Bump version to 0.0.33

.pre-commit-config.yaml

@@ -1,5 +1,5 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff
-    rev: v0.0.28
+    rev: v0.0.33
     hooks:
       - id: lint

Cargo.lock

@@ -1744,7 +1744,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.28"
+version = "0.0.33"
 dependencies = [
  "anyhow",
  "bincode",
@@ -1759,6 +1759,7 @@ dependencies = [
  "filetime",
  "glob",
  "itertools",
+ "lazy_static",
  "log",
  "notify",
  "once_cell",
@@ -1787,7 +1788,7 @@ dependencies = [
 [[package]]
 name = "rustpython-ast"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=ff6112d7c70729be76eaad8c9e5b8ef24d13de99#ff6112d7c70729be76eaad8c9e5b8ef24d13de99"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "num-bigint",
  "rustpython-compiler-core",
@@ -1796,7 +1797,7 @@ dependencies = [
 [[package]]
 name = "rustpython-compiler-core"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=ff6112d7c70729be76eaad8c9e5b8ef24d13de99#ff6112d7c70729be76eaad8c9e5b8ef24d13de99"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "bincode",
  "bitflags",
@@ -1813,7 +1814,7 @@ dependencies = [
 [[package]]
 name = "rustpython-parser"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=ff6112d7c70729be76eaad8c9e5b8ef24d13de99#ff6112d7c70729be76eaad8c9e5b8ef24d13de99"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "ahash",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.28"
+version = "0.0.33"
 edition = "2021"
 
 [lib]
@@ -20,12 +20,13 @@ fern = { version = "0.6.1" }
 filetime = { version = "0.2.17" }
 glob = { version = "0.3.0" }
 itertools = "0.10.3"
+lazy_static = "1.4.0"
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
 once_cell = { version = "1.13.1" }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "ff6112d7c70729be76eaad8c9e5b8ef24d13de99" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "7d21c6923a506e79cc041708d83cef925efd33f4" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }

README.md

@@ -57,7 +57,7 @@ ruff also works with [Pre-Commit](https://pre-commit.com) (requires Cargo on sys
 ```yaml
 repos:
 - repo: https://github.com/charliermarsh/ruff
-  rev: v0.0.28
+  rev: v0.0.33
   hooks:
     - id: lint
 ```
@@ -86,7 +86,7 @@ ruff path/to/code/ --select F401 F403
 See `ruff --help` for more:
 
 ```shell
-ruff (v0.0.28)
+ruff (v0.0.33)
 An extremely fast Python linter.
 
 USAGE:
@@ -96,16 +96,17 @@ ARGS:
     <FILES>...
 
 OPTIONS:
-    -e, --exit-zero             Exit with status code "0", even upon detecting errors
-    -f, --fix                   Attempt to automatically fix lint errors
-    -h, --help                  Print help information
-        --ignore <IGNORE>...    Comma-separated 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>...    Comma-separated list of error codes to enable
-    -v, --verbose               Enable verbose logging
-    -w, --watch                 Run in watch mode by re-running whenever files change
+    -e, --exit-zero               Exit with status code "0", even upon detecting errors
+        --exclude <EXCLUDE>...    List of file and/or directory patterns to exclude from checks
+    -f, --fix                     Attempt to automatically fix lint errors
+    -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
+    -w, --watch                   Run in watch mode by re-running whenever files change
 ```
 
 ### Compatibility with Black
@@ -116,6 +117,31 @@ compatible out-of-the-box as long as the `line-length` setting is consistent bet
 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).
 
+### 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.)
+
+Under those conditions, Flake8 implements about 58 rules, give or take. At time of writing, ruff
+implements 28 rules. (Note that these 28 rules likely cover a disproportionate share of errors:
+unused imports, undefined variables, etc.)
+
+Of the unimplemented rules, ruff is missing:
+
+- 15 rules related to string `.format` calls.
+- 6 rules related to misplaced `yield`, `break`, and `return` statements.
+- 3 rules related to syntax errors in doctests and annotations.
+- 2 rules related to redefining unused names.
+
+...along with a variety of others that don't fit neatly into any specific category.
+
+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`.
+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 |
@@ -131,6 +157,10 @@ lint rules that are obviated by Black (e.g., stylistic rules).
 | F401 | UnusedImport | `...` imported but unused |
 | F403 | ImportStarUsage | Unable to detect undefined names |
 | 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` |
 | F634 | IfTuple | If test is a tuple, which is always `True` |
 | F704 | YieldOutsideFunction | a `yield` or `yield from` statement outside of a function/method |
@@ -177,7 +207,7 @@ git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpy
 Add this `pyproject.toml` to the CPython directory:
 
 ```toml
-[tool.linter]
+[tool.ruff]
 line-length = 88
 exclude = [
     "Lib/lib2to3/tests/data/bom.py",

examples/generate_rules_table.rs

@@ -13,13 +13,17 @@ fn main() {
         CheckKind::ImportStarUsage,
         CheckKind::LineTooLong,
         CheckKind::ModuleImportNotAtTopOfFile,
+        CheckKind::MultiValueRepeatedKeyLiteral,
+        CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
         CheckKind::NoAssertEquals,
         CheckKind::NoneComparison(RejectedCmpop::Eq),
         CheckKind::NotInTest,
         CheckKind::NotIsTest,
         CheckKind::RaiseNotImplemented,
         CheckKind::ReturnOutsideFunction,
+        CheckKind::TooManyExpressionsInStarredAssignment,
         CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
+        CheckKind::TwoStarredExpressions,
         CheckKind::UndefinedExport("...".to_string()),
         CheckKind::UndefinedLocal("...".to_string()),
         CheckKind::UndefinedName("...".to_string()),

resources/test/fixtures/E731.py

@@ -1,2 +1,6 @@
+from typing import Callable, Iterable
+
 a = lambda x: x**2
 b = map(lambda x: 2 * x, range(3))
+c: Callable = lambda x: x**2
+d: Iterable = map(lambda x: 2 * x, range(3))

resources/test/fixtures/F401.py

@@ -1,6 +1,7 @@
 from __future__ import all_feature_names
 import os
 import functools
+from datetime import datetime
 from collections import (
     Counter,
     OrderedDict,
@@ -10,11 +11,18 @@ 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()
@@ -23,3 +31,11 @@ class X:
 
 __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/F601.py

@@ -0,0 +1,12 @@
+x = {
+    "a": 1,
+    "a": 2,
+    "b": 3,
+    ("a", "b"): 3,
+    ("a", "b"): 4,
+    1.0: 2,
+    1: 0,
+    1: 3,
+    b"123": 1,
+    b"123": 4,
+}

resources/test/fixtures/F602.py

@@ -0,0 +1,7 @@
+a = 1
+b = 2
+x = {
+    a: 1,
+    a: 2,
+    b: 3,
+}

resources/test/fixtures/F622.py

@@ -0,0 +1,3 @@
+*a, *b, c = (1, 2, 3)
+*a, b, c = (1, 2, 3)
+a, b, *c = (1, 2, 3)

resources/test/fixtures/F821.py

@@ -33,14 +33,47 @@ def ternary_optarg(prec, exp_range, itr):
 class Foo:
     CLASS_VAR = 1
     REFERENCES_CLASS_VAR = {"CLASS_VAR": CLASS_VAR}
+    ANNOTATED_CLASS_VAR: int = 2
+
+
+from typing import Literal
 
 
 class Class:
+    copy_on_model_validation: Literal["none", "deep", "shallow"]
+    post_init_call: Literal["before_validation", "after_validation"]
+
     def __init__(self):
-        # TODO(charlie): This should be recognized as a defined variable.
-        Class  # noqa: F821
+        Class
+
 
 try:
     x = 1 / 0
 except Exception as e:
     print(e)
+
+
+y: int = 1
+
+x: "Bar" = 1
+
+[first] = ["yup"]
+
+
+from typing import List, TypedDict
+
+
+class Item(TypedDict):
+    nodes: List[TypedDict("Node", {"name": str})]
+
+
+from enum import Enum
+
+
+class Ticket:
+    class Status(Enum):
+        OPEN = "OPEN"
+        CLOSED = "CLOSED"
+
+    def set_status(self, status: Status):
+        self.status = status

resources/test/fixtures/pyproject.toml

@@ -13,6 +13,10 @@ select = [
     "F401",
     "F403",
     "F541",
+    "F601",
+    "F602",
+    "F621",
+    "F622",
     "F631",
     "F634",
     "F704",

src/ast.rs

@@ -0,0 +1,5 @@
+pub mod checks;
+pub mod operations;
+pub mod relocate;
+pub mod types;
+pub mod visitor;

src/ast/checks.rs

@@ -0,0 +1,430 @@
+use std::collections::BTreeSet;
+
+use itertools::izip;
+use rustpython_parser::ast::{
+    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Keyword,
+    Location, Stmt, Unaryop,
+};
+
+use crate::ast::operations::SourceCodeLocator;
+use crate::ast::types::{Binding, BindingKind, Scope};
+use crate::autofix::{fixer, fixes};
+use crate::checks::{Check, CheckKind, Fix, RejectedCmpop};
+
+/// Check IfTuple compliance.
+pub fn check_if_tuple(test: &Expr, location: Location) -> Option<Check> {
+    if let ExprKind::Tuple { elts, .. } = &test.node {
+        if !elts.is_empty() {
+            return Some(Check::new(CheckKind::IfTuple, location));
+        }
+    }
+    None
+}
+
+/// Check AssertTuple compliance.
+pub fn check_assert_tuple(test: &Expr, location: Location) -> Option<Check> {
+    if let ExprKind::Tuple { elts, .. } = &test.node {
+        if !elts.is_empty() {
+            return Some(Check::new(CheckKind::AssertTuple, location));
+        }
+    }
+    None
+}
+
+/// Check NotInTest and NotIsTest compliance.
+pub fn check_not_tests(
+    op: &Unaryop,
+    operand: &Expr,
+    check_not_in: bool,
+    check_not_is: bool,
+) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    if matches!(op, Unaryop::Not) {
+        if let ExprKind::Compare { ops, .. } = &operand.node {
+            match ops[..] {
+                [Cmpop::In] => {
+                    if check_not_in {
+                        checks.push(Check::new(CheckKind::NotInTest, operand.location));
+                    }
+                }
+                [Cmpop::Is] => {
+                    if check_not_is {
+                        checks.push(Check::new(CheckKind::NotIsTest, operand.location));
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    checks
+}
+
+/// Check UnusedVariable compliance.
+pub fn check_unused_variables(scope: &Scope) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    for (name, binding) in scope.values.iter() {
+        // TODO(charlie): Ignore if using `locals`.
+        if binding.used.is_none()
+            && 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,
+            ));
+        }
+    }
+
+    checks
+}
+
+/// Check DoNotAssignLambda compliance.
+pub fn check_do_not_assign_lambda(value: &Expr, location: Location) -> Option<Check> {
+    if let ExprKind::Lambda { .. } = &value.node {
+        Some(Check::new(CheckKind::DoNotAssignLambda, location))
+    } else {
+        None
+    }
+}
+
+/// Check UselessObjectInheritance compliance.
+pub fn check_useless_object_inheritance(
+    stmt: &Stmt,
+    name: &str,
+    bases: &[Expr],
+    keywords: &[Keyword],
+    scope: &Scope,
+    locator: &mut SourceCodeLocator,
+    autofix: &fixer::Mode,
+) -> Option<Check> {
+    for expr in bases {
+        if let ExprKind::Name { id, .. } = &expr.node {
+            if id == "object" {
+                match scope.values.get(id) {
+                    None
+                    | Some(Binding {
+                        kind: BindingKind::Builtin,
+                        ..
+                    }) => {
+                        let mut check = Check::new(
+                            CheckKind::UselessObjectInheritance(name.to_string()),
+                            expr.location,
+                        );
+                        if matches!(autofix, fixer::Mode::Generate)
+                            || matches!(autofix, fixer::Mode::Apply)
+                        {
+                            if let Some(fix) = fixes::remove_class_def_base(
+                                locator,
+                                &stmt.location,
+                                expr.location,
+                                bases,
+                                keywords,
+                            ) {
+                                check.amend(fix);
+                            }
+                        }
+                        return Some(check);
+                    }
+                    _ => {}
+                }
+            }
+        }
+    }
+
+    None
+}
+
+/// Check DefaultExceptNotLast compliance.
+pub fn check_default_except_not_last(handlers: &Vec<Excepthandler>) -> Option<Check> {
+    for (idx, handler) in handlers.iter().enumerate() {
+        let ExcepthandlerKind::ExceptHandler { type_, .. } = &handler.node;
+        if type_.is_none() && idx < handlers.len() - 1 {
+            return Some(Check::new(
+                CheckKind::DefaultExceptNotLast,
+                handler.location,
+            ));
+        }
+    }
+
+    None
+}
+
+/// Check RaiseNotImplemented compliance.
+pub fn check_raise_not_implemented(expr: &Expr) -> Option<Check> {
+    match &expr.node {
+        ExprKind::Call { func, .. } => {
+            if let ExprKind::Name { id, .. } = &func.node {
+                if id == "NotImplemented" {
+                    return Some(Check::new(CheckKind::RaiseNotImplemented, expr.location));
+                }
+            }
+        }
+        ExprKind::Name { id, .. } => {
+            if id == "NotImplemented" {
+                return Some(Check::new(CheckKind::RaiseNotImplemented, expr.location));
+            }
+        }
+        _ => {}
+    }
+
+    None
+}
+
+/// Check DuplicateArgumentName compliance.
+pub fn check_duplicate_arguments(arguments: &Arguments) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    // Collect all the arguments into a single vector.
+    let mut all_arguments: Vec<&Arg> = arguments
+        .args
+        .iter()
+        .chain(arguments.posonlyargs.iter())
+        .chain(arguments.kwonlyargs.iter())
+        .collect();
+    if let Some(arg) = &arguments.vararg {
+        all_arguments.push(arg);
+    }
+    if let Some(arg) = &arguments.kwarg {
+        all_arguments.push(arg);
+    }
+
+    // Search for duplicates.
+    let mut idents: BTreeSet<&str> = BTreeSet::new();
+    for arg in all_arguments {
+        let ident = &arg.node.arg;
+        if idents.contains(ident.as_str()) {
+            checks.push(Check::new(CheckKind::DuplicateArgumentName, arg.location));
+        }
+        idents.insert(ident);
+    }
+
+    checks
+}
+
+/// Check AssertEquals compliance.
+pub fn check_assert_equals(expr: &Expr, autofix: &fixer::Mode) -> Option<Check> {
+    if let ExprKind::Attribute { value, attr, .. } = &expr.node {
+        if attr == "assertEquals" {
+            if let ExprKind::Name { id, .. } = &value.node {
+                if id == "self" {
+                    let mut check = Check::new(CheckKind::NoAssertEquals, expr.location);
+                    if matches!(autofix, fixer::Mode::Generate)
+                        || matches!(autofix, 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),
+    Variable(&'a String),
+}
+
+fn convert_to_value(expr: &Expr) -> Option<DictionaryKey> {
+    match &expr.node {
+        ExprKind::Constant { value, .. } => Some(DictionaryKey::Constant(value)),
+        ExprKind::Name { id, .. } => Some(DictionaryKey::Variable(id)),
+        _ => None,
+    }
+}
+
+/// Check MultiValueRepeatedKeyLiteral and MultiValueRepeatedKeyVariable compliance.
+pub fn check_repeated_keys(
+    keys: &Vec<Expr>,
+    check_repeated_literals: bool,
+    check_repeated_variables: bool,
+) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    let num_keys = keys.len();
+    for i in 0..num_keys {
+        let k1 = &keys[i];
+        let v1 = convert_to_value(k1);
+        for k2 in keys.iter().take(num_keys).skip(i + 1) {
+            let v2 = convert_to_value(k2);
+            match (&v1, &v2) {
+                (Some(DictionaryKey::Constant(v1)), Some(DictionaryKey::Constant(v2))) => {
+                    if check_repeated_literals && v1 == v2 {
+                        checks.push(Check::new(
+                            CheckKind::MultiValueRepeatedKeyLiteral,
+                            k2.location,
+                        ))
+                    }
+                }
+                (Some(DictionaryKey::Variable(v1)), Some(DictionaryKey::Variable(v2))) => {
+                    if check_repeated_variables && v1 == v2 {
+                        checks.push(Check::new(
+                            CheckKind::MultiValueRepeatedKeyVariable(v2.to_string()),
+                            k2.location,
+                        ))
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    checks
+}
+
+/// Check TrueFalseComparison and NoneComparison compliance.
+pub fn check_literal_comparisons(
+    left: &Expr,
+    ops: &Vec<Cmpop>,
+    comparators: &Vec<Expr>,
+    check_none_comparisons: bool,
+    check_true_false_comparisons: bool,
+) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
+    let op = ops.first().unwrap();
+    let comparator = left;
+
+    // Check `left`.
+    if check_none_comparisons
+        && matches!(
+            comparator.node,
+            ExprKind::Constant {
+                value: Constant::None,
+                kind: None
+            }
+        )
+    {
+        if matches!(op, Cmpop::Eq) {
+            checks.push(Check::new(
+                CheckKind::NoneComparison(RejectedCmpop::Eq),
+                comparator.location,
+            ));
+        }
+        if matches!(op, Cmpop::NotEq) {
+            checks.push(Check::new(
+                CheckKind::NoneComparison(RejectedCmpop::NotEq),
+                comparator.location,
+            ));
+        }
+    }
+
+    if check_true_false_comparisons {
+        if let ExprKind::Constant {
+            value: Constant::Bool(value),
+            kind: None,
+        } = comparator.node
+        {
+            if matches!(op, Cmpop::Eq) {
+                checks.push(Check::new(
+                    CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
+                    comparator.location,
+                ));
+            }
+            if matches!(op, Cmpop::NotEq) {
+                checks.push(Check::new(
+                    CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
+                    comparator.location,
+                ));
+            }
+        }
+    }
+
+    // Check each comparator in order.
+    for (op, comparator) in izip!(ops, comparators) {
+        if check_none_comparisons
+            && matches!(
+                comparator.node,
+                ExprKind::Constant {
+                    value: Constant::None,
+                    kind: None
+                }
+            )
+        {
+            if matches!(op, Cmpop::Eq) {
+                checks.push(Check::new(
+                    CheckKind::NoneComparison(RejectedCmpop::Eq),
+                    comparator.location,
+                ));
+            }
+            if matches!(op, Cmpop::NotEq) {
+                checks.push(Check::new(
+                    CheckKind::NoneComparison(RejectedCmpop::NotEq),
+                    comparator.location,
+                ));
+            }
+        }
+
+        if check_true_false_comparisons {
+            if let ExprKind::Constant {
+                value: Constant::Bool(value),
+                kind: None,
+            } = comparator.node
+            {
+                if matches!(op, Cmpop::Eq) {
+                    checks.push(Check::new(
+                        CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
+                        comparator.location,
+                    ));
+                }
+                if matches!(op, Cmpop::NotEq) {
+                    checks.push(Check::new(
+                        CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
+                        comparator.location,
+                    ));
+                }
+            }
+        }
+    }
+
+    checks
+}
+
+/// Check TwoStarredExpressions and TooManyExpressionsInStarredAssignment compliance.
+pub fn check_starred_expressions(
+    elts: &[Expr],
+    location: Location,
+    check_too_many_expressions: bool,
+    check_two_starred_expressions: bool,
+) -> Option<Check> {
+    let mut has_starred: bool = false;
+    let mut starred_index: Option<usize> = None;
+    for (index, elt) in elts.iter().enumerate() {
+        if matches!(elt.node, ExprKind::Starred { .. }) {
+            if has_starred && check_two_starred_expressions {
+                return Some(Check::new(CheckKind::TwoStarredExpressions, location));
+            }
+            has_starred = true;
+            starred_index = Some(index);
+        }
+    }
+
+    if check_too_many_expressions {
+        if let Some(starred_index) = starred_index {
+            if starred_index >= 1 << 8 || elts.len() - starred_index > 1 << 24 {
+                return Some(Check::new(
+                    CheckKind::TooManyExpressionsInStarredAssignment,
+                    location,
+                ));
+            }
+        }
+    }
+
+    None
+}

src/ast/operations.rs

@@ -1,56 +1,6 @@
-use std::collections::BTreeMap;
-use std::sync::atomic::{AtomicUsize, Ordering};
-
 use rustpython_parser::ast::{Constant, Expr, ExprKind, Location, Stmt, StmtKind};
 
-fn id() -> usize {
-    static COUNTER: AtomicUsize = AtomicUsize::new(1);
-    COUNTER.fetch_add(1, Ordering::Relaxed)
-}
-
-pub enum ScopeKind {
-    Class,
-    Function,
-    Generator,
-    Module,
-}
-
-pub struct Scope {
-    pub id: usize,
-    pub kind: ScopeKind,
-    pub values: BTreeMap<String, Binding>,
-}
-
-impl Scope {
-    pub fn new(kind: ScopeKind) -> Self {
-        Scope {
-            id: id(),
-            kind,
-            values: BTreeMap::new(),
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub enum BindingKind {
-    Argument,
-    Assignment,
-    Builtin,
-    ClassDefinition,
-    Definition,
-    Export(Vec<String>),
-    FutureImportation,
-    Importation(String),
-    StarImportation,
-    SubmoduleImportation(String),
-}
-
-#[derive(Clone, Debug)]
-pub struct Binding {
-    pub kind: BindingKind,
-    pub location: Location,
-    pub used: Option<usize>,
-}
+use crate::ast::types::{BindingKind, Scope};
 
 /// Extract the names bound to a given __all__ assignment.
 pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
@@ -116,6 +66,40 @@ pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
     names
 }
 
+/// Check if a node is parent of a conditional branch.
+pub fn on_conditional_branch(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::If { .. })
+            || matches!(parent.node, StmtKind::While { .. })
+        {
+            return true;
+        }
+        if let StmtKind::Expr { value } = &parent.node {
+            if matches!(value.node, ExprKind::IfExp { .. }) {
+                return true;
+            }
+        }
+    }
+
+    false
+}
+
+/// Check if a node is in a nested block.
+pub fn in_nested_block(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::Try { .. })
+            || matches!(parent.node, StmtKind::If { .. })
+            || matches!(parent.node, StmtKind::With { .. })
+        {
+            return true;
+        }
+    }
+
+    false
+}
+
 /// Struct used to efficiently slice source code at (row, column) Locations.
 pub struct SourceCodeLocator<'a> {
     content: &'a str,

src/ast/relocate.rs

@@ -0,0 +1,137 @@
+use rustpython_parser::ast::{Expr, ExprKind, Keyword, Location};
+
+fn relocate_keyword(keyword: &mut Keyword, location: Location) {
+    keyword.location = 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;
+    match &mut expr.node {
+        ExprKind::BoolOp { values, .. } => {
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::NamedExpr { target, value } => {
+            relocate_expr(target, location);
+            relocate_expr(value, location);
+        }
+        ExprKind::BinOp { left, right, .. } => {
+            relocate_expr(left, location);
+            relocate_expr(right, location);
+        }
+        ExprKind::UnaryOp { operand, .. } => {
+            relocate_expr(operand, location);
+        }
+        ExprKind::Lambda { body, .. } => {
+            relocate_expr(body, location);
+        }
+        ExprKind::IfExp { test, body, orelse } => {
+            relocate_expr(test, location);
+            relocate_expr(body, location);
+            relocate_expr(orelse, location);
+        }
+        ExprKind::Dict { keys, values } => {
+            for expr in keys {
+                relocate_expr(expr, location);
+            }
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Set { elts } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::ListComp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::SetComp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::DictComp { key, value, .. } => {
+            relocate_expr(key, location);
+            relocate_expr(value, location);
+        }
+        ExprKind::GeneratorExp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::Await { value } => relocate_expr(value, location),
+        ExprKind::Yield { value } => {
+            if let Some(expr) = value {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::YieldFrom { value } => relocate_expr(value, location),
+        ExprKind::Compare {
+            left, comparators, ..
+        } => {
+            relocate_expr(left, location);
+            for expr in comparators {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Call {
+            func,
+            args,
+            keywords,
+        } => {
+            relocate_expr(func, location);
+            for expr in args {
+                relocate_expr(expr, location);
+            }
+            for keyword in keywords {
+                relocate_keyword(keyword, location);
+            }
+        }
+        ExprKind::FormattedValue {
+            value, format_spec, ..
+        } => {
+            relocate_expr(value, location);
+            if let Some(expr) = format_spec {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::JoinedStr { values } => {
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Constant { .. } => {}
+        ExprKind::Attribute { value, .. } => {
+            relocate_expr(value, location);
+        }
+        ExprKind::Subscript { value, slice, .. } => {
+            relocate_expr(value, location);
+            relocate_expr(slice, location);
+        }
+        ExprKind::Starred { value, .. } => {
+            relocate_expr(value, location);
+        }
+        ExprKind::Name { .. } => {}
+        ExprKind::List { elts, .. } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Tuple { elts, .. } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Slice { lower, upper, step } => {
+            if let Some(expr) = lower {
+                relocate_expr(expr, location);
+            }
+            if let Some(expr) = upper {
+                relocate_expr(expr, location);
+            }
+            if let Some(expr) = step {
+                relocate_expr(expr, location);
+            }
+        }
+    }
+}

src/ast/types.rs

@@ -0,0 +1,55 @@
+use std::collections::BTreeMap;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use rustpython_parser::ast::Location;
+
+fn id() -> usize {
+    static COUNTER: AtomicUsize = AtomicUsize::new(1);
+    COUNTER.fetch_add(1, Ordering::Relaxed)
+}
+
+#[derive(Clone, Debug)]
+pub enum ScopeKind {
+    Class,
+    Function,
+    Generator,
+    Module,
+}
+
+#[derive(Clone, Debug)]
+pub struct Scope {
+    pub id: usize,
+    pub kind: ScopeKind,
+    pub values: BTreeMap<String, Binding>,
+}
+
+impl Scope {
+    pub fn new(kind: ScopeKind) -> Self {
+        Scope {
+            id: id(),
+            kind,
+            values: BTreeMap::new(),
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum BindingKind {
+    Argument,
+    Assignment,
+    Builtin,
+    ClassDefinition,
+    Definition,
+    Export(Vec<String>),
+    FutureImportation,
+    Importation(String),
+    StarImportation,
+    SubmoduleImportation(String),
+}
+
+#[derive(Clone, Debug)]
+pub struct Binding {
+    pub kind: BindingKind,
+    pub location: Location,
+    pub used: Option<usize>,
+}

src/ast/visitor.rs

@@ -4,102 +4,141 @@ use rustpython_parser::ast::{
     PatternKind, Stmt, StmtKind, Unaryop, Withitem,
 };
 
-pub trait Visitor {
-    fn visit_stmt(&mut self, stmt: &Stmt) {
+pub trait Visitor<'a> {
+    fn visit_stmt(&mut self, stmt: &'a Stmt) {
         walk_stmt(self, stmt);
     }
-    fn visit_annotation(&mut self, expr: &Expr) {
+    fn visit_annotation(&mut self, expr: &'a Expr) {
         walk_expr(self, expr);
     }
-    fn visit_expr(&mut self, expr: &Expr, _parent: Option<&Stmt>) {
+    fn visit_expr(&mut self, expr: &'a Expr) {
         walk_expr(self, expr);
     }
-    fn visit_constant(&mut self, constant: &Constant) {
+    fn visit_constant(&mut self, constant: &'a Constant) {
         walk_constant(self, constant);
     }
-    fn visit_expr_context(&mut self, expr_content: &ExprContext) {
+    fn visit_expr_context(&mut self, expr_content: &'a ExprContext) {
         walk_expr_context(self, expr_content);
     }
-    fn visit_boolop(&mut self, boolop: &Boolop) {
+    fn visit_boolop(&mut self, boolop: &'a Boolop) {
         walk_boolop(self, boolop);
     }
-    fn visit_operator(&mut self, operator: &Operator) {
+    fn visit_operator(&mut self, operator: &'a Operator) {
         walk_operator(self, operator);
     }
-    fn visit_unaryop(&mut self, unaryop: &Unaryop) {
+    fn visit_unaryop(&mut self, unaryop: &'a Unaryop) {
         walk_unaryop(self, unaryop);
     }
-    fn visit_cmpop(&mut self, cmpop: &Cmpop) {
+    fn visit_cmpop(&mut self, cmpop: &'a Cmpop) {
         walk_cmpop(self, cmpop);
     }
-    fn visit_comprehension(&mut self, comprehension: &Comprehension) {
+    fn visit_comprehension(&mut self, comprehension: &'a Comprehension) {
         walk_comprehension(self, comprehension);
     }
-    fn visit_excepthandler(&mut self, excepthandler: &Excepthandler) {
+    fn visit_excepthandler(&mut self, excepthandler: &'a Excepthandler) {
         walk_excepthandler(self, excepthandler);
     }
-    fn visit_arguments(&mut self, arguments: &Arguments) {
+    fn visit_arguments(&mut self, arguments: &'a Arguments) {
         walk_arguments(self, arguments);
     }
-    fn visit_arg(&mut self, arg: &Arg) {
+    fn visit_arg(&mut self, arg: &'a Arg) {
         walk_arg(self, arg);
     }
-    fn visit_keyword(&mut self, keyword: &Keyword) {
+    fn visit_keyword(&mut self, keyword: &'a Keyword) {
         walk_keyword(self, keyword);
     }
-    fn visit_alias(&mut self, alias: &Alias) {
+    fn visit_alias(&mut self, alias: &'a Alias) {
         walk_alias(self, alias);
     }
-    fn visit_withitem(&mut self, withitem: &Withitem) {
+    fn visit_withitem(&mut self, withitem: &'a Withitem) {
         walk_withitem(self, withitem);
     }
-    fn visit_match_case(&mut self, match_case: &MatchCase) {
+    fn visit_match_case(&mut self, match_case: &'a MatchCase) {
         walk_match_case(self, match_case);
     }
-    fn visit_pattern(&mut self, pattern: &Pattern) {
+    fn visit_pattern(&mut self, pattern: &'a Pattern) {
         walk_pattern(self, pattern);
     }
 }
 
-pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
+pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
     match &stmt.node {
-        StmtKind::FunctionDef { args, body, .. } => {
+        StmtKind::FunctionDef {
+            args,
+            body,
+            decorator_list,
+            returns,
+            ..
+        } => {
             visitor.visit_arguments(args);
+            for expr in decorator_list {
+                visitor.visit_expr(expr);
+            }
+            for expr in returns {
+                visitor.visit_annotation(expr);
+            }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
-        StmtKind::AsyncFunctionDef { args, body, .. } => {
+        StmtKind::AsyncFunctionDef {
+            args,
+            body,
+            decorator_list,
+            returns,
+            ..
+        } => {
             visitor.visit_arguments(args);
+            for expr in decorator_list {
+                visitor.visit_expr(expr);
+            }
+            for expr in returns {
+                visitor.visit_annotation(expr);
+            }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
-        StmtKind::ClassDef { body, .. } => {
+        StmtKind::ClassDef {
+            bases,
+            keywords,
+            body,
+            decorator_list,
+            ..
+        } => {
+            for expr in bases {
+                visitor.visit_expr(expr);
+            }
+            for keyword in keywords {
+                visitor.visit_keyword(keyword);
+            }
+            for expr in decorator_list {
+                visitor.visit_expr(expr);
+            }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Return { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Delete { targets } => {
             for expr in targets {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Assign { targets, value, .. } => {
+            visitor.visit_expr(value);
             for expr in targets {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             }
-            visitor.visit_expr(value, Some(stmt))
         }
         StmtKind::AugAssign { target, op, value } => {
-            visitor.visit_expr(target, Some(stmt));
+            visitor.visit_expr(target);
             visitor.visit_operator(op);
-            visitor.visit_expr(value, Some(stmt));
+            visitor.visit_expr(value);
         }
         StmtKind::AnnAssign {
             target,
@@ -107,11 +146,11 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             value,
             ..
         } => {
-            visitor.visit_expr(target, Some(stmt));
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             }
+            visitor.visit_expr(target);
         }
         StmtKind::For {
             target,
@@ -120,13 +159,13 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             orelse,
             ..
         } => {
-            visitor.visit_expr(target, Some(stmt));
-            visitor.visit_expr(iter, Some(stmt));
+            visitor.visit_expr(target);
+            visitor.visit_expr(iter);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncFor {
@@ -136,31 +175,31 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             orelse,
             ..
         } => {
-            visitor.visit_expr(target, Some(stmt));
-            visitor.visit_expr(iter, Some(stmt));
+            visitor.visit_expr(target);
+            visitor.visit_expr(iter);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::While { test, body, orelse } => {
-            visitor.visit_expr(test, Some(stmt));
+            visitor.visit_expr(test);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::If { test, body, orelse } => {
-            visitor.visit_expr(test, Some(stmt));
+            visitor.visit_expr(test);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::With { items, body, .. } => {
@@ -168,7 +207,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
                 visitor.visit_withitem(withitem);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncWith { items, body, .. } => {
@@ -176,22 +215,22 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
                 visitor.visit_withitem(withitem);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Match { subject, cases } => {
             // TODO(charlie): Handle `cases`.
-            visitor.visit_expr(subject, Some(stmt));
+            visitor.visit_expr(subject);
             for match_case in cases {
                 visitor.visit_match_case(match_case);
             }
         }
         StmtKind::Raise { exc, cause } => {
             if let Some(expr) = exc {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             };
             if let Some(expr) = cause {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             };
         }
         StmtKind::Try {
@@ -201,22 +240,22 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             finalbody,
         } => {
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for excepthandler in handlers {
                 visitor.visit_excepthandler(excepthandler)
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in finalbody {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Assert { test, msg } => {
-            visitor.visit_expr(test, None);
+            visitor.visit_expr(test);
             if let Some(expr) = msg {
-                visitor.visit_expr(expr, Some(stmt))
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Import { names } => {
@@ -231,67 +270,67 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         }
         StmtKind::Global { .. } => {}
         StmtKind::Nonlocal { .. } => {}
-        StmtKind::Expr { value } => visitor.visit_expr(value, Some(stmt)),
+        StmtKind::Expr { value } => visitor.visit_expr(value),
         StmtKind::Pass => {}
         StmtKind::Break => {}
         StmtKind::Continue => {}
     }
 }
 
-pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
+pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
     match &expr.node {
         ExprKind::BoolOp { op, values } => {
             visitor.visit_boolop(op);
             for expr in values {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::NamedExpr { target, value } => {
-            visitor.visit_expr(target, None);
-            visitor.visit_expr(value, None);
+            visitor.visit_expr(target);
+            visitor.visit_expr(value);
         }
         ExprKind::BinOp { left, op, right } => {
-            visitor.visit_expr(left, None);
+            visitor.visit_expr(left);
             visitor.visit_operator(op);
-            visitor.visit_expr(right, None);
+            visitor.visit_expr(right);
         }
         ExprKind::UnaryOp { op, operand } => {
             visitor.visit_unaryop(op);
-            visitor.visit_expr(operand, None);
+            visitor.visit_expr(operand);
         }
         ExprKind::Lambda { args, body } => {
             visitor.visit_arguments(args);
-            visitor.visit_expr(body, None);
+            visitor.visit_expr(body);
         }
         ExprKind::IfExp { test, body, orelse } => {
-            visitor.visit_expr(test, None);
-            visitor.visit_expr(body, None);
-            visitor.visit_expr(orelse, None);
+            visitor.visit_expr(test);
+            visitor.visit_expr(body);
+            visitor.visit_expr(orelse);
         }
         ExprKind::Dict { keys, values } => {
             for expr in keys {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
             for expr in values {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Set { elts } => {
             for expr in elts {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::ListComp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
-            visitor.visit_expr(elt, None);
+            visitor.visit_expr(elt);
         }
         ExprKind::SetComp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
-            visitor.visit_expr(elt, None);
+            visitor.visit_expr(elt);
         }
         ExprKind::DictComp {
             key,
@@ -299,35 +338,35 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
             generators,
         } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
-            visitor.visit_expr(key, None);
-            visitor.visit_expr(value, None);
+            visitor.visit_expr(key);
+            visitor.visit_expr(value);
         }
         ExprKind::GeneratorExp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
-            visitor.visit_expr(elt, None);
+            visitor.visit_expr(elt);
         }
-        ExprKind::Await { value } => visitor.visit_expr(value, None),
+        ExprKind::Await { value } => visitor.visit_expr(value),
         ExprKind::Yield { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
-        ExprKind::YieldFrom { value } => visitor.visit_expr(value, None),
+        ExprKind::YieldFrom { value } => visitor.visit_expr(value),
         ExprKind::Compare {
             left,
             ops,
             comparators,
         } => {
-            visitor.visit_expr(left, None);
+            visitor.visit_expr(left);
             for cmpop in ops {
                 visitor.visit_cmpop(cmpop);
             }
             for expr in comparators {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Call {
@@ -335,9 +374,9 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
             args,
             keywords,
         } => {
-            visitor.visit_expr(func, None);
+            visitor.visit_expr(func);
             for expr in args {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             for keyword in keywords {
                 visitor.visit_keyword(keyword);
@@ -346,28 +385,28 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         ExprKind::FormattedValue {
             value, format_spec, ..
         } => {
-            visitor.visit_expr(value, None);
+            visitor.visit_expr(value);
             if let Some(expr) = format_spec {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::JoinedStr { values } => {
             for expr in values {
-                visitor.visit_expr(expr, None)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Constant { value, .. } => visitor.visit_constant(value),
         ExprKind::Attribute { value, ctx, .. } => {
-            visitor.visit_expr(value, None);
+            visitor.visit_expr(value);
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Subscript { value, slice, ctx } => {
-            visitor.visit_expr(value, None);
-            visitor.visit_expr(slice, None);
+            visitor.visit_expr(value);
+            visitor.visit_expr(slice);
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Starred { value, ctx } => {
-            visitor.visit_expr(value, None);
+            visitor.visit_expr(value);
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Name { ctx, .. } => {
@@ -375,31 +414,31 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         }
         ExprKind::List { elts, ctx } => {
             for expr in elts {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Tuple { elts, ctx } => {
             for expr in elts {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Slice { lower, upper, step } => {
             if let Some(expr) = lower {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             if let Some(expr) = upper {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             if let Some(expr) = step {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
         }
     }
 }
 
-pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant) {
+pub fn walk_constant<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, constant: &'a Constant) {
     if let Constant::Tuple(constants) = constant {
         for constant in constants {
             visitor.visit_constant(constant)
@@ -407,19 +446,25 @@ pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant)
     }
 }
 
-pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &Comprehension) {
-    visitor.visit_expr(&comprehension.target, None);
-    visitor.visit_expr(&comprehension.iter, None);
+pub fn walk_comprehension<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    comprehension: &'a Comprehension,
+) {
+    visitor.visit_expr(&comprehension.target);
+    visitor.visit_expr(&comprehension.iter);
     for expr in &comprehension.ifs {
-        visitor.visit_expr(expr, None);
+        visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &Excepthandler) {
+pub fn walk_excepthandler<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    excepthandler: &'a Excepthandler,
+) {
     match &excepthandler.node {
         ExcepthandlerKind::ExceptHandler { type_, body, .. } => {
             if let Some(expr) = type_ {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             for stmt in body {
                 visitor.visit_stmt(stmt);
@@ -428,7 +473,7 @@ pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &
     }
 }
 
-pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Arguments) {
+pub fn walk_arguments<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, arguments: &'a Arguments) {
     for arg in &arguments.posonlyargs {
         visitor.visit_arg(arg);
     }
@@ -436,61 +481,61 @@ pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Argument
         visitor.visit_arg(arg);
     }
     if let Some(arg) = &arguments.vararg {
-        visitor.visit_arg(arg)
+        visitor.visit_arg(arg);
     }
     for arg in &arguments.kwonlyargs {
         visitor.visit_arg(arg);
     }
     for expr in &arguments.kw_defaults {
-        visitor.visit_expr(expr, None)
+        visitor.visit_expr(expr);
     }
     if let Some(arg) = &arguments.kwarg {
-        visitor.visit_arg(arg)
+        visitor.visit_arg(arg);
     }
     for expr in &arguments.defaults {
-        visitor.visit_expr(expr, None)
+        visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_arg<V: Visitor + ?Sized>(visitor: &mut V, arg: &Arg) {
+pub fn walk_arg<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, arg: &'a Arg) {
     if let Some(expr) = &arg.node.annotation {
-        visitor.visit_annotation(expr)
+        visitor.visit_annotation(expr);
     }
 }
 
-pub fn walk_keyword<V: Visitor + ?Sized>(visitor: &mut V, keyword: &Keyword) {
-    visitor.visit_expr(&keyword.node.value, None);
+pub fn walk_keyword<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, keyword: &'a Keyword) {
+    visitor.visit_expr(&keyword.node.value);
 }
 
-pub fn walk_withitem<V: Visitor + ?Sized>(visitor: &mut V, withitem: &Withitem) {
-    visitor.visit_expr(&withitem.context_expr, None);
+pub fn walk_withitem<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, withitem: &'a Withitem) {
+    visitor.visit_expr(&withitem.context_expr);
     if let Some(expr) = &withitem.optional_vars {
-        visitor.visit_expr(expr, None);
+        visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_match_case<V: Visitor + ?Sized>(visitor: &mut V, match_case: &MatchCase) {
+pub fn walk_match_case<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, match_case: &'a MatchCase) {
     visitor.visit_pattern(&match_case.pattern);
     if let Some(expr) = &match_case.guard {
-        visitor.visit_expr(expr, None);
+        visitor.visit_expr(expr);
     }
     for stmt in &match_case.body {
         visitor.visit_stmt(stmt);
     }
 }
 
-pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
+pub fn walk_pattern<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, pattern: &'a Pattern) {
     match &pattern.node {
-        PatternKind::MatchValue { value } => visitor.visit_expr(value, None),
+        PatternKind::MatchValue { value } => visitor.visit_expr(value),
         PatternKind::MatchSingleton { value } => visitor.visit_constant(value),
         PatternKind::MatchSequence { patterns } => {
             for pattern in patterns {
-                visitor.visit_pattern(pattern)
+                visitor.visit_pattern(pattern);
             }
         }
         PatternKind::MatchMapping { keys, patterns, .. } => {
             for expr in keys {
-                visitor.visit_expr(expr, None);
+                visitor.visit_expr(expr);
             }
             for pattern in patterns {
                 visitor.visit_pattern(pattern);
@@ -502,7 +547,7 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
             kwd_patterns,
             ..
         } => {
-            visitor.visit_expr(cls, None);
+            visitor.visit_expr(cls);
             for pattern in patterns {
                 visitor.visit_pattern(pattern);
             }
@@ -514,7 +559,7 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
         PatternKind::MatchStar { .. } => {}
         PatternKind::MatchAs { pattern, .. } => {
             if let Some(pattern) = pattern {
-                visitor.visit_pattern(pattern)
+                visitor.visit_pattern(pattern);
             }
         }
         PatternKind::MatchOr { patterns } => {
@@ -527,24 +572,28 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_expr_context<V: Visitor + ?Sized>(visitor: &mut V, expr_context: &ExprContext) {}
+pub fn walk_expr_context<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    expr_context: &'a ExprContext,
+) {
+}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_boolop<V: Visitor + ?Sized>(visitor: &mut V, boolop: &Boolop) {}
+pub fn walk_boolop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, boolop: &'a Boolop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_operator<V: Visitor + ?Sized>(visitor: &mut V, operator: &Operator) {}
+pub fn walk_operator<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, operator: &'a Operator) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_unaryop<V: Visitor + ?Sized>(visitor: &mut V, unaryop: &Unaryop) {}
+pub fn walk_unaryop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, unaryop: &'a Unaryop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_cmpop<V: Visitor + ?Sized>(visitor: &mut V, cmpop: &Cmpop) {}
+pub fn walk_cmpop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, cmpop: &'a Cmpop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_alias<V: Visitor + ?Sized>(visitor: &mut V, alias: &Alias) {}
+pub fn walk_alias<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, alias: &'a Alias) {}

src/autofix.rs

@@ -1,216 +1,2 @@
-use std::fs;
-use std::path::Path;
-
-use anyhow::Result;
-use rustpython_parser::ast::Location;
-
-use crate::checks::{Check, Fix};
-
-#[derive(Hash)]
-pub enum Mode {
-    Generate,
-    Apply,
-    None,
-}
-
-impl From<bool> for Mode {
-    fn from(value: bool) -> Self {
-        match value {
-            true => Mode::Apply,
-            false => Mode::None,
-        }
-    }
-}
-
-/// Auto-fix errors in a file, and write the fixed source code to disk.
-pub fn fix_file(checks: &mut [Check], contents: &str, path: &Path) -> Result<()> {
-    if checks.iter().all(|check| check.fix.is_none()) {
-        return Ok(());
-    }
-
-    let output = apply_fixes(
-        checks.iter_mut().filter_map(|check| check.fix.as_mut()),
-        contents,
-    );
-
-    fs::write(path, output).map_err(|e| e.into())
-}
-
-/// Apply a series of fixes.
-fn apply_fixes<'a>(fixes: impl Iterator<Item = &'a mut Fix>, contents: &str) -> String {
-    let lines: Vec<&str> = contents.lines().collect();
-
-    let mut output = "".to_string();
-    let mut last_pos: Location = Location::new(0, 0);
-
-    for fix in fixes {
-        // Best-effort approach: if this fix overlaps with a fix we've already applied, skip it.
-        if last_pos > fix.start {
-            continue;
-        }
-
-        if fix.start.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] {
-                output.push_str(line);
-                output.push('\n');
-            }
-            output.push_str(&lines[fix.start.row() - 1][..fix.start.column() - 1]);
-            output.push_str(&fix.content);
-        } else {
-            output.push_str(
-                &lines[last_pos.row() - 1][last_pos.column() - 1..fix.start.column() - 1],
-            );
-            output.push_str(&fix.content);
-        }
-
-        last_pos = fix.end;
-        fix.applied = true;
-    }
-
-    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()..] {
-        output.push_str(line);
-        output.push('\n');
-    }
-
-    output
-}
-
-#[cfg(test)]
-mod tests {
-    use anyhow::Result;
-    use rustpython_parser::ast::Location;
-
-    use crate::autofix::apply_fixes;
-    use crate::checks::Fix;
-
-    #[test]
-    fn empty_file() -> Result<()> {
-        let mut fixes = vec![];
-        let actual = apply_fixes(fixes.iter_mut(), "");
-        let expected = "";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
-    }
-
-    #[test]
-    fn apply_single_replacement() -> Result<()> {
-        let mut fixes = vec![Fix {
-            content: "Bar".to_string(),
-            start: Location::new(1, 9),
-            end: Location::new(1, 15),
-            applied: false,
-        }];
-        let actual = apply_fixes(
-            fixes.iter_mut(),
-            "class A(object):
-        ...
-",
-        );
-
-        let expected = "class A(Bar):
-        ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
-    }
-
-    #[test]
-    fn apply_single_removal() -> Result<()> {
-        let mut fixes = vec![Fix {
-            content: "".to_string(),
-            start: Location::new(1, 8),
-            end: Location::new(1, 16),
-            applied: false,
-        }];
-        let actual = apply_fixes(
-            fixes.iter_mut(),
-            "class A(object):
-        ...
-",
-        );
-
-        let expected = "class A:
-        ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
-    }
-
-    #[test]
-    fn apply_double_removal() -> Result<()> {
-        let mut fixes = vec![
-            Fix {
-                content: "".to_string(),
-                start: Location::new(1, 8),
-                end: Location::new(1, 17),
-                applied: false,
-            },
-            Fix {
-                content: "".to_string(),
-                start: Location::new(1, 17),
-                end: Location::new(1, 24),
-                applied: false,
-            },
-        ];
-        let actual = apply_fixes(
-            fixes.iter_mut(),
-            "class A(object, object):
-        ...
-",
-        );
-
-        let expected = "class A:
-        ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
-    }
-
-    #[test]
-    fn ignore_overlapping_fixes() -> Result<()> {
-        let mut fixes = vec![
-            Fix {
-                content: "".to_string(),
-                start: Location::new(1, 8),
-                end: Location::new(1, 16),
-                applied: false,
-            },
-            Fix {
-                content: "ignored".to_string(),
-                start: Location::new(1, 10),
-                end: Location::new(1, 12),
-                applied: false,
-            },
-        ];
-        let actual = apply_fixes(
-            fixes.iter_mut(),
-            "class A(object):
-    ...
-",
-        );
-
-        let expected = "class A:
-    ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
-    }
-}
+pub mod fixer;
+pub mod fixes;

src/autofix/fixer.rs

@@ -0,0 +1,216 @@
+use std::fs;
+use std::path::Path;
+
+use anyhow::Result;
+use rustpython_parser::ast::Location;
+
+use crate::checks::{Check, Fix};
+
+#[derive(Hash)]
+pub enum Mode {
+    Generate,
+    Apply,
+    None,
+}
+
+impl From<bool> for Mode {
+    fn from(value: bool) -> Self {
+        match value {
+            true => Mode::Apply,
+            false => Mode::None,
+        }
+    }
+}
+
+/// Auto-fix errors in a file, and write the fixed source code to disk.
+pub fn fix_file(checks: &mut [Check], contents: &str, path: &Path) -> Result<()> {
+    if checks.iter().all(|check| check.fix.is_none()) {
+        return Ok(());
+    }
+
+    let output = apply_fixes(
+        checks.iter_mut().filter_map(|check| check.fix.as_mut()),
+        contents,
+    );
+
+    fs::write(path, output).map_err(|e| e.into())
+}
+
+/// Apply a series of fixes.
+fn apply_fixes<'a>(fixes: impl Iterator<Item = &'a mut Fix>, contents: &str) -> String {
+    let lines: Vec<&str> = contents.lines().collect();
+
+    let mut output = "".to_string();
+    let mut last_pos: Location = Location::new(0, 0);
+
+    for fix in fixes {
+        // Best-effort approach: if this fix overlaps with a fix we've already applied, skip it.
+        if last_pos > fix.start {
+            continue;
+        }
+
+        if fix.start.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] {
+                output.push_str(line);
+                output.push('\n');
+            }
+            output.push_str(&lines[fix.start.row() - 1][..fix.start.column() - 1]);
+            output.push_str(&fix.content);
+        } else {
+            output.push_str(
+                &lines[last_pos.row() - 1][last_pos.column() - 1..fix.start.column() - 1],
+            );
+            output.push_str(&fix.content);
+        }
+
+        last_pos = fix.end;
+        fix.applied = true;
+    }
+
+    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()..] {
+        output.push_str(line);
+        output.push('\n');
+    }
+
+    output
+}
+
+#[cfg(test)]
+mod tests {
+    use anyhow::Result;
+    use rustpython_parser::ast::Location;
+
+    use crate::autofix::fixer::apply_fixes;
+    use crate::checks::Fix;
+
+    #[test]
+    fn empty_file() -> Result<()> {
+        let mut fixes = vec![];
+        let actual = apply_fixes(fixes.iter_mut(), "");
+        let expected = "";
+
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn apply_single_replacement() -> Result<()> {
+        let mut fixes = vec![Fix {
+            content: "Bar".to_string(),
+            start: Location::new(1, 9),
+            end: Location::new(1, 15),
+            applied: false,
+        }];
+        let actual = apply_fixes(
+            fixes.iter_mut(),
+            "class A(object):
+        ...
+",
+        );
+
+        let expected = "class A(Bar):
+        ...
+";
+
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn apply_single_removal() -> Result<()> {
+        let mut fixes = vec![Fix {
+            content: "".to_string(),
+            start: Location::new(1, 8),
+            end: Location::new(1, 16),
+            applied: false,
+        }];
+        let actual = apply_fixes(
+            fixes.iter_mut(),
+            "class A(object):
+        ...
+",
+        );
+
+        let expected = "class A:
+        ...
+";
+
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn apply_double_removal() -> Result<()> {
+        let mut fixes = vec![
+            Fix {
+                content: "".to_string(),
+                start: Location::new(1, 8),
+                end: Location::new(1, 17),
+                applied: false,
+            },
+            Fix {
+                content: "".to_string(),
+                start: Location::new(1, 17),
+                end: Location::new(1, 24),
+                applied: false,
+            },
+        ];
+        let actual = apply_fixes(
+            fixes.iter_mut(),
+            "class A(object, object):
+        ...
+",
+        );
+
+        let expected = "class A:
+        ...
+";
+
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn ignore_overlapping_fixes() -> Result<()> {
+        let mut fixes = vec![
+            Fix {
+                content: "".to_string(),
+                start: Location::new(1, 8),
+                end: Location::new(1, 16),
+                applied: false,
+            },
+            Fix {
+                content: "ignored".to_string(),
+                start: Location::new(1, 10),
+                end: Location::new(1, 12),
+                applied: false,
+            },
+        ];
+        let actual = apply_fixes(
+            fixes.iter_mut(),
+            "class A(object):
+    ...
+",
+        );
+
+        let expected = "class A:
+    ...
+";
+
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+}

src/autofix/fixes.rs

@@ -1,8 +1,8 @@
-use crate::ast_ops::SourceCodeLocator;
 use rustpython_parser::ast::{Expr, Keyword, Location};
 use rustpython_parser::lexer;
 use rustpython_parser::token::Tok;
 
+use crate::ast::operations::SourceCodeLocator;
 use crate::checks::Fix;
 
 /// Convert a location within a file (relative to `base`) to an absolute position.

src/cache.rs

@@ -3,12 +3,12 @@ use std::fs::Metadata;
 use std::hash::{Hash, Hasher};
 use std::path::Path;
 
-use crate::autofix;
 use cacache::Error::EntryNotFound;
 use filetime::FileTime;
 use log::error;
 use serde::{Deserialize, Serialize};
 
+use crate::autofix::fixer;
 use crate::message::Message;
 use crate::settings::Settings;
 
@@ -62,7 +62,7 @@ impl From<bool> for Mode {
     fn from(value: bool) -> Self {
         match value {
             true => Mode::ReadWrite,
-            false => Mode::WriteOnly,
+            false => Mode::None,
         }
     }
 }
@@ -71,7 +71,7 @@ fn cache_dir() -> &'static str {
     "./.ruff_cache"
 }
 
-fn cache_key(path: &Path, settings: &Settings, autofix: &autofix::Mode) -> String {
+fn cache_key(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> String {
     let mut hasher = DefaultHasher::new();
     settings.hash(&mut hasher);
     autofix.hash(&mut hasher);
@@ -87,7 +87,7 @@ pub fn get(
     path: &Path,
     metadata: &Metadata,
     settings: &Settings,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
     mode: &Mode,
 ) -> Option<Vec<Message>> {
     if !mode.allow_read() {
@@ -116,7 +116,7 @@ pub fn set(
     path: &Path,
     metadata: &Metadata,
     settings: &Settings,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
     messages: &[Message],
     mode: &Mode,
 ) {

src/checks.rs

@@ -19,6 +19,10 @@ pub enum CheckCode {
     F401,
     F403,
     F541,
+    F601,
+    F602,
+    F621,
+    F622,
     F631,
     F634,
     F704,
@@ -50,6 +54,10 @@ impl FromStr for CheckCode {
             "F401" => Ok(CheckCode::F401),
             "F403" => Ok(CheckCode::F403),
             "F541" => Ok(CheckCode::F541),
+            "F601" => Ok(CheckCode::F601),
+            "F602" => Ok(CheckCode::F602),
+            "F621" => Ok(CheckCode::F621),
+            "F622" => Ok(CheckCode::F622),
             "F631" => Ok(CheckCode::F631),
             "F634" => Ok(CheckCode::F634),
             "F704" => Ok(CheckCode::F704),
@@ -82,6 +90,10 @@ impl CheckCode {
             CheckCode::F401 => "F401",
             CheckCode::F403 => "F403",
             CheckCode::F541 => "F541",
+            CheckCode::F601 => "F601",
+            CheckCode::F602 => "F602",
+            CheckCode::F621 => "F621",
+            CheckCode::F622 => "F622",
             CheckCode::F631 => "F631",
             CheckCode::F634 => "F634",
             CheckCode::F704 => "F704",
@@ -112,6 +124,10 @@ impl CheckCode {
             CheckCode::F401 => &LintSource::AST,
             CheckCode::F403 => &LintSource::AST,
             CheckCode::F541 => &LintSource::AST,
+            CheckCode::F601 => &LintSource::AST,
+            CheckCode::F602 => &LintSource::AST,
+            CheckCode::F621 => &LintSource::AST,
+            CheckCode::F622 => &LintSource::AST,
             CheckCode::F631 => &LintSource::AST,
             CheckCode::F634 => &LintSource::AST,
             CheckCode::F704 => &LintSource::AST,
@@ -154,13 +170,17 @@ pub enum CheckKind {
     ImportStarUsage,
     LineTooLong,
     ModuleImportNotAtTopOfFile,
+    MultiValueRepeatedKeyLiteral,
+    MultiValueRepeatedKeyVariable(String),
     NoAssertEquals,
     NoneComparison(RejectedCmpop),
     NotInTest,
     NotIsTest,
     RaiseNotImplemented,
     ReturnOutsideFunction,
+    TooManyExpressionsInStarredAssignment,
     TrueFalseComparison(bool, RejectedCmpop),
+    TwoStarredExpressions,
     UndefinedExport(String),
     UndefinedLocal(String),
     UndefinedName(String),
@@ -184,13 +204,19 @@ impl CheckKind {
             CheckKind::LineTooLong => "LineTooLong",
             CheckKind::DoNotAssignLambda => "DoNotAssignLambda",
             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::TooManyExpressionsInStarredAssignment => {
+                "TooManyExpressionsInStarredAssignment"
+            }
             CheckKind::TrueFalseComparison(_, _) => "TrueFalseComparison",
+            CheckKind::TwoStarredExpressions => "TwoStarredExpressions",
             CheckKind::UndefinedExport(_) => "UndefinedExport",
             CheckKind::UndefinedLocal(_) => "UndefinedLocal",
             CheckKind::UndefinedName(_) => "UndefinedName",
@@ -214,13 +240,17 @@ impl CheckKind {
             CheckKind::LineTooLong => &CheckCode::E501,
             CheckKind::DoNotAssignLambda => &CheckCode::E731,
             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::TooManyExpressionsInStarredAssignment => &CheckCode::F621,
             CheckKind::TrueFalseComparison(_, _) => &CheckCode::E712,
+            CheckKind::TwoStarredExpressions => &CheckCode::F622,
             CheckKind::UndefinedExport(_) => &CheckCode::F822,
             CheckKind::UndefinedLocal(_) => &CheckCode::F823,
             CheckKind::UndefinedName(_) => &CheckCode::F821,
@@ -258,6 +288,12 @@ impl CheckKind {
             CheckKind::ModuleImportNotAtTopOfFile => {
                 "Module level import not at top of file".to_string()
             }
+            CheckKind::MultiValueRepeatedKeyLiteral => {
+                "Dictionary key literal repeated".to_string()
+            }
+            CheckKind::MultiValueRepeatedKeyVariable(name) => {
+                format!("Dictionary key `{name}` repeated")
+            }
             CheckKind::NoAssertEquals => {
                 "`assertEquals` is deprecated, use `assertEqual` instead".to_string()
             }
@@ -275,6 +311,9 @@ impl CheckKind {
             CheckKind::ReturnOutsideFunction => {
                 "a `return` statement outside of a function/method".to_string()
             }
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "too many expressions in star-unpacking assignment".to_string()
+            }
             CheckKind::TrueFalseComparison(value, op) => match *value {
                 true => match op {
                     RejectedCmpop::Eq => {
@@ -293,6 +332,7 @@ impl CheckKind {
                     }
                 },
             },
+            CheckKind::TwoStarredExpressions => "two starred expressions in assignment".to_string(),
             CheckKind::UndefinedExport(name) => {
                 format!("Undefined name `{name}` in `__all__`")
             }
@@ -328,13 +368,17 @@ impl CheckKind {
             CheckKind::DoNotAssignLambda => false,
             CheckKind::LineTooLong => false,
             CheckKind::ModuleImportNotAtTopOfFile => false,
+            CheckKind::MultiValueRepeatedKeyLiteral => false,
+            CheckKind::MultiValueRepeatedKeyVariable(_) => false,
             CheckKind::NoAssertEquals => true,
             CheckKind::NotInTest => false,
             CheckKind::NotIsTest => false,
             CheckKind::NoneComparison(_) => false,
             CheckKind::RaiseNotImplemented => false,
             CheckKind::ReturnOutsideFunction => false,
+            CheckKind::TooManyExpressionsInStarredAssignment => false,
             CheckKind::TrueFalseComparison(_, _) => false,
+            CheckKind::TwoStarredExpressions => false,
             CheckKind::UndefinedExport(_) => false,
             CheckKind::UndefinedLocal(_) => false,
             CheckKind::UndefinedName(_) => false,

src/lib.rs

@@ -1,17 +1,15 @@
 extern crate core;
 
-mod ast_ops;
+mod ast;
 mod autofix;
-mod builtins;
 mod cache;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;
-mod fixer;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
 mod pyproject;
+mod python;
 pub mod settings;
-mod visitor;

src/linter.rs

@@ -4,15 +4,16 @@ use anyhow::Result;
 use log::debug;
 use rustpython_parser::parser;
 
-use crate::autofix::fix_file;
+use crate::autofix::fixer;
+use crate::autofix::fixer::fix_file;
 use crate::check_ast::check_ast;
 use crate::check_lines::check_lines;
 use crate::checks::{Check, LintSource};
 use crate::message::Message;
 use crate::settings::Settings;
-use crate::{autofix, cache, fs};
+use crate::{cache, fs};
 
-fn check_path(path: &Path, settings: &Settings, autofix: &autofix::Mode) -> Result<Vec<Check>> {
+fn check_path(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> Result<Vec<Check>> {
     // Read the file from disk.
     let contents = fs::read_file(path)?;
 
@@ -40,7 +41,7 @@ pub fn lint_path(
     path: &Path,
     settings: &Settings,
     mode: &cache::Mode,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
 ) -> Result<Vec<Message>> {
     let metadata = path.metadata()?;
 
@@ -57,7 +58,7 @@ pub fn lint_path(
     let mut checks = check_path(path, settings, autofix)?;
 
     // Apply autofix.
-    if matches!(autofix, autofix::Mode::Apply) {
+    if matches!(autofix, fixer::Mode::Apply) {
         fix_file(&mut checks, &contents, path)?;
     };
 
@@ -84,21 +85,23 @@ mod tests {
     use anyhow::Result;
     use rustpython_parser::ast::Location;
 
+    use crate::autofix::fixer;
     use crate::checks::{Check, CheckCode, CheckKind, Fix, RejectedCmpop};
     use crate::linter::check_path;
-    use crate::{autofix, settings};
+    use crate::settings;
 
     #[test]
     fn e402() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E402.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E402]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::ModuleImportNotAtTopOfFile,
             location: Location::new(20, 1),
@@ -114,15 +117,16 @@ mod tests {
 
     #[test]
     fn e501() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E501.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E501]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::LineTooLong,
             location: Location::new(5, 89),
@@ -138,15 +142,16 @@ mod tests {
 
     #[test]
     fn e711() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E711.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E711]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::NoneComparison(RejectedCmpop::Eq),
@@ -169,15 +174,16 @@ mod tests {
 
     #[test]
     fn e712() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E712.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E712]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
@@ -211,15 +217,16 @@ mod tests {
 
     #[test]
     fn e713() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E713.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E713]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::NotInTest,
             location: Location::new(2, 12),
@@ -235,15 +242,16 @@ mod tests {
 
     #[test]
     fn e714() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E714.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E714]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::NotIsTest,
             location: Location::new(1, 13),
@@ -259,20 +267,28 @@ mod tests {
 
     #[test]
     fn e731() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/E731.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E731]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
-        let expected = vec![Check {
-            kind: CheckKind::DoNotAssignLambda,
-            location: Location::new(1, 1),
-            fix: None,
-        }];
+        actual.sort_by_key(|check| check.location);
+        let expected = vec![
+            Check {
+                kind: CheckKind::DoNotAssignLambda,
+                location: Location::new(3, 1),
+                fix: None,
+            },
+            Check {
+                kind: CheckKind::DoNotAssignLambda,
+                location: Location::new(5, 1),
+                fix: None,
+            },
+        ];
 
         assert_eq!(actual.len(), expected.len());
         for i in 0..actual.len() {
@@ -284,21 +300,17 @@ mod tests {
 
     #[test]
     fn f401() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F401.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F401]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
-            Check {
-                kind: CheckKind::UnusedImport("logging.handlers".to_string()),
-                location: Location::new(12, 1),
-                fix: None,
-            },
             Check {
                 kind: CheckKind::UnusedImport("functools".to_string()),
                 location: Location::new(3, 1),
@@ -306,7 +318,12 @@ mod tests {
             },
             Check {
                 kind: CheckKind::UnusedImport("collections.OrderedDict".to_string()),
-                location: Location::new(4, 1),
+                location: Location::new(5, 1),
+                fix: None,
+            },
+            Check {
+                kind: CheckKind::UnusedImport("logging.handlers".to_string()),
+                location: Location::new(13, 1),
                 fix: None,
             },
         ];
@@ -320,15 +337,16 @@ mod tests {
 
     #[test]
     fn f403() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F403.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F403]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::ImportStarUsage,
@@ -350,15 +368,16 @@ mod tests {
     }
     #[test]
     fn f541() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F541.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F541]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::FStringMissingPlaceholders,
@@ -385,16 +404,101 @@ mod tests {
     }
 
     #[test]
-    fn f631() -> Result<()> {
+    fn f601() -> Result<()> {
         let actual = check_path(
+            Path::new("./resources/test/fixtures/F601.py"),
+            &settings::Settings {
+                line_length: 88,
+                exclude: vec![],
+                select: BTreeSet::from([CheckCode::F601]),
+            },
+            &fixer::Mode::Generate,
+        )?;
+        let expected = vec![
+            Check {
+                kind: CheckKind::MultiValueRepeatedKeyLiteral,
+                location: Location::new(3, 6),
+                fix: None,
+            },
+            Check {
+                kind: CheckKind::MultiValueRepeatedKeyLiteral,
+                location: Location::new(9, 5),
+                fix: None,
+            },
+            Check {
+                kind: CheckKind::MultiValueRepeatedKeyLiteral,
+                location: Location::new(11, 7),
+                fix: None,
+            },
+        ];
+        assert_eq!(actual.len(), expected.len());
+        for i in 0..actual.len() {
+            assert_eq!(actual[i], expected[i]);
+        }
+
+        Ok(())
+    }
+
+    #[test]
+    fn f602() -> Result<()> {
+        let actual = check_path(
+            Path::new("./resources/test/fixtures/F602.py"),
+            &settings::Settings {
+                line_length: 88,
+                exclude: vec![],
+                select: BTreeSet::from([CheckCode::F602]),
+            },
+            &fixer::Mode::Generate,
+        )?;
+        let expected = vec![Check {
+            kind: CheckKind::MultiValueRepeatedKeyVariable("a".to_string()),
+            location: Location::new(5, 5),
+            fix: None,
+        }];
+        assert_eq!(actual.len(), expected.len());
+        for i in 0..actual.len() {
+            assert_eq!(actual[i], expected[i]);
+        }
+
+        Ok(())
+    }
+
+    #[test]
+    fn f622() -> Result<()> {
+        let actual = check_path(
+            Path::new("./resources/test/fixtures/F622.py"),
+            &settings::Settings {
+                line_length: 88,
+                exclude: vec![],
+                select: BTreeSet::from([CheckCode::F622]),
+            },
+            &fixer::Mode::Generate,
+        )?;
+        let expected = vec![Check {
+            kind: CheckKind::TwoStarredExpressions,
+            location: Location::new(1, 1),
+            fix: None,
+        }];
+        assert_eq!(actual.len(), expected.len());
+        for i in 0..actual.len() {
+            assert_eq!(actual[i], expected[i]);
+        }
+
+        Ok(())
+    }
+
+    #[test]
+    fn f631() -> Result<()> {
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F631.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F631]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::AssertTuple,
@@ -417,15 +521,16 @@ mod tests {
 
     #[test]
     fn f634() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F634.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F634]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::IfTuple,
@@ -448,15 +553,16 @@ mod tests {
 
     #[test]
     fn f704() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F704.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F704]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::YieldOutsideFunction,
@@ -484,15 +590,16 @@ mod tests {
 
     #[test]
     fn f706() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F706.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F706]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::ReturnOutsideFunction,
@@ -515,15 +622,16 @@ mod tests {
 
     #[test]
     fn f707() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F707.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F707]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::DefaultExceptNotLast,
@@ -551,15 +659,16 @@ mod tests {
 
     #[test]
     fn f821() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F821.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F821]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::UndefinedName("self".to_string()),
@@ -581,6 +690,11 @@ mod tests {
                 location: Location::new(21, 12),
                 fix: None,
             },
+            Check {
+                kind: CheckKind::UndefinedName("Bar".to_string()),
+                location: Location::new(58, 5),
+                fix: None,
+            },
         ];
         assert_eq!(actual.len(), expected.len());
         for i in 0..actual.len() {
@@ -592,15 +706,16 @@ mod tests {
 
     #[test]
     fn f822() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F822.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F822]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::UndefinedExport("b".to_string()),
             location: Location::new(3, 1),
@@ -616,15 +731,16 @@ mod tests {
 
     #[test]
     fn f823() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F823.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F823]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::UndefinedLocal("my_var".to_string()),
             location: Location::new(6, 5),
@@ -640,15 +756,16 @@ mod tests {
 
     #[test]
     fn f831() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F831.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F831]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::DuplicateArgumentName,
@@ -676,15 +793,16 @@ mod tests {
 
     #[test]
     fn f841() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F841.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F841]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::UnusedVariable("e".to_string()),
@@ -707,24 +825,25 @@ mod tests {
 
     #[test]
     fn f901() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F901.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F901]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::RaiseNotImplemented,
-                location: Location::new(2, 5),
+                location: Location::new(2, 25),
                 fix: None,
             },
             Check {
                 kind: CheckKind::RaiseNotImplemented,
-                location: Location::new(6, 5),
+                location: Location::new(6, 11),
                 fix: None,
             },
         ];
@@ -738,15 +857,16 @@ mod tests {
 
     #[test]
     fn r001() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/R001.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::R001]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::UselessObjectInheritance("A".to_string()),
@@ -959,19 +1079,20 @@ mod tests {
 
     #[test]
     fn r002() -> Result<()> {
-        let actual = check_path(
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/R002.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::R002]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::NoAssertEquals,
-                location: Location::new(1, 19),
+                location: Location::new(1, 5),
                 fix: Some(Fix {
                     content: "assertEqual".to_string(),
                     start: Location::new(1, 6),
@@ -981,7 +1102,7 @@ mod tests {
             },
             Check {
                 kind: CheckKind::NoAssertEquals,
-                location: Location::new(2, 18),
+                location: Location::new(2, 5),
                 fix: Some(Fix {
                     content: "assertEqual".to_string(),
                     start: Location::new(2, 6),

src/main.rs

@@ -6,6 +6,7 @@ use std::time::Instant;
 use anyhow::Result;
 use clap::{Parser, ValueHint};
 use colored::Colorize;
+use glob::Pattern;
 use log::{debug, error};
 use notify::{raw_watcher, RecursiveMode, Watcher};
 use rayon::prelude::*;
@@ -47,12 +48,15 @@ struct Cli {
     /// Disable cache reads.
     #[clap(short, long, action)]
     no_cache: bool,
-    /// Comma-separated list of error codes to enable.
+    /// List of error codes to enable.
     #[clap(long, multiple = true)]
     select: Vec<CheckCode>,
-    /// Comma-separated list of error codes to ignore.
+    /// List of error codes to ignore.
     #[clap(long, multiple = true)]
     ignore: Vec<CheckCode>,
+    /// List of file and/or directory patterns to exclude from checks.
+    #[clap(long, multiple = true)]
+    exclude: Vec<Pattern>,
 }
 
 #[cfg(feature = "update-informer")]
@@ -188,6 +192,9 @@ fn inner_main() -> Result<ExitCode> {
     if !cli.ignore.is_empty() {
         settings.ignore(&cli.ignore);
     }
+    if !cli.exclude.is_empty() {
+        settings.exclude(cli.exclude);
+    }
 
     if cli.watch {
         if cli.fix {

src/message.rs

@@ -20,7 +20,7 @@ impl Ord for Message {
         (&self.filename, self.location.row(), self.location.column()).cmp(&(
             &other.filename,
             other.location.row(),
-            self.location.column(),
+            other.location.column(),
         ))
     }
 }

src/pyproject.rs

@@ -1,4 +1,3 @@
-use std::collections::BTreeSet;
 use std::path::{Path, PathBuf};
 
 use anyhow::Result;
@@ -40,7 +39,8 @@ pub fn load_config<'a>(paths: impl IntoIterator<Item = &'a Path>) -> Result<(Pat
 pub struct Config {
     pub line_length: Option<usize>,
     pub exclude: Option<Vec<PathBuf>>,
-    pub select: Option<BTreeSet<CheckCode>>,
+    pub select: Option<Vec<CheckCode>>,
+    pub ignore: Option<Vec<CheckCode>>,
 }
 
 #[derive(Debug, PartialEq, Eq, Deserialize)]
@@ -90,7 +90,6 @@ fn find_project_root<'a>(sources: impl IntoIterator<Item = &'a Path>) -> Option<
 
 #[cfg(test)]
 mod tests {
-    use std::collections::BTreeSet;
     use std::path::Path;
 
     use anyhow::Result;
@@ -125,6 +124,7 @@ mod tests {
                     line_length: None,
                     exclude: None,
                     select: None,
+                    ignore: None,
                 })
             })
         );
@@ -143,6 +143,7 @@ line-length = 79
                     line_length: Some(79),
                     exclude: None,
                     select: None,
+                    ignore: None,
                 })
             })
         );
@@ -161,6 +162,7 @@ exclude = ["foo.py"]
                     line_length: None,
                     exclude: Some(vec![Path::new("foo.py").to_path_buf()]),
                     select: None,
+                    ignore: None,
                 })
             })
         );
@@ -178,7 +180,27 @@ select = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    select: Some(BTreeSet::from([CheckCode::E501])),
+                    select: Some(vec![CheckCode::E501]),
+                    ignore: None,
+                })
+            })
+        );
+
+        let pyproject: PyProject = toml::from_str(
+            r#"
+[tool.black]
+[tool.ruff]
+ignore = ["E501"]
+"#,
+        )?;
+        assert_eq!(
+            pyproject.tool,
+            Some(Tools {
+                ruff: Some(Config {
+                    line_length: None,
+                    exclude: None,
+                    select: None,
+                    ignore: Some(vec![CheckCode::E501]),
                 })
             })
         );
@@ -236,7 +258,7 @@ other-attribute = 1
                     Path::new("excluded.py").to_path_buf(),
                     Path::new("**/migrations").to_path_buf()
                 ]),
-                select: Some(BTreeSet::from([
+                select: Some(vec![
                     CheckCode::E402,
                     CheckCode::E501,
                     CheckCode::E711,
@@ -248,6 +270,10 @@ other-attribute = 1
                     CheckCode::F401,
                     CheckCode::F403,
                     CheckCode::F541,
+                    CheckCode::F601,
+                    CheckCode::F602,
+                    CheckCode::F621,
+                    CheckCode::F622,
                     CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,
@@ -261,7 +287,8 @@ other-attribute = 1
                     CheckCode::F901,
                     CheckCode::R001,
                     CheckCode::R002,
-                ])),
+                ]),
+                ignore: None,
             }
         );
 

src/python.rs

@@ -0,0 +1,2 @@
+pub mod builtins;
+pub mod typing;

src/python/builtins.rs

@@ -156,8 +156,8 @@ pub const BUILTINS: &[&str] = &[
 // Globally defined names which are not attributes of the builtins module, or are only present on
 // some platforms.
 pub const MAGIC_GLOBALS: &[&str] = &[
-    "__file__",
-    "__builtins__",
-    "__annotations__",
     "WindowsError",
+    "__annotations__",
+    "__builtins__",
+    "__file__",
 ];

src/python/typing.rs

@@ -0,0 +1,88 @@
+use lazy_static::lazy_static;
+use std::collections::BTreeSet;
+
+lazy_static! {
+    static ref ANNOTATED_SUBSCRIPTS: BTreeSet<&'static str> = BTreeSet::from([
+        "AbstractAsyncContextManager",
+        "AbstractContextManager",
+        "AbstractSet",
+        "AsyncContextManager",
+        "AsyncGenerator",
+        "AsyncIterable",
+        "AsyncIterator",
+        "Awaitable",
+        "BinaryIO",
+        "BsdDbShelf",
+        "ByteString",
+        "Callable",
+        "ChainMap",
+        "ClassVar",
+        "Collection",
+        "Concatenate",
+        "Container",
+        "ContextManager",
+        "Coroutine",
+        "Counter",
+        "Counter",
+        "DbfilenameShelf",
+        "DefaultDict",
+        "Deque",
+        "Dict",
+        "Field",
+        "Final",
+        "FrozenSet",
+        "Generator",
+        "Iterator",
+        "Generic",
+        "IO",
+        "ItemsView",
+        "Iterable",
+        "Iterator",
+        "KeysView",
+        "LifoQueue",
+        "List",
+        "Mapping",
+        "MappingProxyType",
+        "MappingView",
+        "Match",
+        "MutableMapping",
+        "MutableSequence",
+        "MutableSet",
+        "Optional",
+        "OrderedDict",
+        "PathLike",
+        "Pattern",
+        "PriorityQueue",
+        "Protocol",
+        "Queue",
+        "Reversible",
+        "Sequence",
+        "Set",
+        "Shelf",
+        "SimpleQueue",
+        "TextIO",
+        "Tuple",
+        "Type",
+        "TypeGuard",
+        "Union",
+        "ValuesView",
+        "WeakKeyDictionary",
+        "WeakMethod",
+        "WeakSet",
+        "WeakValueDictionary",
+        "cached_property",
+        "defaultdict",
+        "deque",
+        "dict",
+        "frozenset",
+        "list",
+        "partialmethod",
+        "set",
+        "tuple",
+        "type",
+    ]);
+}
+
+pub fn is_annotated_subscript(name: &str) -> bool {
+    ANNOTATED_SUBSCRIPTS.contains(name)
+}

src/settings.rs

@@ -27,7 +27,7 @@ impl Hash for Settings {
 impl Settings {
     pub fn from_paths<'a>(paths: impl IntoIterator<Item = &'a Path>) -> Result<Self> {
         let (project_root, config) = load_config(paths)?;
-        Ok(Settings {
+        let mut settings = Settings {
             line_length: config.line_length.unwrap_or(88),
             exclude: config
                 .exclude
@@ -42,8 +42,8 @@ impl Settings {
                 })
                 .map(|path| Pattern::new(&path.to_string_lossy()).expect("Invalid pattern."))
                 .collect(),
-            select: config.select.unwrap_or_else(|| {
-                BTreeSet::from([
+            select: BTreeSet::from_iter(config.select.unwrap_or_else(|| {
+                vec![
                     CheckCode::E402,
                     CheckCode::E501,
                     CheckCode::E711,
@@ -55,6 +55,10 @@ impl Settings {
                     CheckCode::F401,
                     CheckCode::F403,
                     CheckCode::F541,
+                    CheckCode::F601,
+                    CheckCode::F602,
+                    CheckCode::F621,
+                    CheckCode::F622,
                     CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,
@@ -69,9 +73,13 @@ impl Settings {
                     // Disable refactoring codes by default.
                     // CheckCode::R001,
                     // CheckCode::R002,
-                ])
-            }),
-        })
+                ]
+            })),
+        };
+        if let Some(ignore) = &config.ignore {
+            settings.ignore(ignore);
+        }
+        Ok(settings)
     }
 
     pub fn select(&mut self, codes: Vec<CheckCode>) {
@@ -86,4 +94,8 @@ impl Settings {
             self.select.remove(code);
         }
     }
+
+    pub fn exclude(&mut self, exclude: Vec<Pattern>) {
+        self.exclude = exclude;
+    }
 }