Bump version to 0.0.30

.github/workflows/release.yaml

@@ -1,6 +1,8 @@
 name: Release
 
 on:
+  pull_request:
+    branches: [main]
   create:
     tags:
       - v*
@@ -127,7 +129,7 @@ jobs:
         with:
           target: ${{ matrix.target }}
           manylinux: auto
-          args: --release --out dist
+          args: --no-default-features --release --out dist
           maturin-version: "v0.13.0"
       - uses: uraimo/run-on-arch-action@v2.0.5
         if: matrix.target != 'ppc64'

.pre-commit-config.yaml

@@ -1,5 +1,5 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff
-    rev: v0.0.27
+    rev: v0.0.30
     hooks:
       - id: lint

Cargo.lock

@@ -1744,7 +1744,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.27"
+version = "0.0.30"
 dependencies = [
  "anyhow",
  "bincode",
@@ -1787,7 +1787,7 @@ 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=8cc3d23ddaa6339bf56608adaeefabff3ad329e7#8cc3d23ddaa6339bf56608adaeefabff3ad329e7"
 dependencies = [
  "num-bigint",
  "rustpython-compiler-core",
@@ -1796,7 +1796,7 @@ 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=8cc3d23ddaa6339bf56608adaeefabff3ad329e7#8cc3d23ddaa6339bf56608adaeefabff3ad329e7"
 dependencies = [
  "bincode",
  "bitflags",
@@ -1813,7 +1813,7 @@ 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=8cc3d23ddaa6339bf56608adaeefabff3ad329e7#8cc3d23ddaa6339bf56608adaeefabff3ad329e7"
 dependencies = [
  "ahash",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.27"
+version = "0.0.30"
 edition = "2021"
 
 [lib]
@@ -25,13 +25,17 @@ 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 = "8cc3d23ddaa6339bf56608adaeefabff3ad329e7" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }
-update-informer = { version = "0.5.0", default_features = false, features = ["pypi"] }
+update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
 walkdir = { version = "2.3.2" }
 
+[features]
+default = ["update-informer"]
+update-informer = ["dep:update-informer"]
+
 [profile.release]
 panic = "abort"
 lto = "thin"

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: v0.0.27
+  rev: v0.0.30
   hooks:
     - id: lint
 ```
@@ -86,7 +86,7 @@ ruff path/to/code/ --select F401 F403
 See `ruff --help` for more:
 
 ```shell
-ruff (v0.0.27)
+ruff (v0.0.30)
 An extremely fast Python linter.
 
 USAGE:
@@ -116,6 +116,31 @@ 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 24 rules. (Note that these 24 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 +156,8 @@ 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 |
 | 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 |

examples/generate_rules_table.rs

@@ -13,6 +13,8 @@ fn main() {
         CheckKind::ImportStarUsage,
         CheckKind::LineTooLong,
         CheckKind::ModuleImportNotAtTopOfFile,
+        CheckKind::MultiValueRepeatedKeyLiteral,
+        CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
         CheckKind::NoAssertEquals,
         CheckKind::NoneComparison(RejectedCmpop::Eq),
         CheckKind::NotInTest,

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 +11,15 @@ import multiprocessing.pool
 import multiprocessing.process
 import logging.config
 import logging.handlers
+from typing import NamedTuple, Dict, Type, TypeVar, List, Set
 
 from blah import ClassA, ClassB, ClassC
 
 
 class X:
+    datetime: datetime
+    foo: Type["NamedTuple"]
+
     def a(self) -> "namedtuple":
         x = os.environ["1"]
         y = Counter()
@@ -23,3 +28,7 @@ class X:
 
 __all__ = ["ClassA"] + ["ClassB"]
 __all__ += ["ClassC"]
+
+X = TypeVar("X")
+Y = TypeVar("Y", bound="Dict")
+Z = TypeVar("Z", "List", "Set")

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/F821.py

@@ -33,14 +33,26 @@ 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

resources/test/fixtures/pyproject.toml

@@ -13,6 +13,8 @@ select = [
     "F401",
     "F403",
     "F541",
+    "F601",
+    "F602",
     "F631",
     "F634",
     "F704",

src/ast_ops.rs

@@ -8,6 +8,7 @@ fn id() -> usize {
     COUNTER.fetch_add(1, Ordering::Relaxed)
 }
 
+#[derive(Clone, Debug)]
 pub enum ScopeKind {
     Class,
     Function,
@@ -15,6 +16,7 @@ pub enum ScopeKind {
     Module,
 }
 
+#[derive(Clone, Debug)]
 pub struct Scope {
     pub id: usize,
     pub kind: ScopeKind,

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;
 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,
         }
     }
 }

src/check_ast.rs

@@ -4,7 +4,7 @@ use std::path::Path;
 use itertools::izip;
 use rustpython_parser::ast::{
     Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind,
-    Location, Stmt, StmtKind, Suite, Unaryop,
+    KeywordData, Location, Stmt, StmtKind, Suite, Unaryop,
 };
 use rustpython_parser::parser;
 
@@ -13,27 +13,41 @@ use crate::ast_ops::{
 };
 use crate::builtins::{BUILTINS, MAGIC_GLOBALS};
 use crate::checks::{Check, CheckCode, CheckKind, Fix, RejectedCmpop};
+use crate::relocator::relocate_expr;
 use crate::settings::Settings;
 use crate::visitor::{walk_excepthandler, Visitor};
 use crate::{autofix, fixer, visitor};
 
+pub const GLOBAL_SCOPE_INDEX: usize = 0;
+
 struct Checker<'a> {
+    // Input data.
     locator: SourceCodeLocator<'a>,
     settings: &'a Settings,
     autofix: &'a autofix::Mode,
     path: &'a str,
+    // Computed checks.
     checks: Vec<Check>,
+    // Retain all scopes and parent nodes, along with a stack of indexes to track which are active
+    // at various points in time.
+    parents: Vec<&'a Stmt>,
+    parent_stack: Vec<usize>,
     scopes: Vec<Scope>,
-    dead_scopes: Vec<Scope>,
-    deferred: Vec<String>,
+    scope_stack: Vec<usize>,
+    dead_scopes: Vec<usize>,
+    deferred_annotations: Vec<(Location, &'a str)>,
+    deferred_functions: Vec<(&'a Stmt, Vec<usize>, Vec<usize>)>,
+    deferred_lambdas: Vec<(&'a Expr, Vec<usize>, Vec<usize>)>,
+    // Derivative state.
     in_f_string: bool,
     in_annotation: bool,
+    in_literal: bool,
     seen_non_import: bool,
     seen_docstring: bool,
 }
 
-impl Checker<'_> {
-    pub fn new<'a>(
+impl<'a> Checker<'a> {
+    pub fn new(
         settings: &'a Settings,
         autofix: &'a autofix::Mode,
         path: &'a str,
@@ -45,28 +59,64 @@ impl Checker<'_> {
             path,
             locator: SourceCodeLocator::new(content),
             checks: vec![],
+            parents: vec![],
+            parent_stack: vec![],
             scopes: vec![],
+            scope_stack: vec![],
             dead_scopes: vec![],
-            deferred: vec![],
+            deferred_annotations: vec![],
+            deferred_functions: vec![],
+            deferred_lambdas: vec![],
             in_f_string: false,
             in_annotation: false,
+            in_literal: false,
             seen_non_import: false,
             seen_docstring: false,
         }
     }
 }
 
-impl Visitor for Checker<'_> {
-    fn visit_stmt(&mut self, stmt: &Stmt) {
+#[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,
+    }
+}
+
+fn match_name_or_attr(expr: &Expr, target: &str) -> bool {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => target == attr,
+        ExprKind::Name { id, .. } => target == id,
+        _ => false,
+    }
+}
+
+impl<'a, 'b> Visitor<'b> for Checker<'a>
+where
+    'b: 'a,
+{
+    fn visit_stmt(&mut self, stmt: &'b Stmt) {
+        self.push_parent(stmt);
+
+        // Pre-visit.
         match &stmt.node {
             StmtKind::Global { names } | StmtKind::Nonlocal { names } => {
                 // TODO(charlie): Handle doctests.
-                let global_scope_index = 0;
-                let global_scope_id = self.scopes[global_scope_index].id;
-                let current_scope_id = self.scopes.last().expect("No current scope found.").id;
+                let global_scope_id = self.scopes[GLOBAL_SCOPE_INDEX].id;
+
+                let current_scope =
+                    &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+                let current_scope_id = current_scope.id;
                 if current_scope_id != global_scope_id {
                     for name in names {
-                        for scope in self.scopes.iter_mut().skip(global_scope_index + 1) {
+                        for scope in self.scopes.iter_mut().skip(GLOBAL_SCOPE_INDEX + 1) {
                             scope.values.insert(
                                 name.to_string(),
                                 Binding {
@@ -92,7 +142,7 @@ impl Visitor for Checker<'_> {
                 ..
             } => {
                 for expr in decorator_list {
-                    self.visit_expr(expr, Some(stmt));
+                    self.visit_expr(expr);
                 }
                 for expr in returns {
                     self.visit_annotation(expr);
@@ -105,7 +155,6 @@ impl Visitor for Checker<'_> {
                         location: stmt.location,
                     },
                 );
-                self.push_scope(Scope::new(ScopeKind::Function));
             }
             StmtKind::Return { .. } => {
                 if self
@@ -113,8 +162,8 @@ impl Visitor for Checker<'_> {
                     .select
                     .contains(CheckKind::ReturnOutsideFunction.code())
                 {
-                    if let Some(scope) = self.scopes.last() {
-                        match scope.kind {
+                    if let Some(scope_index) = self.scope_stack.last().cloned() {
+                        match self.scopes[scope_index].kind {
                             ScopeKind::Class | ScopeKind::Module => {
                                 self.checks.push(Check::new(
                                     CheckKind::ReturnOutsideFunction,
@@ -137,7 +186,8 @@ impl Visitor for Checker<'_> {
                     for expr in bases {
                         if let ExprKind::Name { id, .. } = &expr.node {
                             if id == "object" {
-                                let scope = self.scopes.last().expect("No current scope found.");
+                                let scope = &self.scopes
+                                    [*(self.scope_stack.last().expect("No current scope found."))];
                                 match scope.values.get(id) {
                                     None
                                     | Some(Binding {
@@ -172,13 +222,13 @@ impl Visitor for Checker<'_> {
                 }
 
                 for expr in bases {
-                    self.visit_expr(expr, Some(stmt))
+                    self.visit_expr(expr)
                 }
                 for keyword in keywords {
                     self.visit_keyword(keyword)
                 }
                 for expr in decorator_list {
-                    self.visit_expr(expr, Some(stmt))
+                    self.visit_expr(expr)
                 }
                 self.push_scope(Scope::new(ScopeKind::Class))
             }
@@ -257,7 +307,13 @@ impl Visitor for Checker<'_> {
                             name,
                             Binding {
                                 kind: BindingKind::FutureImportation,
-                                used: Some(self.scopes.last().expect("No current scope found.").id),
+                                used: Some(
+                                    self.scopes[*(self
+                                        .scope_stack
+                                        .last()
+                                        .expect("No current scope found."))]
+                                    .id,
+                                ),
                                 location: stmt.location,
                             },
                         );
@@ -391,47 +447,47 @@ impl Visitor for Checker<'_> {
                     }
                 }
             }
-            StmtKind::Delete { .. } | StmtKind::AnnAssign { .. } => {
+            StmtKind::AnnAssign { value, .. } => {
+                self.seen_non_import = true;
+                if self
+                    .settings
+                    .select
+                    .contains(CheckKind::DoNotAssignLambda.code())
+                {
+                    if let Some(v) = value {
+                        if let ExprKind::Lambda { .. } = v.node {
+                            self.checks
+                                .push(Check::new(CheckKind::DoNotAssignLambda, stmt.location));
+                        }
+                    }
+                }
+            }
+            StmtKind::Delete { .. } => {
                 self.seen_non_import = true;
             }
             _ => {}
         }
 
-        visitor::walk_stmt(self, stmt);
-
+        // Recurse.
         match &stmt.node {
-            StmtKind::ClassDef { .. } => {
-                if let Some(scope) = self.scopes.pop() {
-                    self.dead_scopes.push(scope);
-                }
-            }
             StmtKind::FunctionDef { .. } | StmtKind::AsyncFunctionDef { .. } => {
-                let scope = self.scopes.last().expect("No current scope found.");
-                for (name, binding) in scope.values.iter() {
-                    // TODO(charlie): Ignore if using `locals`.
-                    if self.settings.select.contains(&CheckCode::F841)
-                        && binding.used.is_none()
-                        && name != "_"
-                        && name != "__tracebackhide__"
-                        && name != "__traceback_info__"
-                        && name != "__traceback_supplement__"
-                        && matches!(binding.kind, BindingKind::Assignment)
-                    {
-                        self.checks.push(Check::new(
-                            CheckKind::UnusedVariable(name.to_string()),
-                            binding.location,
-                        ));
-                    }
-                }
-
-                if let Some(scope) = self.scopes.pop() {
-                    self.dead_scopes.push(scope);
+                self.deferred_functions.push((
+                    stmt,
+                    self.scope_stack.clone(),
+                    self.parent_stack.clone(),
+                ));
+            }
+            StmtKind::ClassDef { body, .. } => {
+                for stmt in body {
+                    self.visit_stmt(stmt);
                 }
             }
-            _ => {}
+            _ => visitor::walk_stmt(self, stmt),
         };
 
+        // Post-visit.
         if let StmtKind::ClassDef { name, .. } = &stmt.node {
+            self.pop_scope();
             self.add_binding(
                 name.to_string(),
                 Binding {
@@ -440,21 +496,36 @@ impl Visitor for Checker<'_> {
                     location: stmt.location,
                 },
             );
-        }
-    }
-    fn visit_annotation(&mut self, expr: &Expr) {
-        let initial = self.in_annotation;
-        self.in_annotation = true;
-        self.visit_expr(expr, None);
-        self.in_annotation = initial;
+        };
+
+        self.pop_parent();
     }
 
-    fn visit_expr(&mut self, expr: &Expr, parent: Option<&Stmt>) {
-        let initial = self.in_f_string;
+    fn visit_annotation(&mut self, expr: &'b Expr) {
+        let prev_in_annotation = self.in_annotation;
+        self.in_annotation = true;
+        self.visit_expr(expr);
+        self.in_annotation = prev_in_annotation;
+    }
+
+    fn visit_expr(&mut self, expr: &'b Expr) {
+        let prev_in_f_string = self.in_f_string;
+        let prev_in_literal = self.in_literal;
+
+        // Pre-visit.
         match &expr.node {
+            ExprKind::Subscript { value, .. } => {
+                if match_name_or_attr(value, "Literal") {
+                    self.in_literal = true;
+                }
+            }
             ExprKind::Name { ctx, .. } => match ctx {
                 ExprContext::Load => self.handle_node_load(expr),
-                ExprContext::Store => self.handle_node_store(expr, parent),
+                ExprContext::Store => {
+                    let parent =
+                        self.parents[*(self.parent_stack.last().expect("No parent found."))];
+                    self.handle_node_store(expr, Some(parent));
+                }
                 ExprContext::Del => self.handle_node_delete(expr),
             },
             ExprKind::Call { func, .. } => {
@@ -488,13 +559,54 @@ impl Visitor for Checker<'_> {
                     }
                 }
             }
+            ExprKind::Dict { keys, .. } => {
+                if self.settings.select.contains(&CheckCode::F601)
+                    || self.settings.select.contains(&CheckCode::F602)
+                {
+                    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 self.settings.select.contains(&CheckCode::F601) && v1 == v2 {
+                                        self.checks.push(Check::new(
+                                            CheckKind::MultiValueRepeatedKeyLiteral,
+                                            k2.location,
+                                        ))
+                                    }
+                                }
+                                (
+                                    Some(DictionaryKey::Variable(v1)),
+                                    Some(DictionaryKey::Variable(v2)),
+                                ) => {
+                                    if self.settings.select.contains(&CheckCode::F602) && v1 == v2 {
+                                        self.checks.push(Check::new(
+                                            CheckKind::MultiValueRepeatedKeyVariable(
+                                                v2.to_string(),
+                                            ),
+                                            k2.location,
+                                        ))
+                                    }
+                                }
+                                _ => {}
+                            }
+                        }
+                    }
+                }
+            }
             ExprKind::GeneratorExp { .. }
             | ExprKind::ListComp { .. }
             | ExprKind::DictComp { .. }
             | ExprKind::SetComp { .. } => self.push_scope(Scope::new(ScopeKind::Generator)),
-            ExprKind::Lambda { .. } => self.push_scope(Scope::new(ScopeKind::Function)),
             ExprKind::Yield { .. } | ExprKind::YieldFrom { .. } => {
-                let scope = self.scopes.last().expect("No current scope found.");
+                let scope =
+                    &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
                 if self
                     .settings
                     .select
@@ -647,35 +759,80 @@ impl Visitor for Checker<'_> {
             ExprKind::Constant {
                 value: Constant::Str(value),
                 ..
-            } if self.in_annotation => self.deferred.push(value.to_string()),
+            } if self.in_annotation && !self.in_literal => {
+                self.deferred_annotations.push((expr.location, value));
+            }
             _ => {}
         };
 
-        visitor::walk_expr(self, expr);
+        // Recurse.
+        match &expr.node {
+            ExprKind::Lambda { .. } => {
+                self.deferred_lambdas.push((
+                    expr,
+                    self.scope_stack.clone(),
+                    self.parent_stack.clone(),
+                ));
+            }
+            ExprKind::Call {
+                func,
+                args,
+                keywords,
+            } => {
+                if match_name_or_attr(func, "TypeVar") {
+                    self.visit_expr(func);
+                    for expr in args.iter().skip(1) {
+                        self.visit_annotation(expr);
+                    }
+                    for keyword in keywords {
+                        let KeywordData { arg, value } = &keyword.node;
+                        if let Some(id) = arg {
+                            if id == "bound" {
+                                self.visit_annotation(value);
+                            } else {
+                                self.visit_expr(value);
+                            }
+                        }
+                    }
+                } else {
+                    visitor::walk_expr(self, expr);
+                }
+            }
+            ExprKind::Subscript { value, slice, ctx } => {
+                if match_name_or_attr(value, "Type") {
+                    self.visit_expr(value);
+                    self.visit_annotation(slice);
+                    self.visit_expr_context(ctx);
+                } else {
+                    visitor::walk_expr(self, expr);
+                }
+            }
+            _ => visitor::walk_expr(self, expr),
+        }
 
+        // Post-visit.
         match &expr.node {
             ExprKind::GeneratorExp { .. }
             | ExprKind::ListComp { .. }
             | ExprKind::DictComp { .. }
-            | ExprKind::SetComp { .. }
-            | ExprKind::Lambda { .. } => {
-                if let Some(scope) = self.scopes.pop() {
-                    self.dead_scopes.push(scope);
-                }
-            }
-            ExprKind::JoinedStr { .. } => {
-                self.in_f_string = initial;
+            | ExprKind::SetComp { .. } => {
+                self.pop_scope();
             }
             _ => {}
         };
+        self.in_literal = prev_in_literal;
+        self.in_f_string = prev_in_f_string;
     }
 
-    fn visit_excepthandler(&mut self, excepthandler: &Excepthandler) {
+    fn visit_excepthandler(&mut self, excepthandler: &'b Excepthandler) {
         match &excepthandler.node {
             ExcepthandlerKind::ExceptHandler { name, .. } => match name {
                 Some(name) => {
-                    let scope = self.scopes.last().expect("No current scope found.");
+                    let scope =
+                        &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
                     if scope.values.contains_key(name) {
+                        let parent =
+                            self.parents[*(self.parent_stack.last().expect("No parent found."))];
                         self.handle_node_store(
                             &Expr::new(
                                 excepthandler.location,
@@ -684,12 +841,16 @@ impl Visitor for Checker<'_> {
                                     ctx: ExprContext::Store,
                                 },
                             ),
-                            None,
+                            Some(parent),
                         );
+                        self.parents.push(parent);
                     }
 
-                    let scope = self.scopes.last().expect("No current scope found.");
-                    let prev_definition = scope.values.get(name).cloned();
+                    let parent =
+                        self.parents[*(self.parent_stack.last().expect("No parent found."))];
+                    let scope =
+                        &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+                    let definition = scope.values.get(name).cloned();
                     self.handle_node_store(
                         &Expr::new(
                             excepthandler.location,
@@ -698,13 +859,15 @@ impl Visitor for Checker<'_> {
                                 ctx: ExprContext::Store,
                             },
                         ),
-                        None,
+                        Some(parent),
                     );
+                    self.parents.push(parent);
 
                     walk_excepthandler(self, excepthandler);
 
-                    let scope = self.scopes.last_mut().expect("No current scope found.");
-                    if let Some(binding) = scope.values.remove(name) {
+                    let scope = &mut self.scopes
+                        [*(self.scope_stack.last().expect("No current scope found."))];
+                    if let Some(binding) = &scope.values.remove(name) {
                         if self.settings.select.contains(&CheckCode::F841) && binding.used.is_none()
                         {
                             self.checks.push(Check::new(
@@ -714,7 +877,7 @@ impl Visitor for Checker<'_> {
                         }
                     }
 
-                    if let Some(binding) = prev_definition {
+                    if let Some(binding) = definition {
                         scope.values.insert(name.to_string(), binding);
                     }
                 }
@@ -723,7 +886,7 @@ impl Visitor for Checker<'_> {
         }
     }
 
-    fn visit_arguments(&mut self, arguments: &Arguments) {
+    fn visit_arguments(&mut self, arguments: &'b Arguments) {
         if self
             .settings
             .select
@@ -759,7 +922,7 @@ impl Visitor for Checker<'_> {
         visitor::walk_arguments(self, arguments);
     }
 
-    fn visit_arg(&mut self, arg: &Arg) {
+    fn visit_arg(&mut self, arg: &'b Arg) {
         self.add_binding(
             arg.node.arg.to_string(),
             Binding {
@@ -772,41 +935,58 @@ impl Visitor for Checker<'_> {
     }
 }
 
-impl Checker<'_> {
+impl<'a> Checker<'a> {
+    fn push_parent(&mut self, parent: &'a Stmt) {
+        self.parent_stack.push(self.parents.len());
+        self.parents.push(parent);
+    }
+
+    fn pop_parent(&mut self) {
+        self.parent_stack
+            .pop()
+            .expect("Attempted to pop without scope.");
+    }
+
     fn push_scope(&mut self, scope: Scope) {
+        self.scope_stack.push(self.scopes.len());
         self.scopes.push(scope);
     }
 
     fn pop_scope(&mut self) {
-        self.dead_scopes
-            .push(self.scopes.pop().expect("Attempted to pop without scope."));
+        self.dead_scopes.push(
+            self.scope_stack
+                .pop()
+                .expect("Attempted to pop without scope."),
+        );
     }
 
     fn bind_builtins(&mut self) {
+        let scope = &mut self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+
         for builtin in BUILTINS {
-            self.add_binding(
+            scope.values.insert(
                 builtin.to_string(),
                 Binding {
                     kind: BindingKind::Builtin,
                     location: Default::default(),
                     used: None,
                 },
-            )
+            );
         }
         for builtin in MAGIC_GLOBALS {
-            self.add_binding(
+            scope.values.insert(
                 builtin.to_string(),
                 Binding {
                     kind: BindingKind::Builtin,
                     location: Default::default(),
                     used: None,
                 },
-            )
+            );
         }
     }
 
     fn add_binding(&mut self, name: String, binding: Binding) {
-        let scope = self.scopes.last_mut().expect("No current scope found.");
+        let scope = &mut self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
 
         // TODO(charlie): Don't treat annotations as assignments if there is an existing value.
         let binding = match scope.values.get(&name) {
@@ -822,14 +1002,17 @@ impl Checker<'_> {
 
     fn handle_node_load(&mut self, expr: &Expr) {
         if let ExprKind::Name { id, .. } = &expr.node {
-            let scope_id = self.scopes.last_mut().expect("No current scope found.").id;
+            let scope_id =
+                self.scopes[*(self.scope_stack.last().expect("No current scope found."))].id;
+
             let mut first_iter = true;
-            let mut in_generators = false;
-            for scope in self.scopes.iter_mut().rev() {
+            let mut in_generator = false;
+            for scope_index in self.scope_stack.iter().rev() {
+                let scope = &mut self.scopes[*scope_index];
                 if matches!(scope.kind, ScopeKind::Class) {
                     if id == "__class__" {
                         return;
-                    } else if !first_iter && !in_generators {
+                    } else if !first_iter && !in_generator {
                         continue;
                     }
                 }
@@ -839,7 +1022,7 @@ impl Checker<'_> {
                 }
 
                 first_iter = false;
-                in_generators = matches!(scope.kind, ScopeKind::Generator);
+                in_generator = matches!(scope.kind, ScopeKind::Generator);
             }
 
             if self.settings.select.contains(&CheckCode::F821) {
@@ -853,7 +1036,8 @@ impl Checker<'_> {
 
     fn handle_node_store(&mut self, expr: &Expr, parent: Option<&Stmt>) {
         if let ExprKind::Name { id, .. } = &expr.node {
-            let current = self.scopes.last().expect("No current scope found.");
+            let current =
+                &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
 
             if self.settings.select.contains(&CheckCode::F823)
                 && matches!(current.kind, ScopeKind::Function)
@@ -883,16 +1067,14 @@ impl Checker<'_> {
             // TODO(charlie): Handle alternate binding types (like `Annotation`).
             if id == "__all__"
                 && matches!(current.kind, ScopeKind::Module)
-                && match parent {
-                    None => false,
-                    Some(stmt) => {
+                && parent
+                    .map(|stmt| {
                         matches!(stmt.node, StmtKind::Assign { .. })
                             || matches!(stmt.node, StmtKind::AugAssign { .. })
                             || matches!(stmt.node, StmtKind::AnnAssign { .. })
-                    }
-                }
+                    })
+                    .unwrap_or_default()
             {
-                // Really need parent here.
                 self.add_binding(
                     id.to_string(),
                     Binding {
@@ -916,9 +1098,9 @@ impl Checker<'_> {
 
     fn handle_node_delete(&mut self, expr: &Expr) {
         if let ExprKind::Name { id, .. } = &expr.node {
-            let current = self.scopes.last_mut().expect("No current scope found.");
-            if current.values.remove(id).is_none()
-                && self.settings.select.contains(&CheckCode::F821)
+            let scope =
+                &mut self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+            if scope.values.remove(id).is_none() && self.settings.select.contains(&CheckCode::F821)
             {
                 self.checks.push(Check::new(
                     CheckKind::UndefinedName(id.clone()),
@@ -928,12 +1110,96 @@ impl Checker<'_> {
         }
     }
 
-    fn check_deferred(&mut self, path: &str) {
-        for value in self.deferred.clone() {
-            if let Ok(expr) = &parser::parse_expression(&value, path) {
-                self.visit_expr(expr, None);
+    fn check_deferred_annotations<'b>(&mut self, path: &str, allocator: &'b mut Vec<Expr>)
+    where
+        'b: 'a,
+    {
+        while !self.deferred_annotations.is_empty() {
+            let (location, expression) = self.deferred_annotations.pop().unwrap();
+            if let Ok(mut expr) = parser::parse_expression(expression, path) {
+                relocate_expr(&mut expr, location);
+                allocator.push(expr);
             }
         }
+        for expr in allocator {
+            self.visit_expr(expr);
+        }
+    }
+
+    fn check_deferred_functions(&mut self) {
+        while !self.deferred_functions.is_empty() {
+            let (stmt, scopes, parents) = self.deferred_functions.pop().unwrap();
+
+            self.parent_stack = parents;
+            self.scope_stack = scopes;
+            self.push_scope(Scope::new(ScopeKind::Function));
+
+            match &stmt.node {
+                StmtKind::FunctionDef { body, args, .. }
+                | StmtKind::AsyncFunctionDef { body, args, .. } => {
+                    self.visit_arguments(args);
+                    for stmt in body {
+                        self.visit_stmt(stmt);
+                    }
+                }
+                _ => {}
+            }
+
+            let scope = &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+            for (name, binding) in scope.values.iter() {
+                // TODO(charlie): Ignore if using `locals`.
+                if self.settings.select.contains(&CheckCode::F841)
+                    && binding.used.is_none()
+                    && name != "_"
+                    && name != "__tracebackhide__"
+                    && name != "__traceback_info__"
+                    && name != "__traceback_supplement__"
+                    && matches!(binding.kind, BindingKind::Assignment)
+                {
+                    self.checks.push(Check::new(
+                        CheckKind::UnusedVariable(name.to_string()),
+                        binding.location,
+                    ));
+                }
+            }
+
+            self.pop_scope();
+        }
+    }
+
+    fn check_deferred_lambdas(&mut self) {
+        while !self.deferred_lambdas.is_empty() {
+            let (expr, scopes, parents) = self.deferred_lambdas.pop().unwrap();
+
+            self.parent_stack = parents;
+            self.scope_stack = scopes;
+            self.push_scope(Scope::new(ScopeKind::Function));
+
+            if let ExprKind::Lambda { args, body } = &expr.node {
+                self.visit_arguments(args);
+                self.visit_expr(body);
+            }
+
+            let scope = &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+            for (name, binding) in scope.values.iter() {
+                // TODO(charlie): Ignore if using `locals`.
+                if self.settings.select.contains(&CheckCode::F841)
+                    && binding.used.is_none()
+                    && name != "_"
+                    && name != "__tracebackhide__"
+                    && name != "__traceback_info__"
+                    && name != "__traceback_supplement__"
+                    && matches!(binding.kind, BindingKind::Assignment)
+                {
+                    self.checks.push(Check::new(
+                        CheckKind::UnusedVariable(name.to_string()),
+                        binding.location,
+                    ));
+                }
+            }
+
+            self.pop_scope();
+        }
     }
 
     fn check_dead_scopes(&mut self) {
@@ -943,7 +1209,9 @@ impl Checker<'_> {
             return;
         }
 
-        for scope in &self.dead_scopes {
+        for index in self.dead_scopes.clone() {
+            let scope = &self.scopes[index];
+
             let all_binding = scope.values.get("__all__");
             let all_names = all_binding.and_then(|binding| match &binding.kind {
                 BindingKind::Export(names) => Some(names),
@@ -1003,12 +1271,21 @@ pub fn check_ast(
     checker.push_scope(Scope::new(ScopeKind::Module));
     checker.bind_builtins();
 
+    // Iterate over the AST.
     for stmt in python_ast {
         checker.visit_stmt(stmt);
     }
-    checker.check_deferred(path);
 
+    // Check any deferred statements.
+    checker.check_deferred_functions();
+    checker.check_deferred_lambdas();
+    let mut allocator = vec![];
+    checker.check_deferred_annotations(path, &mut allocator);
+
+    // Reset the scope to module-level, and check all consumed scopes.
+    checker.scope_stack = vec![GLOBAL_SCOPE_INDEX];
     checker.pop_scope();
     checker.check_dead_scopes();
+
     checker.checks
 }

src/checks.rs

@@ -19,6 +19,8 @@ pub enum CheckCode {
     F401,
     F403,
     F541,
+    F601,
+    F602,
     F631,
     F634,
     F704,
@@ -50,6 +52,8 @@ impl FromStr for CheckCode {
             "F401" => Ok(CheckCode::F401),
             "F403" => Ok(CheckCode::F403),
             "F541" => Ok(CheckCode::F541),
+            "F601" => Ok(CheckCode::F601),
+            "F602" => Ok(CheckCode::F602),
             "F631" => Ok(CheckCode::F631),
             "F634" => Ok(CheckCode::F634),
             "F704" => Ok(CheckCode::F704),
@@ -82,6 +86,8 @@ impl CheckCode {
             CheckCode::F401 => "F401",
             CheckCode::F403 => "F403",
             CheckCode::F541 => "F541",
+            CheckCode::F601 => "F601",
+            CheckCode::F602 => "F602",
             CheckCode::F631 => "F631",
             CheckCode::F634 => "F634",
             CheckCode::F704 => "F704",
@@ -112,6 +118,8 @@ impl CheckCode {
             CheckCode::F401 => &LintSource::AST,
             CheckCode::F403 => &LintSource::AST,
             CheckCode::F541 => &LintSource::AST,
+            CheckCode::F601 => &LintSource::AST,
+            CheckCode::F602 => &LintSource::AST,
             CheckCode::F631 => &LintSource::AST,
             CheckCode::F634 => &LintSource::AST,
             CheckCode::F704 => &LintSource::AST,
@@ -154,6 +162,8 @@ pub enum CheckKind {
     ImportStarUsage,
     LineTooLong,
     ModuleImportNotAtTopOfFile,
+    MultiValueRepeatedKeyLiteral,
+    MultiValueRepeatedKeyVariable(String),
     NoAssertEquals,
     NoneComparison(RejectedCmpop),
     NotInTest,
@@ -184,6 +194,8 @@ 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",
@@ -214,6 +226,8 @@ 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,
@@ -258,6 +272,12 @@ 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()
             }
@@ -328,6 +348,8 @@ 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,

src/fixer.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_ops::SourceCodeLocator;
 use crate::checks::Fix;
 
 /// Convert a location within a file (relative to `base`) to an absolute position.

src/lib.rs

@@ -13,5 +13,6 @@ pub mod linter;
 pub mod logging;
 pub mod message;
 mod pyproject;
+mod relocator;
 pub mod settings;
 mod visitor;

src/linter.rs

@@ -90,7 +90,7 @@ mod tests {
 
     #[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,
@@ -99,6 +99,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::ModuleImportNotAtTopOfFile,
             location: Location::new(20, 1),
@@ -114,7 +115,7 @@ 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,
@@ -123,6 +124,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::LineTooLong,
             location: Location::new(5, 89),
@@ -138,7 +140,7 @@ 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,
@@ -147,6 +149,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::NoneComparison(RejectedCmpop::Eq),
@@ -169,7 +172,7 @@ 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,
@@ -178,6 +181,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
@@ -211,7 +215,7 @@ 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,
@@ -220,6 +224,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::NotInTest,
             location: Location::new(2, 12),
@@ -235,7 +240,7 @@ 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,
@@ -244,6 +249,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::NotIsTest,
             location: Location::new(1, 13),
@@ -259,7 +265,7 @@ 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,
@@ -268,11 +274,19 @@ mod tests {
             },
             &autofix::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() {
@@ -284,7 +298,7 @@ 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,
@@ -293,12 +307,8 @@ mod tests {
             },
             &autofix::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 +316,12 @@ 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,
             },
         ];
@@ -320,7 +335,7 @@ 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,
@@ -329,6 +344,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::ImportStarUsage,
@@ -350,7 +366,7 @@ 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,
@@ -359,6 +375,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::FStringMissingPlaceholders,
@@ -385,8 +402,68 @@ 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]),
+            },
+            &autofix::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]),
+            },
+            &autofix::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 f631() -> Result<()> {
+        let mut actual = check_path(
             Path::new("./resources/test/fixtures/F631.py"),
             &settings::Settings {
                 line_length: 88,
@@ -395,6 +472,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::AssertTuple,
@@ -417,7 +495,7 @@ 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,
@@ -426,6 +504,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::IfTuple,
@@ -448,7 +527,7 @@ 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,
@@ -457,6 +536,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::YieldOutsideFunction,
@@ -484,7 +564,7 @@ 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,
@@ -493,6 +573,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::ReturnOutsideFunction,
@@ -515,7 +596,7 @@ 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,
@@ -524,6 +605,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::DefaultExceptNotLast,
@@ -551,7 +633,7 @@ 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,
@@ -560,6 +642,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::UndefinedName("self".to_string()),
@@ -581,6 +664,11 @@ 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() {
@@ -592,7 +680,7 @@ 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,
@@ -601,6 +689,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
             kind: CheckKind::UndefinedExport("b".to_string()),
             location: Location::new(3, 1),
@@ -616,7 +705,7 @@ 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,
@@ -625,6 +714,7 @@ mod tests {
             },
             &autofix::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),
@@ -640,7 +730,7 @@ 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,
@@ -649,6 +739,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::DuplicateArgumentName,
@@ -676,7 +767,7 @@ 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,
@@ -685,6 +776,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::UnusedVariable("e".to_string()),
@@ -707,7 +799,7 @@ 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,
@@ -716,6 +808,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::RaiseNotImplemented,
@@ -738,7 +831,7 @@ 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,
@@ -747,6 +840,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::UselessObjectInheritance("A".to_string()),
@@ -959,7 +1053,7 @@ 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,
@@ -968,6 +1062,7 @@ mod tests {
             },
             &autofix::Mode::Generate,
         )?;
+        actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::NoAssertEquals,

src/main.rs

@@ -12,13 +12,13 @@ use rayon::prelude::*;
 use walkdir::DirEntry;
 
 use ::ruff::checks::CheckCode;
+use ::ruff::checks::CheckKind;
 use ::ruff::fs::iter_python_files;
 use ::ruff::linter::lint_path;
 use ::ruff::logging::set_up_logging;
 use ::ruff::message::Message;
 use ::ruff::settings::Settings;
 use ::ruff::tell_user;
-use ruff::checks::CheckKind;
 
 const CARGO_PKG_NAME: &str = env!("CARGO_PKG_NAME");
 const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
@@ -55,6 +55,30 @@ struct Cli {
     ignore: Vec<CheckCode>,
 }
 
+#[cfg(feature = "update-informer")]
+fn check_for_updates() {
+    use update_informer::{registry, Check};
+
+    let informer = update_informer::new(registry::PyPI, CARGO_PKG_NAME, CARGO_PKG_VERSION);
+
+    if let Some(new_version) = informer.check_version().ok().flatten() {
+        let msg = format!(
+            "A new version of {pkg_name} is available: v{pkg_version} -> {new_version}",
+            pkg_name = CARGO_PKG_NAME.italic().cyan(),
+            pkg_version = CARGO_PKG_VERSION,
+            new_version = new_version.to_string().green()
+        );
+
+        let cmd = format!(
+            "Run to update: {cmd} {pkg_name}",
+            cmd = "pip3 install --upgrade".green(),
+            pkg_name = CARGO_PKG_NAME.green()
+        );
+
+        println!("\n{msg}\n{cmd}");
+    }
+}
+
 fn run_once(
     files: &[PathBuf],
     settings: &Settings,
@@ -210,6 +234,7 @@ fn inner_main() -> Result<ExitCode> {
             report_once(&messages)?;
         }
 
+        #[cfg(feature = "update-informer")]
         check_for_updates();
 
         if !messages.is_empty() && !cli.exit_zero {
@@ -220,29 +245,6 @@ fn inner_main() -> Result<ExitCode> {
     Ok(ExitCode::SUCCESS)
 }
 
-fn check_for_updates() {
-    use update_informer::{registry, Check};
-
-    let informer = update_informer::new(registry::PyPI, CARGO_PKG_NAME, CARGO_PKG_VERSION);
-
-    if let Some(new_version) = informer.check_version().ok().flatten() {
-        let msg = format!(
-            "A new version of {pkg_name} is available: v{pkg_version} -> {new_version}",
-            pkg_name = CARGO_PKG_NAME.italic().cyan(),
-            pkg_version = CARGO_PKG_VERSION,
-            new_version = new_version.to_string().green()
-        );
-
-        let cmd = format!(
-            "Run to update: {cmd} {pkg_name}",
-            cmd = "pip3 install --upgrade".green(),
-            pkg_name = CARGO_PKG_NAME.green()
-        );
-
-        println!("\n{msg}\n{cmd}");
-    }
-}
-
 fn main() -> ExitCode {
     match inner_main() {
         Ok(code) => code,

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 +270,8 @@ other-attribute = 1
                     CheckCode::F401,
                     CheckCode::F403,
                     CheckCode::F541,
+                    CheckCode::F601,
+                    CheckCode::F602,
                     CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,
@@ -261,7 +285,8 @@ other-attribute = 1
                     CheckCode::F901,
                     CheckCode::R001,
                     CheckCode::R002,
-                ])),
+                ]),
+                ignore: None,
             }
         );
 

src/relocator.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/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 +55,8 @@ impl Settings {
                     CheckCode::F401,
                     CheckCode::F403,
                     CheckCode::F541,
+                    CheckCode::F601,
+                    CheckCode::F602,
                     CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,
@@ -69,9 +71,13 @@ 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>) {

src/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) {}