Try out rust-python-parser (nom-based)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.53"
+version = "0.0.56"
 edition = "2021"
 
 [lib]
@@ -27,12 +27,15 @@ once_cell = { version = "1.13.1" }
 path-absolutize = { version = "3.0.13", features = ["once_cell_cache"] }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
+rustpython-ast = { features = ["unparse"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
 rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
+rustpython-common = { git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }
 update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
 walkdir = { version = "2.3.2" }
+python-parser = "0.2.0"
 
 [dev-dependencies]
 insta = { version = "1.19.1", features = ["yaml"] }

README.md

@@ -213,6 +213,7 @@ ruff also implements some of the most popular Flake8 plugins natively, including
 - [`flake8-builtins`](https://pypi.org/project/flake8-builtins/)
 - [`flake8-super`](https://pypi.org/project/flake8-super/)
 - [`flake8-print`](https://pypi.org/project/flake8-print/)
+- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (partial)
 
 Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis Flake8:
 
@@ -222,59 +223,64 @@ Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis F
 
 ## Rules
 
-| Code | Name | Message |
-| ---- | ----- | ------- |
-| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file |
-| E501 | LineTooLong | Line too long (89 > 88 characters) |
-| E711 | NoneComparison | Comparison to `None` should be `cond is None` |
-| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` |
-| E713 | NotInTest | Test for membership should be `not in` |
-| E714 | NotIsTest | Test for object identity should be `is not` |
-| E721 | TypeComparison | do not compare types, use `isinstance()` |
-| E722 | DoNotUseBareExcept | Do not use bare `except` |
-| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def |
-| E741 | AmbiguousVariableName | ambiguous variable name '...' |
-| E742 | AmbiguousClassName | ambiguous class name '...' |
-| E743 | AmbiguousFunctionName | ambiguous function name '...' |
-| E902 | IOError | ... |
-| E999 | SyntaxError | SyntaxError: ... |
-| F401 | UnusedImport | `...` imported but unused |
-| F402 | ImportShadowedByLoopVar | import '...' from line 1 shadowed by loop variable |
-| F403 | ImportStarUsed | `from ... import *` used; unable to detect undefined names |
-| F404 | LateFutureImport | from __future__ imports must occur at the beginning of the file |
-| F405 | ImportStarUsage | '...' may be undefined, or defined from star imports: ... |
-| F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level |
-| F407 | FutureFeatureNotDefined | future feature '...' is not defined |
-| F541 | FStringMissingPlaceholders | f-string without any placeholders |
-| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |
-| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |
-| F621 | TooManyExpressionsInStarredAssignment | too many expressions in star-unpacking assignment |
-| F622 | TwoStarredExpressions | two starred expressions in assignment |
-| F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |
-| F632 | IsLiteral | use ==/!= to compare constant literals |
-| F633 | InvalidPrintSyntax | use of >> is invalid with print function |
-| F634 | IfTuple | If test is a tuple, which is always `True` |
-| F701 | BreakOutsideLoop | `break` outside loop |
-| F702 | ContinueOutsideLoop | `continue` not properly in loop |
-| F704 | YieldOutsideFunction | a `yield` or `yield from` statement outside of a function/method |
-| F706 | ReturnOutsideFunction | a `return` statement outside of a function/method |
-| F707 | DefaultExceptNotLast | an `except:` block as not the last exception handler |
-| F722 | ForwardAnnotationSyntaxError | syntax error in forward annotation '...' |
-| F821 | UndefinedName | Undefined name `...` |
-| F822 | UndefinedExport | Undefined name `...` in `__all__` |
-| F823 | UndefinedLocal | Local variable `...` referenced before assignment |
-| F831 | DuplicateArgumentName | Duplicate argument name in function definition |
-| F841 | UnusedVariable | Local variable `...` is assigned to but never used |
-| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` |
-| A001 | BuiltinVariableShadowing | Variable `...` is shadowing a python builtin |
-| A002 | BuiltinArgumentShadowing | Argument `...` is shadowing a python builtin |
-| A003 | BuiltinAttributeShadowing | class attribute `...` is shadowing a python builtin |
-| SPR001 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` |
-| T201 | PrintFound | `print` found |
-| T203 | PPrintFound | `pprint` found` |
-| R001 | UselessObjectInheritance | Class `...` inherits from object |
-| R002 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |
-| M001 | UnusedNOQA | Unused `noqa` directive |
+The ✅ emoji indicates a rule is enabled by default.
+
+The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` command-line option.
+
+| Code | Name | Message |     |     |
+| ---- | ---- | ------- | --- | --- |
+| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file | ✅ |  |
+| E501 | LineTooLong | Line too long (89 > 88 characters) | ✅ |  |
+| E711 | NoneComparison | Comparison to `None` should be `cond is None` | ✅ |  |
+| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` | ✅ |  |
+| E713 | NotInTest | Test for membership should be `not in` | ✅ |  |
+| E714 | NotIsTest | Test for object identity should be `is not` | ✅ |  |
+| E721 | TypeComparison | Do not compare types, use `isinstance()` | ✅ |  |
+| E722 | DoNotUseBareExcept | Do not use bare `except` | ✅ |  |
+| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def | ✅ |  |
+| E741 | AmbiguousVariableName | Ambiguous variable name: `...` | ✅ |  |
+| E742 | AmbiguousClassName | Ambiguous class name: `...` | ✅ |  |
+| E743 | AmbiguousFunctionName | Ambiguous function name: `...` | ✅ |  |
+| E902 | IOError | IOError: `...` | ✅ |  |
+| E999 | SyntaxError | SyntaxError: `...` | ✅ |  |
+| F401 | UnusedImport | `...` imported but unused | ✅ | 🛠 |
+| F402 | ImportShadowedByLoopVar | Import `...` from line 1 shadowed by loop variable | ✅ |  |
+| F403 | ImportStarUsed | `from ... import *` used; unable to detect undefined names | ✅ |  |
+| F404 | LateFutureImport | `from __future__` imports must occur at the beginning of the file | ✅ |  |
+| F405 | ImportStarUsage | `...` may be undefined, or defined from star imports: `...` | ✅ |  |
+| F406 | ImportStarNotPermitted | `from ... import *` only allowed at module level | ✅ |  |
+| F407 | FutureFeatureNotDefined | Future feature `...` is not defined | ✅ |  |
+| F541 | FStringMissingPlaceholders | f-string without any placeholders | ✅ |  |
+| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated | ✅ |  |
+| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated | ✅ |  |
+| F621 | ExpressionsInStarAssignment | Too many expressions in star-unpacking assignment | ✅ |  |
+| F622 | TwoStarredExpressions | Two starred expressions in assignment | ✅ |  |
+| F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` | ✅ |  |
+| F632 | IsLiteral | Use `==` and `!=` to compare constant literals | ✅ |  |
+| F633 | InvalidPrintSyntax | Use of `>>` is invalid with `print` function | ✅ |  |
+| F634 | IfTuple | If test is a tuple, which is always `True` | ✅ |  |
+| F701 | BreakOutsideLoop | `break` outside loop | ✅ |  |
+| F702 | ContinueOutsideLoop | `continue` not properly in loop | ✅ |  |
+| F704 | YieldOutsideFunction | `yield` or `yield from` statement outside of a function/method | ✅ |  |
+| F706 | ReturnOutsideFunction | `return` statement outside of a function/method | ✅ |  |
+| F707 | DefaultExceptNotLast | An `except:` block as not the last exception handler | ✅ |  |
+| F722 | ForwardAnnotationSyntaxError | Syntax error in forward annotation: `...` | ✅ |  |
+| F821 | UndefinedName | Undefined name `...` | ✅ |  |
+| F822 | UndefinedExport | Undefined name `...` in `__all__` | ✅ |  |
+| F823 | UndefinedLocal | Local variable `...` referenced before assignment | ✅ |  |
+| F831 | DuplicateArgumentName | Duplicate argument name in function definition | ✅ |  |
+| F841 | UnusedVariable | Local variable `...` is assigned to but never used | ✅ |  |
+| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` | ✅ |  |
+| A001 | BuiltinVariableShadowing | Variable `...` is shadowing a python builtin |  |  |
+| A002 | BuiltinArgumentShadowing | Argument `...` is shadowing a python builtin |  |  |
+| A003 | BuiltinAttributeShadowing | Class attribute `...` is shadowing a python builtin |  |  |
+| SPR001 | SuperCallWithParameters | Use `super()` instead of `super(__class__, self)` |  | 🛠 |
+| T201 | PrintFound | `print` found |  | 🛠 |
+| T203 | PPrintFound | `pprint` found |  | 🛠 |
+| U001 | UselessMetaclassType | `__metaclass__ = type` is implied |  | 🛠 |
+| R001 | UselessObjectInheritance | Class `...` inherits from object |  | 🛠 |
+| R002 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |  | 🛠 |
+| M001 | UnusedNOQA | Unused `noqa` directive |  | 🛠 |
 
 ## Integrations
 
@@ -477,4 +483,4 @@ MIT
 ## Contributing
 
 Contributions are welcome and hugely appreciated. To get started, check out the
-[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTORS.md).
+[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTING.md).

examples/generate_rules_table.rs

@@ -1,19 +1,27 @@
 /// Generate a Markdown-compatible table of supported lint rules.
-use ruff::checks::{CheckCode, ALL_CHECK_CODES};
+use ruff::checks::{CheckCode, ALL_CHECK_CODES, DEFAULT_CHECK_CODES};
 
 fn main() {
     let mut check_codes: Vec<CheckCode> = ALL_CHECK_CODES.to_vec();
     check_codes.sort();
 
-    println!("| Code | Name | Message |");
-    println!("| ---- | ----- | ------- |");
+    println!("| Code | Name | Message |     |     |");
+    println!("| ---- | ---- | ------- | --- | --- |");
     for check_code in check_codes {
         let check_kind = check_code.kind();
+        let default_token = if DEFAULT_CHECK_CODES.contains(&check_code) {
+            "✅"
+        } else {
+            ""
+        };
+        let fix_token = if check_kind.fixable() { "🛠" } else { "" };
         println!(
-            "| {} | {} | {} |",
+            "| {} | {} | {} | {} | {} |",
             check_kind.code().as_str(),
             check_kind.name(),
-            check_kind.body()
+            check_kind.body(),
+            default_token,
+            fix_token
         );
     }
 }

examples/generate_source_code.rs

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

examples/parse_python.rs

@@ -0,0 +1,23 @@
+/// Print the AST for a given Python file.
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::Parser;
+
+use ruff::fs;
+
+#[derive(Debug, Parser)]
+struct Cli {
+    #[arg(required = true)]
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let contents = fs::read_file(&cli.file)?;
+    let ast = python_parser::file_input(python_parser::make_strspan(&contents))?.1;
+    println!("{:?}", ast);
+
+    Ok(())
+}

output.py

@@ -0,0 +1,37 @@
+from collections import Counter
+
+
+def f() -> None:
+    """Docstring goes here."""
+    for x in range(5):
+        print(x)
+    else:
+        print("Nope!")
+
+
+a = {
+    "a",
+    "b",
+    "c",
+    "a",
+    "b",
+    "c",
+    "a",
+    "b",
+    "c",
+    "a",
+    "b",
+    "c",
+    "a",
+    "b",
+    "c",
+    "a",
+    "b",
+    "c",
+    "a",
+    "b",
+    "c",
+}
+
+cls(title=title, before_text=before_text, after_text=after_text, before_description=before_description, after_description=after_description, transform_type=transform_type)
+

resources/test/fixtures/SPR001.py

@@ -20,3 +20,46 @@ class Child(Parent):
             Child,
             self,
         ).method()  # wrong
+
+
+class BaseClass:
+    def f(self):
+        print("f")
+
+
+def defined_outside(self):
+    super(MyClass, self).f()  # CANNOT use super()
+
+
+class MyClass(BaseClass):
+    def normal(self):
+        super(MyClass, self).f()  # can use super()
+        super().f()
+
+    def different_argument(self, other):
+        super(MyClass, other).f()  # CANNOT use super()
+
+    def comprehension_scope(self):
+        [super(MyClass, self).f() for x in [1]]  # CANNOT use super()
+
+    def inner_functions(self):
+        def outer_argument():
+            super(MyClass, self).f()  # CANNOT use super()
+
+        def inner_argument(self):
+            super(MyClass, self).f()  # can use super()
+            super().f()
+
+        outer_argument()
+        inner_argument(self)
+
+    def inner_class(self):
+        class InnerClass:
+            super(MyClass, self).f()  # CANNOT use super()
+
+            def method(inner_self):
+                super(MyClass, self).f()  # CANNOT use super()
+
+        InnerClass().method()
+
+    defined_outside = defined_outside

resources/test/fixtures/U001.py

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

src/ast/checks.rs

@@ -3,16 +3,14 @@ use std::collections::BTreeSet;
 use itertools::izip;
 use regex::Regex;
 use rustpython_parser::ast::{
-    Arg, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind, Keyword,
-    Location, Stmt, StmtKind, Unaryop,
+    Arg, ArgData, Arguments, Cmpop, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprKind,
+    Stmt, StmtKind, Unaryop,
 };
 
-use crate::ast::operations::SourceCodeLocator;
 use crate::ast::types::{
     Binding, BindingKind, CheckLocator, FunctionScope, Range, Scope, ScopeKind,
 };
-use crate::autofix::{fixer, fixes};
-use crate::checks::{Check, CheckKind, Fix, RejectedCmpop};
+use crate::checks::{Check, CheckKind, RejectedCmpop};
 use crate::python::builtins::BUILTINS;
 
 /// Check IfTuple compliance.
@@ -116,6 +114,26 @@ pub fn check_do_not_assign_lambda(value: &Expr, location: Range) -> Option<Check
     }
 }
 
+/// Check UselessMetaclassType compliance.
+pub fn check_useless_metaclass_type(
+    targets: &Vec<Expr>,
+    value: &Expr,
+    location: Range,
+) -> Option<Check> {
+    if targets.len() == 1 {
+        if let ExprKind::Name { id, .. } = targets.first().map(|expr| &expr.node).unwrap() {
+            if id == "__metaclass__" {
+                if let ExprKind::Name { id, .. } = &value.node {
+                    if id == "type" {
+                        return Some(Check::new(CheckKind::UselessMetaclassType, location));
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
 fn is_ambiguous_name(name: &str) -> bool {
     name == "l" || name == "I" || name == "O"
 }
@@ -158,13 +176,9 @@ pub fn check_ambiguous_function_name(name: &str, location: Range) -> Option<Chec
 
 /// 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 {
@@ -175,22 +189,10 @@ pub fn check_useless_object_inheritance(
                         kind: BindingKind::Builtin,
                         ..
                     }) => {
-                        let mut check = Check::new(
+                        return Some(Check::new(
                             CheckKind::UselessObjectInheritance(name.to_string()),
                             Range::from_located(expr),
-                        );
-                        if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                            if let Some(fix) = fixes::remove_class_def_base(
-                                locator,
-                                &stmt.location,
-                                expr.location,
-                                bases,
-                                keywords,
-                            ) {
-                                check.amend(fix);
-                            }
-                        }
-                        return Some(check);
+                        ));
                     }
                     _ => {}
                 }
@@ -278,28 +280,15 @@ pub fn check_duplicate_arguments(arguments: &Arguments) -> Vec<Check> {
 }
 
 /// Check AssertEquals compliance.
-pub fn check_assert_equals(expr: &Expr, autofix: &fixer::Mode) -> Option<Check> {
+pub fn check_assert_equals(expr: &Expr) -> 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, Range::from_located(expr));
-                    if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                        check.amend(Fix {
-                            content: "assertEqual".to_string(),
-                            location: Location::new(
-                                expr.location.row(),
-                                expr.location.column() + 1,
-                            ),
-                            end_location: Location::new(
-                                expr.location.row(),
-                                expr.location.column() + 1 + "assertEquals".len(),
-                            ),
-                            applied: false,
-                        });
-                    }
-                    return Some(check);
+                    return Some(Check::new(
+                        CheckKind::NoAssertEquals,
+                        Range::from_located(expr),
+                    ));
                 }
             }
         }
@@ -576,10 +565,7 @@ pub fn check_starred_expressions(
     if check_too_many_expressions {
         if let Some(starred_index) = starred_index {
             if starred_index >= 1 << 8 || elts.len() - starred_index > 1 << 24 {
-                return Some(Check::new(
-                    CheckKind::TooManyExpressionsInStarredAssignment,
-                    location,
-                ));
+                return Some(Check::new(CheckKind::ExpressionsInStarAssignment, location));
             }
         }
     }
@@ -696,39 +682,94 @@ pub fn check_builtin_shadowing(
     }
 }
 
+/// Returns `true` if a call is an argumented `super` invocation.
+pub fn is_super_call_with_arguments(func: &Expr, args: &Vec<Expr>) -> bool {
+    // Check: is this a `super` call?
+    if let ExprKind::Name { id, .. } = &func.node {
+        id == "super" && !args.is_empty()
+    } else {
+        false
+    }
+}
+
 // flake8-super
 /// Check that `super()` has no args
 pub fn check_super_args(
+    scope: &Scope,
+    parents: &[&Stmt],
     expr: &Expr,
     func: &Expr,
     args: &Vec<Expr>,
-    locator: &mut SourceCodeLocator,
-    autofix: &fixer::Mode,
 ) -> Option<Check> {
-    if let ExprKind::Name { id, .. } = &func.node {
-        if id == "super" && !args.is_empty() {
-            let mut check = Check::new(
-                CheckKind::SuperCallWithParameters,
-                Range::from_located(expr),
-            );
-            if matches!(autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                if let Some(fix) = fixes::remove_super_arguments(locator, expr) {
-                    check.amend(fix);
+    if !is_super_call_with_arguments(func, args) {
+        return None;
+    }
+
+    // Check: are we in a Function scope?
+    if !matches!(scope.kind, ScopeKind::Function { .. }) {
+        return None;
+    }
+
+    let mut parents = parents.iter().rev();
+
+    // For a `super` invocation to be unnecessary, the first argument needs to match the enclosing
+    // class, and the second argument needs to match the first argument to the enclosing function.
+    if let [first_arg, second_arg] = args.as_slice() {
+        // Find the enclosing function definition (if any).
+        if let Some(StmtKind::FunctionDef {
+            args: parent_args, ..
+        }) = parents
+            .find(|stmt| matches!(stmt.node, StmtKind::FunctionDef { .. }))
+            .map(|stmt| &stmt.node)
+        {
+            // Extract the name of the first argument to the enclosing function.
+            if let Some(ArgData {
+                arg: parent_arg, ..
+            }) = parent_args.args.first().map(|expr| &expr.node)
+            {
+                // Find the enclosing class definition (if any).
+                if let Some(StmtKind::ClassDef {
+                    name: parent_name, ..
+                }) = parents
+                    .find(|stmt| matches!(stmt.node, StmtKind::ClassDef { .. }))
+                    .map(|stmt| &stmt.node)
+                {
+                    if let (
+                        ExprKind::Name {
+                            id: first_arg_id, ..
+                        },
+                        ExprKind::Name {
+                            id: second_arg_id, ..
+                        },
+                    ) = (&first_arg.node, &second_arg.node)
+                    {
+                        if first_arg_id == parent_name && second_arg_id == parent_arg {
+                            return Some(Check::new(
+                                CheckKind::SuperCallWithParameters,
+                                Range::from_located(expr),
+                            ));
+                        }
+                    }
                 }
             }
-            return Some(check);
         }
     }
+
     None
 }
 
 // flake8-print
 /// Check whether a function call is a `print` or `pprint` invocation
-pub fn check_print_call(expr: &Expr, func: &Expr) -> Option<Check> {
+pub fn check_print_call(
+    expr: &Expr,
+    func: &Expr,
+    check_print: bool,
+    check_pprint: bool,
+) -> Option<Check> {
     if let ExprKind::Name { id, .. } = &func.node {
-        if id == "print" {
+        if check_print && id == "print" {
             return Some(Check::new(CheckKind::PrintFound, Range::from_located(expr)));
-        } else if id == "pprint" {
+        } else if check_pprint && id == "pprint" {
             return Some(Check::new(
                 CheckKind::PPrintFound,
                 Range::from_located(expr),
@@ -738,7 +779,7 @@ pub fn check_print_call(expr: &Expr, func: &Expr) -> Option<Check> {
 
     if let ExprKind::Attribute { value, attr, .. } = &func.node {
         if let ExprKind::Name { id, .. } = &value.node {
-            if id == "pprint" && attr == "pprint" {
+            if check_pprint && id == "pprint" && attr == "pprint" {
                 return Some(Check::new(
                     CheckKind::PPrintFound,
                     Range::from_located(expr),

src/check_ast.rs

@@ -19,9 +19,9 @@ use crate::ast::types::{
 };
 use crate::ast::visitor::{walk_excepthandler, Visitor};
 use crate::ast::{checks, operations, visitor};
-use crate::autofix::fixes::remove_stmt;
 use crate::autofix::{fixer, fixes};
 use crate::checks::{Check, CheckCode, CheckKind};
+use crate::plugins;
 use crate::python::builtins::{BUILTINS, MAGIC_GLOBALS};
 use crate::python::future::ALL_FEATURE_NAMES;
 use crate::python::typing;
@@ -31,18 +31,22 @@ pub const GLOBAL_SCOPE_INDEX: usize = 0;
 
 static DUNDER_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"__[^\s]+__").unwrap());
 
-struct Checker<'a> {
+pub struct Checker<'a> {
     // Input data.
-    locator: SourceCodeLocator<'a>,
-    settings: &'a Settings,
-    autofix: &'a fixer::Mode,
     path: &'a Path,
+    // TODO(charlie): Separate immutable from mutable state. (None of these should ever change.)
+    pub(crate) locator: SourceCodeLocator<'a>,
+    pub(crate) settings: &'a Settings,
+    pub(crate) autofix: &'a fixer::Mode,
     // Computed checks.
     checks: Vec<Check>,
+    // Edit tracking.
+    // TODO(charlie): Instead of exposing deletions, wrap in a public API.
+    pub(crate) deletions: BTreeSet<usize>,
     // Retain all scopes and parent nodes, along with a stack of indexes to track which are active
     // at various points in time.
-    parents: Vec<&'a Stmt>,
-    parent_stack: Vec<usize>,
+    pub(crate) parents: Vec<&'a Stmt>,
+    pub(crate) parent_stack: Vec<usize>,
     scopes: Vec<Scope>,
     scope_stack: Vec<usize>,
     dead_scopes: Vec<usize>,
@@ -51,7 +55,7 @@ struct Checker<'a> {
     deferred_functions: Vec<(&'a Stmt, Vec<usize>, Vec<usize>)>,
     deferred_lambdas: Vec<(&'a Expr, Vec<usize>, Vec<usize>)>,
     deferred_assignments: Vec<usize>,
-    // Derivative state.
+    // Internal, derivative state.
     in_f_string: Option<Range>,
     in_annotation: bool,
     in_literal: bool,
@@ -59,8 +63,6 @@ struct Checker<'a> {
     seen_docstring: bool,
     futures_allowed: bool,
     annotations_future_enabled: bool,
-    // Edit tracking.
-    deletions: BTreeSet<usize>,
 }
 
 impl<'a> Checker<'a> {
@@ -217,8 +219,7 @@ where
             StmtKind::Global { names } | StmtKind::Nonlocal { names } => {
                 let global_scope_id = self.scopes[GLOBAL_SCOPE_INDEX].id;
 
-                let current_scope =
-                    &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+                let current_scope = self.current_scope();
                 let current_scope_id = current_scope.id;
                 if current_scope_id != global_scope_id {
                     for name in names {
@@ -235,7 +236,7 @@ where
                     }
                 }
 
-                if self.settings.select.contains(&CheckCode::E741) {
+                if self.settings.enabled.contains(&CheckCode::E741) {
                     let location = self.locate_check(Range::from_located(stmt));
                     self.checks.extend(
                         names.iter().filter_map(|name| {
@@ -245,7 +246,7 @@ where
                 }
             }
             StmtKind::Break => {
-                if self.settings.select.contains(&CheckCode::F701) {
+                if self.settings.enabled.contains(&CheckCode::F701) {
                     if let Some(check) = checks::check_break_outside_loop(
                         stmt,
                         &self.parents,
@@ -257,7 +258,7 @@ where
                 }
             }
             StmtKind::Continue => {
-                if self.settings.select.contains(&CheckCode::F702) {
+                if self.settings.enabled.contains(&CheckCode::F702) {
                     if let Some(check) = checks::check_continue_outside_loop(
                         stmt,
                         &self.parents,
@@ -282,7 +283,7 @@ where
                 args,
                 ..
             } => {
-                if self.settings.select.contains(&CheckCode::E743) {
+                if self.settings.enabled.contains(&CheckCode::E743) {
                     if let Some(check) = checks::check_ambiguous_function_name(
                         name,
                         self.locate_check(Range::from_located(stmt)),
@@ -343,7 +344,7 @@ where
             StmtKind::Return { .. } => {
                 if self
                     .settings
-                    .select
+                    .enabled
                     .contains(CheckKind::ReturnOutsideFunction.code())
                 {
                     if let Some(scope_index) = self.scope_stack.last().cloned() {
@@ -366,23 +367,11 @@ where
                 decorator_list,
                 ..
             } => {
-                if self.settings.select.contains(&CheckCode::R001) {
-                    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);
-                    }
+                if self.settings.enabled.contains(&CheckCode::R001) {
+                    plugins::useless_object_inheritance(self, stmt, name, bases, keywords);
                 }
 
-                if self.settings.select.contains(&CheckCode::E742) {
+                if self.settings.enabled.contains(&CheckCode::E742) {
                     if let Some(check) = checks::check_ambiguous_class_name(
                         name,
                         self.locate_check(Range::from_located(stmt)),
@@ -411,7 +400,7 @@ where
             StmtKind::Import { names } => {
                 if self
                     .settings
-                    .select
+                    .enabled
                     .contains(CheckKind::ModuleImportNotAtTopOfFile.code())
                     && self.seen_non_import
                     && stmt.location.column() == 1
@@ -471,7 +460,7 @@ where
             } => {
                 if self
                     .settings
-                    .select
+                    .enabled
                     .contains(CheckKind::ModuleImportNotAtTopOfFile.code())
                     && self.seen_non_import
                     && stmt.location.column() == 1
@@ -509,7 +498,7 @@ where
                             self.annotations_future_enabled = true;
                         }
 
-                        if self.settings.select.contains(&CheckCode::F407)
+                        if self.settings.enabled.contains(&CheckCode::F407)
                             && !ALL_FEATURE_NAMES.contains(&alias.node.name.deref())
                         {
                             self.checks.push(Check::new(
@@ -518,7 +507,7 @@ where
                             ));
                         }
 
-                        if self.settings.select.contains(&CheckCode::F404) && !self.futures_allowed
+                        if self.settings.enabled.contains(&CheckCode::F404) && !self.futures_allowed
                         {
                             self.checks.push(Check::new(
                                 CheckKind::LateFutureImport,
@@ -541,7 +530,7 @@ where
                             },
                         );
 
-                        if self.settings.select.contains(&CheckCode::F406) {
+                        if self.settings.enabled.contains(&CheckCode::F406) {
                             let scope = &self.scopes
                                 [*(self.scope_stack.last().expect("No current scope found."))];
                             if !matches!(scope.kind, ScopeKind::Module) {
@@ -552,7 +541,7 @@ where
                             }
                         }
 
-                        if self.settings.select.contains(&CheckCode::F403) {
+                        if self.settings.enabled.contains(&CheckCode::F403) {
                             self.checks.push(Check::new(
                                 CheckKind::ImportStarUsed(module_name.to_string()),
                                 self.locate_check(Range::from_located(stmt)),
@@ -585,7 +574,7 @@ where
                 }
             }
             StmtKind::Raise { exc, .. } => {
-                if self.settings.select.contains(&CheckCode::F901) {
+                if self.settings.enabled.contains(&CheckCode::F901) {
                     if let Some(expr) = exc {
                         if let Some(check) = checks::check_raise_not_implemented(expr) {
                             self.checks.push(check);
@@ -597,33 +586,24 @@ where
                 self.handle_node_load(target);
             }
             StmtKind::If { test, .. } => {
-                if self.settings.select.contains(&CheckCode::F634) {
-                    if let Some(check) =
-                        checks::check_if_tuple(test, self.locate_check(Range::from_located(stmt)))
-                    {
-                        self.checks.push(check);
-                    }
+                if self.settings.enabled.contains(&CheckCode::F634) {
+                    plugins::if_tuple(self, stmt, test);
                 }
             }
             StmtKind::Assert { test, .. } => {
-                if self.settings.select.contains(CheckKind::AssertTuple.code()) {
-                    if let Some(check) = checks::check_assert_tuple(
-                        test,
-                        self.locate_check(Range::from_located(stmt)),
-                    ) {
-                        self.checks.push(check);
-                    }
+                if self.settings.enabled.contains(&CheckCode::F631) {
+                    plugins::assert_tuple(self, stmt, test);
                 }
             }
             StmtKind::Try { handlers, .. } => {
-                if self.settings.select.contains(&CheckCode::F707) {
+                if self.settings.enabled.contains(&CheckCode::F707) {
                     if let Some(check) = checks::check_default_except_not_last(handlers) {
                         self.checks.push(check);
                     }
                 }
             }
-            StmtKind::Assign { value, .. } => {
-                if self.settings.select.contains(&CheckCode::E731) {
+            StmtKind::Assign { targets, value, .. } => {
+                if self.settings.enabled.contains(&CheckCode::E731) {
                     if let Some(check) = checks::check_do_not_assign_lambda(
                         value,
                         self.locate_check(Range::from_located(stmt)),
@@ -631,9 +611,12 @@ where
                         self.checks.push(check);
                     }
                 }
+                if self.settings.enabled.contains(&CheckCode::U001) {
+                    plugins::useless_metaclass_type(self, stmt, value, targets);
+                }
             }
             StmtKind::AnnAssign { value, .. } => {
-                if self.settings.select.contains(&CheckCode::E731) {
+                if self.settings.enabled.contains(&CheckCode::E731) {
                     if let Some(value) = value {
                         if let Some(check) = checks::check_do_not_assign_lambda(
                             value,
@@ -713,9 +696,9 @@ where
             ExprKind::Tuple { elts, ctx } | ExprKind::List { elts, ctx } => {
                 if matches!(ctx, ExprContext::Store) {
                     let check_too_many_expressions =
-                        self.settings.select.contains(&CheckCode::F621);
+                        self.settings.enabled.contains(&CheckCode::F621);
                     let check_two_starred_expressions =
-                        self.settings.select.contains(&CheckCode::F622);
+                        self.settings.enabled.contains(&CheckCode::F622);
                     if let Some(check) = checks::check_starred_expressions(
                         elts,
                         check_too_many_expressions,
@@ -729,7 +712,7 @@ where
             ExprKind::Name { id, ctx } => match ctx {
                 ExprContext::Load => self.handle_node_load(expr),
                 ExprContext::Store => {
-                    if self.settings.select.contains(&CheckCode::E741) {
+                    if self.settings.enabled.contains(&CheckCode::E741) {
                         if let Some(check) = checks::check_ambiguous_variable_name(
                             id,
                             self.locate_check(Range::from_located(expr)),
@@ -740,63 +723,25 @@ where
 
                     self.check_builtin_shadowing(id, Range::from_located(expr), true);
 
-                    let parent =
-                        self.parents[*(self.parent_stack.last().expect("No parent found."))];
-                    self.handle_node_store(expr, parent);
+                    self.handle_node_store(expr, self.current_parent());
                 }
                 ExprContext::Del => self.handle_node_delete(expr),
             },
             ExprKind::Call { func, args, .. } => {
-                if self.settings.select.contains(&CheckCode::R002) {
-                    if let Some(check) = checks::check_assert_equals(func, self.autofix) {
-                        self.checks.push(check)
-                    }
+                if self.settings.enabled.contains(&CheckCode::R002) {
+                    plugins::assert_equals(self, func);
                 }
 
                 // flake8-super
-                if self.settings.select.contains(&CheckCode::SPR001) {
-                    if let Some(check) =
-                        checks::check_super_args(expr, func, args, &mut self.locator, self.autofix)
-                    {
-                        self.checks.push(check)
-                    }
+                if self.settings.enabled.contains(&CheckCode::SPR001) {
+                    plugins::super_call_with_parameters(self, expr, func, args);
                 }
 
                 // flake8-print
-                if self.settings.select.contains(&CheckCode::T201)
-                    || self.settings.select.contains(&CheckCode::T203)
+                if self.settings.enabled.contains(&CheckCode::T201)
+                    || self.settings.enabled.contains(&CheckCode::T203)
                 {
-                    if let Some(mut check) = checks::check_print_call(expr, func) {
-                        if matches!(self.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
-                            let context = self.binding_context();
-                            if matches!(
-                                self.parents[context.defined_by].node,
-                                StmtKind::Expr { .. }
-                            ) {
-                                let deleted: Vec<&Stmt> = self
-                                    .deletions
-                                    .iter()
-                                    .map(|index| self.parents[*index])
-                                    .collect();
-
-                                match remove_stmt(
-                                    self.parents[context.defined_by],
-                                    context.defined_in.map(|index| self.parents[index]),
-                                    &deleted,
-                                ) {
-                                    Ok(fix) => {
-                                        if fix.content.is_empty() || fix.content == "pass" {
-                                            self.deletions.insert(context.defined_by);
-                                        }
-                                        check.amend(fix)
-                                    }
-                                    Err(e) => error!("Failed to fix unused imports: {}", e),
-                                }
-                            }
-                        }
-
-                        self.checks.push(check)
-                    }
+                    plugins::print_call(self, expr, func);
                 }
 
                 if let ExprKind::Name { id, ctx } = &func.node {
@@ -815,8 +760,8 @@ where
                 }
             }
             ExprKind::Dict { keys, .. } => {
-                let check_repeated_literals = self.settings.select.contains(&CheckCode::F601);
-                let check_repeated_variables = self.settings.select.contains(&CheckCode::F602);
+                let check_repeated_literals = self.settings.enabled.contains(&CheckCode::F601);
+                let check_repeated_variables = self.settings.enabled.contains(&CheckCode::F602);
                 if check_repeated_literals || check_repeated_variables {
                     self.checks.extend(checks::check_repeated_keys(
                         keys,
@@ -827,11 +772,10 @@ where
                 }
             }
             ExprKind::Yield { .. } | ExprKind::YieldFrom { .. } | ExprKind::Await { .. } => {
-                let scope =
-                    &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+                let scope = self.current_scope();
                 if self
                     .settings
-                    .select
+                    .enabled
                     .contains(CheckKind::YieldOutsideFunction.code())
                     && matches!(scope.kind, ScopeKind::Class | ScopeKind::Module)
                 {
@@ -845,7 +789,7 @@ where
                 if self.in_f_string.is_none()
                     && self
                         .settings
-                        .select
+                        .enabled
                         .contains(CheckKind::FStringMissingPlaceholders.code())
                     && !values
                         .iter()
@@ -863,28 +807,13 @@ where
                 op: Operator::RShift,
                 ..
             } => {
-                if self.settings.select.contains(&CheckCode::F633) {
-                    if let ExprKind::Name { id, .. } = &left.node {
-                        if id == "print" {
-                            let scope = &self.scopes
-                                [*(self.scope_stack.last().expect("No current scope found."))];
-                            if let Some(Binding {
-                                kind: BindingKind::Builtin,
-                                ..
-                            }) = scope.values.get("print")
-                            {
-                                self.checks.push(Check::new(
-                                    CheckKind::InvalidPrintSyntax,
-                                    Range::from_located(left),
-                                ));
-                            }
-                        }
-                    }
+                if self.settings.enabled.contains(&CheckCode::F633) {
+                    plugins::invalid_print_syntax(self, left);
                 }
             }
             ExprKind::UnaryOp { op, operand } => {
-                let check_not_in = self.settings.select.contains(&CheckCode::E713);
-                let check_not_is = self.settings.select.contains(&CheckCode::E714);
+                let check_not_in = self.settings.enabled.contains(&CheckCode::E713);
+                let check_not_is = self.settings.enabled.contains(&CheckCode::E714);
                 if check_not_in || check_not_is {
                     self.checks.extend(checks::check_not_tests(
                         op,
@@ -900,8 +829,8 @@ where
                 ops,
                 comparators,
             } => {
-                let check_none_comparisons = self.settings.select.contains(&CheckCode::E711);
-                let check_true_false_comparisons = self.settings.select.contains(&CheckCode::E712);
+                let check_none_comparisons = self.settings.enabled.contains(&CheckCode::E711);
+                let check_true_false_comparisons = self.settings.enabled.contains(&CheckCode::E712);
                 if check_none_comparisons || check_true_false_comparisons {
                     self.checks.extend(checks::check_literal_comparisons(
                         left,
@@ -913,7 +842,7 @@ where
                     ));
                 }
 
-                if self.settings.select.contains(&CheckCode::F632) {
+                if self.settings.enabled.contains(&CheckCode::F632) {
                     self.checks.extend(checks::check_is_literal(
                         left,
                         ops,
@@ -922,7 +851,7 @@ where
                     ));
                 }
 
-                if self.settings.select.contains(&CheckCode::E721) {
+                if self.settings.enabled.contains(&CheckCode::E721) {
                     self.checks.extend(checks::check_type_comparison(
                         ops,
                         comparators,
@@ -1116,7 +1045,7 @@ where
     fn visit_excepthandler(&mut self, excepthandler: &'b Excepthandler) {
         match &excepthandler.node {
             ExcepthandlerKind::ExceptHandler { type_, name, .. } => {
-                if self.settings.select.contains(&CheckCode::E722) && type_.is_none() {
+                if self.settings.enabled.contains(&CheckCode::E722) && type_.is_none() {
                     self.checks.push(Check::new(
                         CheckKind::DoNotUseBareExcept,
                         Range::from_located(excepthandler),
@@ -1124,7 +1053,7 @@ where
                 }
                 match name {
                     Some(name) => {
-                        if self.settings.select.contains(&CheckCode::E741) {
+                        if self.settings.enabled.contains(&CheckCode::E741) {
                             if let Some(check) = checks::check_ambiguous_variable_name(
                                 name,
                                 self.locate_check(Range::from_located(excepthandler)),
@@ -1139,11 +1068,7 @@ where
                             false,
                         );
 
-                        let scope = &self.scopes
-                            [*(self.scope_stack.last().expect("No current scope found."))];
-                        if scope.values.contains_key(name) {
-                            let parent = self.parents
-                                [*(self.parent_stack.last().expect("No parent found."))];
+                        if self.current_scope().values.contains_key(name) {
                             self.handle_node_store(
                                 &Expr::new(
                                     excepthandler.location,
@@ -1153,15 +1078,11 @@ where
                                         ctx: ExprContext::Store,
                                     },
                                 ),
-                                parent,
+                                self.current_parent(),
                             );
                         }
 
-                        let parent =
-                            self.parents[*(self.parent_stack.last().expect("No parent found."))];
-                        let scope = &self.scopes
-                            [*(self.scope_stack.last().expect("No current scope found."))];
-                        let definition = scope.values.get(name).cloned();
+                        let definition = self.current_scope().values.get(name).cloned();
                         self.handle_node_store(
                             &Expr::new(
                                 excepthandler.location,
@@ -1171,7 +1092,7 @@ where
                                     ctx: ExprContext::Store,
                                 },
                             ),
-                            parent,
+                            self.current_parent(),
                         );
 
                         walk_excepthandler(self, excepthandler);
@@ -1179,7 +1100,7 @@ where
                         let scope = &mut self.scopes
                             [*(self.scope_stack.last().expect("No current scope found."))];
                         if let Some(binding) = &scope.values.remove(name) {
-                            if self.settings.select.contains(&CheckCode::F841)
+                            if self.settings.enabled.contains(&CheckCode::F841)
                                 && binding.used.is_none()
                             {
                                 self.checks.push(Check::new(
@@ -1200,7 +1121,7 @@ where
     }
 
     fn visit_arguments(&mut self, arguments: &'b Arguments) {
-        if self.settings.select.contains(&CheckCode::F831) {
+        if self.settings.enabled.contains(&CheckCode::F831) {
             self.checks
                 .extend(checks::check_duplicate_arguments(arguments));
         }
@@ -1234,7 +1155,7 @@ where
             },
         );
 
-        if self.settings.select.contains(&CheckCode::E741) {
+        if self.settings.enabled.contains(&CheckCode::E741) {
             if let Some(check) = checks::check_ambiguous_variable_name(
                 &arg.node.arg,
                 self.locate_check(Range::from_located(arg)),
@@ -1254,6 +1175,10 @@ impl CheckLocator for Checker<'_> {
 }
 
 impl<'a> Checker<'a> {
+    pub fn add_check(&mut self, check: Check) {
+        self.checks.push(check);
+    }
+
     fn push_parent(&mut self, parent: &'a Stmt) {
         self.parent_stack.push(self.parents.len());
         self.parents.push(parent);
@@ -1303,7 +1228,15 @@ impl<'a> Checker<'a> {
         }
     }
 
-    fn binding_context(&self) -> BindingContext {
+    pub fn current_scope(&self) -> &Scope {
+        &self.scopes[*(self.scope_stack.last().expect("No current scope found."))]
+    }
+
+    pub fn current_parent(&self) -> &'a Stmt {
+        self.parents[*(self.parent_stack.last().expect("No parent found."))]
+    }
+
+    pub fn binding_context(&self) -> BindingContext {
         let mut rev = self.parent_stack.iter().rev().fuse();
         let defined_by = *rev.next().expect("Expected to bind within a statement.");
         let defined_in = rev.next().cloned();
@@ -1320,7 +1253,7 @@ impl<'a> Checker<'a> {
         let binding = match scope.values.get(&name) {
             None => binding,
             Some(existing) => {
-                if self.settings.select.contains(&CheckCode::F402)
+                if self.settings.enabled.contains(&CheckCode::F402)
                     && matches!(binding.kind, BindingKind::LoopVar)
                     && matches!(
                         existing.kind,
@@ -1374,27 +1307,27 @@ impl<'a> Checker<'a> {
             }
 
             if import_starred {
-                if self.settings.select.contains(&CheckCode::F405) {
+                if self.settings.enabled.contains(&CheckCode::F405) {
                     let mut from_list = vec![];
                     for scope_index in self.scope_stack.iter().rev() {
                         let scope = &self.scopes[*scope_index];
                         for (name, binding) in scope.values.iter() {
                             if matches!(binding.kind, BindingKind::StarImportation) {
-                                from_list.push(name.as_str());
+                                from_list.push(name.to_string());
                             }
                         }
                     }
                     from_list.sort();
 
                     self.checks.push(Check::new(
-                        CheckKind::ImportStarUsage(id.clone(), from_list.join(", ")),
+                        CheckKind::ImportStarUsage(id.clone(), from_list),
                         self.locate_check(Range::from_located(expr)),
                     ));
                 }
                 return;
             }
 
-            if self.settings.select.contains(&CheckCode::F821) {
+            if self.settings.enabled.contains(&CheckCode::F821) {
                 // Allow __path__.
                 if self.path.ends_with("__init__.py") && id == "__path__" {
                     return;
@@ -1412,7 +1345,7 @@ impl<'a> Checker<'a> {
             let current =
                 &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
 
-            if self.settings.select.contains(&CheckCode::F823)
+            if self.settings.enabled.contains(&CheckCode::F823)
                 && matches!(current.kind, ScopeKind::Function(_))
                 && !current.values.contains_key(id)
             {
@@ -1512,7 +1445,7 @@ impl<'a> Checker<'a> {
 
             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)
+            if scope.values.remove(id).is_none() && self.settings.enabled.contains(&CheckCode::F821)
             {
                 self.checks.push(Check::new(
                     CheckKind::UndefinedName(id.clone()),
@@ -1538,7 +1471,7 @@ impl<'a> Checker<'a> {
             if let Ok(mut expr) = parser::parse_expression(expression, "<filename>") {
                 relocate_expr(&mut expr, location);
                 allocator.push(expr);
-            } else if self.settings.select.contains(&CheckCode::F722) {
+            } else if self.settings.enabled.contains(&CheckCode::F722) {
                 self.checks.push(Check::new(
                     CheckKind::ForwardAnnotationSyntaxError(expression.to_string()),
                     self.locate_check(location),
@@ -1593,7 +1526,7 @@ impl<'a> Checker<'a> {
     }
 
     fn check_deferred_assignments(&mut self) {
-        if self.settings.select.contains(&CheckCode::F841) {
+        if self.settings.enabled.contains(&CheckCode::F841) {
             while let Some(index) = self.deferred_assignments.pop() {
                 self.checks.extend(checks::check_unused_variables(
                     &self.scopes[index],
@@ -1605,9 +1538,9 @@ impl<'a> Checker<'a> {
     }
 
     fn check_dead_scopes(&mut self) {
-        if !self.settings.select.contains(&CheckCode::F401)
-            && !self.settings.select.contains(&CheckCode::F405)
-            && !self.settings.select.contains(&CheckCode::F822)
+        if !self.settings.enabled.contains(&CheckCode::F401)
+            && !self.settings.enabled.contains(&CheckCode::F405)
+            && !self.settings.enabled.contains(&CheckCode::F822)
         {
             return;
         }
@@ -1621,7 +1554,7 @@ impl<'a> Checker<'a> {
                 _ => None,
             });
 
-            if self.settings.select.contains(&CheckCode::F822)
+            if self.settings.enabled.contains(&CheckCode::F822)
                 && !scope.import_starred
                 && !self.path.ends_with("__init__.py")
             {
@@ -1639,13 +1572,13 @@ impl<'a> Checker<'a> {
                 }
             }
 
-            if self.settings.select.contains(&CheckCode::F405) && scope.import_starred {
+            if self.settings.enabled.contains(&CheckCode::F405) && scope.import_starred {
                 if let Some(all_binding) = all_binding {
                     if let Some(names) = all_names {
                         let mut from_list = vec![];
                         for (name, binding) in scope.values.iter() {
                             if matches!(binding.kind, BindingKind::StarImportation) {
-                                from_list.push(name.as_str());
+                                from_list.push(name.to_string());
                             }
                         }
                         from_list.sort();
@@ -1653,7 +1586,7 @@ impl<'a> Checker<'a> {
                         for name in names {
                             if !scope.values.contains_key(name) {
                                 self.checks.push(Check::new(
-                                    CheckKind::ImportStarUsage(name.clone(), from_list.join(", ")),
+                                    CheckKind::ImportStarUsage(name.clone(), from_list.clone()),
                                     self.locate_check(all_binding.range),
                                 ));
                             }
@@ -1662,7 +1595,7 @@ impl<'a> Checker<'a> {
                 }
             }
 
-            if self.settings.select.contains(&CheckCode::F401) {
+            if self.settings.enabled.contains(&CheckCode::F401) {
                 // Collect all unused imports by location. (Multiple unused imports at the same
                 // location indicates an `import from`.)
                 let mut unused: BTreeMap<(ImportKind, usize, Option<usize>), Vec<&str>> =
@@ -1741,11 +1674,11 @@ impl<'a> Checker<'a> {
     }
 
     fn check_builtin_shadowing(&mut self, name: &str, location: Range, is_attribute: bool) {
-        let scope = &self.scopes[*(self.scope_stack.last().expect("No current scope found."))];
+        let scope = self.current_scope();
 
         // flake8-builtins
         if is_attribute && matches!(scope.kind, ScopeKind::Class) {
-            if self.settings.select.contains(&CheckCode::A003) {
+            if self.settings.enabled.contains(&CheckCode::A003) {
                 if let Some(check) = checks::check_builtin_shadowing(
                     name,
                     self.locate_check(location),
@@ -1754,7 +1687,7 @@ impl<'a> Checker<'a> {
                     self.checks.push(check);
                 }
             }
-        } else if self.settings.select.contains(&CheckCode::A001) {
+        } else if self.settings.enabled.contains(&CheckCode::A001) {
             if let Some(check) = checks::check_builtin_shadowing(
                 name,
                 self.locate_check(location),
@@ -1766,7 +1699,7 @@ impl<'a> Checker<'a> {
     }
 
     fn check_builtin_arg_shadowing(&mut self, name: &str, location: Range) {
-        if self.settings.select.contains(&CheckCode::A002) {
+        if self.settings.enabled.contains(&CheckCode::A002) {
             if let Some(check) = checks::check_builtin_shadowing(
                 name,
                 self.locate_check(location),

src/check_lines.rs

@@ -32,8 +32,8 @@ pub fn check_lines(
     settings: &Settings,
     autofix: &fixer::Mode,
 ) {
-    let enforce_line_too_long = settings.select.contains(&CheckCode::E501);
-    let enforce_noqa = settings.select.contains(&CheckCode::M001);
+    let enforce_line_too_long = settings.enabled.contains(&CheckCode::E501);
+    let enforce_noqa = settings.enabled.contains(&CheckCode::M001);
 
     let mut noqa_directives: BTreeMap<usize, (Directive, Vec<&str>)> = BTreeMap::new();
 

src/checks.rs

@@ -2,6 +2,7 @@ use std::str::FromStr;
 
 use crate::ast::types::Range;
 use anyhow::Result;
+use itertools::Itertools;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
 
@@ -52,7 +53,7 @@ pub const DEFAULT_CHECK_CODES: [CheckCode; 42] = [
     CheckCode::F901,
 ];
 
-pub const ALL_CHECK_CODES: [CheckCode; 51] = [
+pub const ALL_CHECK_CODES: [CheckCode; 52] = [
     // pycodestyle
     CheckCode::E402,
     CheckCode::E501,
@@ -106,11 +107,13 @@ pub const ALL_CHECK_CODES: [CheckCode; 51] = [
     // flake8-print
     CheckCode::T201,
     CheckCode::T203,
-    // Meta
-    CheckCode::M001,
+    // pyupgrade
+    CheckCode::U001,
     // Refactor
     CheckCode::R001,
     CheckCode::R002,
+    // Meta
+    CheckCode::M001,
 ];
 
 #[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize, Hash, PartialOrd, Ord)]
@@ -168,6 +171,8 @@ pub enum CheckCode {
     // flake8-print
     T201,
     T203,
+    // pyupgrade
+    U001,
     // Refactor
     R001,
     R002,
@@ -230,6 +235,11 @@ impl FromStr for CheckCode {
             "A003" => Ok(CheckCode::A003),
             // flake8-super
             "SPR001" => Ok(CheckCode::SPR001),
+            // flake8-print
+            "T201" => Ok(CheckCode::T201),
+            "T203" => Ok(CheckCode::T203),
+            // pyupgrade
+            "U001" => Ok(CheckCode::U001),
             // Refactor
             "R001" => Ok(CheckCode::R001),
             "R002" => Ok(CheckCode::R002),
@@ -296,6 +306,8 @@ impl CheckCode {
             // flake8-print
             CheckCode::T201 => "T201",
             CheckCode::T203 => "T203",
+            // pyupgrade
+            CheckCode::U001 => "U001",
             // Refactor
             CheckCode::R001 => "R001",
             CheckCode::R002 => "R002",
@@ -329,20 +341,22 @@ impl CheckCode {
             CheckCode::E741 => CheckKind::AmbiguousVariableName("...".to_string()),
             CheckCode::E742 => CheckKind::AmbiguousClassName("...".to_string()),
             CheckCode::E743 => CheckKind::AmbiguousFunctionName("...".to_string()),
-            CheckCode::E902 => CheckKind::IOError("...".to_string()),
-            CheckCode::E999 => CheckKind::SyntaxError("...".to_string()),
+            CheckCode::E902 => CheckKind::IOError("IOError: `...`".to_string()),
+            CheckCode::E999 => CheckKind::SyntaxError("`...`".to_string()),
             // pyflakes
             CheckCode::F401 => CheckKind::UnusedImport("...".to_string()),
             CheckCode::F402 => CheckKind::ImportShadowedByLoopVar("...".to_string(), 1),
             CheckCode::F403 => CheckKind::ImportStarUsed("...".to_string()),
             CheckCode::F404 => CheckKind::LateFutureImport,
-            CheckCode::F405 => CheckKind::ImportStarUsage("...".to_string(), "...".to_string()),
+            CheckCode::F405 => {
+                CheckKind::ImportStarUsage("...".to_string(), vec!["...".to_string()])
+            }
             CheckCode::F406 => CheckKind::ImportStarNotPermitted("...".to_string()),
             CheckCode::F407 => CheckKind::FutureFeatureNotDefined("...".to_string()),
             CheckCode::F541 => CheckKind::FStringMissingPlaceholders,
             CheckCode::F601 => CheckKind::MultiValueRepeatedKeyLiteral,
             CheckCode::F602 => CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
-            CheckCode::F621 => CheckKind::TooManyExpressionsInStarredAssignment,
+            CheckCode::F621 => CheckKind::ExpressionsInStarAssignment,
             CheckCode::F622 => CheckKind::TwoStarredExpressions,
             CheckCode::F631 => CheckKind::AssertTuple,
             CheckCode::F632 => CheckKind::IsLiteral,
@@ -369,6 +383,8 @@ impl CheckCode {
             // flake8-print
             CheckCode::T201 => CheckKind::PrintFound,
             CheckCode::T203 => CheckKind::PPrintFound,
+            // pyupgrade
+            CheckCode::U001 => CheckKind::UselessMetaclassType,
             // Refactor
             CheckCode::R001 => CheckKind::UselessObjectInheritance("...".to_string()),
             CheckCode::R002 => CheckKind::NoAssertEquals,
@@ -393,7 +409,6 @@ pub enum RejectedCmpop {
 
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum CheckKind {
-    UnusedNOQA(Option<String>),
     AmbiguousClassName(String),
     AmbiguousFunctionName(String),
     AmbiguousVariableName(String),
@@ -404,14 +419,15 @@ pub enum CheckKind {
     DoNotAssignLambda,
     DoNotUseBareExcept,
     DuplicateArgumentName,
-    ForwardAnnotationSyntaxError(String),
+    ExpressionsInStarAssignment,
     FStringMissingPlaceholders,
+    ForwardAnnotationSyntaxError(String),
     FutureFeatureNotDefined(String),
     IOError(String),
     IfTuple,
     ImportShadowedByLoopVar(String, usize),
     ImportStarNotPermitted(String),
-    ImportStarUsage(String, String),
+    ImportStarUsage(String, Vec<String>),
     ImportStarUsed(String),
     InvalidPrintSyntax,
     IsLiteral,
@@ -427,7 +443,6 @@ pub enum CheckKind {
     RaiseNotImplemented,
     ReturnOutsideFunction,
     SyntaxError(String),
-    TooManyExpressionsInStarredAssignment,
     TrueFalseComparison(bool, RejectedCmpop),
     TwoStarredExpressions,
     TypeComparison,
@@ -435,7 +450,9 @@ pub enum CheckKind {
     UndefinedLocal(String),
     UndefinedName(String),
     UnusedImport(String),
+    UnusedNOQA(Option<String>),
     UnusedVariable(String),
+    UselessMetaclassType,
     UselessObjectInheritance(String),
     YieldOutsideFunction,
     // flake8-builtin
@@ -463,6 +480,7 @@ impl CheckKind {
             CheckKind::DoNotAssignLambda => "DoNotAssignLambda",
             CheckKind::DoNotUseBareExcept => "DoNotUseBareExcept",
             CheckKind::DuplicateArgumentName => "DuplicateArgumentName",
+            CheckKind::ExpressionsInStarAssignment => "ExpressionsInStarAssignment",
             CheckKind::FStringMissingPlaceholders => "FStringMissingPlaceholders",
             CheckKind::ForwardAnnotationSyntaxError(_) => "ForwardAnnotationSyntaxError",
             CheckKind::FutureFeatureNotDefined(_) => "FutureFeatureNotDefined",
@@ -479,16 +497,12 @@ impl CheckKind {
             CheckKind::ModuleImportNotAtTopOfFile => "ModuleImportNotAtTopOfFile",
             CheckKind::MultiValueRepeatedKeyLiteral => "MultiValueRepeatedKeyLiteral",
             CheckKind::MultiValueRepeatedKeyVariable(_) => "MultiValueRepeatedKeyVariable",
-            CheckKind::NoAssertEquals => "NoAssertEquals",
             CheckKind::NoneComparison(_) => "NoneComparison",
             CheckKind::NotInTest => "NotInTest",
             CheckKind::NotIsTest => "NotIsTest",
             CheckKind::RaiseNotImplemented => "RaiseNotImplemented",
             CheckKind::ReturnOutsideFunction => "ReturnOutsideFunction",
             CheckKind::SyntaxError(_) => "SyntaxError",
-            CheckKind::TooManyExpressionsInStarredAssignment => {
-                "TooManyExpressionsInStarredAssignment"
-            }
             CheckKind::TrueFalseComparison(_, _) => "TrueFalseComparison",
             CheckKind::TwoStarredExpressions => "TwoStarredExpressions",
             CheckKind::TypeComparison => "TypeComparison",
@@ -497,9 +511,7 @@ impl CheckKind {
             CheckKind::UndefinedName(_) => "UndefinedName",
             CheckKind::UnusedImport(_) => "UnusedImport",
             CheckKind::UnusedVariable(_) => "UnusedVariable",
-            CheckKind::UselessObjectInheritance(_) => "UselessObjectInheritance",
             CheckKind::YieldOutsideFunction => "YieldOutsideFunction",
-            CheckKind::UnusedNOQA(_) => "UnusedNOQA",
             // flake8-builtins
             CheckKind::BuiltinVariableShadowing(_) => "BuiltinVariableShadowing",
             CheckKind::BuiltinArgumentShadowing(_) => "BuiltinArgumentShadowing",
@@ -509,6 +521,13 @@ impl CheckKind {
             // flake8-print
             CheckKind::PrintFound => "PrintFound",
             CheckKind::PPrintFound => "PPrintFound",
+            // pyupgrade
+            CheckKind::UselessMetaclassType => "UselessMetaclassType",
+            // Refactor
+            CheckKind::NoAssertEquals => "NoAssertEquals",
+            CheckKind::UselessObjectInheritance(_) => "UselessObjectInheritance",
+            // Meta
+            CheckKind::UnusedNOQA(_) => "UnusedNOQA",
         }
     }
 
@@ -541,14 +560,13 @@ impl CheckKind {
             CheckKind::ModuleImportNotAtTopOfFile => &CheckCode::E402,
             CheckKind::MultiValueRepeatedKeyLiteral => &CheckCode::F601,
             CheckKind::MultiValueRepeatedKeyVariable(_) => &CheckCode::F602,
-            CheckKind::NoAssertEquals => &CheckCode::R002,
             CheckKind::NoneComparison(_) => &CheckCode::E711,
             CheckKind::NotInTest => &CheckCode::E713,
             CheckKind::NotIsTest => &CheckCode::E714,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
             CheckKind::SyntaxError(_) => &CheckCode::E999,
-            CheckKind::TooManyExpressionsInStarredAssignment => &CheckCode::F621,
+            CheckKind::ExpressionsInStarAssignment => &CheckCode::F621,
             CheckKind::TrueFalseComparison(_, _) => &CheckCode::E712,
             CheckKind::TwoStarredExpressions => &CheckCode::F622,
             CheckKind::TypeComparison => &CheckCode::E721,
@@ -556,9 +574,7 @@ impl CheckKind {
             CheckKind::UndefinedLocal(_) => &CheckCode::F823,
             CheckKind::UndefinedName(_) => &CheckCode::F821,
             CheckKind::UnusedImport(_) => &CheckCode::F401,
-            CheckKind::UnusedNOQA(_) => &CheckCode::M001,
             CheckKind::UnusedVariable(_) => &CheckCode::F841,
-            CheckKind::UselessObjectInheritance(_) => &CheckCode::R001,
             CheckKind::YieldOutsideFunction => &CheckCode::F704,
             // flake8-builtins
             CheckKind::BuiltinVariableShadowing(_) => &CheckCode::A001,
@@ -569,6 +585,13 @@ impl CheckKind {
             // flake8-print
             CheckKind::PrintFound => &CheckCode::T201,
             CheckKind::PPrintFound => &CheckCode::T203,
+            // pyupgrade
+            CheckKind::UselessMetaclassType => &CheckCode::U001,
+            // Refactor
+            CheckKind::NoAssertEquals => &CheckCode::R002,
+            CheckKind::UselessObjectInheritance(_) => &CheckCode::R001,
+            // Meta
+            CheckKind::UnusedNOQA(_) => &CheckCode::M001,
         }
     }
 
@@ -576,13 +599,13 @@ impl CheckKind {
     pub fn body(&self) -> String {
         match self {
             CheckKind::AmbiguousClassName(name) => {
-                format!("ambiguous class name '{}'", name)
+                format!("Ambiguous class name: `{}`", name)
             }
             CheckKind::AmbiguousFunctionName(name) => {
-                format!("ambiguous function name '{}'", name)
+                format!("Ambiguous function name: `{}`", name)
             }
             CheckKind::AmbiguousVariableName(name) => {
-                format!("ambiguous variable name '{}'", name)
+                format!("Ambiguous variable name: `{}`", name)
             }
             CheckKind::AssertTuple => {
                 "Assert test is a non-empty tuple, which is always `True`".to_string()
@@ -590,7 +613,7 @@ impl CheckKind {
             CheckKind::BreakOutsideLoop => "`break` outside loop".to_string(),
             CheckKind::ContinueOutsideLoop => "`continue` not properly in loop".to_string(),
             CheckKind::DefaultExceptNotLast => {
-                "an `except:` block as not the last exception handler".to_string()
+                "An `except:` block as not the last exception handler".to_string()
             }
             CheckKind::DoNotAssignLambda => {
                 "Do not assign a lambda expression, use a def".to_string()
@@ -600,19 +623,21 @@ impl CheckKind {
                 "Duplicate argument name in function definition".to_string()
             }
             CheckKind::ForwardAnnotationSyntaxError(body) => {
-                format!("syntax error in forward annotation '{body}'")
+                format!("Syntax error in forward annotation: `{body}`")
             }
             CheckKind::FStringMissingPlaceholders => {
                 "f-string without any placeholders".to_string()
             }
             CheckKind::FutureFeatureNotDefined(name) => {
-                format!("future feature '{name}' is not defined")
+                format!("Future feature `{name}` is not defined")
             }
             CheckKind::IOError(message) => message.clone(),
             CheckKind::IfTuple => "If test is a tuple, which is always `True`".to_string(),
-            CheckKind::InvalidPrintSyntax => "use of >> is invalid with print function".to_string(),
+            CheckKind::InvalidPrintSyntax => {
+                "Use of `>>` is invalid with `print` function".to_string()
+            }
             CheckKind::ImportShadowedByLoopVar(name, line) => {
-                format!("import '{name}' from line {line} shadowed by loop variable")
+                format!("Import `{name}` from line {line} shadowed by loop variable")
             }
             CheckKind::ImportStarNotPermitted(name) => {
                 format!("`from {name} import *` only allowed at module level")
@@ -621,11 +646,15 @@ impl CheckKind {
                 format!("`from {name} import *` used; unable to detect undefined names")
             }
             CheckKind::ImportStarUsage(name, sources) => {
-                format!("'{name}' may be undefined, or defined from star imports: {sources}")
+                let sources = sources
+                    .iter()
+                    .map(|source| format!("`{}`", source))
+                    .join(", ");
+                format!("`{name}` may be undefined, or defined from star imports: {sources}")
             }
-            CheckKind::IsLiteral => "use ==/!= to compare constant literals".to_string(),
+            CheckKind::IsLiteral => "Use `==` and `!=` to compare constant literals".to_string(),
             CheckKind::LateFutureImport => {
-                "from __future__ imports must occur at the beginning of the file".to_string()
+                "`from __future__` imports must occur at the beginning of the file".to_string()
             }
             CheckKind::LineTooLong(length, limit) => {
                 format!("Line too long ({length} > {limit} characters)")
@@ -639,9 +668,6 @@ impl CheckKind {
             CheckKind::MultiValueRepeatedKeyVariable(name) => {
                 format!("Dictionary key `{name}` repeated")
             }
-            CheckKind::NoAssertEquals => {
-                "`assertEquals` is deprecated, use `assertEqual` instead".to_string()
-            }
             CheckKind::NoneComparison(op) => match op {
                 RejectedCmpop::Eq => "Comparison to `None` should be `cond is None`".to_string(),
                 RejectedCmpop::NotEq => {
@@ -654,11 +680,11 @@ impl CheckKind {
                 "`raise NotImplemented` should be `raise NotImplementedError`".to_string()
             }
             CheckKind::ReturnOutsideFunction => {
-                "a `return` statement outside of a function/method".to_string()
+                "`return` statement outside of a function/method".to_string()
             }
             CheckKind::SyntaxError(message) => format!("SyntaxError: {message}"),
-            CheckKind::TooManyExpressionsInStarredAssignment => {
-                "too many expressions in star-unpacking assignment".to_string()
+            CheckKind::ExpressionsInStarAssignment => {
+                "Too many expressions in star-unpacking assignment".to_string()
             }
             CheckKind::TrueFalseComparison(value, op) => match *value {
                 true => match op {
@@ -678,8 +704,8 @@ impl CheckKind {
                     }
                 },
             },
-            CheckKind::TwoStarredExpressions => "two starred expressions in assignment".to_string(),
-            CheckKind::TypeComparison => "do not compare types, use `isinstance()`".to_string(),
+            CheckKind::TwoStarredExpressions => "Two starred expressions in assignment".to_string(),
+            CheckKind::TypeComparison => "Do not compare types, use `isinstance()`".to_string(),
             CheckKind::UndefinedExport(name) => {
                 format!("Undefined name `{name}` in `__all__`")
             }
@@ -693,16 +719,10 @@ impl CheckKind {
             CheckKind::UnusedVariable(name) => {
                 format!("Local variable `{name}` is assigned to but never used")
             }
-            CheckKind::UselessObjectInheritance(name) => {
-                format!("Class `{name}` inherits from object")
-            }
             CheckKind::YieldOutsideFunction => {
-                "a `yield` or `yield from` statement outside of a function/method".to_string()
+                "`yield` or `yield from` statement outside of a function/method".to_string()
             }
-            CheckKind::UnusedNOQA(code) => match code {
-                None => "Unused `noqa` directive".to_string(),
-                Some(code) => format!("Unused `noqa` directive for: {code}"),
-            },
+
             // flake8-builtins
             CheckKind::BuiltinVariableShadowing(name) => {
                 format!("Variable `{name}` is shadowing a python builtin")
@@ -711,7 +731,7 @@ impl CheckKind {
                 format!("Argument `{name}` is shadowing a python builtin")
             }
             CheckKind::BuiltinAttributeShadowing(name) => {
-                format!("class attribute `{name}` is shadowing a python builtin")
+                format!("Class attribute `{name}` is shadowing a python builtin")
             }
             // flake8-super
             CheckKind::SuperCallWithParameters => {
@@ -719,7 +739,21 @@ impl CheckKind {
             }
             // flake8-print
             CheckKind::PrintFound => "`print` found".to_string(),
-            CheckKind::PPrintFound => "`pprint` found`".to_string(),
+            CheckKind::PPrintFound => "`pprint` found".to_string(),
+            // pyupgrade
+            CheckKind::UselessMetaclassType => "`__metaclass__ = type` is implied".to_string(),
+            // Refactor
+            CheckKind::NoAssertEquals => {
+                "`assertEquals` is deprecated, use `assertEqual` instead".to_string()
+            }
+            CheckKind::UselessObjectInheritance(name) => {
+                format!("Class `{name}` inherits from object")
+            }
+            // Meta
+            CheckKind::UnusedNOQA(code) => match code {
+                None => "Unused `noqa` directive".to_string(),
+                Some(code) => format!("Unused `noqa` directive for: {code}"),
+            },
         }
     }
 
@@ -728,12 +762,13 @@ impl CheckKind {
         matches!(
             self,
             CheckKind::NoAssertEquals
-                | CheckKind::UselessObjectInheritance(_)
-                | CheckKind::UnusedNOQA(_)
+                | CheckKind::PPrintFound
+                | CheckKind::PrintFound
                 | CheckKind::SuperCallWithParameters
                 | CheckKind::UnusedImport(_)
-                | CheckKind::PrintFound
-                | CheckKind::PPrintFound
+                | CheckKind::UnusedNOQA(_)
+                | CheckKind::UselessMetaclassType
+                | CheckKind::UselessObjectInheritance(_)
         )
     }
 }

src/lib.rs

@@ -7,7 +7,7 @@ use rustpython_parser::lexer::LexResult;
 use crate::autofix::fixer::Mode;
 use crate::linter::{check_path, tokenize};
 use crate::message::Message;
-use crate::settings::Settings;
+use crate::settings::{RawSettings, Settings};
 
 mod ast;
 mod autofix;
@@ -15,11 +15,13 @@ pub mod cache;
 pub mod check_ast;
 mod check_lines;
 pub mod checks;
+pub mod code_gen;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
 mod noqa;
+mod plugins;
 pub mod printer;
 pub mod pyproject;
 mod python;
@@ -39,7 +41,7 @@ pub fn check(path: &Path, contents: &str) -> Result<Vec<Message>> {
         None => debug!("Unable to find pyproject.toml; using default settings..."),
     };
 
-    let settings = Settings::from_pyproject(pyproject, project_root)?;
+    let settings = Settings::from_raw(RawSettings::from_pyproject(pyproject, project_root)?);
 
     // Tokenize once.
     let tokens: Vec<LexResult> = tokenize(contents);

src/linter.rs

@@ -1,3 +1,4 @@
+use std::fs::write;
 use std::path::Path;
 
 use anyhow::Result;
@@ -7,10 +8,10 @@ use rustpython_parser::{lexer, parser};
 
 use crate::ast::types::Range;
 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, CheckCode, CheckKind, LintSource};
+use crate::code_gen::SourceGenerator;
 use crate::message::Message;
 use crate::noqa::add_noqa;
 use crate::settings::Settings;
@@ -42,7 +43,7 @@ pub(crate) fn check_path(
 
     // Run the AST-based checks.
     if settings
-        .select
+        .enabled
         .iter()
         .any(|check_code| matches!(check_code.lint_source(), LintSource::AST))
     {
@@ -51,7 +52,7 @@ pub(crate) fn check_path(
                 checks.extend(check_ast(&python_ast, contents, settings, autofix, path))
             }
             Err(parse_error) => {
-                if settings.select.contains(&CheckCode::E999) {
+                if settings.enabled.contains(&CheckCode::E999) {
                     checks.push(Check::new(
                         CheckKind::SyntaxError(parse_error.error.to_string()),
                         Range {
@@ -99,33 +100,19 @@ pub fn lint_path(
     let contents = fs::read_file(path)?;
 
     // Tokenize once.
-    let tokens: Vec<LexResult> = tokenize(&contents);
+    // let tokens: Vec<LexResult> = tokenize(&contents);
 
     // Determine the noqa line for every line in the source.
-    let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
+    // let noqa_line_for = noqa::extract_noqa_line_for(&tokens);
 
-    // Generate checks.
-    let mut checks = check_path(path, &contents, tokens, &noqa_line_for, settings, autofix)?;
+    match python_parser::file_input(python_parser::make_strspan(&contents)) {
+        Ok(x) => {}
+        Err(e) => return Err(anyhow::anyhow!("Err: failed")),
+    }
 
-    // Apply autofix.
-    if matches!(autofix, fixer::Mode::Apply) {
-        fix_file(&mut checks, &contents, path)?;
-    };
+    // let _ = parser::parse_program_tokens(tokens, "<filename>")?;
 
-    // Convert to messages.
-    let messages: Vec<Message> = checks
-        .into_iter()
-        .map(|check| Message {
-            kind: check.kind,
-            fixed: check.fix.map(|fix| fix.applied).unwrap_or_default(),
-            location: check.location,
-            end_location: check.end_location,
-            filename: path.to_string_lossy().to_string(),
-        })
-        .collect();
-    cache::set(path, &metadata, settings, autofix, &messages, mode);
-
-    Ok(messages)
+    Ok(vec![])
 }
 
 pub fn add_noqa_to_path(path: &Path, settings: &Settings) -> Result<usize> {
@@ -151,6 +138,22 @@ pub fn add_noqa_to_path(path: &Path, settings: &Settings) -> Result<usize> {
     add_noqa(&checks, &contents, &noqa_line_for, path)
 }
 
+pub fn autoformat_path(path: &Path) -> Result<()> {
+    // Read the file from disk.
+    let contents = fs::read_file(path)?;
+
+    // Tokenize once.
+    let tokens: Vec<LexResult> = tokenize(&contents);
+
+    // Generate the AST.
+    let python_ast = parser::parse_program_tokens(tokens, "<filename>")?;
+    let mut generator: SourceGenerator = Default::default();
+    generator.unparse_suite(&python_ast)?;
+    write(path, generator.generate()?)?;
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use std::path::Path;
@@ -803,4 +806,16 @@ mod tests {
         insta::assert_yaml_snapshot!(checks);
         Ok(())
     }
+
+    #[test]
+    fn u001() -> Result<()> {
+        let mut checks = check_path(
+            Path::new("./resources/test/fixtures/U001.py"),
+            &settings::Settings::for_rule(CheckCode::U001),
+            &fixer::Mode::Generate,
+        )?;
+        checks.sort_by_key(|check| check.location);
+        insta::assert_yaml_snapshot!(checks);
+        Ok(())
+    }
 }

src/main.rs

@@ -26,6 +26,8 @@ use ::ruff::pyproject::{self, StrCheckCodePair};
 use ::ruff::settings::CurrentSettings;
 use ::ruff::settings::{FilePattern, PerFileIgnore, Settings};
 use ::ruff::tell_user;
+use ruff::linter::autoformat_path;
+use ruff::settings::RawSettings;
 
 const CARGO_PKG_NAME: &str = env!("CARGO_PKG_NAME");
 const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
@@ -87,6 +89,9 @@ struct Cli {
     /// Enable automatic additions of noqa directives to failing lines.
     #[arg(long)]
     add_noqa: bool,
+    /// Enable automatic formatting.
+    #[arg(long)]
+    autoformat: bool,
     /// Regular expression matching the name of dummy variables.
     #[arg(long)]
     dummy_variable_rgx: Option<Regex>,
@@ -116,7 +121,7 @@ fn check_for_updates() {
     }
 }
 
-fn show_settings(settings: Settings) {
+fn show_settings(settings: RawSettings) {
     println!("{:#?}", CurrentSettings::from_settings(settings));
 }
 
@@ -165,7 +170,7 @@ fn run_once(
             }
             .unwrap_or_else(|(path, message)| {
                 if let Some(path) = path {
-                    if settings.select.contains(&CheckCode::E902) {
+                    if settings.enabled.contains(&CheckCode::E902) {
                         vec![Message {
                             kind: CheckKind::IOError(message),
                             fixed: false,
@@ -222,6 +227,33 @@ fn add_noqa(files: &[PathBuf], settings: &Settings) -> Result<usize> {
     Ok(modifications)
 }
 
+fn autoformat(files: &[PathBuf], settings: &Settings) -> Result<usize> {
+    // Collect all the files to format.
+    let start = Instant::now();
+    let paths: Vec<DirEntry> = files
+        .iter()
+        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
+        .flatten()
+        .collect();
+    let duration = start.elapsed();
+    debug!("Identified files to lint in: {:?}", duration);
+
+    let start = Instant::now();
+    let modifications = paths
+        .par_iter()
+        .map(|entry| {
+            let path = entry.path();
+            autoformat_path(path)
+        })
+        .flatten()
+        .count();
+
+    let duration = start.elapsed();
+    debug!("Auto-formatted files in: {:?}", duration);
+
+    Ok(modifications)
+}
+
 fn inner_main() -> Result<ExitCode> {
     let cli = Cli::parse();
 
@@ -256,7 +288,7 @@ fn inner_main() -> Result<ExitCode> {
         .map(|pair| PerFileIgnore::new(pair, &project_root))
         .collect();
 
-    let mut settings = Settings::from_pyproject(pyproject, project_root)?;
+    let mut settings = RawSettings::from_pyproject(pyproject, project_root)?;
     if !exclude.is_empty() {
         settings.exclude = exclude;
     }
@@ -267,17 +299,16 @@ fn inner_main() -> Result<ExitCode> {
         settings.per_file_ignores = per_file_ignores;
     }
     if !cli.select.is_empty() {
-        settings.clear();
-        settings.select(cli.select);
+        settings.select = cli.select;
     }
     if !cli.extend_select.is_empty() {
-        settings.select(cli.extend_select);
+        settings.extend_select = cli.extend_select;
     }
     if !cli.ignore.is_empty() {
-        settings.ignore(&cli.ignore);
+        settings.ignore = cli.ignore;
     }
     if !cli.extend_ignore.is_empty() {
-        settings.ignore(&cli.extend_ignore);
+        settings.extend_ignore = cli.extend_ignore;
     }
     if let Some(dummy_variable_rgx) = cli.dummy_variable_rgx {
         settings.dummy_variable_rgx = dummy_variable_rgx;
@@ -287,15 +318,18 @@ fn inner_main() -> Result<ExitCode> {
         eprintln!("Error: specify --show-settings or show-files (not both).");
         return Ok(ExitCode::FAILURE);
     }
-    if cli.show_files {
-        show_files(&cli.files, &settings);
-        return Ok(ExitCode::SUCCESS);
-    }
     if cli.show_settings {
         show_settings(settings);
         return Ok(ExitCode::SUCCESS);
     }
 
+    let settings = Settings::from_raw(settings);
+
+    if cli.show_files {
+        show_files(&cli.files, &settings);
+        return Ok(ExitCode::SUCCESS);
+    }
+
     cache::init()?;
 
     let mut printer = Printer::new(cli.format, cli.verbose);
@@ -308,6 +342,10 @@ fn inner_main() -> Result<ExitCode> {
             eprintln!("Warning: --no-qa is not enabled in watch mode.");
         }
 
+        if cli.autoformat {
+            eprintln!("Warning: --autoformat is not enabled in watch mode.");
+        }
+
         if cli.format != SerializationFormat::Text {
             eprintln!("Warning: --format 'text' is used in watch mode.");
         }
@@ -351,6 +389,11 @@ fn inner_main() -> Result<ExitCode> {
         if modifications > 0 {
             println!("Added {modifications} noqa directives.");
         }
+    } else if cli.autoformat {
+        let modifications = autoformat(&cli.files, &settings)?;
+        if modifications > 0 {
+            println!("Formatted {modifications} files.");
+        }
     } else {
         let messages = run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?;
         if !cli.quiet {

src/plugins.rs

@@ -0,0 +1,17 @@
+mod assert_equals;
+mod assert_tuple;
+mod if_tuple;
+mod invalid_print_syntax;
+mod print_call;
+mod super_call_with_parameters;
+mod useless_metaclass_type;
+mod useless_object_inheritance;
+
+pub use assert_equals::assert_equals;
+pub use assert_tuple::assert_tuple;
+pub use if_tuple::if_tuple;
+pub use invalid_print_syntax::invalid_print_syntax;
+pub use print_call::print_call;
+pub use super_call_with_parameters::super_call_with_parameters;
+pub use useless_metaclass_type::useless_metaclass_type;
+pub use useless_object_inheritance::useless_object_inheritance;

src/plugins/assert_equals.rs

@@ -0,0 +1,23 @@
+use rustpython_ast::{Expr, Location};
+
+use crate::ast::checks;
+use crate::autofix::fixer;
+use crate::check_ast::Checker;
+use crate::checks::Fix;
+
+pub fn assert_equals(checker: &mut Checker, expr: &Expr) {
+    if let Some(mut check) = checks::check_assert_equals(expr) {
+        if matches!(checker.autofix, fixer::Mode::Generate | fixer::Mode::Apply) {
+            check.amend(Fix {
+                content: "assertEqual".to_string(),
+                location: Location::new(expr.location.row(), expr.location.column() + 1),
+                end_location: Location::new(
+                    expr.location.row(),
+                    expr.location.column() + 1 + "assertEquals".len(),
+                ),
+                applied: false,
+            });
+        }
+        checker.add_check(check);
+    }
+}

src/plugins/assert_tuple.rs

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

src/plugins/if_tuple.rs

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

src/plugins/invalid_print_syntax.rs

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

src/plugins/print_call.rs

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

src/plugins/super_call_with_parameters.rs

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

src/plugins/useless_metaclass_type.rs

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

src/plugins/useless_object_inheritance.rs

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

src/pyproject.rs

@@ -29,10 +29,17 @@ pub fn load_config(pyproject: &Option<PathBuf>) -> Result<Config> {
 pub struct Config {
     pub line_length: Option<usize>,
     pub exclude: Option<Vec<String>>,
-    pub extend_exclude: Option<Vec<String>>,
+    #[serde(default)]
+    pub extend_exclude: Vec<String>,
     pub select: Option<Vec<CheckCode>>,
-    pub ignore: Option<Vec<CheckCode>>,
-    pub per_file_ignores: Option<Vec<StrCheckCodePair>>,
+    #[serde(default)]
+    pub extend_select: Vec<CheckCode>,
+    #[serde(default)]
+    pub ignore: Vec<CheckCode>,
+    #[serde(default)]
+    pub extend_ignore: Vec<CheckCode>,
+    #[serde(default)]
+    pub per_file_ignores: Vec<StrCheckCodePair>,
     pub dummy_variable_rgx: Option<String>,
 }
 
@@ -175,10 +182,12 @@ mod tests {
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
                 })
             })
@@ -197,10 +206,12 @@ line-length = 79
                 ruff: Some(Config {
                     line_length: Some(79),
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
                 })
             })
@@ -219,10 +230,12 @@ exclude = ["foo.py"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: Some(vec!["foo.py".to_string()]),
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
                 })
             })
@@ -241,10 +254,12 @@ select = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: Some(vec![CheckCode::E501]),
-                    ignore: None,
-                    per_file_ignores: None,
+                    extend_select: vec![],
+                    ignore: vec![],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
                 })
             })
@@ -254,6 +269,7 @@ select = ["E501"]
             r#"
 [tool.black]
 [tool.ruff]
+extend-select = ["M001"]
 ignore = ["E501"]
 "#,
         )?;
@@ -263,10 +279,12 @@ ignore = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    extend_exclude: None,
+                    extend_exclude: vec![],
                     select: None,
-                    ignore: Some(vec![CheckCode::E501]),
-                    per_file_ignores: None,
+                    extend_select: vec![CheckCode::M001],
+                    ignore: vec![CheckCode::E501],
+                    extend_ignore: vec![],
+                    per_file_ignores: vec![],
                     dummy_variable_rgx: None,
                 })
             })
@@ -325,14 +343,16 @@ other-attribute = 1
             Config {
                 line_length: Some(88),
                 exclude: None,
-                extend_exclude: Some(vec![
+                extend_exclude: vec![
                     "excluded.py".to_string(),
                     "migrations".to_string(),
                     "directory/also_excluded.py".to_string(),
-                ]),
+                ],
                 select: None,
-                ignore: None,
-                per_file_ignores: None,
+                extend_select: vec![],
+                ignore: vec![],
+                extend_ignore: vec![],
+                per_file_ignores: vec![],
                 dummy_variable_rgx: None,
             }
         );

src/settings.rs

@@ -51,56 +51,18 @@ impl PerFileIgnore {
 }
 
 #[derive(Debug)]
-pub struct Settings {
-    pub pyproject: Option<PathBuf>,
-    pub project_root: Option<PathBuf>,
-    pub line_length: usize,
+pub struct RawSettings {
+    pub dummy_variable_rgx: Regex,
     pub exclude: Vec<FilePattern>,
     pub extend_exclude: Vec<FilePattern>,
-    pub select: BTreeSet<CheckCode>,
+    pub extend_ignore: Vec<CheckCode>,
+    pub extend_select: Vec<CheckCode>,
+    pub ignore: Vec<CheckCode>,
+    pub line_length: usize,
     pub per_file_ignores: Vec<PerFileIgnore>,
-    pub dummy_variable_rgx: Regex,
-}
-
-impl Settings {
-    pub fn for_rule(check_code: CheckCode) -> Self {
-        Self {
-            pyproject: None,
-            project_root: None,
-            line_length: 88,
-            exclude: vec![],
-            extend_exclude: vec![],
-            select: BTreeSet::from([check_code]),
-            per_file_ignores: vec![],
-            dummy_variable_rgx: DEFAULT_DUMMY_VARIABLE_RGX.clone(),
-        }
-    }
-
-    pub fn for_rules(check_codes: Vec<CheckCode>) -> Self {
-        Self {
-            pyproject: None,
-            project_root: None,
-            line_length: 88,
-            exclude: vec![],
-            extend_exclude: vec![],
-            select: BTreeSet::from_iter(check_codes),
-            per_file_ignores: vec![],
-            dummy_variable_rgx: DEFAULT_DUMMY_VARIABLE_RGX.clone(),
-        }
-    }
-}
-
-impl Hash for Settings {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.line_length.hash(state);
-        self.dummy_variable_rgx.as_str().hash(state);
-        for value in self.select.iter() {
-            value.hash(state);
-        }
-        for value in self.per_file_ignores.iter() {
-            value.hash(state);
-        }
-    }
+    pub project_root: Option<PathBuf>,
+    pub pyproject: Option<PathBuf>,
+    pub select: Vec<CheckCode>,
 }
 
 static DEFAULT_EXCLUDE: Lazy<Vec<FilePattern>> = Lazy::new(|| {
@@ -130,14 +92,18 @@ static DEFAULT_EXCLUDE: Lazy<Vec<FilePattern>> = Lazy::new(|| {
 static DEFAULT_DUMMY_VARIABLE_RGX: Lazy<Regex> =
     Lazy::new(|| Regex::new("^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$").unwrap());
 
-impl Settings {
+impl RawSettings {
     pub fn from_pyproject(
         pyproject: Option<PathBuf>,
         project_root: Option<PathBuf>,
     ) -> Result<Self> {
         let config = load_config(&pyproject)?;
-        let mut settings = Settings {
-            line_length: config.line_length.unwrap_or(88),
+        Ok(RawSettings {
+            dummy_variable_rgx: match config.dummy_variable_rgx {
+                Some(pattern) => Regex::new(&pattern)
+                    .map_err(|e| anyhow!("Invalid dummy-variable-rgx value: {e}"))?,
+                None => DEFAULT_DUMMY_VARIABLE_RGX.clone(),
+            },
             exclude: config
                 .exclude
                 .map(|paths| {
@@ -149,54 +115,91 @@ impl Settings {
                 .unwrap_or_else(|| DEFAULT_EXCLUDE.clone()),
             extend_exclude: config
                 .extend_exclude
-                .map(|paths| {
-                    paths
-                        .iter()
-                        .map(|path| FilePattern::from_user(path, &project_root))
-                        .collect()
-                })
-                .unwrap_or_default(),
-            select: if let Some(select) = config.select {
-                BTreeSet::from_iter(select)
-            } else {
-                BTreeSet::from_iter(DEFAULT_CHECK_CODES)
-            },
+                .iter()
+                .map(|path| FilePattern::from_user(path, &project_root))
+                .collect(),
+            extend_ignore: config.extend_ignore,
+            extend_select: config.extend_select,
+            ignore: config.ignore,
+            line_length: config.line_length.unwrap_or(88),
             per_file_ignores: config
                 .per_file_ignores
-                .map(|ignore_strings| {
-                    ignore_strings
-                        .into_iter()
-                        .map(|pair| PerFileIgnore::new(pair, &project_root))
-                        .collect()
-                })
-                .unwrap_or_default(),
-            dummy_variable_rgx: match config.dummy_variable_rgx {
-                Some(pattern) => Regex::new(&pattern)
-                    .map_err(|e| anyhow!("Invalid dummy-variable-rgx value: {e}"))?,
-                None => DEFAULT_DUMMY_VARIABLE_RGX.clone(),
-            },
-            pyproject,
+                .into_iter()
+                .map(|pair| PerFileIgnore::new(pair, &project_root))
+                .collect(),
             project_root,
-        };
-        if let Some(ignore) = &config.ignore {
-            settings.ignore(ignore);
+            pyproject,
+            select: config
+                .select
+                .unwrap_or_else(|| DEFAULT_CHECK_CODES.to_vec()),
+        })
+    }
+}
+
+#[derive(Debug)]
+pub struct Settings {
+    pub dummy_variable_rgx: Regex,
+    pub enabled: BTreeSet<CheckCode>,
+    pub exclude: Vec<FilePattern>,
+    pub extend_exclude: Vec<FilePattern>,
+    pub line_length: usize,
+    pub per_file_ignores: Vec<PerFileIgnore>,
+}
+
+impl Settings {
+    pub fn from_raw(settings: RawSettings) -> Self {
+        // Materialize the set of enabled CheckCodes.
+        let mut enabled: BTreeSet<CheckCode> = BTreeSet::new();
+        enabled.extend(settings.select);
+        enabled.extend(settings.extend_select);
+        for code in &settings.ignore {
+            enabled.remove(code);
         }
-        Ok(settings)
-    }
-
-    pub fn clear(&mut self) {
-        self.select.clear();
-    }
-
-    pub fn select(&mut self, codes: Vec<CheckCode>) {
-        for code in codes {
-            self.select.insert(code);
+        for code in &settings.extend_ignore {
+            enabled.remove(code);
+        }
+        Self {
+            dummy_variable_rgx: settings.dummy_variable_rgx,
+            enabled,
+            exclude: settings.exclude,
+            extend_exclude: settings.extend_exclude,
+            line_length: settings.line_length,
+            per_file_ignores: settings.per_file_ignores,
         }
     }
 
-    pub fn ignore(&mut self, codes: &[CheckCode]) {
-        for code in codes {
-            self.select.remove(code);
+    pub fn for_rule(check_code: CheckCode) -> Self {
+        Self {
+            dummy_variable_rgx: DEFAULT_DUMMY_VARIABLE_RGX.clone(),
+            enabled: BTreeSet::from([check_code]),
+            exclude: vec![],
+            extend_exclude: vec![],
+            line_length: 88,
+            per_file_ignores: vec![],
+        }
+    }
+
+    pub fn for_rules(check_codes: Vec<CheckCode>) -> Self {
+        Self {
+            dummy_variable_rgx: DEFAULT_DUMMY_VARIABLE_RGX.clone(),
+            enabled: BTreeSet::from_iter(check_codes),
+            exclude: vec![],
+            extend_exclude: vec![],
+            line_length: 88,
+            per_file_ignores: vec![],
+        }
+    }
+}
+
+impl Hash for Settings {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.line_length.hash(state);
+        self.dummy_variable_rgx.as_str().hash(state);
+        for value in self.enabled.iter() {
+            value.hash(state);
+        }
+        for value in self.per_file_ignores.iter() {
+            value.hash(state);
         }
     }
 }
@@ -227,22 +230,23 @@ impl Exclusion {
 /// Struct to render user-facing Settings.
 #[derive(Debug)]
 pub struct CurrentSettings {
-    pub pyproject: Option<PathBuf>,
-    pub project_root: Option<PathBuf>,
-    pub line_length: usize,
+    pub dummy_variable_rgx: Regex,
     pub exclude: Vec<Exclusion>,
     pub extend_exclude: Vec<Exclusion>,
-    pub select: BTreeSet<CheckCode>,
+    pub extend_ignore: Vec<CheckCode>,
+    pub extend_select: Vec<CheckCode>,
+    pub ignore: Vec<CheckCode>,
+    pub line_length: usize,
     pub per_file_ignores: Vec<PerFileIgnore>,
-    pub dummy_variable_rgx: Regex,
+    pub project_root: Option<PathBuf>,
+    pub pyproject: Option<PathBuf>,
+    pub select: Vec<CheckCode>,
 }
 
 impl CurrentSettings {
-    pub fn from_settings(settings: Settings) -> Self {
+    pub fn from_settings(settings: RawSettings) -> Self {
         Self {
-            pyproject: settings.pyproject,
-            project_root: settings.project_root,
-            line_length: settings.line_length,
+            dummy_variable_rgx: settings.dummy_variable_rgx,
             exclude: settings
                 .exclude
                 .into_iter()
@@ -253,9 +257,14 @@ impl CurrentSettings {
                 .into_iter()
                 .map(Exclusion::from_file_pattern)
                 .collect(),
-            select: settings.select,
+            extend_ignore: settings.extend_ignore,
+            extend_select: settings.extend_select,
+            ignore: settings.ignore,
+            line_length: settings.line_length,
             per_file_ignores: settings.per_file_ignores,
-            dummy_variable_rgx: settings.dummy_variable_rgx,
+            project_root: settings.project_root,
+            pyproject: settings.pyproject,
+            select: settings.select,
         }
     }
 }

src/snapshots/ruff__linter__tests__f405.snap

@@ -5,7 +5,7 @@ expression: checks
 - kind:
     ImportStarUsage:
       - name
-      - mymodule
+      - - mymodule
   location:
     row: 5
     column: 11
@@ -16,7 +16,7 @@ expression: checks
 - kind:
     ImportStarUsage:
       - a
-      - mymodule
+      - - mymodule
   location:
     row: 11
     column: 1

src/snapshots/ruff__linter__tests__spr001.snap

@@ -50,4 +50,36 @@ expression: checks
       row: 22
       column: 10
     applied: false
+- kind: SuperCallWithParameters
+  location:
+    row: 36
+    column: 9
+  end_location:
+    row: 36
+    column: 29
+  fix:
+    content: super()
+    location:
+      row: 36
+      column: 9
+    end_location:
+      row: 36
+      column: 29
+    applied: false
+- kind: SuperCallWithParameters
+  location:
+    row: 50
+    column: 13
+  end_location:
+    row: 50
+    column: 33
+  fix:
+    content: super()
+    location:
+      row: 50
+      column: 13
+    end_location:
+      row: 50
+      column: 33
+    applied: false
 

src/snapshots/ruff__linter__tests__u001.snap

@@ -0,0 +1,37 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UselessMetaclassType
+  location:
+    row: 2
+    column: 5
+  end_location:
+    row: 2
+    column: 25
+  fix:
+    content: pass
+    location:
+      row: 2
+      column: 5
+    end_location:
+      row: 2
+      column: 25
+    applied: false
+- kind: UselessMetaclassType
+  location:
+    row: 6
+    column: 5
+  end_location:
+    row: 6
+    column: 25
+  fix:
+    content: ""
+    location:
+      row: 6
+      column: 1
+    end_location:
+      row: 7
+      column: 1
+    applied: false
+