Bump version to 0.0.33

.pre-commit-config.yaml

@@ -1,5 +1,5 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff
-    rev: v0.0.30
+    rev: v0.0.33
     hooks:
       - id: lint

Cargo.lock

@@ -1744,7 +1744,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.30"
+version = "0.0.33"
 dependencies = [
  "anyhow",
  "bincode",
@@ -1759,6 +1759,7 @@ dependencies = [
  "filetime",
  "glob",
  "itertools",
+ "lazy_static",
  "log",
  "notify",
  "once_cell",
@@ -1787,7 +1788,7 @@ dependencies = [
 [[package]]
 name = "rustpython-ast"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=8cc3d23ddaa6339bf56608adaeefabff3ad329e7#8cc3d23ddaa6339bf56608adaeefabff3ad329e7"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "num-bigint",
  "rustpython-compiler-core",
@@ -1796,7 +1797,7 @@ dependencies = [
 [[package]]
 name = "rustpython-compiler-core"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=8cc3d23ddaa6339bf56608adaeefabff3ad329e7#8cc3d23ddaa6339bf56608adaeefabff3ad329e7"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "bincode",
  "bitflags",
@@ -1813,7 +1814,7 @@ dependencies = [
 [[package]]
 name = "rustpython-parser"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=8cc3d23ddaa6339bf56608adaeefabff3ad329e7#8cc3d23ddaa6339bf56608adaeefabff3ad329e7"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "ahash",
  "anyhow",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.30"
+version = "0.0.33"
 edition = "2021"
 
 [lib]
@@ -20,12 +20,13 @@ fern = { version = "0.6.1" }
 filetime = { version = "0.2.17" }
 glob = { version = "0.3.0" }
 itertools = "0.10.3"
+lazy_static = "1.4.0"
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
 once_cell = { version = "1.13.1" }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "8cc3d23ddaa6339bf56608adaeefabff3ad329e7" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "7d21c6923a506e79cc041708d83cef925efd33f4" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }

README.md

@@ -57,7 +57,7 @@ ruff also works with [Pre-Commit](https://pre-commit.com) (requires Cargo on sys
 ```yaml
 repos:
 - repo: https://github.com/charliermarsh/ruff
-  rev: v0.0.30
+  rev: v0.0.33
   hooks:
     - id: lint
 ```
@@ -86,7 +86,7 @@ ruff path/to/code/ --select F401 F403
 See `ruff --help` for more:
 
 ```shell
-ruff (v0.0.30)
+ruff (v0.0.33)
 An extremely fast Python linter.
 
 USAGE:
@@ -96,16 +96,17 @@ ARGS:
     <FILES>...
 
 OPTIONS:
-    -e, --exit-zero             Exit with status code "0", even upon detecting errors
-    -f, --fix                   Attempt to automatically fix lint errors
-    -h, --help                  Print help information
-        --ignore <IGNORE>...    Comma-separated list of error codes to ignore
-    -n, --no-cache              Disable cache reads
-    -q, --quiet                 Disable all logging (but still exit with status code "1" upon
-                                detecting errors)
-        --select <SELECT>...    Comma-separated list of error codes to enable
-    -v, --verbose               Enable verbose logging
-    -w, --watch                 Run in watch mode by re-running whenever files change
+    -e, --exit-zero               Exit with status code "0", even upon detecting errors
+        --exclude <EXCLUDE>...    List of file and/or directory patterns to exclude from checks
+    -f, --fix                     Attempt to automatically fix lint errors
+    -h, --help                    Print help information
+        --ignore <IGNORE>...      List of error codes to ignore
+    -n, --no-cache                Disable cache reads
+    -q, --quiet                   Disable all logging (but still exit with status code "1" upon
+                                  detecting errors)
+        --select <SELECT>...      List of error codes to enable
+    -v, --verbose                 Enable verbose logging
+    -w, --watch                   Run in watch mode by re-running whenever files change
 ```
 
 ### Compatibility with Black
@@ -123,7 +124,7 @@ ruff's goal is to achieve feature-parity with Flake8 when used (1) without any p
 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:
+implements 28 rules. (Note that these 28 rules likely cover a disproportionate share of errors:
 unused imports, undefined variables, etc.)
 
 Of the unimplemented rules, ruff is missing:
@@ -158,6 +159,8 @@ Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis F
 | F541 | FStringMissingPlaceholders | f-string without any placeholders |
 | F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |
 | F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |
+| F621 | TooManyExpressionsInStarredAssignment | too many expressions in star-unpacking assignment |
+| F622 | TwoStarredExpressions | two starred expressions in assignment |
 | F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |
 | F634 | IfTuple | If test is a tuple, which is always `True` |
 | F704 | YieldOutsideFunction | a `yield` or `yield from` statement outside of a function/method |
@@ -204,7 +207,7 @@ git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpy
 Add this `pyproject.toml` to the CPython directory:
 
 ```toml
-[tool.linter]
+[tool.ruff]
 line-length = 88
 exclude = [
     "Lib/lib2to3/tests/data/bom.py",

examples/generate_rules_table.rs

@@ -21,7 +21,9 @@ fn main() {
         CheckKind::NotIsTest,
         CheckKind::RaiseNotImplemented,
         CheckKind::ReturnOutsideFunction,
+        CheckKind::TooManyExpressionsInStarredAssignment,
         CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
+        CheckKind::TwoStarredExpressions,
         CheckKind::UndefinedExport("...".to_string()),
         CheckKind::UndefinedLocal("...".to_string()),
         CheckKind::UndefinedName("...".to_string()),

resources/test/fixtures/F401.py

@@ -11,10 +11,13 @@ import multiprocessing.pool
 import multiprocessing.process
 import logging.config
 import logging.handlers
-from typing import NamedTuple, Dict, Type, TypeVar, List, Set
+from typing import TYPING_CHECK, NamedTuple, Dict, Type, TypeVar, List, Set, Union, cast
 
 from blah import ClassA, ClassB, ClassC
 
+if TYPING_CHECK:
+    from models import Fruit, Nut, Vegetable
+
 
 class X:
     datetime: datetime
@@ -32,3 +35,7 @@ __all__ += ["ClassC"]
 X = TypeVar("X")
 Y = TypeVar("Y", bound="Dict")
 Z = TypeVar("Z", "List", "Set")
+
+a = list["Fruit"]
+b = Union["Nut", None]
+c = cast("Vegetable", b)

resources/test/fixtures/F622.py

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

resources/test/fixtures/F821.py

@@ -56,3 +56,24 @@ except Exception as e:
 y: int = 1
 
 x: "Bar" = 1
+
+[first] = ["yup"]
+
+
+from typing import List, TypedDict
+
+
+class Item(TypedDict):
+    nodes: List[TypedDict("Node", {"name": str})]
+
+
+from enum import Enum
+
+
+class Ticket:
+    class Status(Enum):
+        OPEN = "OPEN"
+        CLOSED = "CLOSED"
+
+    def set_status(self, status: Status):
+        self.status = status

resources/test/fixtures/pyproject.toml

@@ -15,6 +15,8 @@ select = [
     "F541",
     "F601",
     "F602",
+    "F621",
+    "F622",
     "F631",
     "F634",
     "F704",

src/ast.rs

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

src/ast/checks.rs

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

src/ast/operations.rs

@@ -1,58 +1,6 @@
-use std::collections::BTreeMap;
-use std::sync::atomic::{AtomicUsize, Ordering};
-
 use rustpython_parser::ast::{Constant, Expr, ExprKind, Location, Stmt, StmtKind};
 
-fn id() -> usize {
-    static COUNTER: AtomicUsize = AtomicUsize::new(1);
-    COUNTER.fetch_add(1, Ordering::Relaxed)
-}
-
-#[derive(Clone, Debug)]
-pub enum ScopeKind {
-    Class,
-    Function,
-    Generator,
-    Module,
-}
-
-#[derive(Clone, Debug)]
-pub struct Scope {
-    pub id: usize,
-    pub kind: ScopeKind,
-    pub values: BTreeMap<String, Binding>,
-}
-
-impl Scope {
-    pub fn new(kind: ScopeKind) -> Self {
-        Scope {
-            id: id(),
-            kind,
-            values: BTreeMap::new(),
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub enum BindingKind {
-    Argument,
-    Assignment,
-    Builtin,
-    ClassDefinition,
-    Definition,
-    Export(Vec<String>),
-    FutureImportation,
-    Importation(String),
-    StarImportation,
-    SubmoduleImportation(String),
-}
-
-#[derive(Clone, Debug)]
-pub struct Binding {
-    pub kind: BindingKind,
-    pub location: Location,
-    pub used: Option<usize>,
-}
+use crate::ast::types::{BindingKind, Scope};
 
 /// Extract the names bound to a given __all__ assignment.
 pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
@@ -118,6 +66,40 @@ pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
     names
 }
 
+/// Check if a node is parent of a conditional branch.
+pub fn on_conditional_branch(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::If { .. })
+            || matches!(parent.node, StmtKind::While { .. })
+        {
+            return true;
+        }
+        if let StmtKind::Expr { value } = &parent.node {
+            if matches!(value.node, ExprKind::IfExp { .. }) {
+                return true;
+            }
+        }
+    }
+
+    false
+}
+
+/// Check if a node is in a nested block.
+pub fn in_nested_block(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::Try { .. })
+            || matches!(parent.node, StmtKind::If { .. })
+            || matches!(parent.node, StmtKind::With { .. })
+        {
+            return true;
+        }
+    }
+
+    false
+}
+
 /// Struct used to efficiently slice source code at (row, column) Locations.
 pub struct SourceCodeLocator<'a> {
     content: &'a str,

src/ast/types.rs

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

src/autofix.rs

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

src/autofix/fixer.rs

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

src/autofix/fixes.rs

@@ -2,7 +2,7 @@ use rustpython_parser::ast::{Expr, Keyword, Location};
 use rustpython_parser::lexer;
 use rustpython_parser::token::Tok;
 
-use crate::ast_ops::SourceCodeLocator;
+use crate::ast::operations::SourceCodeLocator;
 use crate::checks::Fix;
 
 /// Convert a location within a file (relative to `base`) to an absolute position.

src/cache.rs

@@ -8,7 +8,7 @@ use filetime::FileTime;
 use log::error;
 use serde::{Deserialize, Serialize};
 
-use crate::autofix;
+use crate::autofix::fixer;
 use crate::message::Message;
 use crate::settings::Settings;
 
@@ -71,7 +71,7 @@ fn cache_dir() -> &'static str {
     "./.ruff_cache"
 }
 
-fn cache_key(path: &Path, settings: &Settings, autofix: &autofix::Mode) -> String {
+fn cache_key(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> String {
     let mut hasher = DefaultHasher::new();
     settings.hash(&mut hasher);
     autofix.hash(&mut hasher);
@@ -87,7 +87,7 @@ pub fn get(
     path: &Path,
     metadata: &Metadata,
     settings: &Settings,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
     mode: &Mode,
 ) -> Option<Vec<Message>> {
     if !mode.allow_read() {
@@ -116,7 +116,7 @@ pub fn set(
     path: &Path,
     metadata: &Metadata,
     settings: &Settings,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
     messages: &[Message],
     mode: &Mode,
 ) {

src/check_ast.rs

@@ -1,22 +1,21 @@
-use std::collections::BTreeSet;
 use std::path::Path;
 
-use itertools::izip;
 use rustpython_parser::ast::{
-    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind,
-    KeywordData, Location, Stmt, StmtKind, Suite, Unaryop,
+    Arg, Arguments, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind,
+    KeywordData, Location, Stmt, StmtKind, Suite,
 };
 use rustpython_parser::parser;
 
-use crate::ast_ops::{
-    extract_all_names, Binding, BindingKind, Scope, ScopeKind, SourceCodeLocator,
-};
-use crate::builtins::{BUILTINS, MAGIC_GLOBALS};
-use crate::checks::{Check, CheckCode, CheckKind, Fix, RejectedCmpop};
-use crate::relocator::relocate_expr;
+use crate::ast::operations::{extract_all_names, SourceCodeLocator};
+use crate::ast::relocate::relocate_expr;
+use crate::ast::types::{Binding, BindingKind, Scope, ScopeKind};
+use crate::ast::visitor::{walk_excepthandler, Visitor};
+use crate::ast::{checks, operations, visitor};
+use crate::autofix::fixer;
+use crate::checks::{Check, CheckCode, CheckKind};
+use crate::python::builtins::{BUILTINS, MAGIC_GLOBALS};
+use crate::python::typing;
 use crate::settings::Settings;
-use crate::visitor::{walk_excepthandler, Visitor};
-use crate::{autofix, fixer, visitor};
 
 pub const GLOBAL_SCOPE_INDEX: usize = 0;
 
@@ -24,7 +23,7 @@ struct Checker<'a> {
     // Input data.
     locator: SourceCodeLocator<'a>,
     settings: &'a Settings,
-    autofix: &'a autofix::Mode,
+    autofix: &'a fixer::Mode,
     path: &'a str,
     // Computed checks.
     checks: Vec<Check>,
@@ -38,6 +37,7 @@ struct Checker<'a> {
     deferred_annotations: Vec<(Location, &'a str)>,
     deferred_functions: Vec<(&'a Stmt, Vec<usize>, Vec<usize>)>,
     deferred_lambdas: Vec<(&'a Expr, Vec<usize>, Vec<usize>)>,
+    deferred_assignments: Vec<usize>,
     // Derivative state.
     in_f_string: bool,
     in_annotation: bool,
@@ -49,7 +49,7 @@ struct Checker<'a> {
 impl<'a> Checker<'a> {
     pub fn new(
         settings: &'a Settings,
-        autofix: &'a autofix::Mode,
+        autofix: &'a fixer::Mode,
         path: &'a str,
         content: &'a str,
     ) -> Checker<'a> {
@@ -67,6 +67,7 @@ impl<'a> Checker<'a> {
             deferred_annotations: vec![],
             deferred_functions: vec![],
             deferred_lambdas: vec![],
+            deferred_assignments: vec![],
             in_f_string: false,
             in_annotation: false,
             in_literal: false,
@@ -76,20 +77,6 @@ impl<'a> Checker<'a> {
     }
 }
 
-#[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,
@@ -98,6 +85,14 @@ fn match_name_or_attr(expr: &Expr, target: &str) -> bool {
     }
 }
 
+fn is_annotated_subscript(expr: &Expr) -> bool {
+    match &expr.node {
+        ExprKind::Attribute { attr, .. } => typing::is_annotated_subscript(attr),
+        ExprKind::Name { id, .. } => typing::is_annotated_subscript(id),
+        _ => false,
+    }
+}
+
 impl<'a, 'b> Visitor<'b> for Checker<'a>
 where
     'b: 'a,
@@ -105,6 +100,41 @@ where
     fn visit_stmt(&mut self, stmt: &'b Stmt) {
         self.push_parent(stmt);
 
+        // Track whether we've seen docstrings, non-imports, etc.
+        match &stmt.node {
+            StmtKind::Import { .. } => {}
+            StmtKind::ImportFrom { .. } => {}
+            StmtKind::Expr { value } => {
+                if !self.seen_docstring
+                    && stmt.location.column() == 1
+                    && !operations::in_nested_block(&self.parent_stack, &self.parents)
+                {
+                    if let ExprKind::Constant {
+                        value: Constant::Str(_),
+                        ..
+                    } = &value.node
+                    {
+                        self.seen_docstring = true;
+                    }
+                }
+
+                if !self.seen_non_import
+                    && stmt.location.column() == 1
+                    && !operations::in_nested_block(&self.parent_stack, &self.parents)
+                {
+                    self.seen_non_import = true;
+                }
+            }
+            _ => {
+                if !self.seen_non_import
+                    && stmt.location.column() == 1
+                    && !operations::in_nested_block(&self.parent_stack, &self.parents)
+                {
+                    self.seen_non_import = true;
+                }
+            }
+        }
+
         // Pre-visit.
         match &stmt.node {
             StmtKind::Global { names } | StmtKind::Nonlocal { names } => {
@@ -133,20 +163,53 @@ where
                 name,
                 decorator_list,
                 returns,
+                args,
                 ..
             }
             | StmtKind::AsyncFunctionDef {
                 name,
                 decorator_list,
                 returns,
+                args,
                 ..
             } => {
                 for expr in decorator_list {
                     self.visit_expr(expr);
                 }
+                for arg in &args.posonlyargs {
+                    if let Some(expr) = &arg.node.annotation {
+                        self.visit_annotation(expr);
+                    }
+                }
+                for arg in &args.args {
+                    if let Some(expr) = &arg.node.annotation {
+                        self.visit_annotation(expr);
+                    }
+                }
+                if let Some(arg) = &args.vararg {
+                    if let Some(expr) = &arg.node.annotation {
+                        self.visit_annotation(expr);
+                    }
+                }
+                for arg in &args.kwonlyargs {
+                    if let Some(expr) = &arg.node.annotation {
+                        self.visit_annotation(expr);
+                    }
+                }
+                if let Some(arg) = &args.kwarg {
+                    if let Some(expr) = &arg.node.annotation {
+                        self.visit_annotation(expr);
+                    }
+                }
                 for expr in returns {
                     self.visit_annotation(expr);
                 }
+                for expr in &args.kw_defaults {
+                    self.visit_expr(expr);
+                }
+                for expr in &args.defaults {
+                    self.visit_expr(expr);
+                }
                 self.add_binding(
                     name.to_string(),
                     Binding {
@@ -183,41 +246,18 @@ where
                 ..
             } => {
                 if self.settings.select.contains(&CheckCode::R001) {
-                    for expr in bases {
-                        if let ExprKind::Name { id, .. } = &expr.node {
-                            if id == "object" {
-                                let scope = &self.scopes
-                                    [*(self.scope_stack.last().expect("No current scope found."))];
-                                match scope.values.get(id) {
-                                    None
-                                    | Some(Binding {
-                                        kind: BindingKind::Builtin,
-                                        ..
-                                    }) => {
-                                        let mut check = Check::new(
-                                            CheckKind::UselessObjectInheritance(name.to_string()),
-                                            expr.location,
-                                        );
-                                        if matches!(self.autofix, autofix::Mode::Generate)
-                                            || matches!(self.autofix, autofix::Mode::Apply)
-                                        {
-                                            if let Some(fix) = fixer::remove_class_def_base(
-                                                &mut self.locator,
-                                                &stmt.location,
-                                                expr.location,
-                                                bases,
-                                                keywords,
-                                            ) {
-                                                check.amend(fix);
-                                            }
-                                        } else {
-                                        }
-                                        self.checks.push(check);
-                                    }
-                                    _ => {}
-                                }
-                            }
-                        }
+                    let scope =
+                        &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+                    if let Some(check) = checks::check_useless_object_inheritance(
+                        stmt,
+                        name,
+                        bases,
+                        keywords,
+                        scope,
+                        &mut self.locator,
+                        self.autofix,
+                    ) {
+                        self.checks.push(check);
                     }
                 }
 
@@ -327,11 +367,7 @@ where
                             },
                         );
 
-                        if self
-                            .settings
-                            .select
-                            .contains(CheckKind::ImportStarUsage.code())
-                        {
+                        if self.settings.select.contains(&CheckCode::F403) {
                             self.checks
                                 .push(Check::new(CheckKind::ImportStarUsage, stmt.location));
                         }
@@ -348,123 +384,58 @@ where
                     }
                 }
             }
-            StmtKind::If { test, .. } => {
-                if self.settings.select.contains(CheckKind::IfTuple.code()) {
-                    if let ExprKind::Tuple { elts, .. } = &test.node {
-                        if !elts.is_empty() {
-                            self.checks
-                                .push(Check::new(CheckKind::IfTuple, stmt.location));
-                        }
-                    }
-                }
-            }
             StmtKind::Raise { exc, .. } => {
-                if self
-                    .settings
-                    .select
-                    .contains(CheckKind::RaiseNotImplemented.code())
-                {
+                if self.settings.select.contains(&CheckCode::F901) {
                     if let Some(expr) = exc {
-                        match &expr.node {
-                            ExprKind::Call { func, .. } => {
-                                if let ExprKind::Name { id, .. } = &func.node {
-                                    if id == "NotImplemented" {
-                                        self.checks.push(Check::new(
-                                            CheckKind::RaiseNotImplemented,
-                                            stmt.location,
-                                        ));
-                                    }
-                                }
-                            }
-                            ExprKind::Name { id, .. } => {
-                                if id == "NotImplemented" {
-                                    self.checks.push(Check::new(
-                                        CheckKind::RaiseNotImplemented,
-                                        stmt.location,
-                                    ));
-                                }
-                            }
-                            _ => {}
+                        if let Some(check) = checks::check_raise_not_implemented(expr) {
+                            self.checks.push(check);
                         }
                     }
                 }
             }
             StmtKind::AugAssign { target, .. } => {
-                self.seen_non_import = true;
                 self.handle_node_load(target);
             }
+            StmtKind::If { test, .. } => {
+                if self.settings.select.contains(&CheckCode::F634) {
+                    if let Some(check) = checks::check_if_tuple(test, stmt.location) {
+                        self.checks.push(check);
+                    }
+                }
+            }
             StmtKind::Assert { test, .. } => {
-                self.seen_non_import = true;
                 if self.settings.select.contains(CheckKind::AssertTuple.code()) {
-                    if let ExprKind::Tuple { elts, .. } = &test.node {
-                        if !elts.is_empty() {
-                            self.checks
-                                .push(Check::new(CheckKind::AssertTuple, stmt.location));
-                        }
+                    if let Some(check) = checks::check_assert_tuple(test, stmt.location) {
+                        self.checks.push(check);
                     }
                 }
             }
             StmtKind::Try { handlers, .. } => {
-                if self
-                    .settings
-                    .select
-                    .contains(CheckKind::DefaultExceptNotLast.code())
-                {
-                    for (idx, handler) in handlers.iter().enumerate() {
-                        let ExcepthandlerKind::ExceptHandler { type_, .. } = &handler.node;
-                        if type_.is_none() && idx < handlers.len() - 1 {
-                            self.checks.push(Check::new(
-                                CheckKind::DefaultExceptNotLast,
-                                handler.location,
-                            ));
-                        }
+                if self.settings.select.contains(&CheckCode::F707) {
+                    if let Some(check) = checks::check_default_except_not_last(handlers) {
+                        self.checks.push(check);
                     }
                 }
             }
-            StmtKind::Expr { value } => {
-                if !self.seen_docstring {
-                    if let ExprKind::Constant {
-                        value: Constant::Str(_),
-                        ..
-                    } = &value.node
-                    {
-                        self.seen_docstring = true;
-                    }
-                } else {
-                    self.seen_non_import = true;
-                }
-            }
             StmtKind::Assign { value, .. } => {
-                self.seen_non_import = true;
-                if self
-                    .settings
-                    .select
-                    .contains(CheckKind::DoNotAssignLambda.code())
-                {
-                    if let ExprKind::Lambda { .. } = &value.node {
-                        self.checks
-                            .push(Check::new(CheckKind::DoNotAssignLambda, stmt.location));
+                if self.settings.select.contains(&CheckCode::E731) {
+                    if let Some(check) = checks::check_do_not_assign_lambda(value, stmt.location) {
+                        self.checks.push(check);
                     }
                 }
             }
             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));
+                if self.settings.select.contains(&CheckCode::E731) {
+                    if let Some(value) = value {
+                        if let Some(check) =
+                            checks::check_do_not_assign_lambda(value, stmt.location)
+                        {
+                            self.checks.push(check);
                         }
                     }
                 }
             }
-            StmtKind::Delete { .. } => {
-                self.seen_non_import = true;
-            }
+            StmtKind::Delete { .. } => {}
             _ => {}
         }
 
@@ -511,6 +482,7 @@ where
     fn visit_expr(&mut self, expr: &'b Expr) {
         let prev_in_f_string = self.in_f_string;
         let prev_in_literal = self.in_literal;
+        let prev_in_annotation = self.in_annotation;
 
         // Pre-visit.
         match &expr.node {
@@ -519,6 +491,22 @@ where
                     self.in_literal = true;
                 }
             }
+            ExprKind::Tuple { elts, ctx } => {
+                if matches!(ctx, ExprContext::Store) {
+                    let check_too_many_expressions =
+                        self.settings.select.contains(&CheckCode::F621);
+                    let check_two_starred_expressions =
+                        self.settings.select.contains(&CheckCode::F622);
+                    if let Some(check) = checks::check_starred_expressions(
+                        elts,
+                        expr.location,
+                        check_too_many_expressions,
+                        check_two_starred_expressions,
+                    ) {
+                        self.checks.push(check);
+                    }
+                }
+            }
             ExprKind::Name { ctx, .. } => match ctx {
                 ExprContext::Load => self.handle_node_load(expr),
                 ExprContext::Store => {
@@ -530,81 +518,23 @@ where
             },
             ExprKind::Call { func, .. } => {
                 if self.settings.select.contains(&CheckCode::R002) {
-                    if let ExprKind::Attribute { value, attr, .. } = &func.node {
-                        if attr == "assertEquals" {
-                            if let ExprKind::Name { id, .. } = &value.node {
-                                if id == "self" {
-                                    let mut check =
-                                        Check::new(CheckKind::NoAssertEquals, expr.location);
-                                    if matches!(self.autofix, autofix::Mode::Generate)
-                                        || matches!(self.autofix, autofix::Mode::Apply)
-                                    {
-                                        check.amend(Fix {
-                                            content: "assertEqual".to_string(),
-                                            start: Location::new(
-                                                func.location.row(),
-                                                func.location.column() + 1,
-                                            ),
-                                            end: Location::new(
-                                                func.location.row(),
-                                                func.location.column() + 1 + "assertEquals".len(),
-                                            ),
-                                            applied: false,
-                                        });
-                                    }
-                                    self.checks.push(check);
-                                }
-                            }
-                        }
+                    if let Some(check) = checks::check_assert_equals(func, self.autofix) {
+                        self.checks.push(check)
                     }
                 }
             }
             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,
-                                        ))
-                                    }
-                                }
-                                _ => {}
-                            }
-                        }
-                    }
+                let check_repeated_literals = self.settings.select.contains(&CheckCode::F601);
+                let check_repeated_variables = self.settings.select.contains(&CheckCode::F602);
+                if check_repeated_literals || check_repeated_variables {
+                    self.checks.extend(checks::check_repeated_keys(
+                        keys,
+                        check_repeated_literals,
+                        check_repeated_variables,
+                    ));
                 }
             }
-            ExprKind::GeneratorExp { .. }
-            | ExprKind::ListComp { .. }
-            | ExprKind::DictComp { .. }
-            | ExprKind::SetComp { .. } => self.push_scope(Scope::new(ScopeKind::Generator)),
-            ExprKind::Yield { .. } | ExprKind::YieldFrom { .. } => {
+            ExprKind::Yield { .. } | ExprKind::YieldFrom { .. } | ExprKind::Await { .. } => {
                 let scope =
                     &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
                 if self
@@ -636,24 +566,15 @@ where
                 self.in_f_string = true;
             }
             ExprKind::UnaryOp { op, operand } => {
-                if matches!(op, Unaryop::Not) {
-                    if let ExprKind::Compare { ops, .. } = &operand.node {
-                        match ops[..] {
-                            [Cmpop::In] => {
-                                if self.settings.select.contains(CheckKind::NotInTest.code()) {
-                                    self.checks
-                                        .push(Check::new(CheckKind::NotInTest, operand.location));
-                                }
-                            }
-                            [Cmpop::Is] => {
-                                if self.settings.select.contains(CheckKind::NotIsTest.code()) {
-                                    self.checks
-                                        .push(Check::new(CheckKind::NotIsTest, operand.location));
-                                }
-                            }
-                            _ => {}
-                        }
-                    }
+                let check_not_in = self.settings.select.contains(&CheckCode::E713);
+                let check_not_is = self.settings.select.contains(&CheckCode::E714);
+                if check_not_in || check_not_is {
+                    self.checks.extend(checks::check_not_tests(
+                        op,
+                        operand,
+                        check_not_in,
+                        check_not_is,
+                    ));
                 }
             }
             ExprKind::Compare {
@@ -661,99 +582,16 @@ where
                 ops,
                 comparators,
             } => {
-                let op = ops.first().unwrap();
-                let comparator = left;
-
-                // Check `left`.
-                if self.settings.select.contains(&CheckCode::E711)
-                    && matches!(
-                        comparator.node,
-                        ExprKind::Constant {
-                            value: Constant::None,
-                            kind: None
-                        }
-                    )
-                {
-                    if matches!(op, Cmpop::Eq) {
-                        self.checks.push(Check::new(
-                            CheckKind::NoneComparison(RejectedCmpop::Eq),
-                            comparator.location,
-                        ));
-                    }
-                    if matches!(op, Cmpop::NotEq) {
-                        self.checks.push(Check::new(
-                            CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                            comparator.location,
-                        ));
-                    }
-                }
-
-                if self.settings.select.contains(&CheckCode::E712) {
-                    if let ExprKind::Constant {
-                        value: Constant::Bool(value),
-                        kind: None,
-                    } = comparator.node
-                    {
-                        if matches!(op, Cmpop::Eq) {
-                            self.checks.push(Check::new(
-                                CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                                comparator.location,
-                            ));
-                        }
-                        if matches!(op, Cmpop::NotEq) {
-                            self.checks.push(Check::new(
-                                CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                                comparator.location,
-                            ));
-                        }
-                    }
-                }
-
-                // Check each comparator in order.
-                for (op, comparator) in izip!(ops, comparators) {
-                    if self.settings.select.contains(&CheckCode::E711)
-                        && matches!(
-                            comparator.node,
-                            ExprKind::Constant {
-                                value: Constant::None,
-                                kind: None
-                            }
-                        )
-                    {
-                        if matches!(op, Cmpop::Eq) {
-                            self.checks.push(Check::new(
-                                CheckKind::NoneComparison(RejectedCmpop::Eq),
-                                comparator.location,
-                            ));
-                        }
-                        if matches!(op, Cmpop::NotEq) {
-                            self.checks.push(Check::new(
-                                CheckKind::NoneComparison(RejectedCmpop::NotEq),
-                                comparator.location,
-                            ));
-                        }
-                    }
-
-                    if self.settings.select.contains(&CheckCode::E712) {
-                        if let ExprKind::Constant {
-                            value: Constant::Bool(value),
-                            kind: None,
-                        } = comparator.node
-                        {
-                            if matches!(op, Cmpop::Eq) {
-                                self.checks.push(Check::new(
-                                    CheckKind::TrueFalseComparison(value, RejectedCmpop::Eq),
-                                    comparator.location,
-                                ));
-                            }
-                            if matches!(op, Cmpop::NotEq) {
-                                self.checks.push(Check::new(
-                                    CheckKind::TrueFalseComparison(value, RejectedCmpop::NotEq),
-                                    comparator.location,
-                                ));
-                            }
-                        }
-                    }
+                let check_none_comparisons = self.settings.select.contains(&CheckCode::E711);
+                let check_true_false_comparisons = self.settings.select.contains(&CheckCode::E712);
+                if check_none_comparisons || check_true_false_comparisons {
+                    self.checks.extend(checks::check_literal_comparisons(
+                        left,
+                        ops,
+                        comparators,
+                        check_none_comparisons,
+                        check_true_false_comparisons,
+                    ));
                 }
             }
             ExprKind::Constant {
@@ -762,6 +600,10 @@ where
             } if self.in_annotation && !self.in_literal => {
                 self.deferred_annotations.push((expr.location, value));
             }
+            ExprKind::GeneratorExp { .. }
+            | ExprKind::ListComp { .. }
+            | ExprKind::DictComp { .. }
+            | ExprKind::SetComp { .. } => self.push_scope(Scope::new(ScopeKind::Generator)),
             _ => {}
         };
 
@@ -779,7 +621,25 @@ where
                 args,
                 keywords,
             } => {
-                if match_name_or_attr(func, "TypeVar") {
+                if match_name_or_attr(func, "ForwardRef") {
+                    self.visit_expr(func);
+                    for expr in args {
+                        self.visit_annotation(expr);
+                    }
+                } else if match_name_or_attr(func, "cast") {
+                    self.visit_expr(func);
+                    if !args.is_empty() {
+                        self.visit_annotation(&args[0]);
+                    }
+                    for expr in args.iter().skip(1) {
+                        self.visit_expr(expr);
+                    }
+                } else if match_name_or_attr(func, "NewType") {
+                    self.visit_expr(func);
+                    for expr in args.iter().skip(1) {
+                        self.visit_annotation(expr);
+                    }
+                } else if match_name_or_attr(func, "TypeVar") {
                     self.visit_expr(func);
                     for expr in args.iter().skip(1) {
                         self.visit_annotation(expr);
@@ -790,16 +650,72 @@ where
                             if id == "bound" {
                                 self.visit_annotation(value);
                             } else {
+                                self.in_annotation = false;
                                 self.visit_expr(value);
+                                self.in_annotation = prev_in_annotation;
                             }
                         }
                     }
+                } else if match_name_or_attr(func, "NamedTuple") {
+                    self.visit_expr(func);
+
+                    // NamedTuple("a", [("a", int)])
+                    if args.len() > 1 {
+                        match &args[1].node {
+                            ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                                for elt in elts {
+                                    match &elt.node {
+                                        ExprKind::List { elts, .. }
+                                        | ExprKind::Tuple { elts, .. } => {
+                                            if elts.len() == 2 {
+                                                self.in_annotation = false;
+                                                self.visit_expr(&elts[0]);
+                                                self.in_annotation = prev_in_annotation;
+
+                                                self.visit_annotation(&elts[1]);
+                                            }
+                                        }
+                                        _ => {}
+                                    }
+                                }
+                            }
+                            _ => {}
+                        }
+                    }
+
+                    // NamedTuple("a", a=int)
+                    for keyword in keywords {
+                        let KeywordData { value, .. } = &keyword.node;
+                        self.visit_annotation(value);
+                    }
+                } else if match_name_or_attr(func, "TypedDict") {
+                    self.visit_expr(func);
+
+                    // TypedDict("a", {"a": int})
+                    if args.len() > 1 {
+                        if let ExprKind::Dict { keys, values } = &args[1].node {
+                            for key in keys {
+                                self.in_annotation = false;
+                                self.visit_expr(key);
+                                self.in_annotation = prev_in_annotation;
+                            }
+                            for value in values {
+                                self.visit_annotation(value);
+                            }
+                        }
+                    }
+
+                    // TypedDict("a", a=int)
+                    for keyword in keywords {
+                        let KeywordData { value, .. } = &keyword.node;
+                        self.visit_annotation(value);
+                    }
                 } else {
                     visitor::walk_expr(self, expr);
                 }
             }
             ExprKind::Subscript { value, slice, ctx } => {
-                if match_name_or_attr(value, "Type") {
+                if is_annotated_subscript(value) {
                     self.visit_expr(value);
                     self.visit_annotation(slice);
                     self.visit_expr_context(ctx);
@@ -820,6 +736,8 @@ where
             }
             _ => {}
         };
+
+        self.in_annotation = prev_in_annotation;
         self.in_literal = prev_in_literal;
         self.in_f_string = prev_in_f_string;
     }
@@ -887,42 +805,31 @@ where
     }
 
     fn visit_arguments(&mut self, arguments: &'b Arguments) {
-        if self
-            .settings
-            .select
-            .contains(CheckKind::DuplicateArgumentName.code())
-        {
-            // Collect all the arguments into a single vector.
-            let mut all_arguments: Vec<&Arg> = arguments
-                .args
-                .iter()
-                .chain(arguments.posonlyargs.iter())
-                .chain(arguments.kwonlyargs.iter())
-                .collect();
-            if let Some(arg) = &arguments.vararg {
-                all_arguments.push(arg);
-            }
-            if let Some(arg) = &arguments.kwarg {
-                all_arguments.push(arg);
-            }
-
-            // Search for duplicates.
-            let mut idents: BTreeSet<&str> = BTreeSet::new();
-            for arg in all_arguments {
-                let ident = &arg.node.arg;
-                if idents.contains(ident.as_str()) {
-                    self.checks
-                        .push(Check::new(CheckKind::DuplicateArgumentName, arg.location));
-                    break;
-                }
-                idents.insert(ident);
-            }
+        if self.settings.select.contains(&CheckCode::F831) {
+            self.checks
+                .extend(checks::check_duplicate_arguments(arguments));
         }
 
-        visitor::walk_arguments(self, arguments);
+        // Bind, but intentionally avoid walking default expressions, as we handle them upstream.
+        for arg in &arguments.posonlyargs {
+            self.visit_arg(arg);
+        }
+        for arg in &arguments.args {
+            self.visit_arg(arg);
+        }
+        if let Some(arg) = &arguments.vararg {
+            self.visit_arg(arg);
+        }
+        for arg in &arguments.kwonlyargs {
+            self.visit_arg(arg);
+        }
+        if let Some(arg) = &arguments.kwarg {
+            self.visit_arg(arg);
+        }
     }
 
     fn visit_arg(&mut self, arg: &'b Arg) {
+        // Bind, but intentionally avoid walking the annotation, as we handle it upstream.
         self.add_binding(
             arg.node.arg.to_string(),
             Binding {
@@ -931,7 +838,6 @@ where
                 location: arg.location,
             },
         );
-        visitor::walk_arg(self, arg);
     }
 }
 
@@ -1098,6 +1004,11 @@ impl<'a> Checker<'a> {
 
     fn handle_node_delete(&mut self, expr: &Expr) {
         if let ExprKind::Name { id, .. } = &expr.node {
+            // Check if we're on a conditional branch.
+            if operations::on_conditional_branch(&self.parent_stack, &self.parents) {
+                return;
+            }
+
             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)
@@ -1145,23 +1056,8 @@ impl<'a> Checker<'a> {
                 _ => {}
             }
 
-            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.deferred_assignments
+                .push(*self.scope_stack.last().expect("No current scope found."));
 
             self.pop_scope();
         }
@@ -1180,28 +1076,23 @@ impl<'a> Checker<'a> {
                 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.deferred_assignments
+                .push(*self.scope_stack.last().expect("No current scope found."));
 
             self.pop_scope();
         }
     }
 
+    fn check_deferred_assignments(&mut self) {
+        while !self.deferred_assignments.is_empty() {
+            let index = self.deferred_assignments.pop().unwrap();
+            if self.settings.select.contains(&CheckCode::F841) {
+                self.checks
+                    .extend(checks::check_unused_variables(&self.scopes[index]));
+            }
+        }
+    }
+
     fn check_dead_scopes(&mut self) {
         if !self.settings.select.contains(&CheckCode::F822)
             && !self.settings.select.contains(&CheckCode::F401)
@@ -1264,7 +1155,7 @@ pub fn check_ast(
     python_ast: &Suite,
     content: &str,
     settings: &Settings,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
     path: &str,
 ) -> Vec<Check> {
     let mut checker = Checker::new(settings, autofix, path, content);
@@ -1279,6 +1170,7 @@ pub fn check_ast(
     // Check any deferred statements.
     checker.check_deferred_functions();
     checker.check_deferred_lambdas();
+    checker.check_deferred_assignments();
     let mut allocator = vec![];
     checker.check_deferred_annotations(path, &mut allocator);
 

src/checks.rs

@@ -21,6 +21,8 @@ pub enum CheckCode {
     F541,
     F601,
     F602,
+    F621,
+    F622,
     F631,
     F634,
     F704,
@@ -54,6 +56,8 @@ impl FromStr for CheckCode {
             "F541" => Ok(CheckCode::F541),
             "F601" => Ok(CheckCode::F601),
             "F602" => Ok(CheckCode::F602),
+            "F621" => Ok(CheckCode::F621),
+            "F622" => Ok(CheckCode::F622),
             "F631" => Ok(CheckCode::F631),
             "F634" => Ok(CheckCode::F634),
             "F704" => Ok(CheckCode::F704),
@@ -88,6 +92,8 @@ impl CheckCode {
             CheckCode::F541 => "F541",
             CheckCode::F601 => "F601",
             CheckCode::F602 => "F602",
+            CheckCode::F621 => "F621",
+            CheckCode::F622 => "F622",
             CheckCode::F631 => "F631",
             CheckCode::F634 => "F634",
             CheckCode::F704 => "F704",
@@ -120,6 +126,8 @@ impl CheckCode {
             CheckCode::F541 => &LintSource::AST,
             CheckCode::F601 => &LintSource::AST,
             CheckCode::F602 => &LintSource::AST,
+            CheckCode::F621 => &LintSource::AST,
+            CheckCode::F622 => &LintSource::AST,
             CheckCode::F631 => &LintSource::AST,
             CheckCode::F634 => &LintSource::AST,
             CheckCode::F704 => &LintSource::AST,
@@ -170,7 +178,9 @@ pub enum CheckKind {
     NotIsTest,
     RaiseNotImplemented,
     ReturnOutsideFunction,
+    TooManyExpressionsInStarredAssignment,
     TrueFalseComparison(bool, RejectedCmpop),
+    TwoStarredExpressions,
     UndefinedExport(String),
     UndefinedLocal(String),
     UndefinedName(String),
@@ -202,7 +212,11 @@ impl CheckKind {
             CheckKind::NotIsTest => "NotIsTest",
             CheckKind::RaiseNotImplemented => "RaiseNotImplemented",
             CheckKind::ReturnOutsideFunction => "ReturnOutsideFunction",
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "TooManyExpressionsInStarredAssignment"
+            }
             CheckKind::TrueFalseComparison(_, _) => "TrueFalseComparison",
+            CheckKind::TwoStarredExpressions => "TwoStarredExpressions",
             CheckKind::UndefinedExport(_) => "UndefinedExport",
             CheckKind::UndefinedLocal(_) => "UndefinedLocal",
             CheckKind::UndefinedName(_) => "UndefinedName",
@@ -234,7 +248,9 @@ impl CheckKind {
             CheckKind::NotIsTest => &CheckCode::E714,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
+            CheckKind::TooManyExpressionsInStarredAssignment => &CheckCode::F621,
             CheckKind::TrueFalseComparison(_, _) => &CheckCode::E712,
+            CheckKind::TwoStarredExpressions => &CheckCode::F622,
             CheckKind::UndefinedExport(_) => &CheckCode::F822,
             CheckKind::UndefinedLocal(_) => &CheckCode::F823,
             CheckKind::UndefinedName(_) => &CheckCode::F821,
@@ -295,6 +311,9 @@ impl CheckKind {
             CheckKind::ReturnOutsideFunction => {
                 "a `return` statement outside of a function/method".to_string()
             }
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "too many expressions in star-unpacking assignment".to_string()
+            }
             CheckKind::TrueFalseComparison(value, op) => match *value {
                 true => match op {
                     RejectedCmpop::Eq => {
@@ -313,6 +332,7 @@ impl CheckKind {
                     }
                 },
             },
+            CheckKind::TwoStarredExpressions => "two starred expressions in assignment".to_string(),
             CheckKind::UndefinedExport(name) => {
                 format!("Undefined name `{name}` in `__all__`")
             }
@@ -356,7 +376,9 @@ impl CheckKind {
             CheckKind::NoneComparison(_) => false,
             CheckKind::RaiseNotImplemented => false,
             CheckKind::ReturnOutsideFunction => false,
+            CheckKind::TooManyExpressionsInStarredAssignment => false,
             CheckKind::TrueFalseComparison(_, _) => false,
+            CheckKind::TwoStarredExpressions => false,
             CheckKind::UndefinedExport(_) => false,
             CheckKind::UndefinedLocal(_) => false,
             CheckKind::UndefinedName(_) => false,

src/lib.rs

@@ -1,18 +1,15 @@
 extern crate core;
 
-mod ast_ops;
+mod ast;
 mod autofix;
-mod builtins;
 mod cache;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;
-mod fixer;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
 mod pyproject;
-mod relocator;
+mod python;
 pub mod settings;
-mod visitor;

src/linter.rs

@@ -4,15 +4,16 @@ use anyhow::Result;
 use log::debug;
 use rustpython_parser::parser;
 
-use crate::autofix::fix_file;
+use crate::autofix::fixer;
+use crate::autofix::fixer::fix_file;
 use crate::check_ast::check_ast;
 use crate::check_lines::check_lines;
 use crate::checks::{Check, LintSource};
 use crate::message::Message;
 use crate::settings::Settings;
-use crate::{autofix, cache, fs};
+use crate::{cache, fs};
 
-fn check_path(path: &Path, settings: &Settings, autofix: &autofix::Mode) -> Result<Vec<Check>> {
+fn check_path(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> Result<Vec<Check>> {
     // Read the file from disk.
     let contents = fs::read_file(path)?;
 
@@ -40,7 +41,7 @@ pub fn lint_path(
     path: &Path,
     settings: &Settings,
     mode: &cache::Mode,
-    autofix: &autofix::Mode,
+    autofix: &fixer::Mode,
 ) -> Result<Vec<Message>> {
     let metadata = path.metadata()?;
 
@@ -57,7 +58,7 @@ pub fn lint_path(
     let mut checks = check_path(path, settings, autofix)?;
 
     // Apply autofix.
-    if matches!(autofix, autofix::Mode::Apply) {
+    if matches!(autofix, fixer::Mode::Apply) {
         fix_file(&mut checks, &contents, path)?;
     };
 
@@ -84,9 +85,10 @@ mod tests {
     use anyhow::Result;
     use rustpython_parser::ast::Location;
 
+    use crate::autofix::fixer;
     use crate::checks::{Check, CheckCode, CheckKind, Fix, RejectedCmpop};
     use crate::linter::check_path;
-    use crate::{autofix, settings};
+    use crate::settings;
 
     #[test]
     fn e402() -> Result<()> {
@@ -97,7 +99,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E402]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
@@ -122,7 +124,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E501]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
@@ -147,7 +149,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E711]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -179,7 +181,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E712]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -222,7 +224,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E713]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
@@ -247,7 +249,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E714]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
@@ -272,7 +274,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::E731]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -305,7 +307,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F401]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -342,7 +344,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F403]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -373,7 +375,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F541]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -410,7 +412,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F601]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         let expected = vec![
             Check {
@@ -446,7 +448,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F602]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         let expected = vec![Check {
             kind: CheckKind::MultiValueRepeatedKeyVariable("a".to_string()),
@@ -461,6 +463,30 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn f622() -> Result<()> {
+        let actual = check_path(
+            Path::new("./resources/test/fixtures/F622.py"),
+            &settings::Settings {
+                line_length: 88,
+                exclude: vec![],
+                select: BTreeSet::from([CheckCode::F622]),
+            },
+            &fixer::Mode::Generate,
+        )?;
+        let expected = vec![Check {
+            kind: CheckKind::TwoStarredExpressions,
+            location: Location::new(1, 1),
+            fix: None,
+        }];
+        assert_eq!(actual.len(), expected.len());
+        for i in 0..actual.len() {
+            assert_eq!(actual[i], expected[i]);
+        }
+
+        Ok(())
+    }
+
     #[test]
     fn f631() -> Result<()> {
         let mut actual = check_path(
@@ -470,7 +496,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F631]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -502,7 +528,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F634]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -534,7 +560,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F704]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -571,7 +597,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F706]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -603,7 +629,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F707]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -640,7 +666,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F821]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -687,7 +713,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F822]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
@@ -712,7 +738,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F823]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![Check {
@@ -737,7 +763,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F831]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -774,7 +800,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F841]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -806,18 +832,18 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::F901]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::RaiseNotImplemented,
-                location: Location::new(2, 5),
+                location: Location::new(2, 25),
                 fix: None,
             },
             Check {
                 kind: CheckKind::RaiseNotImplemented,
-                location: Location::new(6, 5),
+                location: Location::new(6, 11),
                 fix: None,
             },
         ];
@@ -838,7 +864,7 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::R001]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
@@ -1060,13 +1086,13 @@ mod tests {
                 exclude: vec![],
                 select: BTreeSet::from([CheckCode::R002]),
             },
-            &autofix::Mode::Generate,
+            &fixer::Mode::Generate,
         )?;
         actual.sort_by_key(|check| check.location);
         let expected = vec![
             Check {
                 kind: CheckKind::NoAssertEquals,
-                location: Location::new(1, 19),
+                location: Location::new(1, 5),
                 fix: Some(Fix {
                     content: "assertEqual".to_string(),
                     start: Location::new(1, 6),
@@ -1076,7 +1102,7 @@ mod tests {
             },
             Check {
                 kind: CheckKind::NoAssertEquals,
-                location: Location::new(2, 18),
+                location: Location::new(2, 5),
                 fix: Some(Fix {
                     content: "assertEqual".to_string(),
                     start: Location::new(2, 6),

src/main.rs

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

src/message.rs

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

src/pyproject.rs

@@ -272,6 +272,8 @@ other-attribute = 1
                     CheckCode::F541,
                     CheckCode::F601,
                     CheckCode::F602,
+                    CheckCode::F621,
+                    CheckCode::F622,
                     CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,

src/python.rs

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

src/python/builtins.rs

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

src/python/typing.rs

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

src/settings.rs

@@ -57,6 +57,8 @@ impl Settings {
                     CheckCode::F541,
                     CheckCode::F601,
                     CheckCode::F602,
+                    CheckCode::F621,
+                    CheckCode::F622,
                     CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,
@@ -92,4 +94,8 @@ impl Settings {
             self.select.remove(code);
         }
     }
+
+    pub fn exclude(&mut self, exclude: Vec<Pattern>) {
+        self.exclude = exclude;
+    }
 }