Bump version to 0.0.97

.github/workflows/ci.yaml

@@ -38,6 +38,7 @@ jobs:
         with:
           profile: minimal
           toolchain: nightly-2022-11-01
+          override: true
           components: rustfmt
       - uses: actions/cache@v3
         env:
@@ -62,6 +63,7 @@ jobs:
         with:
           profile: minimal
           toolchain: nightly-2022-11-01
+          override: true
           components: clippy
       - uses: actions/cache@v3
         env:
@@ -86,6 +88,7 @@ jobs:
         with:
           profile: minimal
           toolchain: nightly-2022-11-01
+          override: true
       - uses: actions/cache@v3
         env:
           cache-name: cache-cargo
@@ -109,6 +112,7 @@ jobs:
         with:
           profile: minimal
           toolchain: nightly-2022-11-01
+          override: true
       - uses: actions/setup-python@v4
         with:
           python-version: "3.10"

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.95
+    rev: v0.0.97
     hooks:
       - id: ruff
 

Cargo.lock

@@ -920,7 +920,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8-to-ruff"
-version = "0.0.95-dev.0"
+version = "0.0.97-dev.0"
 dependencies = [
  "anyhow",
  "clap 4.0.15",
@@ -2211,7 +2211,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.95"
+version = "0.0.97"
 dependencies = [
  "anyhow",
  "assert_cmd",

Cargo.toml

@@ -5,7 +5,7 @@ members = [
 
 [package]
 name = "ruff"
-version = "0.0.95"
+version = "0.0.97"
 edition = "2021"
 
 [lib]

README.md

@@ -89,7 +89,7 @@ Ruff also works with [pre-commit](https://pre-commit.com):
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.95
+    rev: v0.0.97
     hooks:
       - id: ruff
 ```
@@ -392,17 +392,17 @@ The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` com
 
 | Code | Name | Message | Fix |
 | ---- | ---- | ------- | --- |
-| C400 | UnnecessaryGeneratorList | Unnecessary generator (rewrite as a `list` comprehension) |  |
-| C401 | UnnecessaryGeneratorSet | Unnecessary generator (rewrite as a `set` comprehension) |  |
-| C402 | UnnecessaryGeneratorDict | Unnecessary generator (rewrite as a `dict` comprehension) |  |
-| C403 | UnnecessaryListComprehensionSet | Unnecessary `list` comprehension (rewrite as a `set` comprehension) |  |
+| C400 | UnnecessaryGeneratorList | Unnecessary generator (rewrite as a `list` comprehension) | 🛠 |
+| C401 | UnnecessaryGeneratorSet | Unnecessary generator (rewrite as a `set` comprehension) | 🛠 |
+| C402 | UnnecessaryGeneratorDict | Unnecessary generator (rewrite as a `dict` comprehension) | 🛠 |
+| C403 | UnnecessaryListComprehensionSet | Unnecessary `list` comprehension (rewrite as a `set` comprehension) | 🛠 |
 | C404 | UnnecessaryListComprehensionDict | Unnecessary `list` comprehension (rewrite as a `dict` comprehension) |  |
-| C405 | UnnecessaryLiteralSet | Unnecessary `(list\|tuple)` literal (rewrite as a `set` literal) |  |
+| C405 | UnnecessaryLiteralSet | Unnecessary `(list\|tuple)` literal (rewrite as a `set` literal) | 🛠 |
 | C406 | UnnecessaryLiteralDict | Unnecessary `(list\|tuple)` literal (rewrite as a `dict` literal) |  |
-| C408 | UnnecessaryCollectionCall | Unnecessary `(dict\|list\|tuple)` call (rewrite as a literal) |  |
-| C409 | UnnecessaryLiteralWithinTupleCall | Unnecessary `(list\|tuple)` literal passed to `tuple()` (remove the outer call to `tuple()`) |  |
-| C410 | UnnecessaryLiteralWithinListCall | Unnecessary `(list\|tuple)` literal passed to `list()` (rewrite as a `list` literal) |  |
-| C411 | UnnecessaryListCall | Unnecessary `list` call (remove the outer call to `list()`) |  |
+| C408 | UnnecessaryCollectionCall | Unnecessary `(dict\|list\|tuple)` call (rewrite as a literal) | 🛠 |
+| C409 | UnnecessaryLiteralWithinTupleCall | Unnecessary `(list\|tuple)` literal passed to `tuple()` (remove the outer call to `tuple()`) | 🛠 |
+| C410 | UnnecessaryLiteralWithinListCall | Unnecessary `(list\|tuple)` literal passed to `list()` (rewrite as a `list` literal) | 🛠 |
+| C411 | UnnecessaryListCall | Unnecessary `list` call (remove the outer call to `list()`) | 🛠 |
 | C413 | UnnecessaryCallAroundSorted | Unnecessary `(list\|reversed)` call around `sorted()` |  |
 | C414 | UnnecessaryDoubleCastOrProcess | Unnecessary `(list\|reversed\|set\|sorted\|tuple)` call within `(list\|set\|sorted\|tuple)()` |  |
 | C415 | UnnecessarySubscriptReversal | Unnecessary subscript reversal of iterable within `(reversed\|set\|sorted)()` |  |
@@ -521,7 +521,7 @@ including:
 - [`flake8-quotes`](https://pypi.org/project/flake8-quotes/)
 - [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
 - [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (10/32)
-- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (8/34)
+- [`pyupgrade`](https://pypi.org/project/pyupgrade/) (10/34)
 - [`autoflake`](https://pypi.org/project/autoflake/) (1/7)
 
 Beyond rule-set parity, Ruff suffers from the following limitations vis-à-vis Flake8:
@@ -545,7 +545,7 @@ Today, Ruff can be used to replace Flake8 when used with any of the following pl
 - [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (10/32)
 
 Ruff also implements the functionality that you get from [`yesqa`](https://github.com/asottile/yesqa),
-and a subset of the rules implemented in [`pyupgrade`](https://pypi.org/project/pyupgrade/) (8/34).
+and a subset of the rules implemented in [`pyupgrade`](https://pypi.org/project/pyupgrade/) (10/34).
 
 If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, free to file an Issue.
 

crates/flake8_to_ruff/Cargo.lock

@@ -771,7 +771,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8_to_ruff"
-version = "0.0.95"
+version = "0.0.97"
 dependencies = [
  "anyhow",
  "clap",
@@ -1975,7 +1975,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.95"
+version = "0.0.97"
 dependencies = [
  "anyhow",
  "bincode",

crates/flake8_to_ruff/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "flake8-to-ruff"
-version = "0.0.95-dev.0"
+version = "0.0.97-dev.0"
 edition = "2021"
 
 [lib]

resources/test/fixtures/C400.py

@@ -1 +1,4 @@
 x = list(x for x in range(3))
+x = list(
+    x for x in range(3)
+)

resources/test/fixtures/C401.py

@@ -1 +1,4 @@
 x = set(x for x in range(3))
+x = set(
+    x for x in range(3)
+)

resources/test/fixtures/C402.py

@@ -1,2 +1,5 @@
 dict((x, x) for x in range(3))
+dict(
+    (x, x) for x in range(3)
+)
 dict(((x, x) for x in range(3)), z=3)

resources/test/fixtures/C403.py

@@ -1 +1,4 @@
 s = set([x for x in range(3)])
+s = set(
+    [x for x in range(3)]
+)

resources/test/fixtures/C409.py

@@ -1,3 +1,10 @@
-t1 = tuple([1, 2])
-t2 = tuple((1, 2))
-t3 = tuple([])
+t1 = tuple([])
+t2 = tuple([1, 2])
+t3 = tuple((1, 2))
+t4 = tuple([
+    1,
+    2
+])
+t5 = tuple(
+    (1, 2)
+)

resources/test/fixtures/N806.py

@@ -2,3 +2,4 @@ def f():
     lower = 0
     Camel = 0
     CONSTANT = 0
+    _ = 0

rust-toolchain

@@ -0,0 +1 @@
+1.64.0

rust-toolchain.toml

@@ -1,2 +0,0 @@
-[toolchain]
-channel = "1.64.0"

src/autofix/fixer.rs

@@ -6,6 +6,8 @@ use rustpython_parser::ast::Location;
 use crate::autofix::{Fix, Patch};
 use crate::checks::Check;
 
+// TODO(charlie): The model here is awkward because `Apply` is only relevant at
+// higher levels in the execution flow.
 #[derive(Hash)]
 pub enum Mode {
     Generate,

src/check_ast.rs

@@ -129,7 +129,9 @@ impl<'a> Checker<'a> {
     /// Return `true` if a patch should be generated under the given autofix
     /// `Mode`.
     pub fn patch(&self) -> bool {
-        self.autofix.patch()
+        // TODO(charlie): We can't fix errors in f-strings until RustPython adds
+        // location data.
+        self.autofix.patch() && self.in_f_string.is_none()
     }
 
     /// Return `true` if the `Expr` is a reference to `typing.${target}`.
@@ -989,7 +991,13 @@ where
                 // flake8-comprehensions
                 if self.settings.enabled.contains(&CheckCode::C400) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_generator_list(
-                        expr, func, args, keywords,
+                        expr,
+                        func,
+                        args,
+                        keywords,
+                        self.locator,
+                        self.patch(),
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };
@@ -997,7 +1005,13 @@ where
 
                 if self.settings.enabled.contains(&CheckCode::C401) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_generator_set(
-                        expr, func, args, keywords,
+                        expr,
+                        func,
+                        args,
+                        keywords,
+                        self.locator,
+                        self.patch(),
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };
@@ -1005,7 +1019,13 @@ where
 
                 if self.settings.enabled.contains(&CheckCode::C402) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_generator_dict(
-                        expr, func, args, keywords,
+                        expr,
+                        func,
+                        args,
+                        keywords,
+                        self.locator,
+                        self.patch(),
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };
@@ -1014,7 +1034,13 @@ where
                 if self.settings.enabled.contains(&CheckCode::C403) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_list_comprehension_set(
-                            expr, func, args, keywords,
+                            expr,
+                            func,
+                            args,
+                            keywords,
+                            self.locator,
+                            self.patch(),
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1024,7 +1050,10 @@ where
                 if self.settings.enabled.contains(&CheckCode::C404) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_list_comprehension_dict(
-                            expr, func, args, keywords,
+                            func,
+                            args,
+                            keywords,
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1033,7 +1062,13 @@ where
 
                 if self.settings.enabled.contains(&CheckCode::C405) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_literal_set(
-                        expr, func, args, keywords,
+                        expr,
+                        func,
+                        args,
+                        keywords,
+                        self.locator,
+                        self.patch(),
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };
@@ -1041,7 +1076,10 @@ where
 
                 if self.settings.enabled.contains(&CheckCode::C406) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_literal_dict(
-                        expr, func, args, keywords,
+                        func,
+                        args,
+                        keywords,
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };
@@ -1049,7 +1087,13 @@ where
 
                 if self.settings.enabled.contains(&CheckCode::C408) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_collection_call(
-                        expr, func, args, keywords,
+                        expr,
+                        func,
+                        args,
+                        keywords,
+                        self.locator,
+                        self.patch(),
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };
@@ -1058,7 +1102,12 @@ where
                 if self.settings.enabled.contains(&CheckCode::C409) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_literal_within_tuple_call(
-                            expr, func, args,
+                            expr,
+                            func,
+                            args,
+                            self.locator,
+                            self.patch(),
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1068,7 +1117,12 @@ where
                 if self.settings.enabled.contains(&CheckCode::C410) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_literal_within_list_call(
-                            expr, func, args,
+                            expr,
+                            func,
+                            args,
+                            self.locator,
+                            self.patch(),
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1076,9 +1130,14 @@ where
                 }
 
                 if self.settings.enabled.contains(&CheckCode::C411) {
-                    if let Some(check) =
-                        flake8_comprehensions::checks::unnecessary_list_call(expr, func, args)
-                    {
+                    if let Some(check) = flake8_comprehensions::checks::unnecessary_list_call(
+                        expr,
+                        func,
+                        args,
+                        self.locator,
+                        self.patch(),
+                        self.locate_check(Range::from_located(expr)),
+                    ) {
                         self.checks.push(check);
                     };
                 }
@@ -1086,7 +1145,9 @@ where
                 if self.settings.enabled.contains(&CheckCode::C413) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_call_around_sorted(
-                            expr, func, args,
+                            func,
+                            args,
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1096,7 +1157,9 @@ where
                 if self.settings.enabled.contains(&CheckCode::C414) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_double_cast_or_process(
-                            expr, func, args,
+                            func,
+                            args,
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1106,7 +1169,9 @@ where
                 if self.settings.enabled.contains(&CheckCode::C415) {
                     if let Some(check) =
                         flake8_comprehensions::checks::unnecessary_subscript_reversal(
-                            expr, func, args,
+                            func,
+                            args,
+                            self.locate_check(Range::from_located(expr)),
                         )
                     {
                         self.checks.push(check);
@@ -1114,9 +1179,11 @@ where
                 }
 
                 if self.settings.enabled.contains(&CheckCode::C417) {
-                    if let Some(check) =
-                        flake8_comprehensions::checks::unnecessary_map(expr, func, args)
-                    {
+                    if let Some(check) = flake8_comprehensions::checks::unnecessary_map(
+                        func,
+                        args,
+                        self.locate_check(Range::from_located(expr)),
+                    ) {
                         self.checks.push(check);
                     };
                 }
@@ -1293,7 +1360,10 @@ where
             ExprKind::ListComp { elt, generators } | ExprKind::SetComp { elt, generators } => {
                 if self.settings.enabled.contains(&CheckCode::C416) {
                     if let Some(check) = flake8_comprehensions::checks::unnecessary_comprehension(
-                        expr, elt, generators,
+                        expr,
+                        elt,
+                        generators,
+                        self.locate_check(Range::from_located(expr)),
                     ) {
                         self.checks.push(check);
                     };

src/checks.rs

@@ -1469,6 +1469,15 @@ impl CheckKind {
                 | CheckKind::SuperCallWithParameters
                 | CheckKind::TypeOfPrimitive(_)
                 | CheckKind::UnnecessaryAbspath
+                | CheckKind::UnnecessaryCollectionCall(_)
+                | CheckKind::UnnecessaryGeneratorDict
+                | CheckKind::UnnecessaryGeneratorList
+                | CheckKind::UnnecessaryGeneratorSet
+                | CheckKind::UnnecessaryListCall
+                | CheckKind::UnnecessaryListComprehensionSet
+                | CheckKind::UnnecessaryLiteralSet(_)
+                | CheckKind::UnnecessaryLiteralWithinListCall(_)
+                | CheckKind::UnnecessaryLiteralWithinTupleCall(_)
                 | CheckKind::UnusedImport(_, false)
                 | CheckKind::UnusedLoopControlVariable(_)
                 | CheckKind::UnusedNOQA(_)

src/cst/matchers.rs

@@ -0,0 +1,19 @@
+use anyhow::Result;
+use libcst_native::Module;
+use rustpython_ast::Located;
+
+use crate::ast::types::Range;
+use crate::source_code_locator::SourceCodeLocator;
+
+pub fn match_tree<'a, T>(
+    locator: &'a SourceCodeLocator,
+    located: &'a Located<T>,
+) -> Result<Module<'a>> {
+    match libcst_native::parse_module(
+        locator.slice_source_code_range(&Range::from_located(located)),
+        None,
+    ) {
+        Ok(module) => Ok(module),
+        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
+    }
+}

src/cst/mod.rs

@@ -1 +1,2 @@
 pub mod helpers;
+pub mod matchers;

src/flake8_bugbear/plugins/assert_false.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Stmt, StmtKind};
 
-use crate::ast::types::Range;
+use crate::ast::types::{CheckLocator, Range};
 use crate::autofix::Fix;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
@@ -42,7 +42,10 @@ pub fn assert_false(checker: &mut Checker, stmt: &Stmt, test: &Expr, msg: &Optio
         ..
     } = &test.node
     {
-        let mut check = Check::new(CheckKind::DoNotAssertFalse, Range::from_located(test));
+        let mut check = Check::new(
+            CheckKind::DoNotAssertFalse,
+            checker.locate_check(Range::from_located(test)),
+        );
         if checker.patch() {
             let mut generator = SourceGenerator::new();
             if let Ok(()) = generator.unparse_stmt(&assertion_error(msg)) {

src/flake8_bugbear/plugins/assert_raises_exception.rs

@@ -1,7 +1,7 @@
 use rustpython_ast::{ExprKind, Stmt, Withitem};
 
 use crate::ast::helpers::match_name_or_attr;
-use crate::ast::types::Range;
+use crate::ast::types::{CheckLocator, Range};
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -17,7 +17,7 @@ pub fn assert_raises_exception(checker: &mut Checker, stmt: &Stmt, items: &[With
             {
                 checker.add_check(Check::new(
                     CheckKind::NoAssertRaisesException,
-                    Range::from_located(stmt),
+                    checker.locate_check(Range::from_located(stmt)),
                 ));
             }
         }

src/flake8_bugbear/plugins/unary_prefix_increment.rs

@@ -1,6 +1,6 @@
 use rustpython_ast::{Expr, ExprKind, Unaryop};
 
-use crate::ast::types::Range;
+use crate::ast::types::{CheckLocator, Range};
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
@@ -11,7 +11,7 @@ pub fn unary_prefix_increment(checker: &mut Checker, expr: &Expr, op: &Unaryop,
             if matches!(op, Unaryop::UAdd) {
                 checker.add_check(Check::new(
                     CheckKind::UnaryPrefixIncrement,
-                    Range::from_located(expr),
+                    checker.locate_check(Range::from_located(expr)),
                 ))
             }
         }

src/flake8_bugbear/plugins/unused_loop_control_variable.rs

@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 
 use rustpython_ast::{Expr, ExprKind, Stmt};
 
-use crate::ast::types::Range;
+use crate::ast::types::{CheckLocator, Range};
 use crate::ast::visitor;
 use crate::ast::visitor::Visitor;
 use crate::autofix::Fix;
@@ -64,7 +64,7 @@ pub fn unused_loop_control_variable(checker: &mut Checker, target: &Expr, body:
 
         let mut check = Check::new(
             CheckKind::UnusedLoopControlVariable(name.to_string()),
-            Range::from_located(expr),
+            checker.locate_check(Range::from_located(expr)),
         );
         if checker.patch() {
             // Prefix the variable name with an underscore.

src/flake8_comprehensions/checks.rs

@@ -1,3 +1,4 @@
+use log::error;
 use num_bigint::BigInt;
 use rustpython_ast::{
     Comprehension, Constant, Expr, ExprKind, Keyword, KeywordData, Located, Unaryop,
@@ -5,6 +6,8 @@ use rustpython_ast::{
 
 use crate::ast::types::Range;
 use crate::checks::{Check, CheckKind};
+use crate::flake8_comprehensions::fixes;
+use crate::source_code_locator::SourceCodeLocator;
 
 fn function_name(func: &Expr) -> Option<&str> {
     if let ExprKind::Name { id, .. } = &func.node {
@@ -49,13 +52,20 @@ pub fn unnecessary_generator_list(
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("list", func, args, keywords)?;
     if let ExprKind::GeneratorExp { .. } = argument {
-        return Some(Check::new(
-            CheckKind::UnnecessaryGeneratorList,
-            Range::from_located(expr),
-        ));
+        let mut check = Check::new(CheckKind::UnnecessaryGeneratorList, location);
+        if fix {
+            match fixes::fix_unnecessary_generator_list(locator, expr) {
+                Ok(fix) => check.amend(fix),
+                Err(e) => error!("Failed to generate fix: {}", e),
+            }
+        }
+        return Some(check);
     }
     None
 }
@@ -66,13 +76,20 @@ pub fn unnecessary_generator_set(
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("set", func, args, keywords)?;
     if let ExprKind::GeneratorExp { .. } = argument {
-        return Some(Check::new(
-            CheckKind::UnnecessaryGeneratorSet,
-            Range::from_located(expr),
-        ));
+        let mut check = Check::new(CheckKind::UnnecessaryGeneratorSet, location);
+        if fix {
+            match fixes::fix_unnecessary_generator_set(locator, expr) {
+                Ok(fix) => check.amend(fix),
+                Err(e) => error!("Failed to generate fix: {}", e),
+            }
+        }
+        return Some(check);
     }
     None
 }
@@ -83,15 +100,22 @@ pub fn unnecessary_generator_dict(
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("dict", func, args, keywords)?;
     if let ExprKind::GeneratorExp { elt, .. } = argument {
         match &elt.node {
             ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
-                return Some(Check::new(
-                    CheckKind::UnnecessaryGeneratorDict,
-                    Range::from_located(expr),
-                ));
+                let mut check = Check::new(CheckKind::UnnecessaryGeneratorDict, location);
+                if fix {
+                    match fixes::fix_unnecessary_generator_dict(locator, expr) {
+                        Ok(fix) => check.amend(fix),
+                        Err(e) => error!("Failed to generate fix: {}", e),
+                    }
+                }
+                return Some(check);
             }
             _ => {}
         }
@@ -105,23 +129,30 @@ pub fn unnecessary_list_comprehension_set(
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("set", func, args, keywords)?;
     if let ExprKind::ListComp { .. } = &argument {
-        return Some(Check::new(
-            CheckKind::UnnecessaryListComprehensionSet,
-            Range::from_located(expr),
-        ));
+        let mut check = Check::new(CheckKind::UnnecessaryListComprehensionSet, location);
+        if fix {
+            match fixes::fix_unnecessary_list_comprehension_set(locator, expr) {
+                Ok(fix) => check.amend(fix),
+                Err(e) => error!("Failed to generate fix: {}", e),
+            }
+        }
+        return Some(check);
     }
     None
 }
 
 /// C404 (`dict([...])`)
 pub fn unnecessary_list_comprehension_dict(
-    expr: &Expr,
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("dict", func, args, keywords)?;
     if let ExprKind::ListComp { elt, .. } = &argument {
@@ -129,7 +160,7 @@ pub fn unnecessary_list_comprehension_dict(
             ExprKind::Tuple { elts, .. } if elts.len() == 2 => {
                 return Some(Check::new(
                     CheckKind::UnnecessaryListComprehensionDict,
-                    Range::from_located(expr),
+                    location,
                 ));
             }
             _ => {}
@@ -144,6 +175,9 @@ pub fn unnecessary_literal_set(
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("set", func, args, keywords)?;
     let kind = match argument {
@@ -151,18 +185,22 @@ pub fn unnecessary_literal_set(
         ExprKind::Tuple { .. } => "tuple",
         _ => return None,
     };
-    Some(Check::new(
-        CheckKind::UnnecessaryLiteralSet(kind.to_string()),
-        Range::from_located(expr),
-    ))
+    let mut check = Check::new(CheckKind::UnnecessaryLiteralSet(kind.to_string()), location);
+    if fix {
+        match fixes::fix_unnecessary_literal_set(locator, expr) {
+            Ok(fix) => check.amend(fix),
+            Err(e) => error!("Failed to generate fix: {}", e),
+        }
+    }
+    Some(check)
 }
 
 /// C406 (`dict([(1, 2)])`)
 pub fn unnecessary_literal_dict(
-    expr: &Expr,
     func: &Expr,
     args: &[Expr],
     keywords: &[Keyword],
+    location: Range,
 ) -> Option<Check> {
     let argument = exactly_one_argument_with_matching_function("dict", func, args, keywords)?;
     let (kind, elts) = match argument {
@@ -180,7 +218,7 @@ pub fn unnecessary_literal_dict(
 
     Some(Check::new(
         CheckKind::UnnecessaryLiteralDict(kind.to_string()),
-        Range::from_located(expr),
+        location,
     ))
 }
 
@@ -190,22 +228,37 @@ pub fn unnecessary_collection_call(
     func: &Expr,
     args: &[Expr],
     keywords: &[Located<KeywordData>],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     if !args.is_empty() {
         return None;
     }
     let id = function_name(func)?;
     match id {
-        "dict" if keywords.is_empty() || keywords.iter().all(|kw| kw.node.arg.is_some()) => (),
+        "dict" if keywords.is_empty() || keywords.iter().all(|kw| kw.node.arg.is_some()) => {
+            // `dict()` or `dict(a=1)` (as opposed to `dict(**a)`)
+        }
         "list" | "tuple" => {
-            // list() or tuple()
+            // `list()` or `tuple()`
         }
         _ => return None,
     };
-    Some(Check::new(
+    let mut check = Check::new(
         CheckKind::UnnecessaryCollectionCall(id.to_string()),
-        Range::from_located(expr),
-    ))
+        location,
+    );
+    if fix {
+        // TODO(charlie): Support fixing `dict(a=1)`.
+        if keywords.is_empty() {
+            match fixes::fix_unnecessary_collection_call(locator, expr) {
+                Ok(fix) => check.amend(fix),
+                Err(e) => error!("Failed to generate fix: {}", e),
+            }
+        }
+    }
+    Some(check)
 }
 
 /// C409
@@ -213,6 +266,9 @@ pub fn unnecessary_literal_within_tuple_call(
     expr: &Expr,
     func: &Expr,
     args: &[Expr],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = first_argument_with_matching_function("tuple", func, args)?;
     let argument_kind = match argument {
@@ -220,10 +276,17 @@ pub fn unnecessary_literal_within_tuple_call(
         ExprKind::List { .. } => "list",
         _ => return None,
     };
-    Some(Check::new(
+    let mut check = Check::new(
         CheckKind::UnnecessaryLiteralWithinTupleCall(argument_kind.to_string()),
-        Range::from_located(expr),
-    ))
+        location,
+    );
+    if fix {
+        match fixes::fix_unnecessary_literal_within_tuple_call(locator, expr) {
+            Ok(fix) => check.amend(fix),
+            Err(e) => error!("Failed to generate fix: {}", e),
+        }
+    }
+    Some(check)
 }
 
 /// C410
@@ -231,6 +294,9 @@ pub fn unnecessary_literal_within_list_call(
     expr: &Expr,
     func: &Expr,
     args: &[Expr],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
 ) -> Option<Check> {
     let argument = first_argument_with_matching_function("list", func, args)?;
     let argument_kind = match argument {
@@ -238,26 +304,48 @@ pub fn unnecessary_literal_within_list_call(
         ExprKind::List { .. } => "list",
         _ => return None,
     };
-    Some(Check::new(
+    let mut check = Check::new(
         CheckKind::UnnecessaryLiteralWithinListCall(argument_kind.to_string()),
-        Range::from_located(expr),
-    ))
+        location,
+    );
+    if fix {
+        match fixes::fix_unnecessary_literal_within_list_call(locator, expr) {
+            Ok(fix) => check.amend(fix),
+            Err(e) => error!("Failed to generate fix: {}", e),
+        }
+    }
+    Some(check)
 }
 
 /// C411
-pub fn unnecessary_list_call(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+pub fn unnecessary_list_call(
+    expr: &Expr,
+    func: &Expr,
+    args: &[Expr],
+    locator: &SourceCodeLocator,
+    fix: bool,
+    location: Range,
+) -> Option<Check> {
     let argument = first_argument_with_matching_function("list", func, args)?;
     if let ExprKind::ListComp { .. } = argument {
-        return Some(Check::new(
-            CheckKind::UnnecessaryListCall,
-            Range::from_located(expr),
-        ));
+        let mut check = Check::new(CheckKind::UnnecessaryListCall, location);
+        if fix {
+            match fixes::fix_unnecessary_list_call(locator, expr) {
+                Ok(fix) => check.amend(fix),
+                Err(e) => error!("Failed to generate fix: {}", e),
+            }
+        }
+        return Some(check);
     }
     None
 }
 
 /// C413
-pub fn unnecessary_call_around_sorted(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+pub fn unnecessary_call_around_sorted(
+    func: &Expr,
+    args: &[Expr],
+    location: Range,
+) -> Option<Check> {
     let outer = function_name(func)?;
     if !(outer == "list" || outer == "reversed") {
         return None;
@@ -266,7 +354,7 @@ pub fn unnecessary_call_around_sorted(expr: &Expr, func: &Expr, args: &[Expr]) -
         if function_name(func)? == "sorted" {
             return Some(Check::new(
                 CheckKind::UnnecessaryCallAroundSorted(outer.to_string()),
-                Range::from_located(expr),
+                location,
             ));
         }
     }
@@ -275,19 +363,19 @@ pub fn unnecessary_call_around_sorted(expr: &Expr, func: &Expr, args: &[Expr]) -
 
 /// C414
 pub fn unnecessary_double_cast_or_process(
-    expr: &Expr,
     func: &Expr,
     args: &[Expr],
+    location: Range,
 ) -> Option<Check> {
     let outer = function_name(func)?;
     if !["list", "tuple", "set", "reversed", "sorted"].contains(&outer) {
         return None;
     }
 
-    fn new_check(inner: &str, outer: &str, expr: &Expr) -> Check {
+    fn new_check(inner: &str, outer: &str, location: Range) -> Check {
         Check::new(
             CheckKind::UnnecessaryDoubleCastOrProcess(inner.to_string(), outer.to_string()),
-            Range::from_located(expr),
+            location,
         )
     }
 
@@ -297,24 +385,28 @@ pub fn unnecessary_double_cast_or_process(
         if (outer == "set" || outer == "sorted")
             && (inner == "list" || inner == "tuple" || inner == "reversed" || inner == "sorted")
         {
-            return Some(new_check(inner, outer, expr));
+            return Some(new_check(inner, outer, location));
         }
 
         // Ex) list(tuple(...))
         if (outer == "list" || outer == "tuple") && (inner == "list" || inner == "tuple") {
-            return Some(new_check(inner, outer, expr));
+            return Some(new_check(inner, outer, location));
         }
 
         // Ex) set(set(...))
         if outer == "set" && inner == "set" {
-            return Some(new_check(inner, outer, expr));
+            return Some(new_check(inner, outer, location));
         }
     }
     None
 }
 
 /// C415
-pub fn unnecessary_subscript_reversal(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
+pub fn unnecessary_subscript_reversal(
+    func: &Expr,
+    args: &[Expr],
+    location: Range,
+) -> Option<Check> {
     let first_arg = args.first()?;
     let id = function_name(func)?;
     if !["set", "sorted", "reversed"].contains(&id) {
@@ -337,7 +429,7 @@ pub fn unnecessary_subscript_reversal(expr: &Expr, func: &Expr, args: &[Expr]) -
                             if *val == BigInt::from(1) {
                                 return Some(Check::new(
                                     CheckKind::UnnecessarySubscriptReversal(id.to_string()),
-                                    Range::from_located(expr),
+                                    location,
                                 ));
                             }
                         }
@@ -354,6 +446,7 @@ pub fn unnecessary_comprehension(
     expr: &Expr,
     elt: &Expr,
     generators: &[Comprehension],
+    location: Range,
 ) -> Option<Check> {
     if generators.len() != 1 {
         return None;
@@ -374,30 +467,27 @@ pub fn unnecessary_comprehension(
     };
     Some(Check::new(
         CheckKind::UnnecessaryComprehension(expr_kind.to_string()),
-        Range::from_located(expr),
+        location,
     ))
 }
 
 /// C417
-pub fn unnecessary_map(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check> {
-    fn new_check(kind: &str, expr: &Expr) -> Check {
-        Check::new(
-            CheckKind::UnnecessaryMap(kind.to_string()),
-            Range::from_located(expr),
-        )
+pub fn unnecessary_map(func: &Expr, args: &[Expr], location: Range) -> Option<Check> {
+    fn new_check(kind: &str, location: Range) -> Check {
+        Check::new(CheckKind::UnnecessaryMap(kind.to_string()), location)
     }
     let id = function_name(func)?;
     match id {
         "map" => {
             if args.len() == 2 && matches!(&args[0].node, ExprKind::Lambda { .. }) {
-                return Some(new_check("generator", expr));
+                return Some(new_check("generator", location));
             }
         }
         "list" | "set" => {
             if let ExprKind::Call { func, args, .. } = &args.first()?.node {
                 let argument = first_argument_with_matching_function("map", func, args)?;
                 if let ExprKind::Lambda { .. } = argument {
-                    return Some(new_check(id, expr));
+                    return Some(new_check(id, location));
                 }
             }
         }
@@ -408,7 +498,7 @@ pub fn unnecessary_map(expr: &Expr, func: &Expr, args: &[Expr]) -> Option<Check>
                     if let ExprKind::Lambda { body, .. } = &argument {
                         if matches!(&body.node, ExprKind::Tuple { elts, .. } | ExprKind::List { elts, .. } if elts.len() == 2)
                         {
-                            return Some(new_check(id, expr));
+                            return Some(new_check(id, location));
                         }
                     }
                 }

src/flake8_comprehensions/fixes.rs

@@ -0,0 +1,473 @@
+use anyhow::Result;
+use libcst_native::{
+    Arg, Call, Codegen, Dict, DictComp, Element, Expr, Expression, LeftCurlyBrace, LeftParen,
+    LeftSquareBracket, List, ListComp, Module, ParenthesizableWhitespace, RightCurlyBrace,
+    RightParen, RightSquareBracket, Set, SetComp, SimpleWhitespace, SmallStatement, Statement,
+    Tuple,
+};
+
+use crate::autofix::Fix;
+use crate::cst::matchers::match_tree;
+use crate::source_code_locator::SourceCodeLocator;
+
+fn match_expr<'a, 'b>(module: &'a mut Module<'b>) -> Result<&'a mut Expr<'b>> {
+    if let Some(Statement::Simple(expr)) = module.body.first_mut() {
+        if let Some(SmallStatement::Expr(expr)) = expr.body.first_mut() {
+            Ok(expr)
+        } else {
+            Err(anyhow::anyhow!(
+                "Expected node to be: SmallStatement::Expr."
+            ))
+        }
+    } else {
+        Err(anyhow::anyhow!("Expected node to be: Statement::Simple."))
+    }
+}
+
+fn match_call<'a, 'b>(expr: &'a mut Expr<'b>) -> Result<&'a mut Call<'b>> {
+    if let Expression::Call(call) = &mut expr.value {
+        Ok(call)
+    } else {
+        Err(anyhow::anyhow!("Expected node to be: Expression::Call."))
+    }
+}
+
+fn match_arg<'a, 'b>(call: &'a Call<'b>) -> Result<&'a Arg<'b>> {
+    if let Some(arg) = call.args.first() {
+        Ok(arg)
+    } else {
+        Err(anyhow::anyhow!("Expected node to be: Arg."))
+    }
+}
+
+/// (C400) Convert `list(x for x in y)` to `[x for x in y]`.
+pub fn fix_unnecessary_generator_list(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    // Expr(Call(GeneratorExp)))) -> Expr(ListComp)))
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+
+    let generator_exp = if let Expression::GeneratorExp(generator_exp) = &arg.value {
+        generator_exp
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected node to be: Expression::GeneratorExp."
+        ));
+    };
+
+    body.value = Expression::ListComp(Box::new(ListComp {
+        elt: generator_exp.elt.clone(),
+        for_in: generator_exp.for_in.clone(),
+        lbracket: LeftSquareBracket {
+            whitespace_after: call.whitespace_before_args.clone(),
+        },
+        rbracket: RightSquareBracket {
+            whitespace_before: arg.whitespace_after_arg.clone(),
+        },
+        lpar: generator_exp.lpar.clone(),
+        rpar: generator_exp.rpar.clone(),
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C401) Convert `set(x for x in y)` to `{x for x in y}`.
+pub fn fix_unnecessary_generator_set(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    // Expr(Call(GeneratorExp)))) -> Expr(SetComp)))
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+
+    let generator_exp = if let Expression::GeneratorExp(generator_exp) = &arg.value {
+        generator_exp
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected node to be: Expression::GeneratorExp."
+        ));
+    };
+
+    body.value = Expression::SetComp(Box::new(SetComp {
+        elt: generator_exp.elt.clone(),
+        for_in: generator_exp.for_in.clone(),
+        lbrace: LeftCurlyBrace {
+            whitespace_after: call.whitespace_before_args.clone(),
+        },
+        rbrace: RightCurlyBrace {
+            whitespace_before: arg.whitespace_after_arg.clone(),
+        },
+        lpar: generator_exp.lpar.clone(),
+        rpar: generator_exp.rpar.clone(),
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C402) Convert `dict((x, x) for x in range(3))` to `{x: x for x in
+/// range(3)}`.
+pub fn fix_unnecessary_generator_dict(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+
+    // Extract the (k, v) from `(k, v) for ...`.
+    let generator_exp = if let Expression::GeneratorExp(generator_exp) = &arg.value {
+        generator_exp
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected node to be: Expression::GeneratorExp."
+        ));
+    };
+    let tuple = if let Expression::Tuple(tuple) = &generator_exp.elt.as_ref() {
+        tuple
+    } else {
+        return Err(anyhow::anyhow!("Expected node to be: Expression::Tuple."));
+    };
+    let key = if let Some(Element::Simple { value, .. }) = &tuple.elements.get(0) {
+        value
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected tuple to contain a key as the first element."
+        ));
+    };
+    let value = if let Some(Element::Simple { value, .. }) = &tuple.elements.get(1) {
+        value
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected tuple to contain a key as the second element."
+        ));
+    };
+
+    body.value = Expression::DictComp(Box::new(DictComp {
+        key: Box::new(key.clone()),
+        value: Box::new(value.clone()),
+        for_in: generator_exp.for_in.clone(),
+        lbrace: LeftCurlyBrace {
+            whitespace_after: call.whitespace_before_args.clone(),
+        },
+        rbrace: RightCurlyBrace {
+            whitespace_before: arg.whitespace_after_arg.clone(),
+        },
+        lpar: Default::default(),
+        rpar: Default::default(),
+        whitespace_before_colon: Default::default(),
+        whitespace_after_colon: ParenthesizableWhitespace::SimpleWhitespace(SimpleWhitespace(" ")),
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C403) Convert `set([x for x in y])` to `{x for x in y}`.
+pub fn fix_unnecessary_list_comprehension_set(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    // Expr(Call(ListComp)))) ->
+    // Expr(SetComp)))
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+
+    let list_comp = if let Expression::ListComp(list_comp) = &arg.value {
+        list_comp
+    } else {
+        return Err(anyhow::anyhow!(
+            "Expected node to be: Expression::ListComp."
+        ));
+    };
+
+    body.value = Expression::SetComp(Box::new(SetComp {
+        elt: list_comp.elt.clone(),
+        for_in: list_comp.for_in.clone(),
+        lbrace: LeftCurlyBrace {
+            whitespace_after: call.whitespace_before_args.clone(),
+        },
+        rbrace: RightCurlyBrace {
+            whitespace_before: arg.whitespace_after_arg.clone(),
+        },
+        lpar: list_comp.lpar.clone(),
+        rpar: list_comp.rpar.clone(),
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C405) Convert `set((1, 2))` to `{1, 2}`.
+pub fn fix_unnecessary_literal_set(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    // Expr(Call(List|Tuple)))) -> Expr(Set)))
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let mut call = match_call(body)?;
+    let arg = match_arg(call)?;
+
+    let elements = match &arg.value {
+        Expression::Tuple(inner) => &inner.elements,
+        Expression::List(inner) => &inner.elements,
+        _ => {
+            return Err(anyhow::anyhow!(
+                "Expected node to be: Expression::Tuple | Expression::List."
+            ))
+        }
+    };
+
+    if elements.is_empty() {
+        call.args = vec![];
+    } else {
+        body.value = Expression::Set(Box::new(Set {
+            elements: elements.clone(),
+            lbrace: LeftCurlyBrace {
+                whitespace_after: call.whitespace_before_args.clone(),
+            },
+            rbrace: RightCurlyBrace {
+                whitespace_before: arg.whitespace_after_arg.clone(),
+            },
+            lpar: Default::default(),
+            rpar: Default::default(),
+        }));
+    }
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C408)
+pub fn fix_unnecessary_collection_call(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    // Expr(Call("list" | "tuple" | "dict")))) -> Expr(List|Tuple|Dict)))
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let name = if let Expression::Name(name) = &call.func.as_ref() {
+        name
+    } else {
+        return Err(anyhow::anyhow!("Expected node to be: Expression::Name."));
+    };
+
+    match name.value {
+        "tuple" => {
+            body.value = Expression::Tuple(Box::new(Tuple {
+                elements: Default::default(),
+                lpar: vec![Default::default()],
+                rpar: vec![Default::default()],
+            }));
+        }
+        "list" => {
+            body.value = Expression::List(Box::new(List {
+                elements: Default::default(),
+                lbracket: Default::default(),
+                rbracket: Default::default(),
+                lpar: Default::default(),
+                rpar: Default::default(),
+            }));
+        }
+        "dict" => {
+            body.value = Expression::Dict(Box::new(Dict {
+                elements: Default::default(),
+                lbrace: Default::default(),
+                rbrace: Default::default(),
+                lpar: Default::default(),
+                rpar: Default::default(),
+            }));
+        }
+        _ => {
+            return Err(anyhow::anyhow!("Expected function name to be one of: \
+                                        'tuple', 'list', 'dict'."
+                .to_string()));
+        }
+    };
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C409) Convert `tuple([1, 2])` to `tuple(1, 2)`
+pub fn fix_unnecessary_literal_within_tuple_call(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+    let (elements, whitespace_after, whitespace_before) = match &arg.value {
+        Expression::Tuple(inner) => (
+            &inner.elements,
+            &inner
+                .lpar
+                .first()
+                .ok_or_else(|| anyhow::anyhow!("Expected at least one set of parentheses."))?
+                .whitespace_after,
+            &inner
+                .rpar
+                .first()
+                .ok_or_else(|| anyhow::anyhow!("Expected at least one set of parentheses."))?
+                .whitespace_before,
+        ),
+        Expression::List(inner) => (
+            &inner.elements,
+            &inner.lbracket.whitespace_after,
+            &inner.rbracket.whitespace_before,
+        ),
+        _ => {
+            return Err(anyhow::anyhow!(
+                "Expected node to be: Expression::Tuple | Expression::List."
+            ))
+        }
+    };
+
+    body.value = Expression::Tuple(Box::new(Tuple {
+        elements: elements.clone(),
+        lpar: vec![LeftParen {
+            whitespace_after: whitespace_after.clone(),
+        }],
+        rpar: vec![RightParen {
+            whitespace_before: whitespace_before.clone(),
+        }],
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C410) Convert `list([1, 2])` to `[1, 2]`
+pub fn fix_unnecessary_literal_within_list_call(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+    let (elements, whitespace_after, whitespace_before) = match &arg.value {
+        Expression::Tuple(inner) => (
+            &inner.elements,
+            &inner
+                .lpar
+                .first()
+                .ok_or_else(|| anyhow::anyhow!("Expected at least one set of parentheses."))?
+                .whitespace_after,
+            &inner
+                .rpar
+                .first()
+                .ok_or_else(|| anyhow::anyhow!("Expected at least one set of parentheses."))?
+                .whitespace_before,
+        ),
+        Expression::List(inner) => (
+            &inner.elements,
+            &inner.lbracket.whitespace_after,
+            &inner.rbracket.whitespace_before,
+        ),
+        _ => {
+            return Err(anyhow::anyhow!(
+                "Expected node to be: Expression::Tuple | Expression::List."
+            ))
+        }
+    };
+
+    body.value = Expression::List(Box::new(List {
+        elements: elements.clone(),
+        lbracket: LeftSquareBracket {
+            whitespace_after: whitespace_after.clone(),
+        },
+        rbracket: RightSquareBracket {
+            whitespace_before: whitespace_before.clone(),
+        },
+        lpar: Default::default(),
+        rpar: Default::default(),
+    }));
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}
+
+/// (C411) Convert `list([i for i in x])` to `[i for i in x]`.
+pub fn fix_unnecessary_list_call(
+    locator: &SourceCodeLocator,
+    expr: &rustpython_ast::Expr,
+) -> Result<Fix> {
+    // Expr(Call(List|Tuple)))) -> Expr(List|Tuple)))
+    let mut tree = match_tree(locator, expr)?;
+    let mut body = match_expr(&mut tree)?;
+    let call = match_call(body)?;
+    let arg = match_arg(call)?;
+
+    body.value = arg.value.clone();
+
+    let mut state = Default::default();
+    tree.codegen(&mut state);
+
+    Ok(Fix::replacement(
+        state.to_string(),
+        expr.location,
+        expr.end_location.unwrap(),
+    ))
+}

src/flake8_comprehensions/mod.rs

@@ -1 +1,2 @@
 pub mod checks;
+mod fixes;

src/flake8_print/checks.rs

@@ -9,25 +9,20 @@ pub fn print_call(
     func: &Expr,
     check_print: bool,
     check_pprint: bool,
+    location: Range,
 ) -> Option<Check> {
     if let ExprKind::Name { id, .. } = &func.node {
         if check_print && id == "print" {
             return Some(Check::new(CheckKind::PrintFound, Range::from_located(expr)));
         } else if check_pprint && id == "pprint" {
-            return Some(Check::new(
-                CheckKind::PPrintFound,
-                Range::from_located(expr),
-            ));
+            return Some(Check::new(CheckKind::PPrintFound, location));
         }
     }
 
     if let ExprKind::Attribute { value, attr, .. } = &func.node {
         if let ExprKind::Name { id, .. } = &value.node {
             if check_pprint && id == "pprint" && attr == "pprint" {
-                return Some(Check::new(
-                    CheckKind::PPrintFound,
-                    Range::from_located(expr),
-                ));
+                return Some(Check::new(CheckKind::PPrintFound, location));
             }
         }
     }

src/flake8_print/plugins/print_call.rs

@@ -1,6 +1,7 @@
 use log::error;
 use rustpython_ast::{Expr, Stmt, StmtKind};
 
+use crate::ast::types::{CheckLocator, Range};
 use crate::autofix::helpers;
 use crate::check_ast::Checker;
 use crate::checks::CheckCode;
@@ -12,6 +13,7 @@ pub fn print_call(checker: &mut Checker, expr: &Expr, func: &Expr) {
         func,
         checker.settings.enabled.contains(&CheckCode::T201),
         checker.settings.enabled.contains(&CheckCode::T203),
+        checker.locate_check(Range::from_located(expr)),
     ) {
         if checker.patch() {
             let context = checker.binding_context();

src/flake8_quotes/settings.rs

@@ -2,7 +2,7 @@
 
 use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Hash)]
 #[serde(deny_unknown_fields, rename_all = "kebab-case")]
 pub enum Quote {
     Single,
@@ -18,7 +18,7 @@ pub struct Options {
     pub avoid_escape: Option<bool>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Hash)]
 pub struct Settings {
     pub inline_quotes: Quote,
     pub multiline_quotes: Quote,
@@ -29,7 +29,7 @@ pub struct Settings {
 impl Settings {
     pub fn from_options(options: Options) -> Self {
         Self {
-            inline_quotes: options.inline_quotes.unwrap_or(Quote::Single),
+            inline_quotes: options.inline_quotes.unwrap_or(Quote::Double),
             multiline_quotes: options.multiline_quotes.unwrap_or(Quote::Double),
             docstring_quotes: options.docstring_quotes.unwrap_or(Quote::Double),
             avoid_escape: options.avoid_escape.unwrap_or(true),
@@ -40,7 +40,7 @@ impl Settings {
 impl Default for Settings {
     fn default() -> Self {
         Self {
-            inline_quotes: Quote::Single,
+            inline_quotes: Quote::Double,
             multiline_quotes: Quote::Double,
             docstring_quotes: Quote::Double,
             avoid_escape: true,

src/lib.rs

@@ -45,8 +45,8 @@ pub mod settings;
 pub mod source_code_locator;
 pub mod visibility;
 
-/// Run ruff over Python source code directly.
-pub fn check(path: &Path, contents: &str) -> Result<Vec<Check>> {
+/// Run Ruff over Python source code directly.
+pub fn check(path: &Path, contents: &str, autofix: bool) -> Result<Vec<Check>> {
     // Find the project root and pyproject.toml.
     let project_root = pyproject::find_project_root(&[path.to_path_buf()]);
     match &project_root {
@@ -75,7 +75,7 @@ pub fn check(path: &Path, contents: &str) -> Result<Vec<Check>> {
         tokens,
         &noqa_line_for,
         &settings,
-        &Mode::None,
+        &if autofix { Mode::Generate } else { Mode::None },
     )?;
 
     Ok(checks)

src/pep8_naming/checks.rs

@@ -118,7 +118,7 @@ pub fn non_lowercase_variable_in_function(scope: &Scope, expr: &Expr, name: &str
     if !matches!(scope.kind, ScopeKind::Function(FunctionScope { .. })) {
         return None;
     }
-    if !is_lower(name) {
+    if name.to_lowercase() != name {
         return Some(Check::new(
             CheckKind::NonLowercaseVariableInFunction(name.to_string()),
             Range::from_located(expr),

src/pep8_naming/settings.rs

@@ -29,7 +29,7 @@ pub struct Options {
     pub staticmethod_decorators: Option<Vec<String>>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Hash)]
 pub struct Settings {
     pub ignore_names: Vec<String>,
     pub classmethod_decorators: Vec<String>,

src/pyflakes/fixes.rs

@@ -2,9 +2,9 @@ use anyhow::Result;
 use libcst_native::{Codegen, ImportNames, NameOrAttribute, SmallStatement, Statement};
 use rustpython_ast::Stmt;
 
-use crate::ast::types::Range;
 use crate::autofix::{helpers, Fix};
 use crate::cst::helpers::compose_module_path;
+use crate::cst::matchers::match_tree;
 use crate::source_code_locator::SourceCodeLocator;
 
 /// Generate a Fix to remove any unused imports from an `import` statement.
@@ -15,13 +15,7 @@ pub fn remove_unused_imports(
     parent: Option<&Stmt>,
     deleted: &[&Stmt],
 ) -> Result<Fix> {
-    let mut tree = match libcst_native::parse_module(
-        locator.slice_source_code_range(&Range::from_located(stmt)),
-        None,
-    ) {
-        Ok(m) => m,
-        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
-    };
+    let mut tree = match_tree(locator, stmt)?;
 
     let body = if let Some(Statement::Simple(body)) = tree.body.first_mut() {
         body
@@ -78,13 +72,7 @@ pub fn remove_unused_import_froms(
     parent: Option<&Stmt>,
     deleted: &[&Stmt],
 ) -> Result<Fix> {
-    let mut tree = match libcst_native::parse_module(
-        locator.slice_source_code_range(&Range::from_located(stmt)),
-        None,
-    ) {
-        Ok(m) => m,
-        Err(_) => return Err(anyhow::anyhow!("Failed to extract CST from source.")),
-    };
+    let mut tree = match_tree(locator, stmt)?;
 
     let body = if let Some(Statement::Simple(body)) = tree.body.first_mut() {
         body

src/settings/mod.rs

@@ -84,14 +84,19 @@ impl Settings {
 
 impl Hash for Settings {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        self.line_length.hash(state);
+        // Add base properties in alphabetical order.
         self.dummy_variable_rgx.as_str().hash(state);
         for value in self.enabled.iter() {
             value.hash(state);
         }
+        self.line_length.hash(state);
         for value in self.per_file_ignores.iter() {
             value.hash(state);
         }
+        self.target_version.hash(state);
+        // Add plugin properties in alphabetical order.
+        self.flake8_quotes.hash(state);
+        self.pep8_naming.hash(state);
     }
 }
 

src/settings/types.rs

@@ -11,7 +11,7 @@ use crate::checks::CheckCode;
 use crate::checks_gen::CheckCodePrefix;
 use crate::fs;
 
-#[derive(Clone, Debug, PartialOrd, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialOrd, PartialEq, Eq, Serialize, Deserialize, Hash)]
 pub enum PythonVersion {
     Py33,
     Py34,

src/snapshots/ruff__linter__tests__C400_C400.py.snap

@@ -9,5 +9,31 @@ expression: checks
   end_location:
     row: 1
     column: 29
-  fix: ~
+  fix:
+    patch:
+      content: "[x for x in range(3)]"
+      location:
+        row: 1
+        column: 4
+      end_location:
+        row: 1
+        column: 29
+    applied: false
+- kind: UnnecessaryGeneratorList
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 4
+    column: 1
+  fix:
+    patch:
+      content: "[\n    x for x in range(3)\n]"
+      location:
+        row: 2
+        column: 4
+      end_location:
+        row: 4
+        column: 1
+    applied: false
 

src/snapshots/ruff__linter__tests__C401_C401.py.snap

@@ -9,5 +9,31 @@ expression: checks
   end_location:
     row: 1
     column: 28
-  fix: ~
+  fix:
+    patch:
+      content: "{x for x in range(3)}"
+      location:
+        row: 1
+        column: 4
+      end_location:
+        row: 1
+        column: 28
+    applied: false
+- kind: UnnecessaryGeneratorSet
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 4
+    column: 1
+  fix:
+    patch:
+      content: "{\n    x for x in range(3)\n}"
+      location:
+        row: 2
+        column: 4
+      end_location:
+        row: 4
+        column: 1
+    applied: false
 

src/snapshots/ruff__linter__tests__C402_C402.py.snap

@@ -9,5 +9,31 @@ expression: checks
   end_location:
     row: 1
     column: 30
-  fix: ~
+  fix:
+    patch:
+      content: "{x: x for x in range(3)}"
+      location:
+        row: 1
+        column: 0
+      end_location:
+        row: 1
+        column: 30
+    applied: false
+- kind: UnnecessaryGeneratorDict
+  location:
+    row: 2
+    column: 0
+  end_location:
+    row: 4
+    column: 1
+  fix:
+    patch:
+      content: "{\n    x: x for x in range(3)\n}"
+      location:
+        row: 2
+        column: 0
+      end_location:
+        row: 4
+        column: 1
+    applied: false
 

src/snapshots/ruff__linter__tests__C403_C403.py.snap

@@ -9,5 +9,31 @@ expression: checks
   end_location:
     row: 1
     column: 30
-  fix: ~
+  fix:
+    patch:
+      content: "{x for x in range(3)}"
+      location:
+        row: 1
+        column: 4
+      end_location:
+        row: 1
+        column: 30
+    applied: false
+- kind: UnnecessaryListComprehensionSet
+  location:
+    row: 2
+    column: 4
+  end_location:
+    row: 4
+    column: 1
+  fix:
+    patch:
+      content: "{\n    x for x in range(3)\n}"
+      location:
+        row: 2
+        column: 4
+      end_location:
+        row: 4
+        column: 1
+    applied: false
 

src/snapshots/ruff__linter__tests__C405_C405.py.snap

@@ -10,7 +10,16 @@ expression: checks
   end_location:
     row: 1
     column: 16
-  fix: ~
+  fix:
+    patch:
+      content: "{1, 2}"
+      location:
+        row: 1
+        column: 5
+      end_location:
+        row: 1
+        column: 16
+    applied: false
 - kind:
     UnnecessaryLiteralSet: tuple
   location:
@@ -19,7 +28,16 @@ expression: checks
   end_location:
     row: 2
     column: 16
-  fix: ~
+  fix:
+    patch:
+      content: "{1, 2}"
+      location:
+        row: 2
+        column: 5
+      end_location:
+        row: 2
+        column: 16
+    applied: false
 - kind:
     UnnecessaryLiteralSet: list
   location:
@@ -28,7 +46,16 @@ expression: checks
   end_location:
     row: 3
     column: 12
-  fix: ~
+  fix:
+    patch:
+      content: set()
+      location:
+        row: 3
+        column: 5
+      end_location:
+        row: 3
+        column: 12
+    applied: false
 - kind:
     UnnecessaryLiteralSet: tuple
   location:
@@ -37,5 +64,14 @@ expression: checks
   end_location:
     row: 4
     column: 12
-  fix: ~
+  fix:
+    patch:
+      content: set()
+      location:
+        row: 4
+        column: 5
+      end_location:
+        row: 4
+        column: 12
+    applied: false
 

src/snapshots/ruff__linter__tests__C408_C408.py.snap

@@ -10,7 +10,16 @@ expression: checks
   end_location:
     row: 1
     column: 11
-  fix: ~
+  fix:
+    patch:
+      content: ()
+      location:
+        row: 1
+        column: 4
+      end_location:
+        row: 1
+        column: 11
+    applied: false
 - kind:
     UnnecessaryCollectionCall: list
   location:
@@ -19,7 +28,16 @@ expression: checks
   end_location:
     row: 2
     column: 10
-  fix: ~
+  fix:
+    patch:
+      content: "[]"
+      location:
+        row: 2
+        column: 4
+      end_location:
+        row: 2
+        column: 10
+    applied: false
 - kind:
     UnnecessaryCollectionCall: dict
   location:
@@ -28,7 +46,16 @@ expression: checks
   end_location:
     row: 3
     column: 11
-  fix: ~
+  fix:
+    patch:
+      content: "{}"
+      location:
+        row: 3
+        column: 5
+      end_location:
+        row: 3
+        column: 11
+    applied: false
 - kind:
     UnnecessaryCollectionCall: dict
   location:

src/snapshots/ruff__linter__tests__C409_C409.py.snap

@@ -9,24 +9,87 @@ expression: checks
     column: 5
   end_location:
     row: 1
-    column: 18
-  fix: ~
-- kind:
-    UnnecessaryLiteralWithinTupleCall: tuple
-  location:
-    row: 2
-    column: 5
-  end_location:
-    row: 2
-    column: 18
-  fix: ~
+    column: 14
+  fix:
+    patch:
+      content: ()
+      location:
+        row: 1
+        column: 5
+      end_location:
+        row: 1
+        column: 14
+    applied: false
 - kind:
     UnnecessaryLiteralWithinTupleCall: list
+  location:
+    row: 2
+    column: 5
+  end_location:
+    row: 2
+    column: 18
+  fix:
+    patch:
+      content: "(1, 2)"
+      location:
+        row: 2
+        column: 5
+      end_location:
+        row: 2
+        column: 18
+    applied: false
+- kind:
+    UnnecessaryLiteralWithinTupleCall: tuple
   location:
     row: 3
     column: 5
   end_location:
     row: 3
-    column: 14
-  fix: ~
+    column: 18
+  fix:
+    patch:
+      content: "(1, 2)"
+      location:
+        row: 3
+        column: 5
+      end_location:
+        row: 3
+        column: 18
+    applied: false
+- kind:
+    UnnecessaryLiteralWithinTupleCall: list
+  location:
+    row: 4
+    column: 5
+  end_location:
+    row: 7
+    column: 2
+  fix:
+    patch:
+      content: "(\n    1,\n    2\n)"
+      location:
+        row: 4
+        column: 5
+      end_location:
+        row: 7
+        column: 2
+    applied: false
+- kind:
+    UnnecessaryLiteralWithinTupleCall: tuple
+  location:
+    row: 8
+    column: 5
+  end_location:
+    row: 10
+    column: 1
+  fix:
+    patch:
+      content: "(1, 2)"
+      location:
+        row: 8
+        column: 5
+      end_location:
+        row: 10
+        column: 1
+    applied: false
 

src/snapshots/ruff__linter__tests__C410_C410.py.snap

@@ -10,7 +10,16 @@ expression: checks
   end_location:
     row: 1
     column: 17
-  fix: ~
+  fix:
+    patch:
+      content: "[1, 2]"
+      location:
+        row: 1
+        column: 5
+      end_location:
+        row: 1
+        column: 17
+    applied: false
 - kind:
     UnnecessaryLiteralWithinListCall: tuple
   location:
@@ -19,7 +28,16 @@ expression: checks
   end_location:
     row: 2
     column: 17
-  fix: ~
+  fix:
+    patch:
+      content: "[1, 2]"
+      location:
+        row: 2
+        column: 5
+      end_location:
+        row: 2
+        column: 17
+    applied: false
 - kind:
     UnnecessaryLiteralWithinListCall: list
   location:
@@ -28,7 +46,16 @@ expression: checks
   end_location:
     row: 3
     column: 13
-  fix: ~
+  fix:
+    patch:
+      content: "[]"
+      location:
+        row: 3
+        column: 5
+      end_location:
+        row: 3
+        column: 13
+    applied: false
 - kind:
     UnnecessaryLiteralWithinListCall: tuple
   location:
@@ -37,5 +64,14 @@ expression: checks
   end_location:
     row: 4
     column: 13
-  fix: ~
+  fix:
+    patch:
+      content: "[]"
+      location:
+        row: 4
+        column: 5
+      end_location:
+        row: 4
+        column: 13
+    applied: false
 

src/snapshots/ruff__linter__tests__C411_C411.py.snap

@@ -9,5 +9,14 @@ expression: checks
   end_location:
     row: 2
     column: 20
-  fix: ~
+  fix:
+    patch:
+      content: "[i for i in x]"
+      location:
+        row: 2
+        column: 0
+      end_location:
+        row: 2
+        column: 20
+    applied: false