            CheckCode::E712 => "E712",
-            CheckCode::E713 => "E713",
-            CheckCode::E714 => "E714",
-            CheckCode::E721 => "E721",
-            CheckCode::E722 => "E722",
-            CheckCode::E731 => "E731",
-            CheckCode::E741 => "E741",
-            CheckCode::E742 => "E742",
-            CheckCode::E743 => "E743",
-            CheckCode::E902 => "E902",
-            CheckCode::E999 => "E999",
-            CheckCode::F401 => "F401",
-            CheckCode::F403 => "F403",
-            CheckCode::F404 => "F404",
-            CheckCode::F406 => "F406",
-            CheckCode::F407 => "F407",
-            CheckCode::F541 => "F541",
-            CheckCode::F601 => "F601",
-            CheckCode::F602 => "F602",
-            CheckCode::F621 => "F621",
-            CheckCode::F622 => "F622",
-            CheckCode::F631 => "F631",
-            CheckCode::F632 => "F632",
-            CheckCode::F633 => "F633",
-            CheckCode::F634 => "F634",
-            CheckCode::F701 => "F701",
-            CheckCode::F702 => "F702",
-            CheckCode::F704 => "F704",
-            CheckCode::F706 => "F706",
-            CheckCode::F707 => "F707",
-            CheckCode::F722 => "F722",
-            CheckCode::F821 => "F821",
-            CheckCode::F822 => "F822",
-            CheckCode::F823 => "F823",
-            CheckCode::F831 => "F831",
-            CheckCode::F841 => "F841",
-            CheckCode::F901 => "F901",
-            CheckCode::R001 => "R001",
-            CheckCode::R002 => "R002",
-        }
-    }
-
-    /// The source for the check (either the AST, the filesystem, or the physical lines).
-    pub fn lint_source(&self) -> &'static LintSource {
-        match self {
-            CheckCode::E501 => &LintSource::Lines,
-            CheckCode::E902 | CheckCode::E999 => &LintSource::FileSystem,
-            _ => &LintSource::AST,
-        }
-    }
-
-    /// A placeholder representation of the CheckKind for the check.
-    pub fn kind(&self) -> CheckKind {
-        match self {
-            CheckCode::E742 => CheckKind::AmbiguousClassName("...".to_string()),
-            CheckCode::E743 => CheckKind::AmbiguousFunctionName("...".to_string()),
-            CheckCode::E741 => CheckKind::AmbiguousVariableName("...".to_string()),
-            CheckCode::F631 => CheckKind::AssertTuple,
-            CheckCode::F701 => CheckKind::BreakOutsideLoop,
-            CheckCode::F702 => CheckKind::ContinueOutsideLoop,
-            CheckCode::F707 => CheckKind::DefaultExceptNotLast,
-            CheckCode::E731 => CheckKind::DoNotAssignLambda,
-            CheckCode::E722 => CheckKind::DoNotUseBareExcept,
-            CheckCode::F831 => CheckKind::DuplicateArgumentName,
-            CheckCode::F541 => CheckKind::FStringMissingPlaceholders,
-            CheckCode::F722 => CheckKind::ForwardAnnotationSyntaxError("...".to_string()),
-            CheckCode::F407 => CheckKind::FutureFeatureNotDefined("...".to_string()),
-            CheckCode::E902 => CheckKind::IOError("...".to_string()),
-            CheckCode::F634 => CheckKind::IfTuple,
-            CheckCode::F406 => CheckKind::ImportStarNotPermitted("...".to_string()),
-            CheckCode::F403 => CheckKind::ImportStarUsage("...".to_string()),
-            CheckCode::F633 => CheckKind::InvalidPrintSyntax,
-            CheckCode::F632 => CheckKind::IsLiteral,
-            CheckCode::F404 => CheckKind::LateFutureImport,
-            CheckCode::E501 => CheckKind::LineTooLong(89, 88),
-            CheckCode::E402 => CheckKind::ModuleImportNotAtTopOfFile,
-            CheckCode::F601 => CheckKind::MultiValueRepeatedKeyLiteral,
-            CheckCode::F602 => CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
-            CheckCode::R002 => CheckKind::NoAssertEquals,
-            CheckCode::E711 => CheckKind::NoneComparison(RejectedCmpop::Eq),
-            CheckCode::E713 => CheckKind::NotInTest,
-            CheckCode::E714 => CheckKind::NotIsTest,
-            CheckCode::F901 => CheckKind::RaiseNotImplemented,
-            CheckCode::F706 => CheckKind::ReturnOutsideFunction,
-            CheckCode::E999 => CheckKind::SyntaxError("...".to_string()),
-            CheckCode::F621 => CheckKind::TooManyExpressionsInStarredAssignment,
-            CheckCode::E712 => CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
-            CheckCode::F622 => CheckKind::TwoStarredExpressions,
-            CheckCode::E721 => CheckKind::TypeComparison,
-            CheckCode::F822 => CheckKind::UndefinedExport("...".to_string()),
-            CheckCode::F823 => CheckKind::UndefinedLocal("...".to_string()),
-            CheckCode::F821 => CheckKind::UndefinedName("...".to_string()),
-            CheckCode::F401 => CheckKind::UnusedImport("...".to_string()),
-            CheckCode::F841 => CheckKind::UnusedVariable("...".to_string()),
-            CheckCode::R001 => CheckKind::UselessObjectInheritance("...".to_string()),
-            CheckCode::F704 => CheckKind::YieldOutsideFunction,
-        }
-    }
+    // flake8-builtins
+    A001,
+    A002,
+    A003,
+    // flake8-comprehensions
+    C400,
+    C401,
+    C402,
+    C403,
+    C404,
+    C405,
+    C406,
+    C408,
+    C415,
+    // flake8-print
+    T201,
+    T203,
+    // pyupgrade
+    U001,
+    U002,
+    U003,
+    U004,
+    U005,
+    U006,
+    U007,
+    U008,
+    // Meta
+    M001,
 }
 
 #[allow(clippy::upper_case_acronyms)]
@@ -268,8 +159,9 @@ pub enum RejectedCmpop {
     NotEq,
 }
 
-#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(AsRefStr, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum CheckKind {
+    // pycodestyle errors
     AmbiguousClassName(String),
     AmbiguousFunctionName(String),
     AmbiguousVariableName(String),
@@ -280,13 +172,16 @@ pub enum CheckKind {
     DoNotAssignLambda,
     DoNotUseBareExcept,
     DuplicateArgumentName,
-    ForwardAnnotationSyntaxError(String),
+    ExpressionsInStarAssignment,
     FStringMissingPlaceholders,
+    ForwardAnnotationSyntaxError(String),
     FutureFeatureNotDefined(String),
     IOError(String),
     IfTuple,
+    ImportShadowedByLoopVar(String, usize),
     ImportStarNotPermitted(String),
-    ImportStarUsage(String),
+    ImportStarUsage(String, Vec<String>),
+    ImportStarUsed(String),
     InvalidPrintSyntax,
     IsLiteral,
     LateFutureImport,
@@ -294,80 +189,158 @@ pub enum CheckKind {
     ModuleImportNotAtTopOfFile,
     MultiValueRepeatedKeyLiteral,
     MultiValueRepeatedKeyVariable(String),
-    NoAssertEquals,
     NoneComparison(RejectedCmpop),
     NotInTest,
     NotIsTest,
     RaiseNotImplemented,
     ReturnOutsideFunction,
     SyntaxError(String),
-    TooManyExpressionsInStarredAssignment,
     TrueFalseComparison(bool, RejectedCmpop),
     TwoStarredExpressions,
     TypeComparison,
     UndefinedExport(String),
     UndefinedLocal(String),
     UndefinedName(String),
-    UnusedImport(String),
+    UnusedImport(Vec<String>),
     UnusedVariable(String),
-    UselessObjectInheritance(String),
     YieldOutsideFunction,
+    // pycodestyle warnings
+    NoNewLineAtEndOfFile,
+    // flake8-builtin
+    BuiltinVariableShadowing(String),
+    BuiltinArgumentShadowing(String),
+    BuiltinAttributeShadowing(String),
+    // flakes8-comprehensions
+    UnnecessaryGeneratorList,
+    UnnecessaryGeneratorSet,
+    UnnecessaryGeneratorDict,
+    UnnecessaryListComprehensionSet,
+    UnnecessaryListComprehensionDict,
+    UnnecessaryLiteralSet(String),
+    UnnecessaryLiteralDict(String),
+    UnnecessaryCollectionCall(String),
+    UnnecessarySubscriptReversal(String),
+    // flake8-print
+    PrintFound,
+    PPrintFound,
+    // pyupgrade
+    TypeOfPrimitive(Primitive),
+    UnnecessaryAbspath,
+    UselessMetaclassType,
+    DeprecatedUnittestAlias(String, String),
+    UselessObjectInheritance(String),
+    UsePEP585Annotation(String),
+    UsePEP604Annotation,
+    SuperCallWithParameters,
+    // Meta
+    UnusedNOQA(Option<String>),
 }
 
-impl CheckKind {
-    /// The name of the check.
-    pub fn name(&self) -> &'static str {
+impl CheckCode {
+    /// The source for the check (either the AST, the filesystem, or the physical lines).
+    pub fn lint_source(&self) -> &'static LintSource {
         match self {
-            CheckKind::AmbiguousClassName(_) => "AmbiguousClassName",
-            CheckKind::AmbiguousFunctionName(_) => "AmbiguousFunctionName",
-            CheckKind::AmbiguousVariableName(_) => "AmbiguousVariableName",
-            CheckKind::AssertTuple => "AssertTuple",
-            CheckKind::BreakOutsideLoop => "BreakOutsideLoop",
-            CheckKind::ContinueOutsideLoop => "ContinueOutsideLoop",
-            CheckKind::DefaultExceptNotLast => "DefaultExceptNotLast",
-            CheckKind::DoNotAssignLambda => "DoNotAssignLambda",
-            CheckKind::DoNotUseBareExcept => "DoNotUseBareExcept",
-            CheckKind::DuplicateArgumentName => "DuplicateArgumentName",
-            CheckKind::FStringMissingPlaceholders => "FStringMissingPlaceholders",
-            CheckKind::ForwardAnnotationSyntaxError(_) => "ForwardAnnotationSyntaxError",
-            CheckKind::FutureFeatureNotDefined(_) => "FutureFeatureNotDefined",
-            CheckKind::IOError(_) => "IOError",
-            CheckKind::IfTuple => "IfTuple",
-            CheckKind::ImportStarNotPermitted(_) => "ImportStarNotPermitted",
-            CheckKind::ImportStarUsage(_) => "ImportStarUsage",
-            CheckKind::InvalidPrintSyntax => "InvalidPrintSyntax",
-            CheckKind::IsLiteral => "IsLiteral",
-            CheckKind::LateFutureImport => "LateFutureImport",
-            CheckKind::LineTooLong(_, _) => "LineTooLong",
-            CheckKind::ModuleImportNotAtTopOfFile => "ModuleImportNotAtTopOfFile",
-            CheckKind::MultiValueRepeatedKeyLiteral => "MultiValueRepeatedKeyLiteral",
-            CheckKind::MultiValueRepeatedKeyVariable(_) => "MultiValueRepeatedKeyVariable",
-            CheckKind::NoAssertEquals => "NoAssertEquals",
-            CheckKind::NoneComparison(_) => "NoneComparison",
-            CheckKind::NotInTest => "NotInTest",
-            CheckKind::NotIsTest => "NotIsTest",
-            CheckKind::RaiseNotImplemented => "RaiseNotImplemented",
-            CheckKind::ReturnOutsideFunction => "ReturnOutsideFunction",
-            CheckKind::SyntaxError(_) => "SyntaxError",
-            CheckKind::TooManyExpressionsInStarredAssignment => {
-                "TooManyExpressionsInStarredAssignment"
-            }
-            CheckKind::TrueFalseComparison(_, _) => "TrueFalseComparison",
-            CheckKind::TwoStarredExpressions => "TwoStarredExpressions",
-            CheckKind::TypeComparison => "TypeComparison",
-            CheckKind::UndefinedExport(_) => "UndefinedExport",
-            CheckKind::UndefinedLocal(_) => "UndefinedLocal",
-            CheckKind::UndefinedName(_) => "UndefinedName",
-            CheckKind::UnusedImport(_) => "UnusedImport",
-            CheckKind::UnusedVariable(_) => "UnusedVariable",
-            CheckKind::UselessObjectInheritance(_) => "UselessObjectInheritance",
-            CheckKind::YieldOutsideFunction => "YieldOutsideFunction",
+            CheckCode::E501 | CheckCode::M001 => &LintSource::Lines,
+            CheckCode::E902 => &LintSource::FileSystem,
+            _ => &LintSource::AST,
         }
     }
 
+    /// A placeholder representation of the CheckKind for the check.
+    pub fn kind(&self) -> CheckKind {
+        match self {
+            // pycodestyle errors
+            CheckCode::E402 => CheckKind::ModuleImportNotAtTopOfFile,
+            CheckCode::E501 => CheckKind::LineTooLong(89, 88),
+            CheckCode::E711 => CheckKind::NoneComparison(RejectedCmpop::Eq),
+            CheckCode::E712 => CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
+            CheckCode::E713 => CheckKind::NotInTest,
+            CheckCode::E714 => CheckKind::NotIsTest,
+            CheckCode::E721 => CheckKind::TypeComparison,
+            CheckCode::E722 => CheckKind::DoNotUseBareExcept,
+            CheckCode::E731 => CheckKind::DoNotAssignLambda,
+            CheckCode::E741 => CheckKind::AmbiguousVariableName("...".to_string()),
+            CheckCode::E742 => CheckKind::AmbiguousClassName("...".to_string()),
+            CheckCode::E743 => CheckKind::AmbiguousFunctionName("...".to_string()),
+            CheckCode::E902 => CheckKind::IOError("IOError: `...`".to_string()),
+            CheckCode::E999 => CheckKind::SyntaxError("`...`".to_string()),
+            // pycodestyle warnings
+            CheckCode::W292 => CheckKind::NoNewLineAtEndOfFile,
+            // pyflakes
+            CheckCode::F401 => CheckKind::UnusedImport(vec!["...".to_string()]),
+            CheckCode::F402 => CheckKind::ImportShadowedByLoopVar("...".to_string(), 1),
+            CheckCode::F403 => CheckKind::ImportStarUsed("...".to_string()),
+            CheckCode::F404 => CheckKind::LateFutureImport,
+            CheckCode::F405 => {
+                CheckKind::ImportStarUsage("...".to_string(), vec!["...".to_string()])
+            }
+            CheckCode::F406 => CheckKind::ImportStarNotPermitted("...".to_string()),
+            CheckCode::F407 => CheckKind::FutureFeatureNotDefined("...".to_string()),
+            CheckCode::F541 => CheckKind::FStringMissingPlaceholders,
+            CheckCode::F601 => CheckKind::MultiValueRepeatedKeyLiteral,
+            CheckCode::F602 => CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
+            CheckCode::F621 => CheckKind::ExpressionsInStarAssignment,
+            CheckCode::F622 => CheckKind::TwoStarredExpressions,
+            CheckCode::F631 => CheckKind::AssertTuple,
+            CheckCode::F632 => CheckKind::IsLiteral,
+            CheckCode::F633 => CheckKind::InvalidPrintSyntax,
+            CheckCode::F634 => CheckKind::IfTuple,
+            CheckCode::F701 => CheckKind::BreakOutsideLoop,
+            CheckCode::F702 => CheckKind::ContinueOutsideLoop,
+            CheckCode::F704 => CheckKind::YieldOutsideFunction,
+            CheckCode::F706 => CheckKind::ReturnOutsideFunction,
+            CheckCode::F707 => CheckKind::DefaultExceptNotLast,
+            CheckCode::F722 => CheckKind::ForwardAnnotationSyntaxError("...".to_string()),
+            CheckCode::F821 => CheckKind::UndefinedName("...".to_string()),
+            CheckCode::F822 => CheckKind::UndefinedExport("...".to_string()),
+            CheckCode::F823 => CheckKind::UndefinedLocal("...".to_string()),
+            CheckCode::F831 => CheckKind::DuplicateArgumentName,
+            CheckCode::F841 => CheckKind::UnusedVariable("...".to_string()),
+            CheckCode::F901 => CheckKind::RaiseNotImplemented,
+            // flake8-builtins
+            CheckCode::A001 => CheckKind::BuiltinVariableShadowing("...".to_string()),
+            CheckCode::A002 => CheckKind::BuiltinArgumentShadowing("...".to_string()),
+            CheckCode::A003 => CheckKind::BuiltinAttributeShadowing("...".to_string()),
+            // flake8-comprehensions
+            CheckCode::C400 => CheckKind::UnnecessaryGeneratorList,
+            CheckCode::C401 => CheckKind::UnnecessaryGeneratorSet,
+            CheckCode::C402 => CheckKind::UnnecessaryGeneratorDict,
+            CheckCode::C403 => CheckKind::UnnecessaryListComprehensionSet,
+            CheckCode::C404 => CheckKind::UnnecessaryListComprehensionDict,
+            CheckCode::C405 => CheckKind::UnnecessaryLiteralSet("<list/tuple>".to_string()),
+            CheckCode::C406 => CheckKind::UnnecessaryLiteralDict("<list/tuple>".to_string()),
+            CheckCode::C408 => {
+                CheckKind::UnnecessaryCollectionCall("<dict/list/tuple>".to_string())
+            }
+            CheckCode::C415 => {
+                CheckKind::UnnecessarySubscriptReversal("<reversed/set/sorted>".to_string())
+            }
+            // flake8-print
+            CheckCode::T201 => CheckKind::PrintFound,
+            CheckCode::T203 => CheckKind::PPrintFound,
+            // pyupgrade
+            CheckCode::U001 => CheckKind::UselessMetaclassType,
+            CheckCode::U002 => CheckKind::UnnecessaryAbspath,
+            CheckCode::U003 => CheckKind::TypeOfPrimitive(Primitive::Str),
+            CheckCode::U004 => CheckKind::UselessObjectInheritance("...".to_string()),
+            CheckCode::U005 => CheckKind::DeprecatedUnittestAlias(
+                "assertEquals".to_string(),
+                "assertEqual".to_string(),
+            ),
+            CheckCode::U006 => CheckKind::UsePEP585Annotation("List".to_string()),
+            CheckCode::U007 => CheckKind::UsePEP604Annotation,
+            CheckCode::U008 => CheckKind::SuperCallWithParameters,
+            // Meta
+            CheckCode::M001 => CheckKind::UnusedNOQA(None),
+        }
+    }
+}
+
+impl CheckKind {
     /// A four-letter shorthand code for the check.
     pub fn code(&self) -> &'static CheckCode {
         match self {
+            // pycodestyle errors
             CheckKind::AmbiguousClassName(_) => &CheckCode::E742,
             CheckKind::AmbiguousFunctionName(_) => &CheckCode::E743,
             CheckKind::AmbiguousVariableName(_) => &CheckCode::E741,
@@ -383,8 +356,10 @@ impl CheckKind {
             CheckKind::FutureFeatureNotDefined(_) => &CheckCode::F407,
             CheckKind::IOError(_) => &CheckCode::E902,
             CheckKind::IfTuple => &CheckCode::F634,
+            CheckKind::ImportShadowedByLoopVar(_, _) => &CheckCode::F402,
             CheckKind::ImportStarNotPermitted(_) => &CheckCode::F406,
-            CheckKind::ImportStarUsage(_) => &CheckCode::F403,
+            CheckKind::ImportStarUsage(_, _) => &CheckCode::F405,
+            CheckKind::ImportStarUsed(_) => &CheckCode::F403,
             CheckKind::InvalidPrintSyntax => &CheckCode::F633,
             CheckKind::IsLiteral => &CheckCode::F632,
             CheckKind::LateFutureImport => &CheckCode::F404,
@@ -392,14 +367,13 @@ impl CheckKind {
             CheckKind::ModuleImportNotAtTopOfFile => &CheckCode::E402,
             CheckKind::MultiValueRepeatedKeyLiteral => &CheckCode::F601,
             CheckKind::MultiValueRepeatedKeyVariable(_) => &CheckCode::F602,
-            CheckKind::NoAssertEquals => &CheckCode::R002,
             CheckKind::NoneComparison(_) => &CheckCode::E711,
             CheckKind::NotInTest => &CheckCode::E713,
             CheckKind::NotIsTest => &CheckCode::E714,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
             CheckKind::SyntaxError(_) => &CheckCode::E999,
-            CheckKind::TooManyExpressionsInStarredAssignment => &CheckCode::F621,
+            CheckKind::ExpressionsInStarAssignment => &CheckCode::F621,
             CheckKind::TrueFalseComparison(_, _) => &CheckCode::E712,
             CheckKind::TwoStarredExpressions => &CheckCode::F622,
             CheckKind::TypeComparison => &CheckCode::E721,
@@ -408,22 +382,52 @@ impl CheckKind {
             CheckKind::UndefinedName(_) => &CheckCode::F821,
             CheckKind::UnusedImport(_) => &CheckCode::F401,
             CheckKind::UnusedVariable(_) => &CheckCode::F841,
-            CheckKind::UselessObjectInheritance(_) => &CheckCode::R001,
             CheckKind::YieldOutsideFunction => &CheckCode::F704,
+            // pycodestyle warnings
+            CheckKind::NoNewLineAtEndOfFile => &CheckCode::W292,
+            // flake8-builtins
+            CheckKind::BuiltinVariableShadowing(_) => &CheckCode::A001,
+            CheckKind::BuiltinArgumentShadowing(_) => &CheckCode::A002,
+            CheckKind::BuiltinAttributeShadowing(_) => &CheckCode::A003,
+            // flake8-comprehensions
+            CheckKind::UnnecessaryGeneratorList => &CheckCode::C400,
+            CheckKind::UnnecessaryGeneratorSet => &CheckCode::C401,
+            CheckKind::UnnecessaryGeneratorDict => &CheckCode::C402,
+            CheckKind::UnnecessaryListComprehensionSet => &CheckCode::C403,
+            CheckKind::UnnecessaryListComprehensionDict => &CheckCode::C404,
+            CheckKind::UnnecessaryLiteralSet(_) => &CheckCode::C405,
+            CheckKind::UnnecessaryLiteralDict(_) => &CheckCode::C406,
+            CheckKind::UnnecessaryCollectionCall(_) => &CheckCode::C408,
+            CheckKind::UnnecessarySubscriptReversal(_) => &CheckCode::C415,
+            // flake8-print
+            CheckKind::PrintFound => &CheckCode::T201,
+            CheckKind::PPrintFound => &CheckCode::T203,
+            // pyupgrade
+            CheckKind::TypeOfPrimitive(_) => &CheckCode::U003,
+            CheckKind::UnnecessaryAbspath => &CheckCode::U002,
+            CheckKind::UselessMetaclassType => &CheckCode::U001,
+            CheckKind::DeprecatedUnittestAlias(_, _) => &CheckCode::U005,
+            CheckKind::UsePEP585Annotation(_) => &CheckCode::U006,
+            CheckKind::UsePEP604Annotation => &CheckCode::U007,
+            CheckKind::UselessObjectInheritance(_) => &CheckCode::U004,
+            CheckKind::SuperCallWithParameters => &CheckCode::U008,
+            // Meta
+            CheckKind::UnusedNOQA(_) => &CheckCode::M001,
         }
     }
 
     /// The body text for the check.
     pub fn body(&self) -> String {
         match self {
+            // pycodestyle errors
             CheckKind::AmbiguousClassName(name) => {
-                format!("ambiguous class name '{}'", name)
+                format!("Ambiguous class name: `{}`", name)
             }
             CheckKind::AmbiguousFunctionName(name) => {
-                format!("ambiguous function name '{}'", name)
+                format!("Ambiguous function name: `{}`", name)
             }
             CheckKind::AmbiguousVariableName(name) => {
-                format!("ambiguous variable name '{}'", name)
+                format!("Ambiguous variable name: `{}`", name)
             }
             CheckKind::AssertTuple => {
                 "Assert test is a non-empty tuple, which is always `True`".to_string()
@@ -431,7 +435,7 @@ impl CheckKind {
             CheckKind::BreakOutsideLoop => "`break` outside loop".to_string(),
             CheckKind::ContinueOutsideLoop => "`continue` not properly in loop".to_string(),
             CheckKind::DefaultExceptNotLast => {
-                "an `except:` block as not the last exception handler".to_string()
+                "An `except:` block as not the last exception handler".to_string()
             }
             CheckKind::DoNotAssignLambda => {
                 "Do not assign a lambda expression, use a def".to_string()
@@ -441,28 +445,38 @@ impl CheckKind {
                 "Duplicate argument name in function definition".to_string()
             }
             CheckKind::ForwardAnnotationSyntaxError(body) => {
-                format!("syntax error in forward annotation '{body}'")
+                format!("Syntax error in forward annotation: `{body}`")
             }
             CheckKind::FStringMissingPlaceholders => {
                 "f-string without any placeholders".to_string()
             }
             CheckKind::FutureFeatureNotDefined(name) => {
-                format!("future feature '{name}' is not defined")
-            }
-            CheckKind::IOError(name) => {
-                format!("No such file or directory: `{name}`")
+                format!("Future feature `{name}` is not defined")
             }
+            CheckKind::IOError(message) => message.clone(),
             CheckKind::IfTuple => "If test is a tuple, which is always `True`".to_string(),
-            CheckKind::InvalidPrintSyntax => "use of >> is invalid with print function".to_string(),
+            CheckKind::InvalidPrintSyntax => {
+                "Use of `>>` is invalid with `print` function".to_string()
+            }
+            CheckKind::ImportShadowedByLoopVar(name, line) => {
+                format!("Import `{name}` from line {line} shadowed by loop variable")
+            }
             CheckKind::ImportStarNotPermitted(name) => {
                 format!("`from {name} import *` only allowed at module level")
             }
-            CheckKind::ImportStarUsage(name) => {
+            CheckKind::ImportStarUsed(name) => {
                 format!("`from {name} import *` used; unable to detect undefined names")
             }
-            CheckKind::IsLiteral => "use ==/!= to compare constant literals".to_string(),
+            CheckKind::ImportStarUsage(name, sources) => {
+                let sources = sources
+                    .iter()
+                    .map(|source| format!("`{}`", source))
+                    .join(", ");
+                format!("`{name}` may be undefined, or defined from star imports: {sources}")
+            }
+            CheckKind::IsLiteral => "Use `==` and `!=` to compare constant literals".to_string(),
             CheckKind::LateFutureImport => {
-                "from __future__ imports must occur at the beginning of the file".to_string()
+                "`from __future__` imports must occur at the beginning of the file".to_string()
             }
             CheckKind::LineTooLong(length, limit) => {
                 format!("Line too long ({length} > {limit} characters)")
@@ -476,9 +490,6 @@ impl CheckKind {
             CheckKind::MultiValueRepeatedKeyVariable(name) => {
                 format!("Dictionary key `{name}` repeated")
             }
-            CheckKind::NoAssertEquals => {
-                "`assertEquals` is deprecated, use `assertEqual` instead".to_string()
-            }
             CheckKind::NoneComparison(op) => match op {
                 RejectedCmpop::Eq => "Comparison to `None` should be `cond is None`".to_string(),
                 RejectedCmpop::NotEq => {
@@ -491,11 +502,11 @@ impl CheckKind {
                 "`raise NotImplemented` should be `raise NotImplementedError`".to_string()
             }
             CheckKind::ReturnOutsideFunction => {
-                "a `return` statement outside of a function/method".to_string()
+                "`return` statement outside of a function/method".to_string()
             }
             CheckKind::SyntaxError(message) => format!("SyntaxError: {message}"),
-            CheckKind::TooManyExpressionsInStarredAssignment => {
-                "too many expressions in star-unpacking assignment".to_string()
+            CheckKind::ExpressionsInStarAssignment => {
+                "Too many expressions in star-unpacking assignment".to_string()
             }
             CheckKind::TrueFalseComparison(value, op) => match *value {
                 true => match op {
@@ -515,8 +526,8 @@ impl CheckKind {
                     }
                 },
             },
-            CheckKind::TwoStarredExpressions => "two starred expressions in assignment".to_string(),
-            CheckKind::TypeComparison => "do not compare types, use `isinstance()`".to_string(),
+            CheckKind::TwoStarredExpressions => "Two starred expressions in assignment".to_string(),
+            CheckKind::TypeComparison => "Do not compare types, use `isinstance()`".to_string(),
             CheckKind::UndefinedExport(name) => {
                 format!("Undefined name `{name}` in `__all__`")
             }
@@ -526,16 +537,89 @@ impl CheckKind {
             CheckKind::UndefinedName(name) => {
                 format!("Undefined name `{name}`")
             }
-            CheckKind::UnusedImport(name) => format!("`{name}` imported but unused"),
+            CheckKind::UnusedImport(names) => {
+                let names = names.iter().map(|name| format!("`{name}`")).join(", ");
+                format!("{names} imported but unused")
+            }
             CheckKind::UnusedVariable(name) => {
                 format!("Local variable `{name}` is assigned to but never used")
             }
+            CheckKind::YieldOutsideFunction => {
+                "`yield` or `yield from` statement outside of a function/method".to_string()
+            }
+            // pycodestyle warnings
+            CheckKind::NoNewLineAtEndOfFile => "No newline at end of file".to_string(),
+            // flake8-builtins
+            CheckKind::BuiltinVariableShadowing(name) => {
+                format!("Variable `{name}` is shadowing a python builtin")
+            }
+            CheckKind::BuiltinArgumentShadowing(name) => {
+                format!("Argument `{name}` is shadowing a python builtin")
+            }
+            CheckKind::BuiltinAttributeShadowing(name) => {
+                format!("Class attribute `{name}` is shadowing a python builtin")
+            }
+            // flake8-comprehensions
+            CheckKind::UnnecessaryGeneratorList => {
+                "Unnecessary generator - rewrite as a list comprehension".to_string()
+            }
+            CheckKind::UnnecessaryGeneratorSet => {
+                "Unnecessary generator - rewrite as a set comprehension".to_string()
+            }
+            CheckKind::UnnecessaryGeneratorDict => {
+                "Unnecessary generator - rewrite as a dict comprehension".to_string()
+            }
+            CheckKind::UnnecessaryListComprehensionSet => {
+                "Unnecessary list comprehension - rewrite as a set comprehension".to_string()
+            }
+            CheckKind::UnnecessaryListComprehensionDict => {
+                "Unnecessary list comprehension - rewrite as a dict comprehension".to_string()
+            }
+            CheckKind::UnnecessaryLiteralSet(obj_type) => {
+                format!("Unnecessary {obj_type} literal - rewrite as a set literal")
+            }
+            CheckKind::UnnecessaryLiteralDict(obj_type) => {
+                format!("Unnecessary {obj_type} literal - rewrite as a dict literal")
+            }
+            CheckKind::UnnecessaryCollectionCall(obj_type) => {
+                format!("Unnecessary {obj_type} call - rewrite as a literal")
+            }
+            CheckKind::UnnecessarySubscriptReversal(func) => {
+                format!("Unnecessary subscript reversal of iterable within {func}()")
+            }
+            // flake8-print
+            CheckKind::PrintFound => "`print` found".to_string(),
+            CheckKind::PPrintFound => "`pprint` found".to_string(),
+            // pyupgrade
+            CheckKind::TypeOfPrimitive(primitive) => {
+                format!("Use `{}` instead of `type(...)`", primitive.builtin())
+            }
+            CheckKind::UnnecessaryAbspath => {
+                "`abspath(__file__)` is unnecessary in Python 3.9 and later".to_string()
+            }
+            CheckKind::UselessMetaclassType => "`__metaclass__ = type` is implied".to_string(),
+            CheckKind::DeprecatedUnittestAlias(alias, target) => {
+                format!("`{}` is deprecated, use `{}` instead", alias, target)
+            }
             CheckKind::UselessObjectInheritance(name) => {
                 format!("Class `{name}` inherits from object")
             }
-            CheckKind::YieldOutsideFunction => {
-                "a `yield` or `yield from` statement outside of a function/method".to_string()
+            CheckKind::UsePEP585Annotation(name) => {
+                format!(
+                    "Use `{}` instead of `{}` for type annotations",
+                    name.to_lowercase(),
+                    name,
+                )
             }
+            CheckKind::UsePEP604Annotation => "Use `X | Y` for type annotations".to_string(),
+            CheckKind::SuperCallWithParameters => {
+                "Use `super()` instead of `super(__class__, self)`".to_string()
+            }
+            // Meta
+            CheckKind::UnusedNOQA(code) => match code {
+                None => "Unused `noqa` directive".to_string(),
+                Some(code) => format!("Unused `noqa` directive for: {code}"),
+            },
         }
     }
 
@@ -543,7 +627,18 @@ impl CheckKind {
     pub fn fixable(&self) -> bool {
         matches!(
             self,
-            CheckKind::NoAssertEquals | CheckKind::UselessObjectInheritance(_)
+            CheckKind::DeprecatedUnittestAlias(_, _)
+                | CheckKind::PPrintFound
+                | CheckKind::PrintFound
+                | CheckKind::SuperCallWithParameters
+                | CheckKind::TypeOfPrimitive(_)
+                | CheckKind::UnnecessaryAbspath
+                | CheckKind::UnusedImport(_)
+                | CheckKind::UnusedNOQA(_)
+                | CheckKind::UselessMetaclassType
+                | CheckKind::UselessObjectInheritance(_)
+                | CheckKind::UsePEP585Annotation(_)
+                | CheckKind::UsePEP604Annotation
         )
     }
 }
@@ -551,8 +646,8 @@ impl CheckKind {
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Fix {
     pub content: String,
-    pub start: Location,
-    pub end: Location,
+    pub location: Location,
+    pub end_location: Location,
     pub applied: bool,
 }
 
@@ -560,19 +655,16 @@ pub struct Fix {
 pub struct Check {
     pub kind: CheckKind,
     pub location: Location,
+    pub end_location: Location,
     pub fix: Option<Fix>,
 }
 
-static NO_QA_REGEX: Lazy<Regex> = Lazy::new(|| {
-    Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").expect("Invalid regex")
-});
-static SPLIT_COMMA_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"[,\s]").expect("Invalid regex"));
-
 impl Check {
-    pub fn new(kind: CheckKind, location: Location) -> Self {
+    pub fn new(kind: CheckKind, span: Range) -> Self {
         Self {
             kind,
-            location,
+            location: span.location,
+            end_location: span.end_location,
             fix: None,
         }
     }
@@ -580,25 +672,26 @@ impl Check {
     pub fn amend(&mut self, fix: Fix) {
         self.fix = Some(fix);
     }
+}
 
-    pub fn is_inline_ignored(&self, line: &str) -> bool {
-        match NO_QA_REGEX.captures(line) {
-            Some(caps) => match caps.name("codes") {
-                Some(codes) => {
-                    for code in SPLIT_COMMA_REGEX
-                        .split(codes.as_str())
-                        .map(|code| code.trim())
-                        .filter(|code| !code.is_empty())
-                    {
-                        if code == self.kind.code().as_str() {
-                            return true;
-                        }
-                    }
-                    false
-                }
-                None => true,
-            },
-            None => false,
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use anyhow::Result;
+    use strum::IntoEnumIterator;
+
+    use crate::checks::CheckCode;
+
+    #[test]
+    fn check_code_serialization() -> Result<()> {
+        for check_code in CheckCode::iter() {
+            assert!(
+                CheckCode::from_str(check_code.as_ref()).is_ok(),
+                "{:?} could not be round-trip serialized.",
+                check_code
+            );
         }
+        Ok(())
     }
 }

src/cli.rs

@@ -0,0 +1,136 @@
+use std::fmt;
+use std::path::PathBuf;
+
+use clap::{command, Parser};
+use log::warn;
+use regex::Regex;
+
+use crate::checks::CheckCode;
+use crate::printer::SerializationFormat;
+use crate::pyproject::StrCheckCodePair;
+use crate::settings::PythonVersion;
+use crate::RawSettings;
+
+#[derive(Debug, Parser)]
+#[command(author, about = "ruff: An extremely fast Python linter.")]
+#[command(version)]
+pub struct Cli {
+    #[arg(required = true)]
+    pub files: Vec<PathBuf>,
+    /// Enable verbose logging.
+    #[arg(short, long)]
+    pub verbose: bool,
+    /// Disable all logging (but still exit with status code "1" upon detecting errors).
+    #[arg(short, long)]
+    pub quiet: bool,
+    /// Exit with status code "0", even upon detecting errors.
+    #[arg(short, long)]
+    pub exit_zero: bool,
+    /// Run in watch mode by re-running whenever files change.
+    #[arg(short, long)]
+    pub watch: bool,
+    /// Attempt to automatically fix lint errors.
+    #[arg(short, long)]
+    pub fix: bool,
+    /// Disable cache reads.
+    #[arg(short, long)]
+    pub no_cache: bool,
+    /// List of error codes to enable.
+    #[arg(long, value_delimiter = ',')]
+    pub select: Vec<CheckCode>,
+    /// Like --select, but adds additional error codes on top of the selected ones.
+    #[arg(long, value_delimiter = ',')]
+    pub extend_select: Vec<CheckCode>,
+    /// List of error codes to ignore.
+    #[arg(long, value_delimiter = ',')]
+    pub ignore: Vec<CheckCode>,
+    /// Like --ignore, but adds additional error codes on top of the ignored ones.
+    #[arg(long, value_delimiter = ',')]
+    pub extend_ignore: Vec<CheckCode>,
+    /// List of paths, used to exclude files and/or directories from checks.
+    #[arg(long, value_delimiter = ',')]
+    pub exclude: Vec<String>,
+    /// Like --exclude, but adds additional files and directories on top of the excluded ones.
+    #[arg(long, value_delimiter = ',')]
+    pub extend_exclude: Vec<String>,
+    /// List of mappings from file pattern to code to exclude
+    #[arg(long, value_delimiter = ',')]
+    pub per_file_ignores: Vec<StrCheckCodePair>,
+    /// Output serialization format for error messages.
+    #[arg(long, value_enum, default_value_t=SerializationFormat::Text)]
+    pub format: SerializationFormat,
+    /// See the files ruff will be run against with the current settings.
+    #[arg(long)]
+    pub show_files: bool,
+    /// See ruff's settings.
+    #[arg(long)]
+    pub show_settings: bool,
+    /// Enable automatic additions of noqa directives to failing lines.
+    #[arg(long)]
+    pub add_noqa: bool,
+    /// Regular expression matching the name of dummy variables.
+    #[arg(long)]
+    pub dummy_variable_rgx: Option<Regex>,
+    /// The minimum Python version that should be supported.
+    #[arg(long)]
+    pub target_version: Option<PythonVersion>,
+    /// Round-trip auto-formatting.
+    // TODO(charlie): This should be a sub-command.
+    #[arg(long, hide = true)]
+    pub autoformat: bool,
+}
+
+pub enum Warnable {
+    Select,
+    ExtendSelect,
+}
+
+impl fmt::Display for Warnable {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Warnable::Select => fmt.write_str("--select"),
+            Warnable::ExtendSelect => fmt.write_str("--extend-select"),
+        }
+    }
+}
+
+/// Warn the user if they attempt to enable a code that won't be respected.
+pub fn warn_on(
+    flag: Warnable,
+    codes: &Vec<CheckCode>,
+    cli_ignore: &Vec<CheckCode>,
+    cli_extend_ignore: &Vec<CheckCode>,
+    pyproject_settings: &RawSettings,
+    pyproject_path: &Option<PathBuf>,
+) {
+    for code in codes {
+        if !cli_ignore.is_empty() {
+            if cli_ignore.contains(code) {
+                warn!("{code:?} was passed to {flag}, but ignored via --ignore")
+            }
+        } else if pyproject_settings.ignore.contains(code) {
+            if let Some(path) = pyproject_path {
+                warn!(
+                    "{code:?} was passed to {flag}, but ignored by the `ignore` field in {}",
+                    path.to_string_lossy()
+                )
+            } else {
+                warn!("{code:?} was passed to {flag}, but ignored by the default `ignore` field",)
+            }
+        }
+        if !cli_extend_ignore.is_empty() {
+            if cli_extend_ignore.contains(code) {
+                warn!("{code:?} was passed to {flag}, but ignored via --extend-ignore")
+            }
+        } else if pyproject_settings.extend_ignore.contains(code) {
+            if let Some(path) = pyproject_path {
+                warn!(
+                    "{code:?} was passed to {flag}, but ignored by the `extend_ignore` field in {}",
+                    path.to_string_lossy()
+                )
+            } else {
+                warn!("{code:?} was passed to {flag}, but ignored by the default `extend_ignore` field")
+            }
+        }
+    }
+}

src/fs.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::BTreeSet;
 use std::fs::File;
 use std::io::{BufReader, Read};
 use std::ops::Deref;
@@ -10,7 +11,8 @@ use path_absolutize::path_dedot;
 use path_absolutize::Absolutize;
 use walkdir::{DirEntry, WalkDir};
 
-use crate::settings::FilePattern;
+use crate::checks::CheckCode;
+use crate::settings::{FilePattern, PerFileIgnore};
 
 /// Extract the absolute path and basename (as strings) from a Path.
 fn extract_path_names(path: &Path) -> Result<(&str, &str)> {
@@ -25,9 +27,12 @@ fn extract_path_names(path: &Path) -> Result<(&str, &str)> {
     Ok((file_path, file_basename))
 }
 
-fn is_excluded(file_path: &str, file_basename: &str, exclude: &[FilePattern]) -> bool {
+fn is_excluded<'a, T>(file_path: &str, file_basename: &str, exclude: T) -> bool
+where
+    T: Iterator<Item = &'a FilePattern>,
+{
     for pattern in exclude {
-        match &pattern {
+        match pattern {
             FilePattern::Simple(basename) => {
                 if *basename == file_basename {
                     return true;
@@ -45,7 +50,7 @@ fn is_excluded(file_path: &str, file_basename: &str, exclude: &[FilePattern]) ->
                     return true;
                 }
             }
-        }
+        };
     }
     false
 }
@@ -59,19 +64,18 @@ pub fn iter_python_files<'a>(
     path: &'a Path,
     exclude: &'a [FilePattern],
     extend_exclude: &'a [FilePattern],
-) -> impl Iterator<Item = DirEntry> + 'a {
+) -> impl Iterator<Item = Result<DirEntry, walkdir::Error>> + 'a {
     // Run some checks over the provided patterns, to enable optimizations below.
     let has_exclude = !exclude.is_empty();
     let has_extend_exclude = !extend_exclude.is_empty();
     let exclude_simple = exclude
         .iter()
         .all(|pattern| matches!(pattern, FilePattern::Simple(_)));
-    let extend_exclude_simple = exclude
+    let extend_exclude_simple = extend_exclude
         .iter()
         .all(|pattern| matches!(pattern, FilePattern::Simple(_)));
 
     WalkDir::new(normalize_path(path))
-        .follow_links(true)
         .into_iter()
         .filter_entry(move |entry| {
             if !has_exclude && !has_extend_exclude {
@@ -85,13 +89,13 @@ pub fn iter_python_files<'a>(
 
                     if has_exclude
                         && (!exclude_simple || file_type.is_dir())
-                        && is_excluded(file_path, file_basename, exclude)
+                        && is_excluded(file_path, file_basename, exclude.iter())
                     {
                         debug!("Ignored path via `exclude`: {:?}", path);
                         false
                     } else if has_extend_exclude
                         && (!extend_exclude_simple || file_type.is_dir())
-                        && is_excluded(file_path, file_basename, extend_exclude)
+                        && is_excluded(file_path, file_basename, extend_exclude.iter())
                     {
                         debug!("Ignored path via `extend-exclude`: {:?}", path);
                         false
@@ -105,18 +109,36 @@ pub fn iter_python_files<'a>(
                 }
             }
         })
-        .filter_map(|entry| entry.ok())
         .filter(|entry| {
-            let path = entry.path();
-            is_included(path)
+            entry.as_ref().map_or(true, |entry| {
+                (entry.depth() == 0 || is_included(entry.path()))
+                    && !entry.file_type().is_dir()
+                    && !(entry.file_type().is_symlink() && entry.path().is_dir())
+            })
         })
 }
 
+/// Create tree set with codes matching the pattern/code pairs.
+pub fn ignores_from_path<'a>(
+    path: &Path,
+    pattern_code_pairs: &'a [PerFileIgnore],
+) -> Result<BTreeSet<&'a CheckCode>> {
+    let (file_path, file_basename) = extract_path_names(path)?;
+    Ok(pattern_code_pairs
+        .iter()
+        .filter(|pattern_code_pair| {
+            is_excluded(
+                file_path,
+                file_basename,
+                [&pattern_code_pair.pattern].into_iter(),
+            )
+        })
+        .map(|pattern_code_pair| &pattern_code_pair.code)
+        .collect())
+}
+
 /// Convert any path to an absolute path (based on the current working directory).
 pub fn normalize_path(path: &Path) -> PathBuf {
-    if path == Path::new(".") || path == Path::new("..") {
-        return path.to_path_buf();
-    }
     if let Ok(path) = path.absolutize() {
         return path.to_path_buf();
     }
@@ -125,9 +147,6 @@ pub fn normalize_path(path: &Path) -> PathBuf {
 
 /// Convert any path to an absolute path (based on the specified project root).
 pub fn normalize_path_to(path: &Path, project_root: &Path) -> PathBuf {
-    if path == Path::new(".") || path == Path::new("..") {
-        return path.to_path_buf();
-    }
     if let Ok(path) = path.absolutize_from(project_root) {
         return path.to_path_buf();
     }
@@ -186,7 +205,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, &exclude));
+        assert!(is_excluded(file_path, file_basename, exclude.iter()));
 
         let path = Path::new("foo/bar").absolutize_from(project_root).unwrap();
         let exclude = vec![FilePattern::from_user(
@@ -194,7 +213,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, &exclude));
+        assert!(is_excluded(file_path, file_basename, exclude.iter()));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
@@ -204,7 +223,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, &exclude));
+        assert!(is_excluded(file_path, file_basename, exclude.iter()));
 
         let path = Path::new("foo/bar").absolutize_from(project_root).unwrap();
         let exclude = vec![FilePattern::from_user(
@@ -212,7 +231,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, &exclude));
+        assert!(is_excluded(file_path, file_basename, exclude.iter()));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
@@ -222,7 +241,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, &exclude));
+        assert!(is_excluded(file_path, file_basename, exclude.iter()));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
@@ -232,7 +251,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, &exclude));
+        assert!(is_excluded(file_path, file_basename, exclude.iter()));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
@@ -242,7 +261,7 @@ mod tests {
             &Some(project_root.to_path_buf()),
         )];
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(!is_excluded(file_path, file_basename, &exclude));
+        assert!(!is_excluded(file_path, file_basename, exclude.iter()));
 
         Ok(())
     }

src/lib.rs

@@ -1,4 +1,13 @@
-extern crate core;
+use std::path::Path;
+
+use anyhow::Result;
+use log::debug;
+use rustpython_parser::lexer::LexResult;
+
+use crate::autofix::fixer::Mode;
+use crate::linter::{check_path, tokenize};
+use crate::message::Message;
+use crate::settings::{RawSettings, Settings};
 
 mod ast;
 mod autofix;
@@ -6,11 +15,62 @@ pub mod cache;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;
+pub mod cli;
+pub mod code_gen;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
+mod noqa;
+mod plugins;
 pub mod printer;
 pub mod pyproject;
 mod python;
 pub mod settings;
+
+/// Run ruff over Python source code directly.
+pub fn check(path: &Path, contents: &str) -> Result<Vec<Message>> {
+    // Find the project root and pyproject.toml.
+    let project_root = pyproject::find_project_root(&[path.to_path_buf()]);
+    match &project_root {
+        Some(path) => debug!("Found project root at: {:?}", path),
+        None => debug!("Unable to identify project root; assuming current directory..."),
+    };
+    let pyproject = pyproject::find_pyproject_toml(&project_root);
+    match &pyproject {
+        Some(path) => debug!("Found pyproject.toml at: {:?}", path),
+        None => debug!("Unable to find pyproject.toml; using default settings..."),
+    };
+
+    let settings = Settings::from_raw(RawSettings::from_pyproject(&pyproject, &project_root)?);
+
+    // Tokenize once.
+    let tokens: Vec<LexResult> = tokenize(contents);
+
+    // Determine the noqa line for every line in the source.
+    let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
+
+    // Generate checks.
+    let checks = check_path(
+        path,
+        contents,
+        tokens,
+        &noqa_line_for,
+        &settings,
+        &Mode::None,
+    )?;
+
+    // Convert to messages.
+    let messages: Vec<Message> = checks
+        .into_iter()
+        .map(|check| Message {
+            kind: check.kind,
+            fixed: check.fix.map(|fix| fix.applied).unwrap_or_default(),
+            location: check.location,
+            end_location: check.end_location,
+            filename: path.to_string_lossy().to_string(),
+        })
+        .collect();
+
+    Ok(messages)
+}

src/main.rs

@@ -1,75 +1,37 @@
-extern crate core;
-
-use std::path::PathBuf;
+use std::io;
+use std::path::{Path, PathBuf};
 use std::process::ExitCode;
 use std::sync::mpsc::channel;
 use std::time::Instant;
 
 use anyhow::Result;
-use clap::{Parser, ValueHint};
+use clap::Parser;
 use colored::Colorize;
 use log::{debug, error};
 use notify::{raw_watcher, RecursiveMode, Watcher};
 use rayon::prelude::*;
 use walkdir::DirEntry;
 
-use ::ruff::cache;
-use ::ruff::checks::CheckCode;
-use ::ruff::checks::CheckKind;
-use ::ruff::fs::iter_python_files;
-use ::ruff::linter::lint_path;
-use ::ruff::logging::set_up_logging;
-use ::ruff::message::Message;
-use ::ruff::printer::{Printer, SerializationFormat};
-use ::ruff::pyproject;
-use ::ruff::settings::{FilePattern, Settings};
-use ::ruff::tell_user;
+use ruff::cache;
+use ruff::checks::CheckCode;
+use ruff::checks::CheckKind;
+use ruff::cli::{warn_on, Cli, Warnable};
+use ruff::fs::iter_python_files;
+use ruff::linter::add_noqa_to_path;
+use ruff::linter::autoformat_path;
+use ruff::linter::lint_path;
+use ruff::logging::set_up_logging;
+use ruff::message::Message;
+use ruff::printer::{Printer, SerializationFormat};
+use ruff::pyproject::{self};
+use ruff::settings::CurrentSettings;
+use ruff::settings::RawSettings;
+use ruff::settings::{FilePattern, PerFileIgnore, Settings};
+use ruff::tell_user;
 
 const CARGO_PKG_NAME: &str = env!("CARGO_PKG_NAME");
 const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
 
-#[derive(Debug, Parser)]
-#[clap(name = format!("{CARGO_PKG_NAME} (v{CARGO_PKG_VERSION})"))]
-#[clap(about = "An extremely fast Python linter.", long_about = None)]
-#[clap(version)]
-struct Cli {
-    #[clap(parse(from_os_str), value_hint = ValueHint::AnyPath, required = true)]
-    files: Vec<PathBuf>,
-    /// Enable verbose logging.
-    #[clap(short, long, action)]
-    verbose: bool,
-    /// Disable all logging (but still exit with status code "1" upon detecting errors).
-    #[clap(short, long, action)]
-    quiet: bool,
-    /// Exit with status code "0", even upon detecting errors.
-    #[clap(short, long, action)]
-    exit_zero: bool,
-    /// Run in watch mode by re-running whenever files change.
-    #[clap(short, long, action)]
-    watch: bool,
-    /// Attempt to automatically fix lint errors.
-    #[clap(short, long, action)]
-    fix: bool,
-    /// Disable cache reads.
-    #[clap(short, long, action)]
-    no_cache: bool,
-    /// List of error codes to enable.
-    #[clap(long, multiple = true)]
-    select: Vec<CheckCode>,
-    /// List of error codes to ignore.
-    #[clap(long, multiple = true)]
-    ignore: Vec<CheckCode>,
-    /// List of paths, used to exclude files and/or directories from checks.
-    #[clap(long, multiple = true)]
-    exclude: Vec<String>,
-    /// Like --exclude, but adds additional files and directories on top of the excluded ones.
-    #[clap(long, multiple = true)]
-    extend_exclude: Vec<String>,
-    /// Output serialization format for error messages.
-    #[clap(long, arg_enum, default_value_t=SerializationFormat::Text)]
-    format: SerializationFormat,
-}
-
 #[cfg(feature = "update-informer")]
 fn check_for_updates() {
     use update_informer::{registry, Check};
@@ -94,6 +56,25 @@ fn check_for_updates() {
     }
 }
 
+fn show_settings(settings: RawSettings, project_root: Option<PathBuf>, pyproject: Option<PathBuf>) {
+    println!(
+        "{:#?}",
+        CurrentSettings::from_settings(settings, project_root, pyproject)
+    );
+}
+
+fn show_files(files: &[PathBuf], settings: &Settings) {
+    let mut entries: Vec<DirEntry> = files
+        .iter()
+        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
+        .flatten()
+        .collect();
+    entries.sort_by(|a, b| a.path().cmp(b.path()));
+    for entry in entries {
+        println!("{}", entry.path().to_string_lossy());
+    }
+}
+
 fn run_once(
     files: &[PathBuf],
     settings: &Settings,
@@ -102,7 +83,7 @@ fn run_once(
 ) -> Result<Vec<Message>> {
     // Collect all the files to check.
     let start = Instant::now();
-    let paths: Vec<DirEntry> = files
+    let paths: Vec<Result<DirEntry, walkdir::Error>> = files
         .iter()
         .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
         .collect();
@@ -113,16 +94,34 @@ fn run_once(
     let mut messages: Vec<Message> = paths
         .par_iter()
         .map(|entry| {
-            lint_path(entry.path(), settings, &cache.into(), &autofix.into()).unwrap_or_else(|e| {
-                if settings.select.contains(&CheckCode::E999) {
-                    vec![Message {
-                        kind: CheckKind::SyntaxError(e.to_string()),
-                        fixed: false,
-                        location: Default::default(),
-                        filename: entry.path().to_string_lossy().to_string(),
-                    }]
+            match entry {
+                Ok(entry) => {
+                    let path = entry.path();
+                    lint_path(path, settings, &cache.into(), &autofix.into())
+                        .map_err(|e| (Some(path.to_owned()), e.to_string()))
+                }
+                Err(e) => Err((
+                    e.path().map(Path::to_owned),
+                    e.io_error()
+                        .map_or_else(|| e.to_string(), io::Error::to_string),
+                )),
+            }
+            .unwrap_or_else(|(path, message)| {
+                if let Some(path) = path {
+                    if settings.enabled.contains(&CheckCode::E902) {
+                        vec![Message {
+                            kind: CheckKind::IOError(message),
+                            fixed: false,
+                            location: Default::default(),
+                            end_location: Default::default(),
+                            filename: path.to_string_lossy().to_string(),
+                        }]
+                    } else {
+                        error!("Failed to check {}: {message}", path.to_string_lossy());
+                        vec![]
+                    }
                 } else {
-                    error!("Failed to check {}: {e:?}", entry.path().to_string_lossy());
+                    error!("{message}");
                     vec![]
                 }
             })
@@ -130,19 +129,6 @@ fn run_once(
         .flatten()
         .collect();
 
-    if settings.select.contains(&CheckCode::E902) {
-        for file in files {
-            if !file.exists() {
-                messages.push(Message {
-                    kind: CheckKind::IOError(file.to_string_lossy().to_string()),
-                    fixed: false,
-                    location: Default::default(),
-                    filename: file.to_string_lossy().to_string(),
-                })
-            }
-        }
-    }
-
     messages.sort_unstable();
     let duration = start.elapsed();
     debug!("Checked files in: {:?}", duration);
@@ -150,6 +136,62 @@ fn run_once(
     Ok(messages)
 }
 
+fn add_noqa(files: &[PathBuf], settings: &Settings) -> Result<usize> {
+    // Collect all the files to check.
+    let start = Instant::now();
+    let paths: Vec<Result<DirEntry, walkdir::Error>> = files
+        .iter()
+        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
+        .collect();
+    let duration = start.elapsed();
+    debug!("Identified files to lint in: {:?}", duration);
+
+    let start = Instant::now();
+    let modifications: usize = paths
+        .par_iter()
+        .map(|entry| match entry {
+            Ok(entry) => {
+                let path = entry.path();
+                add_noqa_to_path(path, settings)
+            }
+            Err(_) => Ok(0),
+        })
+        .flatten()
+        .sum();
+
+    let duration = start.elapsed();
+    debug!("Added noqa to files in: {:?}", duration);
+
+    Ok(modifications)
+}
+
+fn autoformat(files: &[PathBuf], settings: &Settings) -> Result<usize> {
+    // Collect all the files to format.
+    let start = Instant::now();
+    let paths: Vec<DirEntry> = files
+        .iter()
+        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
+        .flatten()
+        .collect();
+    let duration = start.elapsed();
+    debug!("Identified files to lint in: {:?}", duration);
+
+    let start = Instant::now();
+    let modifications = paths
+        .par_iter()
+        .map(|entry| {
+            let path = entry.path();
+            autoformat_path(path)
+        })
+        .flatten()
+        .count();
+
+    let duration = start.elapsed();
+    debug!("Auto-formatted files in: {:?}", duration);
+
+    Ok(modifications)
+}
+
 fn inner_main() -> Result<ExitCode> {
     let cli = Cli::parse();
 
@@ -168,38 +210,101 @@ fn inner_main() -> Result<ExitCode> {
     };
 
     // Parse the settings from the pyproject.toml and command-line arguments.
-    let mut settings = Settings::from_pyproject(&pyproject, &project_root);
+    let exclude: Vec<FilePattern> = cli
+        .exclude
+        .iter()
+        .map(|path| FilePattern::from_user(path, &project_root))
+        .collect();
+    let extend_exclude: Vec<FilePattern> = cli
+        .extend_exclude
+        .iter()
+        .map(|path| FilePattern::from_user(path, &project_root))
+        .collect();
+    let per_file_ignores: Vec<PerFileIgnore> = cli
+        .per_file_ignores
+        .into_iter()
+        .map(|pair| PerFileIgnore::new(pair, &project_root))
+        .collect();
+
+    let mut settings = RawSettings::from_pyproject(&pyproject, &project_root)?;
+    if !exclude.is_empty() {
+        settings.exclude = exclude;
+    }
+    if !extend_exclude.is_empty() {
+        settings.extend_exclude = extend_exclude;
+    }
+    if !per_file_ignores.is_empty() {
+        settings.per_file_ignores = per_file_ignores;
+    }
     if !cli.select.is_empty() {
-        settings.select(cli.select);
+        warn_on(
+            Warnable::Select,
+            &cli.select,
+            &cli.ignore,
+            &cli.extend_ignore,
+            &settings,
+            &pyproject,
+        );
+        settings.select = cli.select;
+    }
+    if !cli.extend_select.is_empty() {
+        warn_on(
+            Warnable::ExtendSelect,
+            &cli.extend_select,
+            &cli.ignore,
+            &cli.extend_ignore,
+            &settings,
+            &pyproject,
+        );
+        settings.extend_select = cli.extend_select;
     }
     if !cli.ignore.is_empty() {
-        settings.ignore(&cli.ignore);
+        settings.ignore = cli.ignore;
     }
-    if !cli.exclude.is_empty() {
-        settings.exclude = cli
-            .exclude
-            .iter()
-            .map(|path| FilePattern::from_user(path, &project_root))
-            .collect();
+    if !cli.extend_ignore.is_empty() {
+        settings.extend_ignore = cli.extend_ignore;
     }
-    if !cli.extend_exclude.is_empty() {
-        settings.extend_exclude = cli
-            .extend_exclude
-            .iter()
-            .map(|path| FilePattern::from_user(path, &project_root))
-            .collect();
+    if let Some(target_version) = cli.target_version {
+        settings.target_version = target_version;
+    }
+    if let Some(dummy_variable_rgx) = cli.dummy_variable_rgx {
+        settings.dummy_variable_rgx = dummy_variable_rgx;
+    }
+
+    if cli.show_settings && cli.show_files {
+        eprintln!("Error: specify --show-settings or show-files (not both).");
+        return Ok(ExitCode::FAILURE);
+    }
+    if cli.show_settings {
+        show_settings(settings, project_root, pyproject);
+        return Ok(ExitCode::SUCCESS);
+    }
+
+    let settings = Settings::from_raw(settings);
+
+    if cli.show_files {
+        show_files(&cli.files, &settings);
+        return Ok(ExitCode::SUCCESS);
     }
 
     cache::init()?;
 
-    let mut printer = Printer::new(cli.format);
+    let mut printer = Printer::new(cli.format, cli.verbose);
     if cli.watch {
         if cli.fix {
-            println!("Warning: --fix is not enabled in watch mode.");
+            eprintln!("Warning: --fix is not enabled in watch mode.");
+        }
+
+        if cli.add_noqa {
+            eprintln!("Warning: --no-qa is not enabled in watch mode.");
+        }
+
+        if cli.autoformat {
+            eprintln!("Warning: --autoformat is not enabled in watch mode.");
         }
 
         if cli.format != SerializationFormat::Text {
-            println!("Warning: --format 'text' is used in watch mode.");
+            eprintln!("Warning: --format 'text' is used in watch mode.");
         }
 
         // Perform an initial run instantly.
@@ -236,6 +341,16 @@ fn inner_main() -> Result<ExitCode> {
                 Err(e) => return Err(e.into()),
             }
         }
+    } else if cli.add_noqa {
+        let modifications = add_noqa(&cli.files, &settings)?;
+        if modifications > 0 {
+            println!("Added {modifications} noqa directives.");
+        }
+    } else if cli.autoformat {
+        let modifications = autoformat(&cli.files, &settings)?;
+        if modifications > 0 {
+            println!("Formatted {modifications} files.");
+        }
     } else {
         let messages = run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?;
         if !cli.quiet {
@@ -245,7 +360,7 @@ fn inner_main() -> Result<ExitCode> {
         #[cfg(feature = "update-informer")]
         check_for_updates();
 
-        if !messages.is_empty() && !cli.exit_zero {
+        if messages.iter().any(|message| !message.fixed) && !cli.exit_zero {
             return Ok(ExitCode::FAILURE);
         }
     }
@@ -256,6 +371,9 @@ fn inner_main() -> Result<ExitCode> {
 fn main() -> ExitCode {
     match inner_main() {
         Ok(code) => code,
-        Err(_) => ExitCode::FAILURE,
+        Err(err) => {
+            eprintln!("{} {:?}", "error".red().bold(), err);
+            ExitCode::FAILURE
+        }
     }
 }

src/message.rs

@@ -14,6 +14,7 @@ pub struct Message {
     pub kind: CheckKind,
     pub fixed: bool,
     pub location: Location,
+    pub end_location: Location,
     pub filename: String,
 }
 
@@ -39,13 +40,12 @@ impl fmt::Display for Message {
             f,
             "{}{}{}{}{}{} {} {}",
             relativize_path(Path::new(&self.filename)).white().bold(),
-            // self.filename.white(),
             ":".cyan(),
             self.location.row(),
             ":".cyan(),
             self.location.column(),
             ":".cyan(),
-            self.kind.code().as_str().red().bold(),
+            self.kind.code().as_ref().red().bold(),
             self.kind.body()
         )
     }

src/noqa.rs

@@ -0,0 +1,309 @@
+use std::cmp::{max, min};
+use std::collections::{BTreeMap, BTreeSet};
+use std::fs;
+use std::path::Path;
+
+use anyhow::Result;
+use once_cell::sync::Lazy;
+use regex::Regex;
+use rustpython_parser::lexer::{LexResult, Tok};
+
+use crate::checks::{Check, CheckCode};
+
+static NO_QA_REGEX: Lazy<Regex> = Lazy::new(|| {
+    Regex::new(r"(?i)(?P<noqa>\s*# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?)")
+        .expect("Invalid regex")
+});
+static SPLIT_COMMA_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"[,\s]").expect("Invalid regex"));
+
+#[derive(Debug)]
+pub enum Directive<'a> {
+    None,
+    All(usize, usize),
+    Codes(usize, usize, Vec<&'a str>),
+}
+
+pub fn extract_noqa_directive(line: &str) -> Directive {
+    match NO_QA_REGEX.captures(line) {
+        Some(caps) => match caps.name("noqa") {
+            Some(noqa) => match caps.name("codes") {
+                Some(codes) => Directive::Codes(
+                    noqa.start(),
+                    noqa.end(),
+                    SPLIT_COMMA_REGEX
+                        .split(codes.as_str())
+                        .map(|code| code.trim())
+                        .filter(|code| !code.is_empty())
+                        .collect(),
+                ),
+                None => Directive::All(noqa.start(), noqa.end()),
+            },
+            None => Directive::None,
+        },
+        None => Directive::None,
+    }
+}
+
+pub fn extract_noqa_line_for(lxr: &[LexResult]) -> Vec<usize> {
+    let mut noqa_line_for: Vec<usize> = vec![];
+
+    let mut min_line = usize::MAX;
+    let mut max_line = usize::MIN;
+    let mut in_string = false;
+
+    for (start, tok, end) in lxr.iter().flatten() {
+        if matches!(tok, Tok::EndOfFile) {
+            break;
+        }
+
+        if matches!(tok, Tok::Newline) {
+            min_line = min(min_line, start.row());
+            max_line = max(max_line, start.row());
+
+            // For now, we only care about preserving noqa directives across multi-line strings.
+            if in_string {
+                for i in (noqa_line_for.len())..(min_line - 1) {
+                    noqa_line_for.push(i + 1);
+                }
+                noqa_line_for.extend(vec![max_line; (max_line + 1) - min_line]);
+            }
+
+            min_line = usize::MAX;
+            max_line = usize::MIN;
+        } else {
+            min_line = min(min_line, start.row());
+            max_line = max(max_line, end.row());
+        }
+        in_string = matches!(tok, Tok::String { .. });
+    }
+
+    noqa_line_for
+}
+
+fn add_noqa_inner(
+    checks: &Vec<Check>,
+    contents: &str,
+    noqa_line_for: &[usize],
+) -> Result<(usize, String)> {
+    let lines: Vec<&str> = contents.lines().collect();
+    let mut matches_by_line: BTreeMap<usize, BTreeSet<&CheckCode>> = BTreeMap::new();
+    for lineno in 0..lines.len() {
+        let mut codes: BTreeSet<&CheckCode> = BTreeSet::new();
+        for check in checks {
+            if check.location.row() == lineno + 1 {
+                codes.insert(check.kind.code());
+            }
+        }
+
+        // Grab the noqa (logical) line number for the current (physical) line.
+        // If there are newlines at the end of the file, they won't be represented in
+        // `noqa_line_for`, so fallback to the current line.
+        let noqa_lineno = noqa_line_for
+            .get(lineno)
+            .map(|lineno| lineno - 1)
+            .unwrap_or(lineno);
+
+        if !codes.is_empty() {
+            let matches = matches_by_line.entry(noqa_lineno).or_default();
+            matches.append(&mut codes);
+        }
+    }
+
+    let mut count: usize = 0;
+    let mut output = "".to_string();
+    for (lineno, line) in lines.iter().enumerate() {
+        match matches_by_line.get(&lineno) {
+            None => {
+                output.push_str(line);
+                output.push('\n');
+            }
+            Some(codes) => {
+                match extract_noqa_directive(line) {
+                    Directive::None => {
+                        output.push_str(line);
+                    }
+                    Directive::All(start, _) => output.push_str(&line[..start]),
+                    Directive::Codes(start, _, _) => output.push_str(&line[..start]),
+                };
+                let codes: Vec<&str> = codes.iter().map(|code| code.as_ref()).collect();
+                output.push_str("  # noqa: ");
+                output.push_str(&codes.join(", "));
+                output.push('\n');
+                count += 1;
+            }
+        }
+    }
+
+    Ok((count, output))
+}
+
+pub fn add_noqa(
+    checks: &Vec<Check>,
+    contents: &str,
+    noqa_line_for: &[usize],
+    path: &Path,
+) -> Result<usize> {
+    let (count, output) = add_noqa_inner(checks, contents, noqa_line_for)?;
+    fs::write(path, output)?;
+    Ok(count)
+}
+
+#[cfg(test)]
+mod tests {
+    use anyhow::Result;
+    use rustpython_parser::ast::Location;
+    use rustpython_parser::lexer;
+    use rustpython_parser::lexer::LexResult;
+
+    use crate::ast::types::Range;
+    use crate::checks::{Check, CheckKind};
+    use crate::noqa::{add_noqa_inner, extract_noqa_line_for};
+
+    #[test]
+    fn extraction() -> Result<()> {
+        let empty: Vec<usize> = Default::default();
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "x = 1
+y = 2
+z = x + 1",
+        )
+        .collect();
+        println!("{:?}", extract_noqa_line_for(&lxr));
+        assert_eq!(extract_noqa_line_for(&lxr), empty);
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "
+x = 1
+y = 2
+z = x + 1",
+        )
+        .collect();
+        println!("{:?}", extract_noqa_line_for(&lxr));
+        assert_eq!(extract_noqa_line_for(&lxr), empty);
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "x = 1
+y = 2
+z = x + 1
+        ",
+        )
+        .collect();
+        println!("{:?}", extract_noqa_line_for(&lxr));
+        assert_eq!(extract_noqa_line_for(&lxr), empty);
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "x = 1
+
+y = 2
+z = x + 1
+        ",
+        )
+        .collect();
+        println!("{:?}", extract_noqa_line_for(&lxr));
+        assert_eq!(extract_noqa_line_for(&lxr), empty);
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "x = '''abc
+def
+ghi
+'''
+y = 2
+z = x + 1",
+        )
+        .collect();
+        assert_eq!(extract_noqa_line_for(&lxr), vec![4, 4, 4, 4]);
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "x = 1
+y = '''abc
+def
+ghi
+'''
+z = 2",
+        )
+        .collect();
+        assert_eq!(extract_noqa_line_for(&lxr), vec![1, 5, 5, 5, 5]);
+
+        let lxr: Vec<LexResult> = lexer::make_tokenizer(
+            "x = 1
+y = '''abc
+def
+ghi
+'''",
+        )
+        .collect();
+        assert_eq!(extract_noqa_line_for(&lxr), vec![1, 5, 5, 5, 5]);
+
+        Ok(())
+    }
+
+    #[test]
+    fn modification() -> Result<()> {
+        let checks = vec![];
+        let contents = "x = 1";
+        let noqa_line_for = vec![1];
+        let (count, output) = add_noqa_inner(&checks, contents, &noqa_line_for)?;
+        assert_eq!(count, 0);
+        assert_eq!(output.trim(), contents.trim());
+
+        let checks = vec![Check::new(
+            CheckKind::UnusedVariable("x".to_string()),
+            Range {
+                location: Location::new(1, 1),
+                end_location: Location::new(1, 1),
+            },
+        )];
+        let contents = "x = 1";
+        let noqa_line_for = vec![1];
+        let (count, output) = add_noqa_inner(&checks, contents, &noqa_line_for)?;
+        assert_eq!(count, 1);
+        assert_eq!(output.trim(), "x = 1  # noqa: F841".trim());
+
+        let checks = vec![
+            Check::new(
+                CheckKind::AmbiguousVariableName("x".to_string()),
+                Range {
+                    location: Location::new(1, 1),
+                    end_location: Location::new(1, 1),
+                },
+            ),
+            Check::new(
+                CheckKind::UnusedVariable("x".to_string()),
+                Range {
+                    location: Location::new(1, 1),
+                    end_location: Location::new(1, 1),
+                },
+            ),
+        ];
+        let contents = "x = 1  # noqa: E741";
+        let noqa_line_for = vec![1];
+        let (count, output) = add_noqa_inner(&checks, contents, &noqa_line_for)?;
+        assert_eq!(count, 1);
+        assert_eq!(output.trim(), "x = 1  # noqa: E741, F841".trim());
+
+        let checks = vec![
+            Check::new(
+                CheckKind::AmbiguousVariableName("x".to_string()),
+                Range {
+                    location: Location::new(1, 1),
+                    end_location: Location::new(1, 1),
+                },
+            ),
+            Check::new(
+                CheckKind::UnusedVariable("x".to_string()),
+                Range {
+                    location: Location::new(1, 1),
+                    end_location: Location::new(1, 1),
+                },
+            ),
+        ];
+        let contents = "x = 1  # noqa";
+        let noqa_line_for = vec![1];
+        let (count, output) = add_noqa_inner(&checks, contents, &noqa_line_for)?;
+        assert_eq!(count, 1);
+        assert_eq!(output.trim(), "x = 1  # noqa: E741, F841".trim());
+
+        Ok(())
+    }
+}

src/plugins.rs

@@ -0,0 +1,25 @@
+pub use assert_tuple::assert_tuple;
+pub use deprecated_unittest_alias::deprecated_unittest_alias;
+pub use if_tuple::if_tuple;
+pub use invalid_print_syntax::invalid_print_syntax;
+pub use print_call::print_call;
+pub use super_call_with_parameters::super_call_with_parameters;
+pub use type_of_primitive::type_of_primitive;
+pub use unnecessary_abspath::unnecessary_abspath;
+pub use use_pep585_annotation::use_pep585_annotation;
+pub use use_pep604_annotation::use_pep604_annotation;
+pub use useless_metaclass_type::useless_metaclass_type;
+pub use useless_object_inheritance::useless_object_inheritance;
+
+mod assert_tuple;
+mod deprecated_unittest_alias;
+mod if_tuple;
+mod invalid_print_syntax;
+mod print_call;
+mod super_call_with_parameters;
+mod type_of_primitive;
+mod unnecessary_abspath;
+mod use_pep585_annotation;
+mod use_pep604_annotation;
+mod useless_metaclass_type;
+mod useless_object_inheritance;

src/plugins/assert_tuple.rs

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

src/plugins/deprecated_unittest_alias.rs

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

src/plugins/if_tuple.rs

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

src/plugins/invalid_print_syntax.rs

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

src/plugins/print_call.rs

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

src/plugins/super_call_with_parameters.rs

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

src/plugins/type_of_primitive.rs

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

src/plugins/unnecessary_abspath.rs

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

src/plugins/use_pep585_annotation.rs

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

src/plugins/use_pep604_annotation.rs

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

src/plugins/useless_metaclass_type.rs

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

src/plugins/useless_object_inheritance.rs

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

src/printer.rs

@@ -1,8 +1,10 @@
-use colored::Colorize;
-
 use anyhow::Result;
 use clap::ValueEnum;
+use colored::Colorize;
+use rustpython_parser::ast::Location;
+use serde::Serialize;
 
+use crate::checks::{CheckCode, CheckKind};
 use crate::message::Message;
 use crate::tell_user;
 
@@ -12,13 +14,25 @@ pub enum SerializationFormat {
     Json,
 }
 
+#[derive(Serialize)]
+struct ExpandedMessage<'a> {
+    kind: &'a CheckKind,
+    code: &'a CheckCode,
+    message: String,
+    fixed: bool,
+    location: Location,
+    end_location: Location,
+    filename: &'a String,
+}
+
 pub struct Printer {
     format: SerializationFormat,
+    verbose: bool,
 }
 
 impl Printer {
-    pub fn new(format: SerializationFormat) -> Self {
-        Self { format }
+    pub fn new(format: SerializationFormat, verbose: bool) -> Self {
+        Self { format, verbose }
     }
 
     pub fn write_once(&mut self, messages: &[Message]) -> Result<()> {
@@ -31,7 +45,23 @@ impl Printer {
 
         match self.format {
             SerializationFormat::Json => {
-                println!("{}", serde_json::to_string_pretty(&messages)?)
+                println!(
+                    "{}",
+                    serde_json::to_string_pretty(
+                        &messages
+                            .iter()
+                            .map(|m| ExpandedMessage {
+                                kind: &m.kind,
+                                code: m.kind.code(),
+                                message: m.kind.body(),
+                                fixed: m.fixed,
+                                location: m.location,
+                                end_location: m.end_location,
+                                filename: &m.filename,
+                            })
+                            .collect::<Vec<_>>()
+                    )?
+                )
             }
             SerializationFormat::Text => {
                 if !fixed.is_empty() {
@@ -40,7 +70,7 @@ impl Printer {
                         outstanding.len(),
                         fixed.len()
                     )
-                } else {
+                } else if !outstanding.is_empty() || self.verbose {
                     println!("Found {} error(s).", outstanding.len())
                 }
 

src/pyproject.rs

@@ -1,31 +1,26 @@
-use std::ops::Deref;
 use std::path::{Path, PathBuf};
+use std::str::FromStr;
 
-use anyhow::Result;
+use anyhow::{anyhow, Result};
 use common_path::common_path_all;
-use path_absolutize::path_dedot;
-use serde::Deserialize;
+use path_absolutize::Absolutize;
+use serde::de;
+use serde::{Deserialize, Deserializer};
 
 use crate::checks::CheckCode;
 use crate::fs;
+use crate::settings::PythonVersion;
 
-pub fn load_config(pyproject: &Option<PathBuf>) -> Config {
+pub fn load_config(pyproject: &Option<PathBuf>) -> Result<Config> {
     match pyproject {
-        Some(pyproject) => match parse_pyproject_toml(pyproject) {
-            Ok(pyproject) => pyproject
-                .tool
-                .and_then(|tool| tool.ruff)
-                .unwrap_or_default(),
-            Err(e) => {
-                println!("Failed to load pyproject.toml: {:?}", e);
-                println!("Falling back to default configuration...");
-                Default::default()
-            }
-        },
+        Some(pyproject) => Ok(parse_pyproject_toml(pyproject)?
+            .tool
+            .and_then(|tool| tool.ruff)
+            .unwrap_or_default()),
         None => {
-            println!("No pyproject.toml found.");
-            println!("Falling back to default configuration...");
-            Default::default()
+            eprintln!("No pyproject.toml found.");
+            eprintln!("Falling back to default configuration...");
+            Ok(Default::default())
         }
     }
 }
@@ -35,9 +30,61 @@ pub fn load_config(pyproject: &Option<PathBuf>) -> Config {
 pub struct Config {
     pub line_length: Option<usize>,
     pub exclude: Option<Vec<String>>,
-    pub extend_exclude: Option<Vec<String>>,
+    #[serde(default)]
+    pub extend_exclude: Vec<String>,
     pub select: Option<Vec<CheckCode>>,
-    pub ignore: Option<Vec<CheckCode>>,
+    #[serde(default)]
+    pub extend_select: Vec<CheckCode>,
+    #[serde(default)]
+    pub ignore: Vec<CheckCode>,
+    #[serde(default)]
+    pub extend_ignore: Vec<CheckCode>,
+    #[serde(default)]
+    pub per_file_ignores: Vec<StrCheckCodePair>,
+    pub dummy_variable_rgx: Option<String>,
+    pub target_version: Option<PythonVersion>,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct StrCheckCodePair {
+    pub pattern: String,
+    pub code: CheckCode,
+}
+
+impl StrCheckCodePair {
+    const EXPECTED_PATTERN: &'static str = "<FilePattern>:<CheckCode> pattern";
+}
+
+impl<'de> Deserialize<'de> for StrCheckCodePair {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let str_result = String::deserialize(deserializer)?;
+        Self::from_str(str_result.as_str()).map_err(|_| {
+            de::Error::invalid_value(
+                de::Unexpected::Str(str_result.as_str()),
+                &Self::EXPECTED_PATTERN,
+            )
+        })
+    }
+}
+
+impl FromStr for StrCheckCodePair {
+    type Err = anyhow::Error;
+
+    fn from_str(string: &str) -> Result<Self, Self::Err> {
+        let (pattern_str, code_string) = {
+            let tokens = string.split(':').collect::<Vec<_>>();
+            if tokens.len() != 2 {
+                return Err(anyhow!("Expected {}", Self::EXPECTED_PATTERN));
+            }
+            (tokens[0], tokens[1])
+        };
+        let code = CheckCode::from_str(code_string)?;
+        let pattern = pattern_str.into();
+        Ok(Self { pattern, code })
+    }
 }
 
 #[derive(Debug, PartialEq, Eq, Deserialize)]
@@ -78,8 +125,10 @@ fn find_user_pyproject_toml() -> Option<PathBuf> {
 }
 
 pub fn find_project_root(sources: &[PathBuf]) -> Option<PathBuf> {
-    let cwd = path_dedot::CWD.deref();
-    let absolute_sources: Vec<PathBuf> = sources.iter().map(|source| cwd.join(source)).collect();
+    let absolute_sources: Vec<PathBuf> = sources
+        .iter()
+        .flat_map(|source| source.absolutize().map(|path| path.to_path_buf()))
+        .collect();
     if let Some(prefix) = common_path_all(absolute_sources.iter().map(PathBuf::as_path)) {
         for directory in prefix.ancestors() {
             if directory.join(".git").is_dir() {
@@ -101,6 +150,7 @@ pub fn find_project_root(sources: &[PathBuf]) -> Option<PathBuf> {
 mod tests {
     use std::env::current_dir;
     use std::path::PathBuf;
+    use std::str::FromStr;
 
     use anyhow::Result;
 
@@ -109,6 +159,8 @@ mod tests {
         find_project_root, find_pyproject_toml, parse_pyproject_toml, Config, PyProject, Tools,
     };
 
+    use super::StrCheckCodePair;
+
     #[test]
     fn deserialize() -> Result<()> {
         let pyproject: PyProject = toml::from_str(r#""#)?;
@@ -133,9 +185,14 @@ mod tests {
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
+                    dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -153,9 +210,14 @@ line-length = 79
                 ruff: Some(Config {
                     line_length: Some(79),
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
+                    dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -173,9 +235,14 @@ exclude = ["foo.py"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: Some(vec!["foo.py".to_string()]),
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
+                    dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -193,9 +260,14 @@ select = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: Some(vec![CheckCode::E501]),
-                    ignore: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
+                    dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -204,6 +276,7 @@ select = ["E501"]
             r#"
 [tool.black]
 [tool.ruff]
+extend-select = ["M001"]
 ignore = ["E501"]
 "#,
         )?;
@@ -213,9 +286,14 @@ ignore = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: Some(vec![CheckCode::E501]),
+                    extend_select: vec![CheckCode::M001],
+                    ignore: vec![CheckCode::E501],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
+                    dummy_variable_rgx: None,
+                    target_version: None,
                 })
             })
         );
@@ -273,16 +351,39 @@ other-attribute = 1
             Config {
                 line_length: Some(88),
                 exclude: None,
-                extend_exclude: Some(vec![
+                extend_exclude: vec![
                     "excluded.py".to_string(),
                     "migrations".to_string(),
                     "directory/also_excluded.py".to_string(),
-                ]),
+                ],
                 select: None,
-                ignore: None,
+                extend_select: vec![],
+                ignore: vec![],
+                extend_ignore: vec![],
+                per_file_ignores: vec![],
+                dummy_variable_rgx: None,
+                target_version: None,
             }
         );
 
         Ok(())
     }
+
+    #[test]
+    fn str_check_code_pair_strings() {
+        let result = StrCheckCodePair::from_str("foo:E501");
+        assert!(result.is_ok());
+        let result = StrCheckCodePair::from_str("E501:foo");
+        assert!(result.is_err());
+        let result = StrCheckCodePair::from_str("E501");
+        assert!(result.is_err());
+        let result = StrCheckCodePair::from_str("foo");
+        assert!(result.is_err());
+        let result = StrCheckCodePair::from_str("foo:E501:E402");
+        assert!(result.is_err());
+        let result = StrCheckCodePair::from_str("**/bar:E501");
+        assert!(result.is_ok());
+        let result = StrCheckCodePair::from_str("bar:E502");
+        assert!(result.is_err());
+    }
 }

src/python/typing.rs

@@ -1,11 +1,13 @@
-use once_cell::sync::Lazy;
 use std::collections::BTreeSet;
 
+use once_cell::sync::Lazy;
+
 static ANNOTATED_SUBSCRIPTS: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
     BTreeSet::from([
         "AbstractAsyncContextManager",
         "AbstractContextManager",
         "AbstractSet",
+        // "Annotated",
         "AsyncContextManager",
         "AsyncGenerator",
         "AsyncIterable",
@@ -86,3 +88,14 @@ static ANNOTATED_SUBSCRIPTS: Lazy<BTreeSet<&'static str>> = Lazy::new(|| {
 pub fn is_annotated_subscript(name: &str) -> bool {
     ANNOTATED_SUBSCRIPTS.contains(name)
 }
+
+pub fn is_pep593_annotated_subscript(name: &str) -> bool {
+    name == "Annotated"
+}
+
+static PEP_585_BUILTINS: Lazy<BTreeSet<&'static str>> =
+    Lazy::new(|| BTreeSet::from(["Dict", "FrozenSet", "List", "Set", "Tuple", "Type"]));
+
+pub fn is_pep585_builtin(name: &str) -> bool {
+    PEP_585_BUILTINS.contains(name)
+}

src/settings.rs

@@ -1,15 +1,51 @@
 use std::collections::BTreeSet;
 use std::hash::{Hash, Hasher};
 use std::path::{Path, PathBuf};
+use std::str::FromStr;
 
+use anyhow::{anyhow, Result};
 use glob::Pattern;
 use once_cell::sync::Lazy;
+use regex::Regex;
+use serde::{Deserialize, Serialize};
 
-use crate::checks::{CheckCode, ALL_CHECK_CODES};
+use crate::checks::{CheckCode, DEFAULT_CHECK_CODES};
 use crate::fs;
-use crate::pyproject::load_config;
+use crate::pyproject::{load_config, StrCheckCodePair};
 
-#[derive(Debug, Clone)]
+#[derive(Clone, Debug, PartialOrd, PartialEq, Eq, Serialize, Deserialize)]
+pub enum PythonVersion {
+    Py33,
+    Py34,
+    Py35,
+    Py36,
+    Py37,
+    Py38,
+    Py39,
+    Py310,
+    Py311,
+}
+
+impl FromStr for PythonVersion {
+    type Err = anyhow::Error;
+
+    fn from_str(string: &str) -> Result<Self, Self::Err> {
+        match string {
+            "py33" => Ok(PythonVersion::Py33),
+            "py34" => Ok(PythonVersion::Py34),
+            "py35" => Ok(PythonVersion::Py35),
+            "py36" => Ok(PythonVersion::Py36),
+            "py37" => Ok(PythonVersion::Py37),
+            "py38" => Ok(PythonVersion::Py38),
+            "py39" => Ok(PythonVersion::Py39),
+            "py310" => Ok(PythonVersion::Py310),
+            "py311" => Ok(PythonVersion::Py311),
+            _ => Err(anyhow!("Unknown version: {}", string)),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Hash)]
 pub enum FilePattern {
     Simple(&'static str),
     Complex(Pattern, Option<Pattern>),
@@ -34,23 +70,34 @@ impl FilePattern {
     }
 }
 
-#[derive(Debug)]
-pub struct Settings {
-    pub line_length: usize,
-    pub exclude: Vec<FilePattern>,
-    pub extend_exclude: Vec<FilePattern>,
-    pub select: BTreeSet<CheckCode>,
+#[derive(Debug, Clone, Hash)]
+pub struct PerFileIgnore {
+    pub pattern: FilePattern,
+    pub code: CheckCode,
 }
 
-impl Hash for Settings {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.line_length.hash(state);
-        for value in self.select.iter() {
-            value.hash(state);
-        }
+impl PerFileIgnore {
+    pub fn new(user_in: StrCheckCodePair, project_root: &Option<PathBuf>) -> Self {
+        let pattern = FilePattern::from_user(user_in.pattern.as_str(), project_root);
+        let code = user_in.code;
+        Self { pattern, code }
     }
 }
 
+#[derive(Debug)]
+pub struct RawSettings {
+    pub dummy_variable_rgx: Regex,
+    pub exclude: Vec<FilePattern>,
+    pub extend_exclude: Vec<FilePattern>,
+    pub extend_ignore: Vec<CheckCode>,
+    pub extend_select: Vec<CheckCode>,
+    pub ignore: Vec<CheckCode>,
+    pub line_length: usize,
+    pub per_file_ignores: Vec<PerFileIgnore>,
+    pub select: Vec<CheckCode>,
+    pub target_version: PythonVersion,
+}
+
 static DEFAULT_EXCLUDE: Lazy<Vec<FilePattern>> = Lazy::new(|| {
     vec![
         FilePattern::Simple(".bzr"),
@@ -75,11 +122,22 @@ static DEFAULT_EXCLUDE: Lazy<Vec<FilePattern>> = Lazy::new(|| {
     ]
 });
 
-impl Settings {
-    pub fn from_pyproject(path: &Option<PathBuf>, project_root: &Option<PathBuf>) -> Self {
-        let config = load_config(path);
-        let mut settings = Settings {
-            line_length: config.line_length.unwrap_or(88),
+static DEFAULT_DUMMY_VARIABLE_RGX: Lazy<Regex> =
+    Lazy::new(|| Regex::new("^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$").unwrap());
+
+impl RawSettings {
+    pub fn from_pyproject(
+        pyproject: &Option<PathBuf>,
+        project_root: &Option<PathBuf>,
+    ) -> Result<Self> {
+        let config = load_config(pyproject)?;
+        Ok(RawSettings {
+            dummy_variable_rgx: match config.dummy_variable_rgx {
+                Some(pattern) => Regex::new(&pattern)
+                    .map_err(|e| anyhow!("Invalid dummy-variable-rgx value: {e}"))?,
+                None => DEFAULT_DUMMY_VARIABLE_RGX.clone(),
+            },
+            target_version: config.target_version.unwrap_or(PythonVersion::Py310),
             exclude: config
                 .exclude
                 .map(|paths| {
@@ -91,35 +149,164 @@ impl Settings {
                 .unwrap_or_else(|| DEFAULT_EXCLUDE.clone()),
             extend_exclude: config
                 .extend_exclude
-                .map(|paths| {
-                    paths
-                        .iter()
-                        .map(|path| FilePattern::from_user(path, project_root))
-                        .collect()
-                })
-                .unwrap_or_default(),
-            select: if let Some(select) = config.select {
-                BTreeSet::from_iter(select)
-            } else {
-                BTreeSet::from_iter(ALL_CHECK_CODES)
-            },
-        };
-        if let Some(ignore) = &config.ignore {
-            settings.ignore(ignore);
-        }
-        settings
+                .iter()
+                .map(|path| FilePattern::from_user(path, project_root))
+                .collect(),
+            extend_ignore: config.extend_ignore,
+            select: config
+                .select
+                .unwrap_or_else(|| DEFAULT_CHECK_CODES.to_vec()),
+            extend_select: config.extend_select,
+            ignore: config.ignore,
+            line_length: config.line_length.unwrap_or(88),
+            per_file_ignores: config
+                .per_file_ignores
+                .into_iter()
+                .map(|pair| PerFileIgnore::new(pair, project_root))
+                .collect(),
+        })
     }
+}
 
-    pub fn select(&mut self, codes: Vec<CheckCode>) {
-        self.select.clear();
-        for code in codes {
-            self.select.insert(code);
+#[derive(Debug)]
+pub struct Settings {
+    pub dummy_variable_rgx: Regex,
+    pub enabled: BTreeSet<CheckCode>,
+    pub exclude: Vec<FilePattern>,
+    pub extend_exclude: Vec<FilePattern>,
+    pub line_length: usize,
+    pub per_file_ignores: Vec<PerFileIgnore>,
+    pub target_version: PythonVersion,
+}
+
+impl Settings {
+    pub fn from_raw(settings: RawSettings) -> Self {
+        // Materialize the set of enabled CheckCodes.
+        let mut enabled: BTreeSet<CheckCode> = BTreeSet::new();
+        enabled.extend(settings.select);
+        enabled.extend(settings.extend_select);
+        for code in &settings.ignore {
+            enabled.remove(code);
+        }
+        for code in &settings.extend_ignore {
+            enabled.remove(code);
+        }
+        Self {
+            dummy_variable_rgx: settings.dummy_variable_rgx,
+            enabled,
+            exclude: settings.exclude,
+            extend_exclude: settings.extend_exclude,
+            line_length: settings.line_length,
+            per_file_ignores: settings.per_file_ignores,
+            target_version: PythonVersion::Py310,
         }
     }
 
-    pub fn ignore(&mut self, codes: &[CheckCode]) {
-        for code in codes {
-            self.select.remove(code);
+    pub fn for_rule(check_code: CheckCode) -> Self {
+        Self {
+            dummy_variable_rgx: DEFAULT_DUMMY_VARIABLE_RGX.clone(),
+            enabled: BTreeSet::from([check_code]),
+            exclude: vec![],
+            extend_exclude: vec![],
+            line_length: 88,
+            per_file_ignores: vec![],
+            target_version: PythonVersion::Py310,
+        }
+    }
+
+    pub fn for_rules(check_codes: Vec<CheckCode>) -> Self {
+        Self {
+            dummy_variable_rgx: DEFAULT_DUMMY_VARIABLE_RGX.clone(),
+            enabled: BTreeSet::from_iter(check_codes),
+            exclude: vec![],
+            extend_exclude: vec![],
+            line_length: 88,
+            per_file_ignores: vec![],
+            target_version: PythonVersion::Py310,
+        }
+    }
+}
+
+impl Hash for Settings {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.line_length.hash(state);
+        self.dummy_variable_rgx.as_str().hash(state);
+        for value in self.enabled.iter() {
+            value.hash(state);
+        }
+        for value in self.per_file_ignores.iter() {
+            value.hash(state);
+        }
+    }
+}
+
+/// Struct to render user-facing exclusion patterns.
+#[derive(Debug)]
+#[allow(dead_code)]
+pub struct Exclusion {
+    basename: Option<String>,
+    absolute: Option<String>,
+}
+
+impl Exclusion {
+    pub fn from_file_pattern(file_pattern: FilePattern) -> Self {
+        match file_pattern {
+            FilePattern::Simple(basename) => Exclusion {
+                basename: Some(basename.to_string()),
+                absolute: None,
+            },
+            FilePattern::Complex(absolute, basename) => Exclusion {
+                basename: basename.map(|pattern| pattern.to_string()),
+                absolute: Some(absolute.to_string()),
+            },
+        }
+    }
+}
+
+/// Struct to render user-facing Settings.
+#[derive(Debug)]
+pub struct CurrentSettings {
+    pub dummy_variable_rgx: Regex,
+    pub exclude: Vec<Exclusion>,
+    pub extend_exclude: Vec<Exclusion>,
+    pub extend_ignore: Vec<CheckCode>,
+    pub extend_select: Vec<CheckCode>,
+    pub ignore: Vec<CheckCode>,
+    pub line_length: usize,
+    pub per_file_ignores: Vec<PerFileIgnore>,
+    pub select: Vec<CheckCode>,
+    pub target_version: PythonVersion,
+    pub project_root: Option<PathBuf>,
+    pub pyproject: Option<PathBuf>,
+}
+
+impl CurrentSettings {
+    pub fn from_settings(
+        settings: RawSettings,
+        project_root: Option<PathBuf>,
+        pyproject: Option<PathBuf>,
+    ) -> Self {
+        Self {
+            dummy_variable_rgx: settings.dummy_variable_rgx,
+            exclude: settings
+                .exclude
+                .into_iter()
+                .map(Exclusion::from_file_pattern)
+                .collect(),
+            extend_exclude: settings
+                .extend_exclude
+                .into_iter()
+                .map(Exclusion::from_file_pattern)
+                .collect(),
+            extend_ignore: settings.extend_ignore,
+            extend_select: settings.extend_select,
+            ignore: settings.ignore,
+            line_length: settings.line_length,
+            per_file_ignores: settings.per_file_ignores,
+            select: settings.select,
+            target_version: settings.target_version,
+            project_root,
+            pyproject,
         }
     }
 }

src/snapshots/ruff__linter__tests__a001.snap

@@ -0,0 +1,167 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind:
+    BuiltinVariableShadowing: sum
+  location:
+    row: 1
+    column: 1
+  end_location:
+    row: 1
+    column: 19
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: int
+  location:
+    row: 2
+    column: 1
+  end_location:
+    row: 2
+    column: 30
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: print
+  location:
+    row: 4
+    column: 1
+  end_location:
+    row: 4
+    column: 6
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: copyright
+  location:
+    row: 5
+    column: 1
+  end_location:
+    row: 5
+    column: 10
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: complex
+  location:
+    row: 6
+    column: 2
+  end_location:
+    row: 6
+    column: 14
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: float
+  location:
+    row: 7
+    column: 1
+  end_location:
+    row: 7
+    column: 6
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: object
+  location:
+    row: 7
+    column: 9
+  end_location:
+    row: 7
+    column: 15
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: min
+  location:
+    row: 8
+    column: 1
+  end_location:
+    row: 8
+    column: 4
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: max
+  location:
+    row: 8
+    column: 6
+  end_location:
+    row: 8
+    column: 9
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: bytes
+  location:
+    row: 10
+    column: 1
+  end_location:
+    row: 13
+    column: 1
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: slice
+  location:
+    row: 13
+    column: 1
+  end_location:
+    row: 16
+    column: 1
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: ValueError
+  location:
+    row: 18
+    column: 1
+  end_location:
+    row: 21
+    column: 1
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: memoryview
+  location:
+    row: 21
+    column: 5
+  end_location:
+    row: 21
+    column: 15
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: bytearray
+  location:
+    row: 21
+    column: 18
+  end_location:
+    row: 21
+    column: 27
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: str
+  location:
+    row: 24
+    column: 22
+  end_location:
+    row: 24
+    column: 25
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: all
+  location:
+    row: 24
+    column: 45
+  end_location:
+    row: 24
+    column: 48
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: any
+  location:
+    row: 24
+    column: 50
+  end_location:
+    row: 24
+    column: 53
+  fix: ~
+- kind:
+    BuiltinVariableShadowing: sum
+  location:
+    row: 27
+    column: 8
+  end_location:
+    row: 27
+    column: 11
+  fix: ~
+

src/snapshots/ruff__linter__tests__a002.snap

@@ -0,0 +1,68 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind:
+    BuiltinArgumentShadowing: str
+  location:
+    row: 1
+    column: 11
+  end_location:
+    row: 1
+    column: 14
+  fix: ~
+- kind:
+    BuiltinArgumentShadowing: type
+  location:
+    row: 1
+    column: 19
+  end_location:
+    row: 1
+    column: 23
+  fix: ~
+- kind:
+    BuiltinArgumentShadowing: complex
+  location:
+    row: 1
+    column: 26
+  end_location:
+    row: 1
+    column: 33
+  fix: ~
+- kind:
+    BuiltinArgumentShadowing: Exception
+  location:
+    row: 1
+    column: 35
+  end_location:
+    row: 1
+    column: 44
+  fix: ~
+- kind:
+    BuiltinArgumentShadowing: getattr
+  location:
+    row: 1
+    column: 48
+  end_location:
+    row: 1
+    column: 55
+  fix: ~
+- kind:
+    BuiltinArgumentShadowing: bytes
+  location:
+    row: 5
+    column: 17
+  end_location:
+    row: 5
+    column: 22
+  fix: ~
+- kind:
+    BuiltinArgumentShadowing: float
+  location:
+    row: 9
+    column: 16
+  end_location:
+    row: 9
+    column: 21
+  fix: ~
+

src/snapshots/ruff__linter__tests__a003.snap

@@ -0,0 +1,23 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind:
+    BuiltinAttributeShadowing: ImportError
+  location:
+    row: 2
+    column: 5
+  end_location:
+    row: 2
+    column: 16
+  fix: ~
+- kind:
+    BuiltinAttributeShadowing: str
+  location:
+    row: 7
+    column: 5
+  end_location:
+    row: 9
+    column: 1
+  fix: ~
+

src/snapshots/ruff__linter__tests__c400.snap

@@ -0,0 +1,13 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UnnecessaryGeneratorList
+  location:
+    row: 1
+    column: 5
+  end_location:
+    row: 1
+    column: 30
+  fix: ~
+

src/snapshots/ruff__linter__tests__c401.snap

@@ -0,0 +1,13 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UnnecessaryGeneratorList
+  location:
+    row: 1
+    column: 5
+  end_location:
+    row: 1
+    column: 29
+  fix: ~
+

src/snapshots/ruff__linter__tests__c402.snap

@@ -0,0 +1,13 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UnnecessaryListComprehensionDict
+  location:
+    row: 1
+    column: 5
+  end_location:
+    row: 1
+    column: 35
+  fix: ~
+

src/snapshots/ruff__linter__tests__c403.snap

@@ -0,0 +1,13 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UnnecessaryListComprehensionSet
+  location:
+    row: 1
+    column: 5
+  end_location:
+    row: 1
+    column: 31
+  fix: ~
+

src/snapshots/ruff__linter__tests__c404.snap

@@ -0,0 +1,13 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UnnecessaryListComprehensionDict
+  location:
+    row: 1
+    column: 5
+  end_location:
+    row: 1
+    column: 37
+  fix: ~
+

src/snapshots/ruff__linter__tests__c405.snap

@@ -0,0 +1,41 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind:
+    UnnecessaryLiteralSet: list
+  location:
+    row: 1
+    column: 6
+  end_location:
+    row: 1
+    column: 17
+  fix: ~
+- kind:
+    UnnecessaryLiteralSet: tuple
+  location:
+    row: 2
+    column: 6
+  end_location:
+    row: 2
+    column: 17
+  fix: ~
+- kind:
+    UnnecessaryLiteralSet: list
+  location:
+    row: 3
+    column: 6
+  end_location:
+    row: 3
+    column: 13
+  fix: ~
+- kind:
+    UnnecessaryLiteralSet: tuple
+  location:
+    row: 4
+    column: 6
+  end_location:
+    row: 4
+    column: 13
+  fix: ~
+

src/snapshots/ruff__linter__tests__c406.snap

@@ -0,0 +1,41 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind:
+    UnnecessaryLiteralDict: list
+  location:
+    row: 1
+    column: 6
+  end_location:
+    row: 1
+    column: 20
+  fix: ~
+- kind:
+    UnnecessaryLiteralDict: tuple
+  location:
+    row: 2
+    column: 6
+  end_location:
+    row: 2
+    column: 21
+  fix: ~
+- kind:
+    UnnecessaryLiteralDict: list
+  location:
+    row: 3
+    column: 6
+  end_location:
+    row: 3
+    column: 14
+  fix: ~
+- kind:
+    UnnecessaryLiteralDict: tuple
+  location:
+    row: 4
+    column: 6
+  end_location:
+    row: 4
+    column: 14
+  fix: ~
+

src/snapshots/ruff__linter__tests__c408.snap

@@ -0,0 +1,41 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind:
+    UnnecessaryCollectionCall: tuple
+  location:
+    row: 1
+    column: 5
+  end_location:
+    row: 1
+    column: 12
+  fix: ~
+- kind:
+    UnnecessaryCollectionCall: list
+  location:
+    row: 2
+    column: 5
+  end_location:
+    row: 2
+    column: 11
+  fix: ~
+- kind:
+    UnnecessaryCollectionCall: dict
+  location:
+    row: 3
+    column: 6
+  end_location:
+    row: 3
+    column: 12
+  fix: ~
+- kind:
+    UnnecessaryCollectionCall: dict
+  location:
+    row: 4
+    column: 6
+  end_location:
+    row: 4
+    column: 15
+  fix: ~
+