Bump version to 0.0.138

This reverts commit bd08fc359d.

.github/workflows/ci.yaml

@@ -82,7 +82,7 @@ jobs:
             ${{ runner.os }}-build-${{ env.cache-name }}-
             ${{ runner.os }}-build-
             ${{ runner.os }}-
-      - run: cargo clippy --workspace --all-targets --all-features -- -D warnings
+      - run: cargo clippy --workspace --all-targets --all-features -- -D warnings -W clippy::pedantic
 
   cargo_test:
     name: "cargo test"

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.134
+    rev: v0.0.138
     hooks:
       - id: ruff
 

Cargo.lock

@@ -670,7 +670,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8-to-ruff"
-version = "0.0.134-dev.0"
+version = "0.0.138-dev.0"
 dependencies = [
  "anyhow",
  "clap 4.0.22",
@@ -769,10 +769,17 @@ dependencies = [
 ]
 
 [[package]]
-name = "glob"
-version = "0.3.0"
+name = "globset"
+version = "0.4.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
+checksum = "0a1e17342619edbc21a964c2afbeb6c820c6a2560032872f397bb97ea127bd0a"
+dependencies = [
+ "aho-corasick",
+ "bstr 0.2.17",
+ "fnv",
+ "log",
+ "regex",
+]
 
 [[package]]
 name = "half"
@@ -1029,7 +1036,7 @@ checksum = "fc7fcc620a3bff7cdd7a365be3376c97191aeaccc2a603e600951e452615bf89"
 [[package]]
 name = "libcst"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/LibCST?rev=a13ec97dd4eb925bde4d426c6e422582793b260c#a13ec97dd4eb925bde4d426c6e422582793b260c"
+source = "git+https://github.com/charliermarsh/LibCST?rev=f2f0b7a487a8725d161fe8b3ed73a6758b21e177#f2f0b7a487a8725d161fe8b3ed73a6758b21e177"
 dependencies = [
  "chic",
  "itertools",
@@ -1044,7 +1051,7 @@ dependencies = [
 [[package]]
 name = "libcst_derive"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/LibCST?rev=a13ec97dd4eb925bde4d426c6e422582793b260c#a13ec97dd4eb925bde4d426c6e422582793b260c"
+source = "git+https://github.com/charliermarsh/LibCST?rev=f2f0b7a487a8725d161fe8b3ed73a6758b21e177#f2f0b7a487a8725d161fe8b3ed73a6758b21e177"
 dependencies = [
  "quote",
  "syn",
@@ -1768,7 +1775,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.134"
+version = "0.0.138"
 dependencies = [
  "annotate-snippets 0.9.1",
  "anyhow",
@@ -1787,7 +1794,7 @@ dependencies = [
  "fern",
  "filetime",
  "getrandom 0.2.8",
- "glob",
+ "globset",
  "insta",
  "itertools",
  "libcst",
@@ -1818,7 +1825,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_dev"
-version = "0.0.134"
+version = "0.0.138"
 dependencies = [
  "anyhow",
  "clap 4.0.22",

Cargo.toml

@@ -6,8 +6,9 @@ members = [
 
 [package]
 name = "ruff"
-version = "0.0.134"
+version = "0.0.138"
 edition = "2021"
+rust-version = "1.65.0"
 
 [lib]
 name = "ruff"
@@ -26,9 +27,9 @@ common-path = { version = "1.0.0" }
 dirs = { version = "4.0.0" }
 fern = { version = "0.6.1" }
 filetime = { version = "0.2.17" }
-glob = { version = "0.3.0" }
+globset = {version = "0.4.9" }
 itertools = { version = "0.10.5" }
-libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "a13ec97dd4eb925bde4d426c6e422582793b260c" }
+libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "f2f0b7a487a8725d161fe8b3ed73a6758b21e177" }
 log = { version = "0.4.17" }
 nohash-hasher = { version = "0.2.0" }
 notify = { version = "4.0.17" }

LICENSE

@@ -443,3 +443,28 @@ are:
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     THE SOFTWARE.
   """
+
+- RustPython, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2020 RustPython Team
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """

README.md

@@ -32,12 +32,14 @@ of plugins), [`isort`](https://pypi.org/project/isort/), [`pydocstyle`](https://
 and [`autoflake`](https://pypi.org/project/autoflake/) all while executing tens or hundreds of times
 faster than any individual tool.
 
-(Coming from Flake8? Try [`flake8-to-ruff`](https://pypi.org/project/flake8-to-ruff/) to
-automatically convert your existing configuration.)
+Ruff is actively developed and used in major open-source projects like:
 
-Ruff is actively developed and used in major open-source projects
-like [FastAPI](https://github.com/tiangolo/fastapi), [Zulip](https://github.com/zulip/zulip),
-[pydantic](https://github.com/pydantic/pydantic), and [Saleor](https://github.com/saleor/saleor).
+- [FastAPI](https://github.com/tiangolo/fastapi)
+- [Bokeh](https://github.com/bokeh/bokeh)
+- [Zulip](https://github.com/zulip/zulip)
+- [Pydantic](https://github.com/pydantic/pydantic)
+- [Saleor](https://github.com/saleor/saleor)
+- [Hatch](https://github.com/pypa/hatch)
 
 Read the [launch blog post](https://notes.crmarsh.com/python-tooling-could-be-much-much-faster).
 
@@ -105,7 +107,7 @@ Ruff also works with [pre-commit](https://pre-commit.com):
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.116
+    rev: v0.0.138
     hooks:
       - id: ruff
 ```
@@ -348,6 +350,7 @@ For more, see [Pyflakes](https://pypi.org/project/pyflakes/2.5.0/) on PyPI.
 | 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 |  |
+| F521 | StringDotFormatInvalidFormat | '...'.format(...) has invalid format string: ... |  |
 | F541 | FStringMissingPlaceholders | f-string without any placeholders |  |
 | F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |  |
 | F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |  |
@@ -572,6 +575,7 @@ For more, see [flake8-bugbear](https://pypi.org/project/flake8-bugbear/22.10.27/
 | B025 | DuplicateTryBlockException | try-except block with duplicate exception `Exception` |  |
 | B026 | StarArgUnpackingAfterKeywordArg | Star-arg unpacking after a keyword argument is strongly discouraged |  |
 | B027 | EmptyMethodWithoutAbstractDecorator | `...` is an empty method in an abstract base class, but has no abstract decorator |  |
+| B904 | RaiseWithoutFromInsideExcept | Within an except clause, raise exceptions with raise ... from err or raise ... from None to distinguish them from errors in exception handling |  |
 
 ### flake8-builtins
 
@@ -821,7 +825,7 @@ including:
 - [`flake8-annotations`](https://pypi.org/project/flake8-annotations/)
 - [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
 - [`flake8-bandit`](https://pypi.org/project/flake8-bandit/) (6/40)
-- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (25/32)
+- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (27/32)
 - [`flake8-2020`](https://pypi.org/project/flake8-2020/)
 - [`flake8-blind-except`](https://pypi.org/project/flake8-blind-except/)
 - [`flake8-boolean-trap`](https://pypi.org/project/flake8-boolean-trap/)
@@ -852,7 +856,7 @@ Today, Ruff can be used to replace Flake8 when used with any of the following pl
 - [`flake8-annotations`](https://pypi.org/project/flake8-annotations/)
 - [`flake8-bandit`](https://pypi.org/project/flake8-bandit/) (6/40)
 - [`flake8-comprehensions`](https://pypi.org/project/flake8-comprehensions/)
-- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (26/32)
+- [`flake8-bugbear`](https://pypi.org/project/flake8-bugbear/) (27/32)
 - [`flake8-2020`](https://pypi.org/project/flake8-2020/)
 - [`flake8-blind-except`](https://pypi.org/project/flake8-blind-except/)
 - [`flake8-boolean-trap`](https://pypi.org/project/flake8-boolean-trap/)

benches/source_code_locator.rs

@@ -10,7 +10,7 @@ fn criterion_benchmark(c: &mut Criterion) {
         b.iter(|| {
             let rope = Rope::from_str(black_box(&contents));
             rope.line_to_char(black_box(4));
-        })
+        });
     });
 }
 

flake8_to_ruff/Cargo.lock

@@ -771,7 +771,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8_to_ruff"
-version = "0.0.134"
+version = "0.0.138"
 dependencies = [
  "anyhow",
  "clap",
@@ -1265,7 +1265,7 @@ checksum = "fc7fcc620a3bff7cdd7a365be3376c97191aeaccc2a603e600951e452615bf89"
 [[package]]
 name = "libcst"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/LibCST?rev=a13ec97dd4eb925bde4d426c6e422582793b260c#a13ec97dd4eb925bde4d426c6e422582793b260c"
+source = "git+https://github.com/charliermarsh/LibCST?rev=f2f0b7a487a8725d161fe8b3ed73a6758b21e177#f2f0b7a487a8725d161fe8b3ed73a6758b21e177"
 dependencies = [
  "chic",
  "itertools",
@@ -1280,7 +1280,7 @@ dependencies = [
 [[package]]
 name = "libcst_derive"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/LibCST?rev=a13ec97dd4eb925bde4d426c6e422582793b260c#a13ec97dd4eb925bde4d426c6e422582793b260c"
+source = "git+https://github.com/charliermarsh/LibCST?rev=f2f0b7a487a8725d161fe8b3ed73a6758b21e177#f2f0b7a487a8725d161fe8b3ed73a6758b21e177"
 dependencies = [
  "quote",
  "syn",
@@ -1975,7 +1975,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.134"
+version = "0.0.138"
 dependencies = [
  "anyhow",
  "bincode",

flake8_to_ruff/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "flake8-to-ruff"
-version = "0.0.134-dev.0"
+version = "0.0.138-dev.0"
 edition = "2021"
 
 [lib]

flake8_to_ruff/src/converter.rs

@@ -18,7 +18,7 @@ pub fn convert(
     plugins: Option<Vec<Plugin>>,
 ) -> Result<Pyproject> {
     // Extract all referenced check code prefixes, to power plugin inference.
-    let mut referenced_codes: BTreeSet<CheckCodePrefix> = Default::default();
+    let mut referenced_codes: BTreeSet<CheckCodePrefix> = BTreeSet::default();
     for (key, value) in flake8 {
         if let Some(value) = value {
             match key.as_str() {
@@ -70,13 +70,13 @@ pub fn convert(
         .unwrap_or_default();
 
     // Parse each supported option.
-    let mut options: Options = Default::default();
-    let mut flake8_annotations: flake8_annotations::settings::Options = Default::default();
-    let mut flake8_bugbear: flake8_bugbear::settings::Options = Default::default();
-    let mut flake8_quotes: flake8_quotes::settings::Options = Default::default();
-    let mut flake8_tidy_imports: flake8_tidy_imports::settings::Options = Default::default();
-    let mut mccabe: mccabe::settings::Options = Default::default();
-    let mut pep8_naming: pep8_naming::settings::Options = Default::default();
+    let mut options = Options::default();
+    let mut flake8_annotations = flake8_annotations::settings::Options::default();
+    let mut flake8_bugbear = flake8_bugbear::settings::Options::default();
+    let mut flake8_quotes = flake8_quotes::settings::Options::default();
+    let mut flake8_tidy_imports = flake8_tidy_imports::settings::Options::default();
+    let mut mccabe = mccabe::settings::Options::default();
+    let mut pep8_naming = pep8_naming::settings::Options::default();
     for (key, value) in flake8 {
         if let Some(value) = value {
             match key.as_str() {
@@ -110,7 +110,7 @@ pub fn convert(
                     match parser::parse_files_to_codes_mapping(value.as_ref()) {
                         Ok(per_file_ignores) => {
                             options.per_file_ignores =
-                                Some(parser::collect_per_file_ignores(per_file_ignores))
+                                Some(parser::collect_per_file_ignores(per_file_ignores));
                         }
                         Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
                     }
@@ -181,7 +181,7 @@ pub fn convert(
                 "ban-relative-imports" | "ban_relative_imports" => match value.trim() {
                     "true" => flake8_tidy_imports.ban_relative_imports = Some(Strictness::All),
                     "parents" => {
-                        flake8_tidy_imports.ban_relative_imports = Some(Strictness::Parents)
+                        flake8_tidy_imports.ban_relative_imports = Some(Strictness::Parents);
                     }
                     _ => eprintln!("Unexpected '{key}' value: {value}"),
                 },
@@ -203,22 +203,22 @@ pub fn convert(
     // Deduplicate and sort.
     options.select = Some(Vec::from_iter(select));
     options.ignore = Some(Vec::from_iter(ignore));
-    if flake8_annotations != Default::default() {
+    if flake8_annotations != flake8_annotations::settings::Options::default() {
         options.flake8_annotations = Some(flake8_annotations);
     }
-    if flake8_bugbear != Default::default() {
+    if flake8_bugbear != flake8_bugbear::settings::Options::default() {
         options.flake8_bugbear = Some(flake8_bugbear);
     }
-    if flake8_quotes != Default::default() {
+    if flake8_quotes != flake8_quotes::settings::Options::default() {
         options.flake8_quotes = Some(flake8_quotes);
     }
-    if flake8_tidy_imports != Default::default() {
+    if flake8_tidy_imports != flake8_tidy_imports::settings::Options::default() {
         options.flake8_tidy_imports = Some(flake8_tidy_imports);
     }
-    if mccabe != Default::default() {
+    if mccabe != mccabe::settings::Options::default() {
         options.mccabe = Some(mccabe);
     }
-    if pep8_naming != Default::default() {
+    if pep8_naming != pep8_naming::settings::Options::default() {
         options.pep8_naming = Some(pep8_naming);
     }
 

flake8_to_ruff/src/lib.rs

@@ -1,4 +1,15 @@
-#![allow(clippy::collapsible_if, clippy::collapsible_else_if)]
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
 
 pub mod converter;
 mod parser;

flake8_to_ruff/src/main.rs

@@ -1,4 +1,16 @@
 //! Utility to generate Ruff's pyproject.toml section from a Flake8 INI file.
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
 
 use std::path::PathBuf;
 

flake8_to_ruff/src/parser.rs

@@ -31,7 +31,7 @@ pub fn parse_prefix_codes(value: &str) -> Vec<CheckCodePrefix> {
 pub fn parse_strings(value: &str) -> Vec<String> {
     COMMA_SEPARATED_LIST_RE
         .split(value)
-        .map(|part| part.trim())
+        .map(str::trim)
         .filter(|part| !part.is_empty())
         .map(String::from)
         .collect()
@@ -92,7 +92,7 @@ impl State {
                         });
                     }
                 }
-                Err(_) => eprintln!("Skipping unrecognized prefix: {}", code),
+                Err(_) => eprintln!("Skipping unrecognized prefix: {code}"),
             }
         }
         codes
@@ -129,14 +129,14 @@ fn tokenize_files_to_codes_mapping(value: &str) -> Vec<Token> {
     }
     tokens.push(Token {
         token_name: TokenType::Eof,
-        src: "".to_string(),
+        src: String::new(),
     });
     tokens
 }
 
 /// Parse a 'files-to-codes' mapping, mimicking Flake8's internal logic.
 ///
-/// See: https://github.com/PyCQA/flake8/blob/7dfe99616fc2f07c0017df2ba5fa884158f3ea8a/src/flake8/utils.py#L45
+/// See: <https://github.com/PyCQA/flake8/blob/7dfe99616fc2f07c0017df2ba5fa884158f3ea8a/src/flake8/utils.py#L45>
 pub fn parse_files_to_codes_mapping(value: &str) -> Result<Vec<PatternPrefixPair>> {
     if value.trim().is_empty() {
         return Ok(vec![]);

resources/test/fixtures/B904.py

@@ -0,0 +1,55 @@
+"""
+Should emit:
+B904 - on lines 10, 11 and 16
+"""
+
+try:
+    raise ValueError
+except ValueError:
+    if "abc":
+        raise TypeError
+    raise UserWarning
+except AssertionError:
+    raise  # Bare `raise` should not be an error
+except Exception as err:
+    assert err
+    raise Exception("No cause here...")
+except BaseException as base_err:
+    # Might use this instead of bare raise with the `.with_traceback()` method
+    raise base_err
+finally:
+    raise Exception("Nothing to chain from, so no warning here")
+
+try:
+    raise ValueError
+except ValueError:
+    # should not emit, since we are not raising something
+    def proxy():
+        raise NameError
+
+
+try:
+    from preferred_library import Thing
+except ImportError:
+    try:
+        from fallback_library import Thing
+    except ImportError:
+
+        class Thing:
+            def __getattr__(self, name):
+                # same as the case above, should not emit.
+                raise AttributeError
+
+
+try:
+    from preferred_library import Thing
+except ImportError:
+    try:
+        from fallback_library import Thing
+    except ImportError:
+
+        def context_switch():
+            try:
+                raise ValueError
+            except ValueError:
+                raise

resources/test/fixtures/F521.py

@@ -0,0 +1,29 @@
+"{".format(1)
+"}".format(1)
+"{foo[}".format(foo=1)
+# too much string recursion (placeholder-in-placeholder)
+"{:{:{}}}".format(1, 2, 3)
+# ruff picks these issues up, but flake8 doesn't
+"{foo[]}".format(foo={"": 1})
+"{foo..}".format(foo=1)
+"{foo..bar}".format(foo=1)
+
+# "{} {1}".format(1, 2)  # F525
+# "{0} {}".format(1, 2)  # F525
+# "{}".format(1, 2)  # F523
+# "{}".format(1, bar=2)  # F522
+# "{} {}".format(1)  # F524
+# "{2}".format()  # F524
+# "{bar}".format()  # F524
+
+# The following are all "good" uses of .format
+"{.__class__}".format("")
+"{foo[bar]}".format(foo={"bar": "barv"})
+"{[bar]}".format({"bar": "barv"})
+"{:{}} {}".format(1, 15, 2)
+"{:2}".format(1)
+"{foo}-{}".format(1, foo=2)
+a = ()
+"{}".format(*a)
+k = {}
+"{foo}".format(**k)

resources/test/fixtures/F841.py

@@ -52,3 +52,16 @@ def f5():
 
     def f7():
         nonlocal b
+
+
+def f6():
+    annotations = []
+    assert len([annotations for annotations in annotations])
+
+
+def f7():
+    def connect():
+        return None, None
+
+    with connect() as (connection, cursor):
+        cursor.execute("SELECT * FROM users")

ruff_dev/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff_dev"
-version = "0.0.134"
+version = "0.0.138"
 edition = "2021"
 
 [dependencies]
@@ -8,7 +8,7 @@ anyhow = { version = "1.0.66" }
 clap = { version = "4.0.1", features = ["derive"] }
 codegen = { version = "0.2.0" }
 itertools = { version = "0.10.5" }
-libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "a13ec97dd4eb925bde4d426c6e422582793b260c" }
+libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "f2f0b7a487a8725d161fe8b3ed73a6758b21e177" }
 ruff = { path = ".." }
 rustpython-ast = { features = ["unparse"], git = "https://github.com/RustPython/RustPython.git", rev = "f885db8c61514f069979861f6b3bd83292086231" }
 rustpython-common = { git = "https://github.com/RustPython/RustPython.git", rev = "f885db8c61514f069979861f6b3bd83292086231" }

ruff_dev/src/generate_check_code_prefix.rs

@@ -24,7 +24,7 @@ pub struct Cli {
 
 pub fn main(cli: &Cli) -> Result<()> {
     // Build up a map from prefix to matching CheckCodes.
-    let mut prefix_to_codes: BTreeMap<String, BTreeSet<CheckCode>> = Default::default();
+    let mut prefix_to_codes: BTreeMap<String, BTreeSet<CheckCode>> = BTreeMap::default();
     for check_code in CheckCode::iter() {
         let as_ref: String = check_code.as_ref().to_string();
         let prefix_len = as_ref
@@ -106,7 +106,7 @@ pub fn main(cli: &Cli) -> Result<()> {
             2 => "Tens",
             1 => "Hundreds",
             0 => "Category",
-            _ => panic!("Invalid prefix: {}", prefix),
+            _ => panic!("Invalid prefix: {prefix}"),
         };
         gen = gen.line(format!(
             "CheckCodePrefix::{prefix} => PrefixSpecificity::{},",
@@ -132,10 +132,10 @@ pub fn main(cli: &Cli) -> Result<()> {
 
     // Write the output to `src/checks_gen.rs` (or stdout).
     if cli.dry_run {
-        println!("{}", output);
+        println!("{output}");
     } else {
         let mut f = OpenOptions::new().write(true).truncate(true).open(FILE)?;
-        write!(f, "{}", output)?;
+        write!(f, "{output}")?;
     }
 
     Ok(())

ruff_dev/src/generate_rules_table.rs

@@ -61,7 +61,7 @@ pub fn main(cli: &Cli) -> Result<()> {
     }
 
     if cli.dry_run {
-        print!("{}", output);
+        print!("{output}");
     } else {
         // Read the existing file.
         let file = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
@@ -84,9 +84,9 @@ pub fn main(cli: &Cli) -> Result<()> {
 
         // Write the prefix, new contents, and suffix.
         let mut f = OpenOptions::new().write(true).truncate(true).open(&file)?;
-        write!(f, "{}\n\n", prefix)?;
-        write!(f, "{}", output)?;
-        write!(f, "{}", suffix)?;
+        write!(f, "{prefix}\n\n")?;
+        write!(f, "{output}")?;
+        write!(f, "{suffix}")?;
     }
 
     Ok(())

ruff_dev/src/generate_source_code.rs

@@ -19,7 +19,7 @@ pub fn main(cli: &Cli) -> Result<()> {
     let contents = fs::read_to_string(&cli.file)?;
     let python_ast = parser::parse_program(&contents, &cli.file.to_string_lossy())?;
     let mut generator = SourceGenerator::new();
-    generator.unparse_suite(&python_ast)?;
+    generator.unparse_suite(&python_ast);
     println!("{}", generator.generate()?);
     Ok(())
 }

ruff_dev/src/lib.rs

@@ -1,3 +1,16 @@
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
+
 pub mod generate_check_code_prefix;
 pub mod generate_rules_table;
 pub mod generate_source_code;

ruff_dev/src/main.rs

@@ -1,3 +1,16 @@
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
+
 use anyhow::Result;
 use clap::{Parser, Subcommand};
 use ruff_dev::{

ruff_dev/src/print_ast.rs

@@ -17,6 +17,6 @@ pub struct Cli {
 pub fn main(cli: &Cli) -> Result<()> {
     let contents = fs::read_to_string(&cli.file)?;
     let python_ast = parser::parse_program(&contents, &cli.file.to_string_lossy())?;
-    println!("{:#?}", python_ast);
+    println!("{python_ast:#?}");
     Ok(())
 }

ruff_dev/src/print_cst.rs

@@ -1,4 +1,4 @@
-//! Print the LibCST CST for a given Python file.
+//! Print the `LibCST` CST for a given Python file.
 
 use std::fs;
 use std::path::PathBuf;
@@ -17,7 +17,7 @@ pub fn main(cli: &Cli) -> Result<()> {
     let contents = fs::read_to_string(&cli.file)?;
     match libcst_native::parse_module(&contents, None) {
         Ok(python_cst) => {
-            println!("{:#?}", python_cst);
+            println!("{python_cst:#?}");
             Ok(())
         }
         Err(_) => Err(anyhow::anyhow!("Failed to parse CST")),

ruff_dev/src/print_tokens.rs

@@ -17,7 +17,7 @@ pub struct Cli {
 pub fn main(cli: &Cli) -> Result<()> {
     let contents = fs::read_to_string(&cli.file)?;
     for (_, tok, _) in lexer::make_tokenizer(&contents).flatten() {
-        println!("{:#?}", tok);
+        println!("{tok:#?}");
     }
     Ok(())
 }

src/ast/helpers.rs

@@ -6,7 +6,6 @@ use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprKind, Location,
 use crate::ast::types::Range;
 use crate::SourceCodeLocator;
 
-#[inline(always)]
 fn collect_call_path_inner<'a>(expr: &'a Expr, parts: &mut Vec<&'a str>) {
     match &expr.node {
         ExprKind::Call { func, .. } => {
@@ -24,7 +23,6 @@ fn collect_call_path_inner<'a>(expr: &'a Expr, parts: &mut Vec<&'a str>) {
 }
 
 /// Convert an `Expr` to its call path (like `List`, or `typing.List`).
-#[inline(always)]
 pub fn compose_call_path(expr: &Expr) -> Option<String> {
     let segments = collect_call_paths(expr);
     if segments.is_empty() {
@@ -35,7 +33,6 @@ pub fn compose_call_path(expr: &Expr) -> Option<String> {
 }
 
 /// Convert an `Expr` to its call path segments (like ["typing", "List"]).
-#[inline(always)]
 pub fn collect_call_paths(expr: &Expr) -> Vec<&str> {
     let mut segments = vec![];
     collect_call_path_inner(expr, &mut segments);
@@ -121,10 +118,9 @@ pub fn match_call_path(
     // `Match`).
     if num_segments == 0 {
         module.is_empty()
-            || from_imports
-                .get(module)
-                .map(|imports| imports.contains(member) || imports.contains("*"))
-                .unwrap_or(false)
+            || from_imports.get(module).map_or(false, |imports| {
+                imports.contains(member) || imports.contains("*")
+            })
     } else {
         let components: Vec<&str> = module.split('.').collect();
 
@@ -148,8 +144,7 @@ pub fn match_call_path(
             let member = components[cut];
             if from_imports
                 .get(&module.as_str())
-                .map(|imports| imports.contains(member))
-                .unwrap_or(false)
+                .map_or(false, |imports| imports.contains(member))
             {
                 return true;
             }

src/ast/operations.rs

@@ -4,8 +4,6 @@ use crate::ast::types::{BindingKind, Scope};
 
 /// Extract the names bound to a given __all__ assignment.
 pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
-    let mut names: Vec<String> = vec![];
-
     fn add_to_names(names: &mut Vec<String>, elts: &[Expr]) {
         for elt in elts {
             if let ExprKind::Constant {
@@ -13,11 +11,13 @@ pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
                 ..
             } = &elt.node
             {
-                names.push(value.to_string())
+                names.push(value.to_string());
             }
         }
     }
 
+    let mut names: Vec<String> = vec![];
+
     // Grab the existing bound __all__ values.
     if let StmtKind::AugAssign { .. } = &stmt.node {
         if let Some(binding) = scope.values.get("__all__") {
@@ -35,7 +35,7 @@ pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
     } {
         match &value.node {
             ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
-                add_to_names(&mut names, elts)
+                add_to_names(&mut names, elts);
             }
             ExprKind::BinOp { left, right, .. } => {
                 let mut current_left = left;

src/ast/visitor.rs

@@ -19,8 +19,8 @@ pub trait Visitor<'a> {
     fn visit_constant(&mut self, constant: &'a Constant) {
         walk_constant(self, constant);
     }
-    fn visit_expr_context(&mut self, expr_content: &'a ExprContext) {
-        walk_expr_context(self, expr_content);
+    fn visit_expr_context(&mut self, expr_context: &'a ExprContext) {
+        walk_expr_context(self, expr_context);
     }
     fn visit_boolop(&mut self, boolop: &'a Boolop) {
         walk_boolop(self, boolop);
@@ -249,7 +249,7 @@ pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
                 visitor.visit_stmt(stmt);
             }
             for excepthandler in handlers {
-                visitor.visit_excepthandler(excepthandler)
+                visitor.visit_excepthandler(excepthandler);
             }
             for stmt in orelse {
                 visitor.visit_stmt(stmt);
@@ -447,7 +447,7 @@ pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
 pub fn walk_constant<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, constant: &'a Constant) {
     if let Constant::Tuple(constants) = constant {
         for constant in constants {
-            visitor.visit_constant(constant)
+            visitor.visit_constant(constant);
         }
     }
 }
@@ -456,8 +456,8 @@ pub fn walk_comprehension<'a, V: Visitor<'a> + ?Sized>(
     visitor: &mut V,
     comprehension: &'a Comprehension,
 ) {
-    visitor.visit_expr(&comprehension.target);
     visitor.visit_expr(&comprehension.iter);
+    visitor.visit_expr(&comprehension.target);
     for expr in &comprehension.ifs {
         visitor.visit_expr(expr);
     }
@@ -577,7 +577,6 @@ pub fn walk_pattern<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, pattern: &'a P
 }
 
 #[allow(unused_variables)]
-#[inline(always)]
 pub fn walk_expr_context<'a, V: Visitor<'a> + ?Sized>(
     visitor: &mut V,
     expr_context: &'a ExprContext,
@@ -585,21 +584,16 @@ pub fn walk_expr_context<'a, V: Visitor<'a> + ?Sized>(
 }
 
 #[allow(unused_variables)]
-#[inline(always)]
 pub fn walk_boolop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, boolop: &'a Boolop) {}
 
 #[allow(unused_variables)]
-#[inline(always)]
 pub fn walk_operator<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, operator: &'a Operator) {}
 
 #[allow(unused_variables)]
-#[inline(always)]
 pub fn walk_unaryop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, unaryop: &'a Unaryop) {}
 
 #[allow(unused_variables)]
-#[inline(always)]
 pub fn walk_cmpop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, cmpop: &'a Cmpop) {}
 
 #[allow(unused_variables)]
-#[inline(always)]
 pub fn walk_alias<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, alias: &'a Alias) {}

src/ast/whitespace.rs

@@ -19,7 +19,7 @@ pub fn leading_space(line: &str) -> String {
 }
 
 /// Extract the leading indentation from a line.
-pub fn indentation<'a, T>(checker: &'a Checker, located: &Located<T>) -> String {
+pub fn indentation<T>(checker: &Checker, located: &Located<T>) -> String {
     let range = Range::from_located(located);
     checker
         .locator

src/autofix/fixer.rs

@@ -10,8 +10,6 @@ use crate::autofix::{Fix, Patch};
 use crate::checks::Check;
 use crate::source_code_locator::SourceCodeLocator;
 
-// 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,
@@ -19,55 +17,55 @@ pub enum Mode {
     None,
 }
 
-impl Mode {
-    /// Return `true` if a patch should be generated under the given `Mode`.
-    pub fn patch(&self) -> bool {
-        match &self {
-            Mode::Generate => true,
-            Mode::Apply => true,
-            Mode::None => false,
+impl From<bool> for Mode {
+    fn from(value: bool) -> Self {
+        if value {
+            Mode::Apply
+        } else {
+            Mode::None
         }
     }
 }
 
-impl From<bool> for Mode {
-    fn from(value: bool) -> Self {
+impl From<&Mode> for bool {
+    fn from(value: &Mode) -> Self {
         match value {
-            true => Mode::Apply,
-            false => Mode::None,
+            Mode::Generate | Mode::Apply => true,
+            Mode::None => false,
         }
     }
 }
 
 /// Auto-fix errors in a file, and write the fixed source code to disk.
 pub fn fix_file<'a>(
-    checks: &'a mut [Check],
+    checks: &'a [Check],
     locator: &'a SourceCodeLocator<'a>,
-) -> Option<Cow<'a, str>> {
+) -> Option<(Cow<'a, str>, usize)> {
     if checks.iter().all(|check| check.fix.is_none()) {
         return None;
     }
 
     Some(apply_fixes(
-        checks.iter_mut().filter_map(|check| check.fix.as_mut()),
+        checks.iter().filter_map(|check| check.fix.as_ref()),
         locator,
     ))
 }
 
 /// Apply a series of fixes.
 fn apply_fixes<'a>(
-    fixes: impl Iterator<Item = &'a mut Fix>,
+    fixes: impl Iterator<Item = &'a Fix>,
     locator: &'a SourceCodeLocator<'a>,
-) -> Cow<'a, str> {
+) -> (Cow<'a, str>, usize) {
     let mut output = RopeBuilder::new();
     let mut last_pos: Location = Location::new(1, 0);
     let mut applied: BTreeSet<&Patch> = BTreeSet::default();
+    let mut num_fixed: usize = 0;
 
     for fix in fixes.sorted_by_key(|fix| fix.patch.location) {
         // If we already applied an identical fix as part of another correction, skip
         // any re-application.
         if applied.contains(&fix.patch) {
-            fix.applied = true;
+            num_fixed += 1;
             continue;
         }
 
@@ -90,19 +88,18 @@ fn apply_fixes<'a>(
         // Track that the fix was applied.
         last_pos = fix.patch.end_location;
         applied.insert(&fix.patch);
-        fix.applied = true;
+        num_fixed += 1;
     }
 
     // Add the remaining content.
     let slice = locator.slice_source_code_at(last_pos);
     output.append(&slice);
 
-    Cow::from(output.finish())
+    (Cow::from(output.finish()), num_fixed)
 }
 
 #[cfg(test)]
 mod tests {
-    use anyhow::Result;
     use rustpython_parser::ast::Location;
 
     use crate::autofix::fixer::apply_fixes;
@@ -110,115 +107,117 @@ mod tests {
     use crate::SourceCodeLocator;
 
     #[test]
-    fn empty_file() -> Result<()> {
-        let mut fixes = vec![];
-        let locator = SourceCodeLocator::new("");
-        let actual = apply_fixes(fixes.iter_mut(), &locator);
-        let expected = "";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
+    fn empty_file() {
+        let fixes = vec![];
+        let locator = SourceCodeLocator::new(r#""#);
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(contents, "");
+        assert_eq!(fixed, 0);
     }
 
     #[test]
-    fn apply_single_replacement() -> Result<()> {
-        let mut fixes = vec![Fix {
+    fn apply_single_replacement() {
+        let fixes = vec![Fix {
             patch: Patch {
                 content: "Bar".to_string(),
                 location: Location::new(1, 8),
                 end_location: Location::new(1, 14),
             },
-            applied: false,
         }];
         let locator = SourceCodeLocator::new(
-            "class A(object):
-        ...
-",
+            r#"
+class A(object):
+    ...
+"#
+            .trim(),
         );
-        let actual = apply_fixes(fixes.iter_mut(), &locator);
-
-        let expected = "class A(Bar):
-        ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(
+            contents,
+            r#"
+class A(Bar):
+    ...
+"#
+            .trim(),
+        );
+        assert_eq!(fixed, 1);
     }
 
     #[test]
-    fn apply_single_removal() -> Result<()> {
-        let mut fixes = vec![Fix {
+    fn apply_single_removal() {
+        let fixes = vec![Fix {
             patch: Patch {
-                content: "".to_string(),
+                content: String::new(),
                 location: Location::new(1, 7),
                 end_location: Location::new(1, 15),
             },
-            applied: false,
         }];
         let locator = SourceCodeLocator::new(
-            "class A(object):
-        ...
-",
+            r#"
+class A(object):
+    ...
+"#
+            .trim(),
         );
-        let actual = apply_fixes(fixes.iter_mut(), &locator);
-
-        let expected = "class A:
-        ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(
+            contents,
+            r#"
+class A:
+    ...
+"#
+            .trim()
+        );
+        assert_eq!(fixed, 1);
     }
 
     #[test]
-    fn apply_double_removal() -> Result<()> {
-        let mut fixes = vec![
+    fn apply_double_removal() {
+        let fixes = vec![
             Fix {
                 patch: Patch {
-                    content: "".to_string(),
+                    content: String::new(),
                     location: Location::new(1, 7),
                     end_location: Location::new(1, 16),
                 },
-                applied: false,
             },
             Fix {
                 patch: Patch {
-                    content: "".to_string(),
+                    content: String::new(),
                     location: Location::new(1, 16),
                     end_location: Location::new(1, 23),
                 },
-                applied: false,
             },
         ];
         let locator = SourceCodeLocator::new(
-            "class A(object, object):
-        ...
-",
+            r#"
+class A(object, object):
+    ...
+"#
+            .trim(),
         );
-        let actual = apply_fixes(fixes.iter_mut(), &locator);
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
 
-        let expected = "class A:
-        ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
+        assert_eq!(
+            contents,
+            r#"
+class A:
+    ...
+"#
+            .trim()
+        );
+        assert_eq!(fixed, 2);
     }
 
     #[test]
-    fn ignore_overlapping_fixes() -> Result<()> {
-        let mut fixes = vec![
+    fn ignore_overlapping_fixes() {
+        let fixes = vec![
             Fix {
                 patch: Patch {
-                    content: "".to_string(),
+                    content: String::new(),
                     location: Location::new(1, 7),
                     end_location: Location::new(1, 15),
                 },
-                applied: false,
             },
             Fix {
                 patch: Patch {
@@ -226,22 +225,24 @@ mod tests {
                     location: Location::new(1, 9),
                     end_location: Location::new(1, 11),
                 },
-                applied: false,
             },
         ];
         let locator = SourceCodeLocator::new(
-            "class A(object):
+            r#"
+class A(object):
     ...
-",
+"#
+            .trim(),
         );
-        let actual = apply_fixes(fixes.iter_mut(), &locator);
-
-        let expected = "class A:
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(
+            contents,
+            r#"
+class A:
     ...
-";
-
-        assert_eq!(actual, expected);
-
-        Ok(())
+"#
+            .trim(),
+        );
+        assert_eq!(fixed, 1);
     }
 }

src/autofix/mod.rs

@@ -14,18 +14,16 @@ pub struct Patch {
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Fix {
     pub patch: Patch,
-    pub applied: bool,
 }
 
 impl Fix {
     pub fn deletion(start: Location, end: Location) -> Self {
         Self {
             patch: Patch {
-                content: "".to_string(),
+                content: String::new(),
                 location: start,
                 end_location: end,
             },
-            applied: false,
         }
     }
 
@@ -36,7 +34,6 @@ impl Fix {
                 location: start,
                 end_location: end,
             },
-            applied: false,
         }
     }
 
@@ -47,18 +44,16 @@ impl Fix {
                 location: at,
                 end_location: at,
             },
-            applied: false,
         }
     }
 
     pub fn dummy(location: Location) -> Self {
         Self {
             patch: Patch {
-                content: "".to_string(),
+                content: String::new(),
                 location,
                 end_location: location,
             },
-            applied: false,
         }
     }
 }

src/cache.rs

@@ -63,9 +63,10 @@ impl Mode {
 
 impl From<bool> for Mode {
     fn from(value: bool) -> Self {
-        match value {
-            true => Mode::ReadWrite,
-            false => Mode::None,
+        if value {
+            Mode::ReadWrite
+        } else {
+            Mode::None
         }
     }
 }
@@ -177,6 +178,6 @@ pub fn set(
         cache_key(path, settings, autofix),
         &bincode::serialize(&check_result).unwrap(),
     ) {
-        error!("Failed to write to cache: {e:?}")
+        error!("Failed to write to cache: {e:?}");
     }
 }

src/check_ast.rs

@@ -1,12 +1,12 @@
 //! Lint rules based on AST traversal.
 
 use std::collections::BTreeMap;
-use std::ops::Deref;
 use std::path::Path;
 
 use itertools::Itertools;
 use log::error;
 use rustc_hash::{FxHashMap, FxHashSet};
+use rustpython_ast::Withitem;
 use rustpython_parser::ast::{
     Arg, Arguments, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind,
     KeywordData, Operator, Stmt, StmtKind, Suite,
@@ -19,11 +19,11 @@ use crate::ast::helpers::{
 use crate::ast::operations::extract_all_names;
 use crate::ast::relocate::relocate_expr;
 use crate::ast::types::{
-    Binding, BindingContext, BindingKind, ClassScope, ImportKind, Range, Scope, ScopeKind,
+    Binding, BindingContext, BindingKind, ClassScope, FunctionScope, ImportKind, Range, Scope,
+    ScopeKind,
 };
-use crate::ast::visitor::{walk_excepthandler, Visitor};
+use crate::ast::visitor::{walk_excepthandler, walk_withitem, Visitor};
 use crate::ast::{helpers, operations, visitor};
-use crate::autofix::fixer;
 use crate::checks::{Check, CheckCode, CheckKind};
 use crate::docstrings::definition::{Definition, DefinitionKind, Documentable};
 use crate::python::builtins::{BUILTINS, MAGIC_GLOBALS};
@@ -42,10 +42,11 @@ use crate::{
 
 const GLOBAL_SCOPE_INDEX: usize = 0;
 
+#[allow(clippy::struct_excessive_bools)]
 pub struct Checker<'a> {
     // Input data.
     path: &'a Path,
-    autofix: &'a fixer::Mode,
+    autofix: bool,
     pub(crate) settings: &'a Settings,
     pub(crate) locator: &'a SourceCodeLocator<'a>,
     // Computed checks.
@@ -77,6 +78,7 @@ pub struct Checker<'a> {
     in_deferred_string_annotation: bool,
     in_literal: bool,
     in_subscript: bool,
+    in_withitem: bool,
     seen_import_boundary: bool,
     futures_allowed: bool,
     annotations_future_enabled: bool,
@@ -86,7 +88,7 @@ pub struct Checker<'a> {
 impl<'a> Checker<'a> {
     pub fn new(
         settings: &'a Settings,
-        autofix: &'a fixer::Mode,
+        autofix: bool,
         path: &'a Path,
         locator: &'a SourceCodeLocator,
     ) -> Checker<'a> {
@@ -95,40 +97,40 @@ impl<'a> Checker<'a> {
             autofix,
             path,
             locator,
-            checks: Default::default(),
-            definitions: Default::default(),
-            deletions: Default::default(),
-            from_imports: Default::default(),
-            import_aliases: Default::default(),
-            parents: Default::default(),
-            parent_stack: Default::default(),
-            scopes: Default::default(),
-            scope_stack: Default::default(),
-            dead_scopes: Default::default(),
-            deferred_string_annotations: Default::default(),
-            deferred_annotations: Default::default(),
-            deferred_functions: Default::default(),
-            deferred_lambdas: Default::default(),
-            deferred_assignments: Default::default(),
+            checks: vec![],
+            definitions: vec![],
+            deletions: FxHashSet::default(),
+            from_imports: FxHashMap::default(),
+            import_aliases: FxHashMap::default(),
+            parents: vec![],
+            parent_stack: vec![],
+            scopes: vec![],
+            scope_stack: vec![],
+            dead_scopes: vec![],
+            deferred_string_annotations: vec![],
+            deferred_annotations: vec![],
+            deferred_functions: vec![],
+            deferred_lambdas: vec![],
+            deferred_assignments: vec![],
             // Internal, derivative state.
             visible_scope: VisibleScope {
                 modifier: Modifier::Module,
                 visibility: module_visibility(path),
             },
-            in_f_string: Default::default(),
-            in_annotation: Default::default(),
-            in_deferred_string_annotation: Default::default(),
-            in_literal: Default::default(),
-            in_subscript: Default::default(),
-            seen_import_boundary: Default::default(),
+            in_f_string: None,
+            in_annotation: false,
+            in_deferred_string_annotation: false,
+            in_literal: false,
+            in_subscript: false,
+            in_withitem: false,
+            seen_import_boundary: false,
             futures_allowed: true,
-            annotations_future_enabled: Default::default(),
-            except_handlers: Default::default(),
+            annotations_future_enabled: false,
+            except_handlers: vec![],
         }
     }
 
     /// Add a `Check` to the `Checker`.
-    #[inline(always)]
     pub(crate) fn add_check(&mut self, check: Check) {
         // If we're in an f-string, override the location. RustPython doesn't produce
         // reliable locations for expressions within f-strings, so we use the
@@ -145,7 +147,6 @@ impl<'a> Checker<'a> {
     }
 
     /// Add multiple `Check` items to the `Checker`.
-    #[inline(always)]
     pub(crate) fn add_checks(&mut self, checks: impl Iterator<Item = Check>) {
         for check in checks {
             self.add_check(check);
@@ -157,7 +158,7 @@ impl<'a> Checker<'a> {
     pub fn patch(&self, code: &CheckCode) -> bool {
         // TODO(charlie): We can't fix errors in f-strings until RustPython adds
         // location data.
-        self.autofix.patch() && self.in_f_string.is_none() && self.settings.fixable.contains(code)
+        self.autofix && self.in_f_string.is_none() && self.settings.fixable.contains(code)
     }
 
     /// Return `true` if the `Expr` is a reference to `typing.${target}`.
@@ -536,20 +537,20 @@ where
                 self.check_builtin_shadowing(name, Range::from_located(stmt), false);
 
                 for expr in bases {
-                    self.visit_expr(expr)
+                    self.visit_expr(expr);
                 }
                 for keyword in keywords {
-                    self.visit_keyword(keyword)
+                    self.visit_keyword(keyword);
                 }
                 for expr in decorator_list {
-                    self.visit_expr(expr)
+                    self.visit_expr(expr);
                 }
                 self.push_scope(Scope::new(ScopeKind::Class(ClassScope {
                     name,
                     bases,
                     keywords,
                     decorator_list,
-                })))
+                })));
             }
             StmtKind::Import { names } => {
                 if self.settings.enabled.contains(&CheckCode::E402) {
@@ -578,7 +579,7 @@ where
                                 used: None,
                                 range: Range::from_located(stmt),
                             },
-                        )
+                        );
                     } else {
                         if let Some(asname) = &alias.node.asname {
                             self.check_builtin_shadowing(asname, Range::from_located(stmt), false);
@@ -603,8 +604,7 @@ where
                                     .node
                                     .asname
                                     .as_ref()
-                                    .map(|asname| asname == &alias.node.name)
-                                    .unwrap_or(false)
+                                    .map_or(false, |asname| asname == &alias.node.name)
                                 {
                                     Some((
                                         self.scopes[*(self
@@ -619,7 +619,7 @@ where
                                 },
                                 range: Range::from_located(stmt),
                             },
-                        )
+                        );
                     }
 
                     if let Some(asname) = &alias.node.asname {
@@ -695,7 +695,7 @@ where
                                     .iter()
                                     .filter(|alias| alias.node.asname.is_none())
                                     .map(|alias| alias.node.name.as_str()),
-                            )
+                            );
                     }
                     for alias in names {
                         if let Some(asname) = &alias.node.asname {
@@ -744,7 +744,7 @@ where
                         }
 
                         if self.settings.enabled.contains(&CheckCode::F407) {
-                            if !ALL_FEATURE_NAMES.contains(&alias.node.name.deref()) {
+                            if !ALL_FEATURE_NAMES.contains(&&*alias.node.name) {
                                 self.add_check(Check::new(
                                     CheckKind::FutureFeatureNotDefined(alias.node.name.to_string()),
                                     Range::from_located(stmt),
@@ -807,7 +807,7 @@ where
                         let name = alias.node.asname.as_ref().unwrap_or(&alias.node.name);
                         let full_name = match module {
                             None => alias.node.name.to_string(),
-                            Some(parent) => format!("{}.{}", parent, alias.node.name),
+                            Some(parent) => format!("{parent}.{}", alias.node.name),
                         };
                         self.add_binding(
                             name,
@@ -823,8 +823,7 @@ where
                                     .node
                                     .asname
                                     .as_ref()
-                                    .map(|asname| asname == &alias.node.name)
-                                    .unwrap_or(false)
+                                    .map_or(false, |asname| asname == &alias.node.name)
                                 {
                                     Some((
                                         self.scopes[*(self
@@ -839,7 +838,7 @@ where
                                 },
                                 range: Range::from_located(stmt),
                             },
-                        )
+                        );
                     }
 
                     if self.settings.enabled.contains(&CheckCode::I252) {
@@ -940,7 +939,7 @@ where
                         self,
                         stmt,
                         test,
-                        msg.as_ref().map(|expr| expr.deref()),
+                        msg.as_ref().map(|expr| &**expr),
                     );
                 }
                 if self.settings.enabled.contains(&CheckCode::S101) {
@@ -983,7 +982,7 @@ where
             StmtKind::Assign { targets, value, .. } => {
                 if self.settings.enabled.contains(&CheckCode::E731) {
                     if let [target] = &targets[..] {
-                        pycodestyle::plugins::do_not_assign_lambda(self, target, value, stmt)
+                        pycodestyle::plugins::do_not_assign_lambda(self, target, value, stmt);
                     }
                 }
                 if self.settings.enabled.contains(&CheckCode::U001) {
@@ -1020,7 +1019,7 @@ where
             StmtKind::Delete { .. } => {}
             StmtKind::Expr { value, .. } => {
                 if self.settings.enabled.contains(&CheckCode::B015) {
-                    flake8_bugbear::plugins::useless_comparison(self, value)
+                    flake8_bugbear::plugins::useless_comparison(self, value);
                 }
             }
             _ => {}
@@ -1085,7 +1084,7 @@ where
                 }
                 self.except_handlers.pop();
                 for excepthandler in handlers {
-                    self.visit_excepthandler(excepthandler)
+                    self.visit_excepthandler(excepthandler);
                 }
                 for stmt in orelse {
                     self.visit_stmt(stmt);
@@ -1244,6 +1243,28 @@ where
                 args,
                 keywords,
             } => {
+                // pyflakes
+                if let ExprKind::Attribute { value, attr, .. } = &func.node {
+                    if let ExprKind::Constant {
+                        value: Constant::Str(value),
+                        ..
+                    } = &value.node
+                    {
+                        if attr == "format" {
+                            // "...".format(...) call
+                            if self.settings.enabled.contains(&CheckCode::F521) {
+                                let location = Range::from_located(expr);
+                                if let Some(check) =
+                                    pyflakes::checks::string_dot_format_invalid(value, location)
+                                {
+                                    self.add_check(check);
+                                }
+                            }
+                        }
+                    }
+                }
+
+                // pyupgrade
                 if self.settings.enabled.contains(&CheckCode::U005) {
                     pyupgrade::plugins::deprecated_unittest_alias(self, func);
                 }
@@ -1624,7 +1645,7 @@ where
                         comparators,
                         check_none_comparisons,
                         check_true_false_comparisons,
-                    )
+                    );
                 }
 
                 if self.settings.enabled.contains(&CheckCode::F632) {
@@ -1721,7 +1742,7 @@ where
                 for expr in &args.defaults {
                     self.visit_expr(expr);
                 }
-                self.push_scope(Scope::new(ScopeKind::Lambda))
+                self.push_scope(Scope::new(ScopeKind::Lambda));
             }
             ExprKind::ListComp { elt, generators } | ExprKind::SetComp { elt, generators } => {
                 if self.settings.enabled.contains(&CheckCode::C416) {
@@ -1736,10 +1757,10 @@ where
                         self.add_check(check);
                     };
                 }
-                self.push_scope(Scope::new(ScopeKind::Generator))
+                self.push_scope(Scope::new(ScopeKind::Generator));
             }
             ExprKind::GeneratorExp { .. } | ExprKind::DictComp { .. } => {
-                self.push_scope(Scope::new(ScopeKind::Generator))
+                self.push_scope(Scope::new(ScopeKind::Generator));
             }
             _ => {}
         };
@@ -1898,7 +1919,7 @@ where
                                         error!(
                                             "Found non-ExprKind::Tuple argument to PEP 593 \
                                              Annotation."
-                                        )
+                                        );
                                     }
                                 }
                             }
@@ -1930,13 +1951,20 @@ where
 
     fn visit_excepthandler(&mut self, excepthandler: &'b Excepthandler) {
         match &excepthandler.node {
-            ExcepthandlerKind::ExceptHandler { type_, name, .. } => {
+            ExcepthandlerKind::ExceptHandler {
+                type_, name, body, ..
+            } => {
                 if self.settings.enabled.contains(&CheckCode::E722) && type_.is_none() {
                     self.add_check(Check::new(
                         CheckKind::DoNotUseBareExcept,
                         Range::from_located(excepthandler),
                     ));
                 }
+                if self.settings.enabled.contains(&CheckCode::B904) {
+                    {
+                        flake8_bugbear::plugins::raise_without_from_inside_except(self, body);
+                    }
+                }
                 match name {
                     Some(name) => {
                         if self.settings.enabled.contains(&CheckCode::E741) {
@@ -2018,10 +2046,10 @@ where
                 .extend(pyflakes::checks::duplicate_arguments(arguments));
         }
         if self.settings.enabled.contains(&CheckCode::B006) {
-            flake8_bugbear::plugins::mutable_argument_default(self, arguments)
+            flake8_bugbear::plugins::mutable_argument_default(self, arguments);
         }
         if self.settings.enabled.contains(&CheckCode::B008) {
-            flake8_bugbear::plugins::function_call_argument_default(self, arguments)
+            flake8_bugbear::plugins::function_call_argument_default(self, arguments);
         }
 
         // flake8-boolean-trap
@@ -2084,6 +2112,13 @@ where
 
         self.check_builtin_arg_shadowing(&arg.node.arg, Range::from_located(arg));
     }
+
+    fn visit_withitem(&mut self, withitem: &'b Withitem) {
+        let prev_in_withitem = self.in_withitem;
+        self.in_withitem = true;
+        walk_withitem(self, withitem);
+        self.in_withitem = prev_in_withitem;
+    }
 }
 
 fn try_mark_used(scope: &mut Scope, scope_id: usize, id: &str, expr: &Expr) -> bool {
@@ -2161,7 +2196,7 @@ impl<'a> Checker<'a> {
                 builtin,
                 Binding {
                     kind: BindingKind::Builtin,
-                    range: Default::default(),
+                    range: Range::default(),
                     used: None,
                 },
             );
@@ -2171,7 +2206,7 @@ impl<'a> Checker<'a> {
                 builtin,
                 Binding {
                     kind: BindingKind::Builtin,
-                    range: Default::default(),
+                    range: Range::default(),
                     used: None,
                 },
             );
@@ -2193,7 +2228,7 @@ impl<'a> Checker<'a> {
     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();
+        let defined_in = rev.next().copied();
         BindingContext {
             defined_by,
             defined_in,
@@ -2314,7 +2349,7 @@ impl<'a> Checker<'a> {
                 self.add_check(Check::new(
                     CheckKind::UndefinedName(id.clone()),
                     Range::from_located(expr),
-                ))
+                ));
             }
         }
     }
@@ -2341,23 +2376,24 @@ impl<'a> Checker<'a> {
                     .current_scope()
                     .values
                     .get(id)
-                    .map(|binding| matches!(binding.kind, BindingKind::Global))
-                    .unwrap_or(false)
+                    .map_or(false, |binding| matches!(binding.kind, BindingKind::Global))
                 {
-                    pep8_naming::plugins::non_lowercase_variable_in_function(self, expr, parent, id)
+                    pep8_naming::plugins::non_lowercase_variable_in_function(
+                        self, expr, parent, id,
+                    );
                 }
             }
         }
 
         if self.settings.enabled.contains(&CheckCode::N815) {
             if matches!(self.current_scope().kind, ScopeKind::Class(..)) {
-                pep8_naming::plugins::mixed_case_variable_in_class_scope(self, expr, parent, id)
+                pep8_naming::plugins::mixed_case_variable_in_class_scope(self, expr, parent, id);
             }
         }
 
         if self.settings.enabled.contains(&CheckCode::N816) {
             if matches!(self.current_scope().kind, ScopeKind::Module) {
-                pep8_naming::plugins::mixed_case_variable_in_global_scope(self, expr, parent, id)
+                pep8_naming::plugins::mixed_case_variable_in_global_scope(self, expr, parent, id);
             }
         }
 
@@ -2389,7 +2425,7 @@ impl<'a> Checker<'a> {
             return;
         }
 
-        if operations::is_unpacking_assignment(parent) {
+        if self.in_withitem || operations::is_unpacking_assignment(parent) {
             self.add_binding(
                 id,
                 Binding {
@@ -2453,7 +2489,7 @@ impl<'a> Checker<'a> {
                 self.add_check(Check::new(
                     CheckKind::UndefinedName(id.to_string()),
                     Range::from_located(expr),
-                ))
+                ));
             }
         }
     }
@@ -2523,7 +2559,7 @@ impl<'a> Checker<'a> {
             self.parent_stack = parents;
             self.scope_stack = scopes;
             self.visible_scope = visibility;
-            self.push_scope(Scope::new(ScopeKind::Function(Default::default())));
+            self.push_scope(Scope::new(ScopeKind::Function(FunctionScope::default())));
 
             match &stmt.node {
                 StmtKind::FunctionDef { body, args, .. }
@@ -2588,9 +2624,7 @@ impl<'a> Checker<'a> {
             let all_binding: Option<&Binding> = scope.values.get("__all__");
             let all_names: Option<Vec<&str>> =
                 all_binding.and_then(|binding| match &binding.kind {
-                    BindingKind::Export(names) => {
-                        Some(names.iter().map(|name| name.as_str()).collect())
-                    }
+                    BindingKind::Export(names) => Some(names.iter().map(String::as_str).collect()),
                     _ => None,
                 });
 
@@ -2648,7 +2682,7 @@ impl<'a> Checker<'a> {
                 let mut unused: BTreeMap<(ImportKind, usize, Option<usize>), Vec<&str>> =
                     BTreeMap::new();
 
-                for (name, binding) in scope.values.iter() {
+                for (name, binding) in &scope.values {
                     if !matches!(
                         binding.kind,
                         BindingKind::Importation(..)
@@ -2892,7 +2926,7 @@ pub fn check_ast(
     python_ast: &Suite,
     locator: &SourceCodeLocator,
     settings: &Settings,
-    autofix: &fixer::Mode,
+    autofix: bool,
     path: &Path,
 ) -> Vec<Check> {
     let mut checker = Checker::new(settings, autofix, path, locator);

src/check_imports.rs

@@ -4,7 +4,6 @@ use nohash_hasher::IntSet;
 use rustpython_parser::ast::Suite;
 
 use crate::ast::visitor::Visitor;
-use crate::autofix::fixer;
 use crate::checks::Check;
 use crate::isort;
 use crate::isort::track::ImportTracker;
@@ -15,12 +14,12 @@ fn check_import_blocks(
     tracker: ImportTracker,
     locator: &SourceCodeLocator,
     settings: &Settings,
-    autofix: &fixer::Mode,
+    autofix: bool,
 ) -> Vec<Check> {
     let mut checks = vec![];
     for block in tracker.into_iter() {
         if !block.is_empty() {
-            if let Some(check) = isort::plugins::check_imports(block, locator, settings, autofix) {
+            if let Some(check) = isort::plugins::check_imports(&block, locator, settings, autofix) {
                 checks.push(check);
             }
         }
@@ -33,7 +32,7 @@ pub fn check_imports(
     locator: &SourceCodeLocator,
     exclusions: &IntSet<usize>,
     settings: &Settings,
-    autofix: &fixer::Mode,
+    autofix: bool,
 ) -> Vec<Check> {
     let mut tracker = ImportTracker::new(exclusions);
     for stmt in python_ast {

src/check_lines.rs

@@ -6,7 +6,7 @@ use regex::Regex;
 use rustpython_parser::ast::Location;
 
 use crate::ast::types::Range;
-use crate::autofix::{fixer, Fix};
+use crate::autofix::Fix;
 use crate::checks::{Check, CheckCode, CheckKind};
 use crate::noqa;
 use crate::noqa::Directive;
@@ -37,7 +37,7 @@ pub fn check_lines(
     contents: &str,
     noqa_line_for: &IntMap<usize, usize>,
     settings: &Settings,
-    autofix: &fixer::Mode,
+    autofix: bool,
 ) {
     let enforce_unnecessary_coding_comment = settings.enabled.contains(&CheckCode::U009);
     let enforce_line_too_long = settings.enabled.contains(&CheckCode::E501);
@@ -73,7 +73,7 @@ pub fn check_lines(
                             end_location: Location::new(lineno + 1, line_length + 1),
                         },
                     );
-                    if autofix.patch() && settings.fixable.contains(check.kind.code()) {
+                    if autofix && settings.fixable.contains(check.kind.code()) {
                         check.amend(Fix::deletion(
                             Location::new(lineno + 1, 0),
                             Location::new(lineno + 1, line_length + 1),
@@ -101,7 +101,7 @@ pub fn check_lines(
             match noqa {
                 (Directive::All(..), matches) => {
                     matches.push(check.kind.code().as_ref());
-                    ignored.push(index)
+                    ignored.push(index);
                 }
                 (Directive::Codes(.., codes), matches) => {
                     if codes.contains(&check.kind.code().as_ref()) {
@@ -195,7 +195,7 @@ pub fn check_lines(
                                 end_location: Location::new(row + 1, end),
                             },
                         );
-                        if autofix.patch() && settings.fixable.contains(check.kind.code()) {
+                        if autofix && settings.fixable.contains(check.kind.code()) {
                             check.amend(Fix::deletion(
                                 Location::new(row + 1, start - spaces),
                                 Location::new(row + 1, lines[row].chars().count()),
@@ -208,10 +208,10 @@ pub fn check_lines(
                     let mut invalid_codes = vec![];
                     let mut valid_codes = vec![];
                     for code in codes {
-                        if !matches.contains(&code) {
-                            invalid_codes.push(code.to_string());
-                        } else {
+                        if matches.contains(&code) {
                             valid_codes.push(code.to_string());
+                        } else {
+                            invalid_codes.push(code.to_string());
                         }
                     }
 
@@ -223,7 +223,7 @@ pub fn check_lines(
                                 end_location: Location::new(row + 1, end),
                             },
                         );
-                        if autofix.patch() && settings.fixable.contains(check.kind.code()) {
+                        if autofix && settings.fixable.contains(check.kind.code()) {
                             if valid_codes.is_empty() {
                                 check.amend(Fix::deletion(
                                     Location::new(row + 1, start - spaces),
@@ -257,14 +257,13 @@ mod tests {
     use nohash_hasher::IntMap;
 
     use super::check_lines;
-    use crate::autofix::fixer;
     use crate::checks::{Check, CheckCode};
     use crate::settings::Settings;
 
     #[test]
     fn e501_non_ascii_char() {
         let line = "'\u{4e9c}' * 2"; // 7 in UTF-32, 9 in UTF-8.
-        let noqa_line_for: IntMap<usize, usize> = Default::default();
+        let noqa_line_for: IntMap<usize, usize> = IntMap::default();
         let check_with_max_line_length = |line_length: usize| {
             let mut checks: Vec<Check> = vec![];
             check_lines(
@@ -275,7 +274,7 @@ mod tests {
                     line_length,
                     ..Settings::for_rule(CheckCode::E501)
                 },
-                &fixer::Mode::Generate,
+                true,
             );
             checks
         };

src/check_tokens.rs

@@ -2,7 +2,6 @@
 
 use rustpython_parser::lexer::{LexResult, Tok};
 
-use crate::autofix::fixer;
 use crate::checks::{Check, CheckCode};
 use crate::lex::docstring_detection::StateMachine;
 use crate::rules::checks::Context;
@@ -10,12 +9,13 @@ use crate::source_code_locator::SourceCodeLocator;
 use crate::{flake8_quotes, pycodestyle, rules, Settings};
 
 pub fn check_tokens(
-    checks: &mut Vec<Check>,
     locator: &SourceCodeLocator,
     tokens: &[LexResult],
     settings: &Settings,
-    autofix: &fixer::Mode,
-) {
+    autofix: bool,
+) -> Vec<Check> {
+    let mut checks: Vec<Check> = vec![];
+
     let enforce_ambiguous_unicode_character = settings.enabled.contains(&CheckCode::RUF001)
         || settings.enabled.contains(&CheckCode::RUF002)
         || settings.enabled.contains(&CheckCode::RUF003);
@@ -25,7 +25,7 @@ pub fn check_tokens(
         || settings.enabled.contains(&CheckCode::Q003);
     let enforce_invalid_escape_sequence = settings.enabled.contains(&CheckCode::W605);
 
-    let mut state_machine: StateMachine = Default::default();
+    let mut state_machine = StateMachine::default();
     for &(start, ref tok, end) in tokens.iter().flatten() {
         let is_docstring = if enforce_ambiguous_unicode_character || enforce_quotes {
             state_machine.consume(tok)
@@ -81,4 +81,6 @@ pub fn check_tokens(
             }
         }
     }
+
+    checks
 }

src/checks.rs

@@ -52,6 +52,7 @@ pub enum CheckCode {
     F405,
     F406,
     F407,
+    F521,
     F541,
     F601,
     F602,
@@ -103,6 +104,7 @@ pub enum CheckCode {
     B025,
     B026,
     B027,
+    B904,
     // flake8-blind-except
     BLE001,
     // flake8-comprehensions
@@ -402,6 +404,7 @@ pub enum CheckKind {
     MultiValueRepeatedKeyVariable(String),
     RaiseNotImplemented,
     ReturnOutsideFunction,
+    StringDotFormatInvalidFormat(String),
     TwoStarredExpressions,
     UndefinedExport(String),
     UndefinedLocal(String),
@@ -441,6 +444,7 @@ pub enum CheckKind {
     DuplicateTryBlockException(String),
     StarArgUnpackingAfterKeywordArg,
     EmptyMethodWithoutAbstractDecorator(String),
+    RaiseWithoutFromInsideExcept,
     // flake8-comprehensions
     UnnecessaryGeneratorList,
     UnnecessaryGeneratorSet,
@@ -613,7 +617,7 @@ impl CheckCode {
         }
     }
 
-    /// A placeholder representation of the CheckKind for the check.
+    /// A placeholder representation of the `CheckKind` for the check.
     pub fn kind(&self) -> CheckKind {
         match self {
             // pycodestyle errors
@@ -644,6 +648,7 @@ impl CheckCode {
             }
             CheckCode::F406 => CheckKind::ImportStarNotPermitted("...".to_string()),
             CheckCode::F407 => CheckKind::FutureFeatureNotDefined("...".to_string()),
+            CheckCode::F521 => CheckKind::StringDotFormatInvalidFormat("...".to_string()),
             CheckCode::F541 => CheckKind::FStringMissingPlaceholders,
             CheckCode::F601 => CheckKind::MultiValueRepeatedKeyLiteral,
             CheckCode::F602 => CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
@@ -699,6 +704,7 @@ impl CheckCode {
             CheckCode::B025 => CheckKind::DuplicateTryBlockException("Exception".to_string()),
             CheckCode::B026 => CheckKind::StarArgUnpackingAfterKeywordArg,
             CheckCode::B027 => CheckKind::EmptyMethodWithoutAbstractDecorator("...".to_string()),
+            CheckCode::B904 => CheckKind::RaiseWithoutFromInsideExcept,
             // flake8-comprehensions
             CheckCode::C400 => CheckKind::UnnecessaryGeneratorList,
             CheckCode::C401 => CheckKind::UnnecessaryGeneratorSet,
@@ -909,6 +915,7 @@ impl CheckCode {
             CheckCode::F405 => CheckCategory::Pyflakes,
             CheckCode::F406 => CheckCategory::Pyflakes,
             CheckCode::F407 => CheckCategory::Pyflakes,
+            CheckCode::F521 => CheckCategory::Pyflakes,
             CheckCode::F541 => CheckCategory::Pyflakes,
             CheckCode::F601 => CheckCategory::Pyflakes,
             CheckCode::F602 => CheckCategory::Pyflakes,
@@ -958,6 +965,7 @@ impl CheckCode {
             CheckCode::B025 => CheckCategory::Flake8Bugbear,
             CheckCode::B026 => CheckCategory::Flake8Bugbear,
             CheckCode::B027 => CheckCategory::Flake8Bugbear,
+            CheckCode::B904 => CheckCategory::Flake8Bugbear,
             CheckCode::BLE001 => CheckCategory::Flake8BlindExcept,
             CheckCode::C400 => CheckCategory::Flake8Comprehensions,
             CheckCode::C401 => CheckCategory::Flake8Comprehensions,
@@ -1132,6 +1140,7 @@ impl CheckKind {
             CheckKind::NotIsTest => &CheckCode::E714,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
+            CheckKind::StringDotFormatInvalidFormat(_) => &CheckCode::F521,
             CheckKind::SyntaxError(_) => &CheckCode::E999,
             CheckKind::ExpressionsInStarAssignment => &CheckCode::F621,
             CheckKind::TrueFalseComparison(..) => &CheckCode::E712,
@@ -1176,6 +1185,7 @@ impl CheckKind {
             CheckKind::DuplicateTryBlockException(_) => &CheckCode::B025,
             CheckKind::StarArgUnpackingAfterKeywordArg => &CheckCode::B026,
             CheckKind::EmptyMethodWithoutAbstractDecorator(_) => &CheckCode::B027,
+            CheckKind::RaiseWithoutFromInsideExcept => &CheckCode::B904,
             // flake8-blind-except
             CheckKind::BlindExcept => &CheckCode::BLE001,
             // flake8-comprehensions
@@ -1334,13 +1344,13 @@ impl CheckKind {
         match self {
             // pycodestyle errors
             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()
@@ -1383,7 +1393,7 @@ impl CheckKind {
             CheckKind::ImportStarUsage(name, sources) => {
                 let sources = sources
                     .iter()
-                    .map(|source| format!("`{}`", source))
+                    .map(|source| format!("`{source}`"))
                     .join(", ");
                 format!("`{name}` may be undefined, or defined from star imports: {sources}")
             }
@@ -1417,28 +1427,25 @@ impl CheckKind {
             CheckKind::ReturnOutsideFunction => {
                 "`return` statement outside of a function/method".to_string()
             }
+            CheckKind::StringDotFormatInvalidFormat(message) => {
+                format!("'...'.format(...) has invalid format string: {message}")
+            }
             CheckKind::SyntaxError(message) => format!("SyntaxError: {message}"),
             CheckKind::ExpressionsInStarAssignment => {
                 "Too many expressions in star-unpacking assignment".to_string()
             }
-            CheckKind::TrueFalseComparison(value, op) => match *value {
-                true => match op {
-                    RejectedCmpop::Eq => {
-                        "Comparison to `True` should be `cond is True`".to_string()
-                    }
-                    RejectedCmpop::NotEq => {
-                        "Comparison to `True` should be `cond is not True`".to_string()
-                    }
-                },
-                false => match op {
-                    RejectedCmpop::Eq => {
-                        "Comparison to `False` should be `cond is False`".to_string()
-                    }
-                    RejectedCmpop::NotEq => {
-                        "Comparison to `False` should be `cond is not False`".to_string()
-                    }
-                },
-            },
+            CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq) => {
+                "Comparison to `True` should be `cond is True`".to_string()
+            }
+            CheckKind::TrueFalseComparison(true, RejectedCmpop::NotEq) => {
+                "Comparison to `True` should be `cond is not True`".to_string()
+            }
+            CheckKind::TrueFalseComparison(false, RejectedCmpop::Eq) => {
+                "Comparison to `False` should be `cond is False`".to_string()
+            }
+            CheckKind::TrueFalseComparison(false, RejectedCmpop::NotEq) => {
+                "Comparison to `False` should be `cond is not False`".to_string()
+            }
             CheckKind::TwoStarredExpressions => "Two starred expressions in assignment".to_string(),
             CheckKind::TypeComparison => "Do not compare types, use `isinstance()`".to_string(),
             CheckKind::UndefinedExport(name) => {
@@ -1586,6 +1593,11 @@ impl CheckKind {
                      decorator"
                 )
             }
+            CheckKind::RaiseWithoutFromInsideExcept => {
+                "Within an except clause, raise exceptions with raise ... from err or raise ... \
+                 from None to distinguish them from errors in exception handling"
+                    .to_string()
+            }
             // flake8-comprehensions
             CheckKind::UnnecessaryGeneratorList => {
                 "Unnecessary generator (rewrite as a `list` comprehension)".to_string()
@@ -2161,13 +2173,12 @@ impl Check {
 mod tests {
     use std::str::FromStr;
 
-    use anyhow::Result;
     use strum::IntoEnumIterator;
 
     use crate::checks::CheckCode;
 
     #[test]
-    fn check_code_serialization() -> Result<()> {
+    fn check_code_serialization() {
         for check_code in CheckCode::iter() {
             assert!(
                 CheckCode::from_str(check_code.as_ref()).is_ok(),
@@ -2175,6 +2186,5 @@ mod tests {
                 check_code
             );
         }
-        Ok(())
     }
 }

src/checks_gen.rs

@@ -1,4 +1,4 @@
-//! File automatically generated by examples/generate_check_code_prefix.rs.
+//! File automatically generated by `examples/generate_check_code_prefix.rs`.
 
 use serde::{Deserialize, Serialize};
 use strum_macros::EnumString;
@@ -63,6 +63,9 @@ pub enum CheckCodePrefix {
     B025,
     B026,
     B027,
+    B9,
+    B90,
+    B904,
     BLE,
     BLE0,
     BLE00,
@@ -416,6 +419,7 @@ impl CheckCodePrefix {
                 CheckCode::B025,
                 CheckCode::B026,
                 CheckCode::B027,
+                CheckCode::B904,
             ],
             CheckCodePrefix::B0 => vec![
                 CheckCode::B002,
@@ -500,6 +504,9 @@ impl CheckCodePrefix {
             CheckCodePrefix::B025 => vec![CheckCode::B025],
             CheckCodePrefix::B026 => vec![CheckCode::B026],
             CheckCodePrefix::B027 => vec![CheckCode::B027],
+            CheckCodePrefix::B9 => vec![CheckCode::B904],
+            CheckCodePrefix::B90 => vec![CheckCode::B904],
+            CheckCodePrefix::B904 => vec![CheckCode::B904],
             CheckCodePrefix::BLE => vec![CheckCode::BLE001],
             CheckCodePrefix::BLE0 => vec![CheckCode::BLE001],
             CheckCodePrefix::BLE00 => vec![CheckCode::BLE001],
@@ -840,6 +847,7 @@ impl CheckCodePrefix {
                 CheckCode::F405,
                 CheckCode::F406,
                 CheckCode::F407,
+                CheckCode::F521,
                 CheckCode::F541,
                 CheckCode::F601,
                 CheckCode::F602,
@@ -1285,6 +1293,9 @@ impl CheckCodePrefix {
             CheckCodePrefix::B025 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B026 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B027 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::B9 => PrefixSpecificity::Hundreds,
+            CheckCodePrefix::B90 => PrefixSpecificity::Tens,
+            CheckCodePrefix::B904 => PrefixSpecificity::Explicit,
             CheckCodePrefix::BLE => PrefixSpecificity::Category,
             CheckCodePrefix::BLE0 => PrefixSpecificity::Hundreds,
             CheckCodePrefix::BLE00 => PrefixSpecificity::Tens,

src/cli.rs

@@ -1,18 +1,19 @@
 use std::path::PathBuf;
 
-use anyhow::Result;
 use clap::{command, Parser};
 use regex::Regex;
 use rustc_hash::FxHashMap;
 
+use crate::checks::CheckCode;
 use crate::checks_gen::CheckCodePrefix;
 use crate::logging::LogLevel;
 use crate::printer::SerializationFormat;
-use crate::settings::types::{PatternPrefixPair, PerFileIgnore, PythonVersion};
+use crate::settings::types::{FilePattern, PatternPrefixPair, PerFileIgnore, PythonVersion};
 
 #[derive(Debug, Parser)]
 #[command(author, about = "Ruff: An extremely fast Python linter.")]
 #[command(version)]
+#[allow(clippy::struct_excessive_bools)]
 pub struct Cli {
     #[arg(required = true)]
     pub files: Vec<PathBuf>,
@@ -59,11 +60,11 @@ pub struct Cli {
     pub extend_ignore: Vec<CheckCodePrefix>,
     /// List of paths, used to exclude files and/or directories from checks.
     #[arg(long, value_delimiter = ',')]
-    pub exclude: Vec<String>,
+    pub exclude: Vec<FilePattern>,
     /// Like --exclude, but adds additional files and directories on top of the
     /// excluded ones.
     #[arg(long, value_delimiter = ',')]
-    pub extend_exclude: Vec<String>,
+    pub extend_exclude: Vec<FilePattern>,
     /// List of error codes to treat as eligible for autofix. Only applicable
     /// when autofix itself is enabled (e.g., via `--fix`).
     #[arg(long, value_delimiter = ',')]
@@ -76,7 +77,7 @@ pub struct Cli {
     #[arg(long, value_delimiter = ',')]
     pub per_file_ignores: Vec<PatternPrefixPair>,
     /// Output serialization format for error messages.
-    #[arg(long, value_enum, default_value_t=SerializationFormat::Text)]
+    #[arg(long, value_enum, default_value_t = SerializationFormat::Text)]
     pub format: SerializationFormat,
     /// Show violations with source code.
     #[arg(long)]
@@ -110,6 +111,9 @@ pub struct Cli {
     /// The name of the file when passing it through stdin.
     #[arg(long)]
     pub stdin_filename: Option<String>,
+    /// Explain a rule.
+    #[arg(long)]
+    pub explain: Option<CheckCode>,
 }
 
 impl Cli {
@@ -144,10 +148,7 @@ pub fn extract_log_level(cli: &Cli) -> LogLevel {
 }
 
 /// Convert a list of `PatternPrefixPair` structs to `PerFileIgnore`.
-pub fn collect_per_file_ignores(
-    pairs: Vec<PatternPrefixPair>,
-    project_root: Option<&PathBuf>,
-) -> Result<Vec<PerFileIgnore>> {
+pub fn collect_per_file_ignores(pairs: Vec<PatternPrefixPair>) -> Vec<PerFileIgnore> {
     let mut per_file_ignores: FxHashMap<String, Vec<CheckCodePrefix>> = FxHashMap::default();
     for pair in pairs {
         per_file_ignores
@@ -156,7 +157,7 @@ pub fn collect_per_file_ignores(
             .push(pair.prefix);
     }
     per_file_ignores
-        .iter()
-        .map(|(pattern, prefixes)| PerFileIgnore::new(pattern, prefixes, project_root))
+        .into_iter()
+        .map(|(pattern, prefixes)| PerFileIgnore::new(pattern, &prefixes))
         .collect()
 }

src/commands.rs

@@ -0,0 +1,66 @@
+use std::path::PathBuf;
+
+use anyhow::Result;
+use serde::Serialize;
+use walkdir::DirEntry;
+
+use crate::checks::CheckCode;
+use crate::fs::iter_python_files;
+use crate::printer::SerializationFormat;
+use crate::{Configuration, Settings};
+
+/// Print the user-facing configuration settings.
+pub fn show_settings(
+    configuration: &Configuration,
+    project_root: Option<&PathBuf>,
+    pyproject: Option<&PathBuf>,
+) {
+    println!("Resolved configuration: {configuration:#?}");
+    println!("Found project root at: {project_root:?}");
+    println!("Found pyproject.toml at: {pyproject:?}");
+}
+
+/// Show the list of files to be checked based on current settings.
+pub fn show_files(files: &[PathBuf], settings: &Settings) {
+    let mut entries: Vec<DirEntry> = files
+        .iter()
+        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
+        .flatten()
+        .collect();
+    entries.sort_by(|a, b| a.path().cmp(b.path()));
+    for entry in entries {
+        println!("{}", entry.path().to_string_lossy());
+    }
+}
+
+#[derive(Serialize)]
+struct Explanation<'a> {
+    code: &'a str,
+    category: &'a str,
+    summary: &'a str,
+}
+
+/// Explain a `CheckCode` to the user.
+pub fn explain(code: &CheckCode, format: SerializationFormat) -> Result<()> {
+    match format {
+        SerializationFormat::Text => {
+            println!(
+                "{} ({}): {}",
+                code.as_ref(),
+                code.category().title(),
+                code.kind().summary()
+            );
+        }
+        SerializationFormat::Json => {
+            println!(
+                "{}",
+                serde_json::to_string_pretty(&Explanation {
+                    code: code.as_ref(),
+                    category: code.category().title(),
+                    summary: &code.kind().summary(),
+                })?
+            );
+        }
+    };
+    Ok(())
+}

src/directives.rs

@@ -11,8 +11,8 @@ use crate::{Settings, SourceCodeLocator};
 
 bitflags! {
     pub struct Flags: u32 {
-        const NOQA = 0b00000001;
-        const ISORT = 0b00000010;
+        const NOQA = 0b0000_0001;
+        const ISORT = 0b0000_0010;
     }
 }
 
@@ -44,12 +44,12 @@ pub fn extract_directives(
         noqa_line_for: if flags.contains(Flags::NOQA) {
             extract_noqa_line_for(lxr)
         } else {
-            Default::default()
+            IntMap::default()
         },
         isort_exclusions: if flags.contains(Flags::ISORT) {
             extract_isort_exclusions(lxr, locator)
         } else {
-            Default::default()
+            IntSet::default()
         },
     }
 }
@@ -113,7 +113,7 @@ pub fn extract_isort_exclusions(lxr: &[LexResult], locator: &SourceCodeLocator)
 
 #[cfg(test)]
 mod tests {
-    use anyhow::Result;
+
     use nohash_hasher::IntMap;
     use rustpython_parser::lexer;
     use rustpython_parser::lexer::LexResult;
@@ -121,8 +121,8 @@ mod tests {
     use crate::directives::extract_noqa_line_for;
 
     #[test]
-    fn extraction() -> Result<()> {
-        let empty: IntMap<usize, usize> = Default::default();
+    fn extraction() {
+        let empty: IntMap<usize, usize> = IntMap::default();
 
         let lxr: Vec<LexResult> = lexer::make_tokenizer(
             "x = 1
@@ -200,7 +200,5 @@ z = x + 1",
             extract_noqa_line_for(&lxr),
             IntMap::from_iter([(2, 5), (3, 5), (4, 5)])
         );
-
-        Ok(())
     }
 }

src/flake8_annotations/mod.rs

@@ -7,7 +7,6 @@ mod tests {
 
     use anyhow::Result;
 
-    use crate::autofix::fixer;
     use crate::checks::CheckCode;
     use crate::linter::test_path;
     use crate::{flake8_annotations, Settings};
@@ -31,7 +30,7 @@ mod tests {
                     CheckCode::ANN401,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -57,7 +56,7 @@ mod tests {
                     CheckCode::ANN102,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -83,7 +82,7 @@ mod tests {
                     CheckCode::ANN206,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -109,7 +108,7 @@ mod tests {
                     CheckCode::ANN206,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -129,7 +128,7 @@ mod tests {
                 },
                 ..Settings::for_rules(vec![CheckCode::ANN401])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);

src/flake8_annotations/plugins.rs

@@ -1,5 +1,3 @@
-use std::ops::Deref;
-
 use rustpython_ast::{Arguments, Constant, Expr, ExprKind, Stmt, StmtKind};
 
 use crate::ast::types::Range;
@@ -25,16 +23,14 @@ where
             StmtKind::FunctionDef { .. } | StmtKind::AsyncFunctionDef { .. } => {
                 // No recurse.
             }
-            StmtKind::Return { value } => {
-                self.returns.push(value.as_ref().map(|expr| expr.deref()))
-            }
+            StmtKind::Return { value } => self.returns.push(value.as_ref().map(|expr| &**expr)),
             _ => visitor::walk_stmt(self, stmt),
         }
     }
 }
 
 fn is_none_returning(body: &[Stmt]) -> bool {
-    let mut visitor: ReturnStatementVisitor = Default::default();
+    let mut visitor = ReturnStatementVisitor::default();
     for stmt in body {
         visitor.visit_stmt(stmt);
     }

src/flake8_annotations/settings.rs

@@ -21,6 +21,7 @@ pub struct Options {
 }
 
 #[derive(Debug, Hash, Default)]
+#[allow(clippy::struct_excessive_bools)]
 pub struct Settings {
     pub mypy_init_return: bool,
     pub suppress_dummy_args: bool,
@@ -29,6 +30,7 @@ pub struct Settings {
 }
 
 impl Settings {
+    #[allow(clippy::needless_pass_by_value)]
     pub fn from_options(options: Options) -> Self {
         Self {
             mypy_init_return: options.mypy_init_return.unwrap_or_default(),

src/flake8_boolean_trap/plugins.rs

@@ -51,7 +51,7 @@ pub fn check_boolean_default_value_in_function_definition(
     checker: &mut Checker,
     arguments: &Arguments,
 ) {
-    for arg in arguments.defaults.iter() {
+    for arg in &arguments.defaults {
         add_if_boolean(
             checker,
             arg,

src/flake8_bugbear/mod.rs

@@ -7,7 +7,6 @@ mod tests {
 
     use anyhow::Result;
 
-    use crate::autofix::fixer;
     use crate::checks::CheckCode;
     use crate::linter::test_path;
     use crate::{flake8_bugbear, Settings};
@@ -26,7 +25,7 @@ mod tests {
                 },
                 ..Settings::for_rules(vec![CheckCode::B008])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);

src/flake8_bugbear/plugins/abstract_base_class.rs

@@ -17,8 +17,7 @@ fn is_abc_class(
             .node
             .arg
             .as_ref()
-            .map(|a| a == "metaclass")
-            .unwrap_or(false)
+            .map_or(false, |a| a == "metaclass")
             && match_module_member(
                 &keyword.node.value,
                 "abc",

src/flake8_bugbear/plugins/assert_false.rs

@@ -1,4 +1,4 @@
-use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Stmt, StmtKind};
+use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Location, Stmt, StmtKind};
 
 use crate::ast::types::Range;
 use crate::autofix::Fix;
@@ -8,16 +8,16 @@ use crate::code_gen::SourceGenerator;
 
 fn assertion_error(msg: Option<&Expr>) -> Stmt {
     Stmt::new(
-        Default::default(),
-        Default::default(),
+        Location::default(),
+        Location::default(),
         StmtKind::Raise {
             exc: Some(Box::new(Expr::new(
-                Default::default(),
-                Default::default(),
+                Location::default(),
+                Location::default(),
                 ExprKind::Call {
                     func: Box::new(Expr::new(
-                        Default::default(),
-                        Default::default(),
+                        Location::default(),
+                        Location::default(),
                         ExprKind::Name {
                             id: "AssertionError".to_string(),
                             ctx: ExprContext::Load,
@@ -46,14 +46,13 @@ pub fn assert_false(checker: &mut Checker, stmt: &Stmt, test: &Expr, msg: Option
         let mut check = Check::new(CheckKind::DoNotAssertFalse, Range::from_located(test));
         if checker.patch(check.kind.code()) {
             let mut generator = SourceGenerator::new();
-            if let Ok(()) = generator.unparse_stmt(&assertion_error(msg)) {
-                if let Ok(content) = generator.generate() {
-                    check.amend(Fix::replacement(
-                        content,
-                        stmt.location,
-                        stmt.end_location.unwrap(),
-                    ));
-                }
+            generator.unparse_stmt(&assertion_error(msg));
+            if let Ok(content) = generator.generate() {
+                check.amend(Fix::replacement(
+                    content,
+                    stmt.location,
+                    stmt.end_location.unwrap(),
+                ));
             }
         }
         checker.add_check(check);

src/flake8_bugbear/plugins/duplicate_exceptions.rs

@@ -1,7 +1,9 @@
 use std::collections::BTreeSet;
 
 use itertools::Itertools;
-use rustpython_ast::{Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind, Stmt};
+use rustpython_ast::{
+    Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind, Location, Stmt,
+};
 
 use crate::ast::helpers;
 use crate::ast::types::Range;
@@ -12,8 +14,8 @@ use crate::code_gen::SourceGenerator;
 
 fn type_pattern(elts: Vec<&Expr>) -> Expr {
     Expr::new(
-        Default::default(),
-        Default::default(),
+        Location::default(),
+        Location::default(),
         ExprKind::Tuple {
             elts: elts.into_iter().cloned().collect(),
             ctx: ExprContext::Load,
@@ -26,9 +28,9 @@ fn duplicate_handler_exceptions<'a>(
     expr: &'a Expr,
     elts: &'a [Expr],
 ) -> BTreeSet<Vec<&'a str>> {
-    let mut seen: BTreeSet<Vec<&str>> = Default::default();
-    let mut duplicates: BTreeSet<Vec<&str>> = Default::default();
-    let mut unique_elts: Vec<&Expr> = Default::default();
+    let mut seen: BTreeSet<Vec<&str>> = BTreeSet::default();
+    let mut duplicates: BTreeSet<Vec<&str>> = BTreeSet::default();
+    let mut unique_elts: Vec<&Expr> = Vec::default();
     for type_ in elts {
         let call_path = helpers::collect_call_paths(type_);
         if !call_path.is_empty() {
@@ -57,14 +59,13 @@ fn duplicate_handler_exceptions<'a>(
             if checker.patch(check.kind.code()) {
                 // TODO(charlie): If we have a single element, remove the tuple.
                 let mut generator = SourceGenerator::new();
-                if let Ok(()) = generator.unparse_expr(&type_pattern(unique_elts), 0) {
-                    if let Ok(content) = generator.generate() {
-                        check.amend(Fix::replacement(
-                            content,
-                            expr.location,
-                            expr.end_location.unwrap(),
-                        ))
-                    }
+                generator.unparse_expr(&type_pattern(unique_elts), 0);
+                if let Ok(content) = generator.generate() {
+                    check.amend(Fix::replacement(
+                        content,
+                        expr.location,
+                        expr.end_location.unwrap(),
+                    ));
                 }
             }
             checker.add_check(check);
@@ -75,8 +76,8 @@ fn duplicate_handler_exceptions<'a>(
 }
 
 pub fn duplicate_exceptions(checker: &mut Checker, stmt: &Stmt, handlers: &[Excepthandler]) {
-    let mut seen: BTreeSet<Vec<&str>> = Default::default();
-    let mut duplicates: BTreeSet<Vec<&str>> = Default::default();
+    let mut seen: BTreeSet<Vec<&str>> = BTreeSet::default();
+    let mut duplicates: BTreeSet<Vec<&str>> = BTreeSet::default();
     for handler in handlers {
         match &handler.node {
             ExcepthandlerKind::ExceptHandler { type_, .. } => {

src/flake8_bugbear/plugins/function_call_argument_default.rs

@@ -60,9 +60,9 @@ where
                     self.checks.push((
                         CheckKind::FunctionCallArgumentDefault(compose_call_path(expr)),
                         Range::from_located(expr),
-                    ))
+                    ));
                 }
-                visitor::walk_expr(self, expr)
+                visitor::walk_expr(self, expr);
             }
             ExprKind::Lambda { .. } => {}
             _ => visitor::walk_expr(self, expr),

src/flake8_bugbear/plugins/getattr_with_constant.rs

@@ -1,4 +1,4 @@
-use rustpython_ast::{Constant, Expr, ExprContext, ExprKind};
+use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Location};
 
 use crate::ast::types::Range;
 use crate::autofix::Fix;
@@ -10,8 +10,8 @@ use crate::python::keyword::KWLIST;
 
 fn attribute(value: &Expr, attr: &str) -> Expr {
     Expr::new(
-        Default::default(),
-        Default::default(),
+        Location::default(),
+        Location::default(),
         ExprKind::Attribute {
             value: Box::new(value.clone()),
             attr: attr.to_string(),
@@ -35,14 +35,13 @@ pub fn getattr_with_constant(checker: &mut Checker, expr: &Expr, func: &Expr, ar
                             Check::new(CheckKind::GetAttrWithConstant, Range::from_located(expr));
                         if checker.patch(check.kind.code()) {
                             let mut generator = SourceGenerator::new();
-                            if let Ok(()) = generator.unparse_expr(&attribute(obj, value), 0) {
-                                if let Ok(content) = generator.generate() {
-                                    check.amend(Fix::replacement(
-                                        content,
-                                        expr.location,
-                                        expr.end_location.unwrap(),
-                                    ));
-                                }
+                            generator.unparse_expr(&attribute(obj, value), 0);
+                            if let Ok(content) = generator.generate() {
+                                check.amend(Fix::replacement(
+                                    content,
+                                    expr.location,
+                                    expr.end_location.unwrap(),
+                                ));
                             }
                         }
                         checker.add_check(check);

src/flake8_bugbear/plugins/loop_variable_overrides_iterator.rs

@@ -31,7 +31,7 @@ where
             }
             ExprKind::Lambda { args, body } => {
                 visitor::walk_expr(self, body);
-                for arg in args.args.iter() {
+                for arg in &args.args {
                     self.names.remove(arg.node.arg.as_str());
                 }
             }

src/flake8_bugbear/plugins/mod.rs

@@ -11,6 +11,7 @@ pub use getattr_with_constant::getattr_with_constant;
 pub use jump_statement_in_finally::jump_statement_in_finally;
 pub use loop_variable_overrides_iterator::loop_variable_overrides_iterator;
 pub use mutable_argument_default::mutable_argument_default;
+pub use raise_without_from_inside_except::raise_without_from_inside_except;
 pub use redundant_tuple_in_exception_handler::redundant_tuple_in_exception_handler;
 pub use setattr_with_constant::setattr_with_constant;
 pub use star_arg_unpacking_after_keyword_arg::star_arg_unpacking_after_keyword_arg;
@@ -35,6 +36,7 @@ mod getattr_with_constant;
 mod jump_statement_in_finally;
 mod loop_variable_overrides_iterator;
 mod mutable_argument_default;
+mod raise_without_from_inside_except;
 mod redundant_tuple_in_exception_handler;
 mod setattr_with_constant;
 mod star_arg_unpacking_after_keyword_arg;

src/flake8_bugbear/plugins/raise_without_from_inside_except.rs

@@ -0,0 +1,56 @@
+use rustpython_ast::{ExprKind, Stmt, StmtKind};
+
+use crate::ast::types::Range;
+use crate::ast::visitor::Visitor;
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind};
+use crate::python::string::is_lower;
+
+struct RaiseVisitor {
+    checks: Vec<Check>,
+}
+
+impl<'a> Visitor<'a> for RaiseVisitor {
+    fn visit_stmt(&mut self, stmt: &'a Stmt) {
+        match &stmt.node {
+            StmtKind::Raise { exc, cause } => {
+                if cause.is_none() {
+                    if let Some(exc) = exc {
+                        match &exc.node {
+                            ExprKind::Name { id, .. } if is_lower(id) => {}
+                            _ => {
+                                self.checks.push(Check::new(
+                                    CheckKind::RaiseWithoutFromInsideExcept,
+                                    Range::from_located(stmt),
+                                ));
+                            }
+                        }
+                    }
+                }
+            }
+            StmtKind::ClassDef { .. }
+            | StmtKind::FunctionDef { .. }
+            | StmtKind::AsyncFunctionDef { .. }
+            | StmtKind::Try { .. } => {}
+            StmtKind::If { body, .. }
+            | StmtKind::While { body, .. }
+            | StmtKind::With { body, .. }
+            | StmtKind::AsyncWith { body, .. }
+            | StmtKind::For { body, .. }
+            | StmtKind::AsyncFor { body, .. } => {
+                for stmt in body {
+                    self.visit_stmt(stmt);
+                }
+            }
+            _ => {}
+        }
+    }
+}
+
+pub fn raise_without_from_inside_except(checker: &mut Checker, body: &[Stmt]) {
+    let mut visitor = RaiseVisitor { checks: vec![] };
+    for stmt in body {
+        visitor.visit_stmt(stmt);
+    }
+    checker.add_checks(visitor.checks.into_iter());
+}

src/flake8_bugbear/plugins/redundant_tuple_in_exception_handler.rs

@@ -64,22 +64,21 @@ pub fn redundant_tuple_in_exception_handler(checker: &mut Checker, handlers: &[E
                     );
                     if checker.patch(check.kind.code()) {
                         let mut generator = SourceGenerator::new();
-                        if let Ok(()) = generator.unparse_expr(elt, 0) {
-                            if let Ok(content) = generator.generate() {
-                                match match_tuple_range(handler, checker.locator) {
-                                    Ok(range) => {
-                                        check.amend(Fix::replacement(
-                                            content,
-                                            range.location,
-                                            range.end_location,
-                                        ));
-                                    }
-                                    Err(e) => error!("Failed to locate parentheses: {}", e),
+                        generator.unparse_expr(elt, 0);
+                        if let Ok(content) = generator.generate() {
+                            match match_tuple_range(handler, checker.locator) {
+                                Ok(range) => {
+                                    check.amend(Fix::replacement(
+                                        content,
+                                        range.location,
+                                        range.end_location,
+                                    ));
                                 }
+                                Err(e) => error!("Failed to locate parentheses: {}", e),
                             }
                         }
                     }
-                    checker.add_check(check)
+                    checker.add_check(check);
                 }
             }
         }

src/flake8_bugbear/plugins/setattr_with_constant.rs

@@ -1,4 +1,6 @@
-use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Stmt, StmtKind};
+use anyhow::Result;
+use log::error;
+use rustpython_ast::{Constant, Expr, ExprContext, ExprKind, Location, Stmt, StmtKind};
 
 use crate::ast::types::Range;
 use crate::autofix::Fix;
@@ -8,14 +10,14 @@ use crate::code_gen::SourceGenerator;
 use crate::python::identifiers::IDENTIFIER_REGEX;
 use crate::python::keyword::KWLIST;
 
-fn assignment(obj: &Expr, name: &str, value: &Expr) -> Option<String> {
+fn assignment(obj: &Expr, name: &str, value: &Expr) -> Result<String> {
     let stmt = Stmt::new(
-        Default::default(),
-        Default::default(),
+        Location::default(),
+        Location::default(),
         StmtKind::Assign {
             targets: vec![Expr::new(
-                Default::default(),
-                Default::default(),
+                Location::default(),
+                Location::default(),
                 ExprKind::Attribute {
                     value: Box::new(obj.clone()),
                     attr: name.to_string(),
@@ -27,10 +29,8 @@ fn assignment(obj: &Expr, name: &str, value: &Expr) -> Option<String> {
         },
     );
     let mut generator = SourceGenerator::new();
-    match generator.unparse_stmt(&stmt) {
-        Ok(()) => generator.generate().ok(),
-        Err(_) => None,
-    }
+    generator.unparse_stmt(&stmt);
+    generator.generate().map_err(std::convert::Into::into)
 }
 
 /// B010
@@ -47,13 +47,14 @@ pub fn setattr_with_constant(checker: &mut Checker, expr: &Expr, func: &Expr, ar
                         let mut check =
                             Check::new(CheckKind::SetAttrWithConstant, Range::from_located(expr));
                         if checker.patch(check.kind.code()) {
-                            if let Some(content) = assignment(obj, name, value) {
-                                check.amend(Fix::replacement(
+                            match assignment(obj, name, value) {
+                                Ok(content) => check.amend(Fix::replacement(
                                     content,
                                     expr.location,
                                     expr.end_location.unwrap(),
-                                ));
-                            }
+                                )),
+                                Err(e) => error!("Failed to fix invalid comparison: {}", e),
+                            };
                         }
                         checker.add_check(check);
                     }

src/flake8_bugbear/plugins/unary_prefix_increment.rs

@@ -12,7 +12,7 @@ pub fn unary_prefix_increment(checker: &mut Checker, expr: &Expr, op: &Unaryop,
                 checker.add_check(Check::new(
                     CheckKind::UnaryPrefixIncrement,
                     Range::from_located(expr),
-                ))
+                ));
             }
         }
     }

src/flake8_bugbear/plugins/unused_loop_control_variable.rs

@@ -17,7 +17,7 @@ struct NameFinder<'a> {
 impl NameFinder<'_> {
     fn new() -> Self {
         NameFinder {
-            names: Default::default(),
+            names: FxHashMap::default(),
         }
     }
 }
@@ -71,7 +71,7 @@ pub fn unused_loop_control_variable(checker: &mut Checker, target: &Expr, body:
                 format!("_{name}"),
                 expr.location,
                 expr.end_location.unwrap(),
-            ))
+            ));
         }
         checker.add_check(check);
     }

src/flake8_builtins/types.rs

@@ -1,3 +1,4 @@
+#[derive(Clone, Copy)]
 pub enum ShadowingType {
     Variable,
     Argument,

src/flake8_comprehensions/checks.rs

@@ -390,11 +390,6 @@ pub fn unnecessary_double_cast_or_process(
     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, location: Range) -> Check {
         Check::new(
             CheckKind::UnnecessaryDoubleCastOrProcess(inner.to_string(), outer.to_string()),
@@ -402,6 +397,11 @@ pub fn unnecessary_double_cast_or_process(
         )
     }
 
+    let outer = function_name(func)?;
+    if !["list", "tuple", "set", "reversed", "sorted"].contains(&outer) {
+        return None;
+    }
+
     if let ExprKind::Call { func, .. } = &args.first()?.node {
         let inner = function_name(func)?;
         // Ex) set(tuple(...))

src/flake8_comprehensions/fixes.rs

@@ -1,9 +1,9 @@
 use anyhow::Result;
 use libcst_native::{
-    Arg, AssignEqual, Call, Codegen, Dict, DictComp, DictElement, Element, Expr, Expression,
-    LeftCurlyBrace, LeftParen, LeftSquareBracket, List, ListComp, Name, ParenthesizableWhitespace,
-    RightCurlyBrace, RightParen, RightSquareBracket, Set, SetComp, SimpleString, SimpleWhitespace,
-    Tuple,
+    Arg, AssignEqual, Call, Codegen, CodegenState, Dict, DictComp, DictElement, Element, Expr,
+    Expression, LeftCurlyBrace, LeftParen, LeftSquareBracket, List, ListComp, Name,
+    ParenthesizableWhitespace, RightCurlyBrace, RightParen, RightSquareBracket, Set, SetComp,
+    SimpleString, SimpleWhitespace, Tuple,
 };
 
 use crate::ast::types::Range;
@@ -60,7 +60,7 @@ pub fn fix_unnecessary_generator_list(
         rpar: generator_exp.rpar.clone(),
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -103,7 +103,7 @@ pub fn fix_unnecessary_generator_set(
         rpar: generator_exp.rpar.clone(),
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -163,13 +163,13 @@ pub fn fix_unnecessary_generator_dict(
         rbrace: RightCurlyBrace {
             whitespace_before: arg.whitespace_after_arg.clone(),
         },
-        lpar: Default::default(),
-        rpar: Default::default(),
-        whitespace_before_colon: Default::default(),
+        lpar: vec![],
+        rpar: vec![],
+        whitespace_before_colon: ParenthesizableWhitespace::default(),
         whitespace_after_colon: ParenthesizableWhitespace::SimpleWhitespace(SimpleWhitespace(" ")),
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -211,7 +211,7 @@ pub fn fix_unnecessary_list_comprehension_set(
         rpar: list_comp.rpar.clone(),
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -269,7 +269,7 @@ pub fn fix_unnecessary_list_comprehension_dict(
         rpar: list_comp.rpar.clone(),
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -312,12 +312,12 @@ pub fn fix_unnecessary_literal_set(
             rbrace: RightCurlyBrace {
                 whitespace_before: arg.whitespace_after_arg.clone(),
             },
-            lpar: Default::default(),
-            rpar: Default::default(),
+            lpar: vec![],
+            rpar: vec![],
         }));
     }
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -363,7 +363,7 @@ pub fn fix_unnecessary_literal_dict(
                             key: key.clone(),
                             value: value.clone(),
                             comma: comma.clone(),
-                            whitespace_before_colon: Default::default(),
+                            whitespace_before_colon: ParenthesizableWhitespace::default(),
                             whitespace_after_colon: ParenthesizableWhitespace::SimpleWhitespace(
                                 SimpleWhitespace(" "),
                             ),
@@ -385,11 +385,11 @@ pub fn fix_unnecessary_literal_dict(
         rbrace: RightCurlyBrace {
             whitespace_before: arg.whitespace_after_arg.clone(),
         },
-        lpar: Default::default(),
-        rpar: Default::default(),
+        lpar: vec![],
+        rpar: vec![],
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -422,28 +422,28 @@ pub fn fix_unnecessary_collection_call(
     match name.value {
         "tuple" => {
             body.value = Expression::Tuple(Box::new(Tuple {
-                elements: Default::default(),
-                lpar: vec![Default::default()],
-                rpar: vec![Default::default()],
+                elements: vec![],
+                lpar: vec![LeftParen::default()],
+                rpar: vec![RightParen::default()],
             }));
         }
         "list" => {
             body.value = Expression::List(Box::new(List {
-                elements: Default::default(),
-                lbracket: Default::default(),
-                rbracket: Default::default(),
-                lpar: Default::default(),
-                rpar: Default::default(),
+                elements: vec![],
+                lbracket: LeftSquareBracket::default(),
+                rbracket: RightSquareBracket::default(),
+                lpar: vec![],
+                rpar: vec![],
             }));
         }
         "dict" => {
             if call.args.is_empty() {
                 body.value = Expression::Dict(Box::new(Dict {
-                    elements: Default::default(),
-                    lbrace: Default::default(),
-                    rbrace: Default::default(),
-                    lpar: Default::default(),
-                    rpar: Default::default(),
+                    elements: vec![],
+                    lbrace: LeftCurlyBrace::default(),
+                    rbrace: RightCurlyBrace::default(),
+                    lpar: vec![],
+                    rpar: vec![],
                 }));
             } else {
                 // Quote each argument.
@@ -465,12 +465,12 @@ pub fn fix_unnecessary_collection_call(
                     .map(|(i, arg)| DictElement::Simple {
                         key: Expression::SimpleString(Box::new(SimpleString {
                             value: &arena[i],
-                            lpar: Default::default(),
-                            rpar: Default::default(),
+                            lpar: vec![],
+                            rpar: vec![],
                         })),
                         value: arg.value.clone(),
                         comma: arg.comma.clone(),
-                        whitespace_before_colon: Default::default(),
+                        whitespace_before_colon: ParenthesizableWhitespace::default(),
                         whitespace_after_colon: ParenthesizableWhitespace::SimpleWhitespace(
                             SimpleWhitespace(" "),
                         ),
@@ -490,8 +490,8 @@ pub fn fix_unnecessary_collection_call(
                             .whitespace_after_arg
                             .clone(),
                     },
-                    lpar: Default::default(),
-                    rpar: Default::default(),
+                    lpar: vec![],
+                    rpar: vec![],
                 }));
             }
         }
@@ -502,7 +502,7 @@ pub fn fix_unnecessary_collection_call(
         }
     };
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -558,7 +558,7 @@ pub fn fix_unnecessary_literal_within_tuple_call(
         }],
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -612,11 +612,11 @@ pub fn fix_unnecessary_literal_within_list_call(
         rbracket: RightSquareBracket {
             whitespace_before: whitespace_before.clone(),
         },
-        lpar: Default::default(),
-        rpar: Default::default(),
+        lpar: vec![],
+        rpar: vec![],
     }));
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -640,7 +640,7 @@ pub fn fix_unnecessary_list_call(
 
     body.value = arg.value.clone();
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -695,22 +695,22 @@ pub fn fix_unnecessary_call_around_sorted(
                 args.push(Arg {
                     value: Expression::Name(Box::new(Name {
                         value: "True",
-                        lpar: Default::default(),
-                        rpar: Default::default(),
+                        lpar: vec![],
+                        rpar: vec![],
                     })),
                     keyword: Some(Name {
                         value: "reverse",
-                        lpar: Default::default(),
-                        rpar: Default::default(),
+                        lpar: vec![],
+                        rpar: vec![],
                     }),
                     equal: Some(AssignEqual {
-                        whitespace_before: Default::default(),
-                        whitespace_after: Default::default(),
+                        whitespace_before: ParenthesizableWhitespace::default(),
+                        whitespace_after: ParenthesizableWhitespace::default(),
                     }),
-                    comma: Default::default(),
-                    star: Default::default(),
-                    whitespace_after_star: Default::default(),
-                    whitespace_after_arg: Default::default(),
+                    comma: None,
+                    star: "",
+                    whitespace_after_star: ParenthesizableWhitespace::default(),
+                    whitespace_after_arg: ParenthesizableWhitespace::default(),
                 });
                 args
             };
@@ -722,11 +722,11 @@ pub fn fix_unnecessary_call_around_sorted(
                 rpar: inner_call.rpar.clone(),
                 whitespace_after_func: inner_call.whitespace_after_func.clone(),
                 whitespace_before_args: inner_call.whitespace_before_args.clone(),
-            }))
+            }));
         }
     }
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(
@@ -750,45 +750,45 @@ pub fn fix_unnecessary_comprehension(
             body.value = Expression::Call(Box::new(Call {
                 func: Box::new(Expression::Name(Box::new(Name {
                     value: "list",
-                    lpar: Default::default(),
-                    rpar: Default::default(),
+                    lpar: vec![],
+                    rpar: vec![],
                 }))),
                 args: vec![Arg {
                     value: inner.for_in.iter.clone(),
-                    keyword: Default::default(),
-                    equal: Default::default(),
-                    comma: Default::default(),
-                    star: Default::default(),
-                    whitespace_after_star: Default::default(),
-                    whitespace_after_arg: Default::default(),
+                    keyword: None,
+                    equal: None,
+                    comma: None,
+                    star: "",
+                    whitespace_after_star: ParenthesizableWhitespace::default(),
+                    whitespace_after_arg: ParenthesizableWhitespace::default(),
                 }],
-                lpar: Default::default(),
-                rpar: Default::default(),
-                whitespace_after_func: Default::default(),
-                whitespace_before_args: Default::default(),
-            }))
+                lpar: vec![],
+                rpar: vec![],
+                whitespace_after_func: ParenthesizableWhitespace::default(),
+                whitespace_before_args: ParenthesizableWhitespace::default(),
+            }));
         }
         Expression::SetComp(inner) => {
             body.value = Expression::Call(Box::new(Call {
                 func: Box::new(Expression::Name(Box::new(Name {
                     value: "set",
-                    lpar: Default::default(),
-                    rpar: Default::default(),
+                    lpar: vec![],
+                    rpar: vec![],
                 }))),
                 args: vec![Arg {
                     value: inner.for_in.iter.clone(),
-                    keyword: Default::default(),
-                    equal: Default::default(),
-                    comma: Default::default(),
-                    star: Default::default(),
-                    whitespace_after_star: Default::default(),
-                    whitespace_after_arg: Default::default(),
+                    keyword: None,
+                    equal: None,
+                    comma: None,
+                    star: "",
+                    whitespace_after_star: ParenthesizableWhitespace::default(),
+                    whitespace_after_arg: ParenthesizableWhitespace::default(),
                 }],
-                lpar: Default::default(),
-                rpar: Default::default(),
-                whitespace_after_func: Default::default(),
-                whitespace_before_args: Default::default(),
-            }))
+                lpar: vec![],
+                rpar: vec![],
+                whitespace_after_func: ParenthesizableWhitespace::default(),
+                whitespace_before_args: ParenthesizableWhitespace::default(),
+            }));
         }
         _ => {
             return Err(anyhow::anyhow!(
@@ -797,7 +797,7 @@ pub fn fix_unnecessary_comprehension(
         }
     }
 
-    let mut state = Default::default();
+    let mut state = CodegenState::default();
     tree.codegen(&mut state);
 
     Ok(Fix::replacement(

src/flake8_print/plugins/print_call.rs

@@ -35,7 +35,7 @@ pub fn print_call(checker: &mut Checker, expr: &Expr, func: &Expr) {
                         if fix.patch.content.is_empty() || fix.patch.content == "pass" {
                             checker.deletions.insert(context.defined_by);
                         }
-                        check.amend(fix)
+                        check.amend(fix);
                     }
                     Err(e) => error!("Failed to remove print call: {}", e),
                 }

src/flake8_quotes/checks.rs

@@ -74,13 +74,13 @@ pub fn quotes(
             return None;
         }
 
-        return Some(Check::new(
+        Some(Check::new(
             CheckKind::BadQuotesDocstring(settings.docstring_quotes.clone()),
             Range {
                 location: start,
                 end_location: end,
             },
-        ));
+        ))
     } else if is_multiline {
         // If our string is or contains a known good string, ignore it.
         if raw_text.contains(good_multiline(&settings.multiline_quotes)) {
@@ -92,13 +92,13 @@ pub fn quotes(
             return None;
         }
 
-        return Some(Check::new(
+        Some(Check::new(
             CheckKind::BadQuotesMultilineString(settings.multiline_quotes.clone()),
             Range {
                 location: start,
                 end_location: end,
             },
-        ));
+        ))
     } else {
         let string_contents = &raw_text[1..raw_text.len() - 1];
 
@@ -131,7 +131,7 @@ pub fn quotes(
                 },
             ));
         }
-    }
 
-    None
+        None
+    }
 }

src/flake8_quotes/mod.rs

@@ -8,7 +8,6 @@ mod tests {
     use anyhow::Result;
     use test_case::test_case;
 
-    use crate::autofix::fixer;
     use crate::checks::CheckCode;
     use crate::flake8_quotes::settings::Quote;
     use crate::linter::test_path;
@@ -39,7 +38,7 @@ mod tests {
                     CheckCode::Q003,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);
@@ -71,7 +70,7 @@ mod tests {
                     CheckCode::Q003,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);
@@ -108,7 +107,7 @@ mod tests {
                     CheckCode::Q003,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);
@@ -145,7 +144,7 @@ mod tests {
                     CheckCode::Q003,
                 ])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);

src/flake8_tidy_imports/mod.rs

@@ -7,7 +7,6 @@ mod tests {
 
     use anyhow::Result;
 
-    use crate::autofix::fixer;
     use crate::checks::CheckCode;
     use crate::flake8_tidy_imports::settings::Strictness;
     use crate::linter::test_path;
@@ -23,7 +22,7 @@ mod tests {
                 },
                 ..Settings::for_rules(vec![CheckCode::I252])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -40,7 +39,7 @@ mod tests {
                 },
                 ..Settings::for_rules(vec![CheckCode::I252])
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);

src/fs.rs

@@ -1,17 +1,16 @@
 use std::borrow::Cow;
+use std::collections::BTreeSet;
 use std::fs::File;
 use std::io::{BufReader, Read};
-use std::ops::Deref;
 use std::path::{Path, PathBuf};
 
 use anyhow::{anyhow, Result};
+use globset::GlobMatcher;
 use log::debug;
 use path_absolutize::{path_dedot, Absolutize};
-use rustc_hash::FxHashSet;
 use walkdir::{DirEntry, WalkDir};
 
 use crate::checks::CheckCode;
-use crate::settings::types::{FilePattern, PerFileIgnore};
 
 /// Extract the absolute path and basename (as strings) from a Path.
 fn extract_path_names(path: &Path) -> Result<(&str, &str)> {
@@ -26,32 +25,8 @@ fn extract_path_names(path: &Path) -> Result<(&str, &str)> {
     Ok((file_path, file_basename))
 }
 
-fn is_excluded<'a, T>(file_path: &str, file_basename: &str, exclude: T) -> bool
-where
-    T: Iterator<Item = &'a FilePattern>,
-{
-    for pattern in exclude {
-        match pattern {
-            FilePattern::Simple(basename) => {
-                if *basename == file_basename {
-                    return true;
-                }
-            }
-            FilePattern::Complex(absolute, basename) => {
-                if absolute.matches(file_path) {
-                    return true;
-                }
-                if basename
-                    .as_ref()
-                    .map(|pattern| pattern.matches(file_basename))
-                    .unwrap_or_default()
-                {
-                    return true;
-                }
-            }
-        };
-    }
-    false
+fn is_excluded(file_path: &str, file_basename: &str, exclude: &globset::GlobSet) -> bool {
+    exclude.is_match(file_path) || exclude.is_match(file_basename)
 }
 
 fn is_included(path: &Path) -> bool {
@@ -61,18 +36,12 @@ fn is_included(path: &Path) -> bool {
 
 pub fn iter_python_files<'a>(
     path: &'a Path,
-    exclude: &'a [FilePattern],
-    extend_exclude: &'a [FilePattern],
+    exclude: &'a globset::GlobSet,
+    extend_exclude: &'a globset::GlobSet,
 ) -> impl Iterator<Item = Result<DirEntry, walkdir::Error>> + 'a {
     // Run some checks over the provided patterns, to enable optimizations below.
     let has_exclude = !exclude.is_empty();
     let has_extend_exclude = !extend_exclude.is_empty();
-    let exclude_simple = exclude
-        .iter()
-        .all(|pattern| matches!(pattern, FilePattern::Simple(_)));
-    let extend_exclude_simple = extend_exclude
-        .iter()
-        .all(|pattern| matches!(pattern, FilePattern::Simple(_)));
 
     WalkDir::new(normalize_path(path))
         .into_iter()
@@ -84,17 +53,11 @@ pub fn iter_python_files<'a>(
             let path = entry.path();
             match extract_path_names(path) {
                 Ok((file_path, file_basename)) => {
-                    let file_type = entry.file_type();
-
-                    if has_exclude
-                        && (!exclude_simple || file_type.is_dir())
-                        && is_excluded(file_path, file_basename, exclude.iter())
-                    {
+                    if has_exclude && is_excluded(file_path, file_basename, exclude) {
                         debug!("Ignored path via `exclude`: {:?}", path);
                         false
                     } else if has_extend_exclude
-                        && (!extend_exclude_simple || file_type.is_dir())
-                        && is_excluded(file_path, file_basename, extend_exclude.iter())
+                        && is_excluded(file_path, file_basename, extend_exclude)
                     {
                         debug!("Ignored path via `extend-exclude`: {:?}", path);
                         false
@@ -102,8 +65,8 @@ pub fn iter_python_files<'a>(
                         true
                     }
                 }
-                Err(_) => {
-                    debug!("Ignored path due to error in parsing: {:?}", path);
+                Err(e) => {
+                    debug!("Ignored path due to error in parsing: {:?}: {}", path, e);
                     true
                 }
             }
@@ -120,19 +83,15 @@ pub fn iter_python_files<'a>(
 /// Create tree set with codes matching the pattern/code pairs.
 pub(crate) fn ignores_from_path<'a>(
     path: &Path,
-    pattern_code_pairs: &'a [PerFileIgnore],
-) -> Result<FxHashSet<&'a CheckCode>> {
+    pattern_code_pairs: &'a [(GlobMatcher, GlobMatcher, BTreeSet<CheckCode>)],
+) -> Result<BTreeSet<&'a CheckCode>> {
     let (file_path, file_basename) = extract_path_names(path)?;
     Ok(pattern_code_pairs
         .iter()
-        .filter(|pattern_code_pair| {
-            is_excluded(
-                file_path,
-                file_basename,
-                [&pattern_code_pair.pattern].into_iter(),
-            )
+        .filter(|(absolute, basename, _)| {
+            basename.is_match(file_basename) || absolute.is_match(file_path)
         })
-        .flat_map(|pattern_code_pair| &pattern_code_pair.codes)
+        .flat_map(|(_, _, codes)| codes)
         .collect())
 }
 
@@ -155,7 +114,7 @@ pub(crate) fn normalize_path_to(path: &Path, project_root: &Path) -> PathBuf {
 
 /// Convert an absolute path to be relative to the current working directory.
 pub(crate) fn relativize_path(path: &Path) -> Cow<str> {
-    if let Ok(path) = path.strip_prefix(path_dedot::CWD.deref()) {
+    if let Ok(path) = path.strip_prefix(&*path_dedot::CWD) {
         return path.to_string_lossy();
     }
     path.to_string_lossy()
@@ -172,9 +131,10 @@ pub(crate) fn read_file(path: &Path) -> Result<String> {
 
 #[cfg(test)]
 mod tests {
-    use std::path::Path;
+    use std::path::{Path, PathBuf};
 
     use anyhow::Result;
+    use globset::GlobSet;
     use path_absolutize::Absolutize;
 
     use crate::fs::{extract_path_names, is_excluded, is_included};
@@ -195,73 +155,86 @@ mod tests {
         assert!(!is_included(&path));
     }
 
+    fn make_exclusion(file_pattern: FilePattern, project_root: Option<&PathBuf>) -> GlobSet {
+        let mut builder = globset::GlobSetBuilder::new();
+        file_pattern.add_to(&mut builder, project_root).unwrap();
+        builder.build().unwrap()
+    }
+
     #[test]
     fn exclusions() -> Result<()> {
         let project_root = Path::new("/tmp/");
 
         let path = Path::new("foo").absolutize_from(project_root).unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "foo",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("foo".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         let path = Path::new("foo/bar").absolutize_from(project_root).unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "bar",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("bar".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
             .unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "baz.py",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("baz.py".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         let path = Path::new("foo/bar").absolutize_from(project_root).unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "foo/bar",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("foo/bar".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
             .unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "foo/bar/baz.py",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("foo/bar/baz.py".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
             .unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "foo/bar/*.py",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("foo/bar/*.py".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         let path = Path::new("foo/bar/baz.py")
             .absolutize_from(project_root)
             .unwrap();
-        let exclude = vec![FilePattern::from_user(
-            "baz",
-            Some(&project_root.to_path_buf()),
-        )?];
+        let exclude = FilePattern::User("baz".to_string());
         let (file_path, file_basename) = extract_path_names(&path)?;
-        assert!(!is_excluded(file_path, file_basename, exclude.iter()));
+        assert!(!is_excluded(
+            file_path,
+            file_basename,
+            &make_exclusion(exclude, Some(&project_root.to_path_buf()))
+        ));
 
         Ok(())
     }

src/isort/categorize.rs

@@ -21,7 +21,7 @@ pub fn categorize(
     known_third_party: &BTreeSet<String>,
     extra_standard_library: &BTreeSet<String>,
 ) -> ImportType {
-    if level.map(|level| *level > 0).unwrap_or(false) {
+    if level.map_or(false, |level| *level > 0) {
         ImportType::LocalFolder
     } else if known_first_party.contains(module_base) {
         ImportType::FirstParty

src/isort/mod.rs

@@ -128,7 +128,7 @@ fn annotate_imports<'a>(
                         asname: alias.node.asname.as_ref(),
                         atop: alias_atop,
                         inline: alias_inline,
-                    })
+                    });
                 }
 
                 annotated.push(AnnotatedImport::ImportFrom {
@@ -146,7 +146,7 @@ fn annotate_imports<'a>(
 }
 
 fn normalize_imports(imports: Vec<AnnotatedImport>) -> ImportBlock {
-    let mut block: ImportBlock = Default::default();
+    let mut block = ImportBlock::default();
     for import in imports {
         match import {
             AnnotatedImport::Import {
@@ -204,7 +204,7 @@ fn normalize_imports(imports: Vec<AnnotatedImport>) -> ImportBlock {
                             entry.inline.push(comment.value);
                         }
                     } else {
-                        let entry = &mut block
+                        let entry = block
                             .import_from_as
                             .entry((
                                 ImportFromData { module, level },
@@ -274,7 +274,7 @@ fn categorize_imports<'a>(
     known_third_party: &BTreeSet<String>,
     extra_standard_library: &BTreeSet<String>,
 ) -> BTreeMap<ImportType, ImportBlock<'a>> {
-    let mut block_by_type: BTreeMap<ImportType, ImportBlock> = Default::default();
+    let mut block_by_type: BTreeMap<ImportType, ImportBlock> = BTreeMap::default();
     // Categorize `StmtKind::Import`.
     for (alias, comments) in block.import {
         let import_type = categorize(
@@ -327,7 +327,7 @@ fn categorize_imports<'a>(
 }
 
 fn sort_imports(block: ImportBlock) -> OrderedImportBlock {
-    let mut ordered: OrderedImportBlock = Default::default();
+    let mut ordered = OrderedImportBlock::default();
 
     // Sort `StmtKind::Import`.
     ordered.import.extend(
@@ -354,12 +354,12 @@ fn sort_imports(block: ImportBlock) -> OrderedImportBlock {
                             (
                                 CommentSet {
                                     atop: comments.atop,
-                                    inline: Default::default(),
+                                    inline: vec![],
                                 },
                                 FxHashMap::from_iter([(
                                     alias,
                                     CommentSet {
-                                        atop: Default::default(),
+                                        atop: vec![],
                                         inline: comments.inline,
                                     },
                                 )]),
@@ -428,22 +428,22 @@ pub fn format_imports(
         let import_block = sort_imports(import_block);
 
         // Add a blank line between every section.
-        if !is_first_block {
-            output.append("\n");
-        } else {
+        if is_first_block {
             is_first_block = false;
+        } else {
+            output.append("\n");
         }
 
         let mut is_first_statement = true;
 
         // Format `StmtKind::Import` statements.
-        for (alias, comments) in import_block.import.iter() {
+        for (alias, comments) in &import_block.import {
             output.append(&format::format_import(alias, comments, is_first_statement));
             is_first_statement = false;
         }
 
         // Format `StmtKind::ImportFrom` statements.
-        for (import_from, comments, aliases) in import_block.import_from.iter() {
+        for (import_from, comments, aliases) in &import_block.import_from {
             output.append(&format::format_import_from(
                 import_from,
                 comments,
@@ -464,7 +464,6 @@ mod tests {
     use anyhow::Result;
     use test_case::test_case;
 
-    use crate::autofix::fixer;
     use crate::checks::CheckCode;
     use crate::linter::test_path;
     use crate::Settings;
@@ -501,7 +500,7 @@ mod tests {
                 src: vec![Path::new("resources/test/fixtures/isort").to_path_buf()],
                 ..Settings::for_rule(CheckCode::I001)
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);

src/isort/plugins.rs

@@ -4,7 +4,7 @@ use textwrap::{dedent, indent};
 use crate::ast::helpers::{match_leading_content, match_trailing_content};
 use crate::ast::types::Range;
 use crate::ast::whitespace::leading_space;
-use crate::autofix::{fixer, Fix};
+use crate::autofix::Fix;
 use crate::checks::CheckKind;
 use crate::isort::{comments, format_imports};
 use crate::{Check, Settings, SourceCodeLocator};
@@ -30,13 +30,13 @@ fn extract_indentation(body: &[&Stmt], locator: &SourceCodeLocator) -> String {
 
 /// I001
 pub fn check_imports(
-    body: Vec<&Stmt>,
+    body: &[&Stmt],
     locator: &SourceCodeLocator,
     settings: &Settings,
-    autofix: &fixer::Mode,
+    autofix: bool,
 ) -> Option<Check> {
-    let range = extract_range(&body);
-    let indentation = extract_indentation(&body, locator);
+    let range = extract_range(body);
+    let indentation = extract_indentation(body, locator);
 
     // Extract comments. Take care to grab any inline comments from the last line.
     let comments = comments::collect_comments(
@@ -53,7 +53,7 @@ pub fn check_imports(
 
     // Generate the sorted import block.
     let expected = format_imports(
-        &body,
+        body,
         comments,
         settings.line_length - indentation.len(),
         &settings.src,
@@ -64,7 +64,7 @@ pub fn check_imports(
 
     if has_leading_content || has_trailing_content {
         let mut check = Check::new(CheckKind::UnsortedImports, range);
-        if autofix.patch() && settings.fixable.contains(check.kind.code()) {
+        if autofix && settings.fixable.contains(check.kind.code()) {
             let mut content = String::new();
             if has_leading_content {
                 content.push('\n');
@@ -90,9 +90,11 @@ pub fn check_imports(
             end_location: Location::new(range.end_location.row() + 1, 0),
         };
         let actual = dedent(&locator.slice_source_code_range(&range));
-        if actual != expected {
+        if actual == expected {
+            None
+        } else {
             let mut check = Check::new(CheckKind::UnsortedImports, range);
-            if autofix.patch() && settings.fixable.contains(check.kind.code()) {
+            if autofix && settings.fixable.contains(check.kind.code()) {
                 check.amend(Fix::replacement(
                     indent(&expected, &indentation),
                     range.location,
@@ -100,8 +102,6 @@ pub fn check_imports(
                 ));
             }
             Some(check)
-        } else {
-            None
         }
     }
 }

src/isort/snapshots/ruff__isort__tests__add_newline_before_comments.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 8
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__combine_import_froms.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 6
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__comments.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 26
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__deduplicate_imports.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 5
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__fit_line_length.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 15
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__fit_line_length_comment.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 5
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__import_from_after_import.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 3
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__leading_prefix.py.snap

@@ -18,7 +18,6 @@ expression: checks
       end_location:
         row: 3
         column: 0
-    applied: false
 - kind: UnsortedImports
   location:
     row: 5
@@ -35,5 +34,4 @@ expression: checks
       end_location:
         row: 7
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__order_by_type.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 13
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__order_relative_imports_by_level.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 5
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__preserve_comment_order.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 12
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__preserve_indentation.py.snap

@@ -18,7 +18,6 @@ expression: checks
       end_location:
         row: 4
         column: 0
-    applied: false
 - kind: UnsortedImports
   location:
     row: 5
@@ -35,5 +34,4 @@ expression: checks
       end_location:
         row: 7
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__reorder_within_section.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 3
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__separate_first_party_imports.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 6
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__separate_future_imports.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 4
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__separate_local_folder_imports.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 5
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__separate_third_party_imports.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 5
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__skip.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 11
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__sort_similar_imports.py.snap

@@ -18,5 +18,4 @@ expression: checks
       end_location:
         row: 27
         column: 0
-    applied: false
 

src/isort/snapshots/ruff__isort__tests__trailing_suffix.py.snap

@@ -18,7 +18,6 @@ expression: checks
       end_location:
         row: 3
         column: 0
-    applied: false
 - kind: UnsortedImports
   location:
     row: 5
@@ -35,5 +34,4 @@ expression: checks
       end_location:
         row: 7
         column: 0
-    applied: false
 

src/isort/sorting.rs

@@ -1,4 +1,4 @@
-/// See: https://github.com/PyCQA/isort/blob/12cc5fbd67eebf92eb2213b03c07b138ae1fb448/isort/sorting.py#L13
+/// See: <https://github.com/PyCQA/isort/blob/12cc5fbd67eebf92eb2213b03c07b138ae1fb448/isort/sorting.py#L13>
 use crate::python::string;
 
 #[derive(PartialOrd, Ord, PartialEq, Eq)]
@@ -23,12 +23,7 @@ pub fn member_key<'a>(
         if name.len() > 1 && string::is_upper(name) {
             // Ex) `CONSTANT`
             Prefix::Constants
-        } else if name
-            .chars()
-            .next()
-            .map(|char| char.is_uppercase())
-            .unwrap_or(false)
-        {
+        } else if name.chars().next().map_or(false, char::is_uppercase) {
             // Ex) `Class`
             Prefix::Classes
         } else {

src/isort/track.rs

@@ -142,7 +142,7 @@ where
                 finalbody,
             } => {
                 for excepthandler in handlers {
-                    self.visit_excepthandler(excepthandler)
+                    self.visit_excepthandler(excepthandler);
                 }
 
                 for stmt in body {

src/lex/docstring_detection.rs

@@ -1,6 +1,6 @@
 //! Extract docstrings via tokenization.
 //!
-//! See: https://github.com/zheller/flake8-quotes/blob/ef0d9a90249a080e460b70ab62bf4b65e5aa5816/flake8_quotes/docstring_detection.py#L29
+//! See: <https://github.com/zheller/flake8-quotes/blob/ef0d9a90249a080e460b70ab62bf4b65e5aa5816/flake8_quotes/docstring_detection.py#L29>
 //!
 //! TODO(charlie): Consolidate with the existing AST-based docstring extraction.
 

src/lib.rs

@@ -1,15 +1,26 @@
-#![allow(clippy::collapsible_if, clippy::collapsible_else_if)]
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
 
 use std::path::Path;
 
 use anyhow::Result;
 use log::debug;
+use rustpython_helpers::tokenize;
 use rustpython_parser::lexer::LexResult;
 use settings::{pyproject, Settings};
 
-use crate::autofix::fixer::Mode;
 use crate::checks::Check;
-use crate::linter::{check_path, tokenize};
+use crate::linter::check_path;
 use crate::settings::configuration::Configuration;
 use crate::source_code_locator::SourceCodeLocator;
 
@@ -24,6 +35,7 @@ pub mod checks;
 pub mod checks_gen;
 pub mod cli;
 pub mod code_gen;
+pub mod commands;
 mod cst;
 mod directives;
 mod docstrings;
@@ -54,10 +66,12 @@ mod pyflakes;
 mod python;
 mod pyupgrade;
 mod rules;
+mod rustpython_helpers;
 pub mod settings;
 pub mod source_code_locator;
 #[cfg(feature = "update-informer")]
 pub mod updates;
+mod vendored;
 pub mod visibility;
 
 /// Run Ruff over Python source code directly.
@@ -74,10 +88,10 @@ pub fn check(path: &Path, contents: &str, autofix: bool) -> Result<Vec<Check>> {
         None => debug!("Unable to find pyproject.toml; using default settings..."),
     };
 
-    let settings = Settings::from_configuration(Configuration::from_pyproject(
-        pyproject.as_ref(),
+    let settings = Settings::from_configuration(
+        Configuration::from_pyproject(pyproject.as_ref(), project_root.as_ref())?,
         project_root.as_ref(),
-    )?);
+    )?;
 
     // Tokenize once.
     let tokens: Vec<LexResult> = tokenize(contents);
@@ -100,7 +114,7 @@ pub fn check(path: &Path, contents: &str, autofix: bool) -> Result<Vec<Check>> {
         &locator,
         &directives,
         &settings,
-        &if autofix { Mode::Generate } else { Mode::None },
+        autofix,
     )?;
 
     Ok(checks)

src/linter.rs

@@ -1,16 +1,13 @@
 use std::fs::write;
 use std::io;
 use std::io::Write;
+use std::ops::AddAssign;
 use std::path::Path;
 
 use anyhow::Result;
 #[cfg(not(target_family = "wasm"))]
 use log::debug;
-use rustpython_ast::{Mod, Suite};
-use rustpython_parser::error::ParseError;
 use rustpython_parser::lexer::LexResult;
-use rustpython_parser::parser::Mode;
-use rustpython_parser::{lexer, parser};
 
 use crate::ast::types::Range;
 use crate::autofix::fixer;
@@ -26,32 +23,29 @@ use crate::message::{Message, Source};
 use crate::noqa::add_noqa;
 use crate::settings::Settings;
 use crate::source_code_locator::SourceCodeLocator;
-use crate::{cache, directives, fs};
+use crate::{cache, directives, fs, rustpython_helpers};
 
-/// Collect tokens up to and including the first error.
-pub(crate) fn tokenize(contents: &str) -> Vec<LexResult> {
-    let mut tokens: Vec<LexResult> = vec![];
-    for tok in lexer::make_tokenizer(contents) {
-        let is_err = tok.is_err();
-        tokens.push(tok);
-        if is_err {
-            break;
-        }
+#[derive(Debug, Default)]
+pub struct Diagnostics {
+    pub messages: Vec<Message>,
+    pub fixed: usize,
+}
+
+impl Diagnostics {
+    pub fn new(messages: Vec<Message>) -> Self {
+        Self { messages, fixed: 0 }
     }
-    tokens
 }
 
-/// Parse a full Python program from its tokens.
-pub(crate) fn parse_program_tokens(
-    lxr: Vec<LexResult>,
-    source_path: &str,
-) -> Result<Suite, ParseError> {
-    parser::parse_tokens(lxr, Mode::Module, source_path).map(|top| match top {
-        Mod::Module { body, .. } => body,
-        _ => unreachable!(),
-    })
+impl AddAssign for Diagnostics {
+    fn add_assign(&mut self, other: Self) {
+        self.messages.extend(other.messages);
+        self.fixed += other.fixed;
+    }
 }
 
+/// Generate a list of `Check` violations from the source code contents at the
+/// given `Path`.
 pub(crate) fn check_path(
     path: &Path,
     contents: &str,
@@ -59,7 +53,7 @@ pub(crate) fn check_path(
     locator: &SourceCodeLocator,
     directives: &Directives,
     settings: &Settings,
-    autofix: &fixer::Mode,
+    autofix: bool,
 ) -> Result<Vec<Check>> {
     // Aggregate all checks.
     let mut checks: Vec<Check> = vec![];
@@ -70,7 +64,7 @@ pub(crate) fn check_path(
         .iter()
         .any(|check_code| matches!(check_code.lint_source(), LintSource::Tokens));
     if use_tokens {
-        check_tokens(&mut checks, locator, &tokens, settings, autofix);
+        checks.extend(check_tokens(locator, &tokens, settings, autofix));
     }
 
     // Run the AST-based checks.
@@ -83,7 +77,7 @@ pub(crate) fn check_path(
         .iter()
         .any(|check_code| matches!(check_code.lint_source(), LintSource::Imports));
     if use_ast || use_imports {
-        match parse_program_tokens(tokens, "<filename>") {
+        match rustpython_helpers::parse_program_tokens(tokens, "<filename>") {
             Ok(python_ast) => {
                 if use_ast {
                     checks.extend(check_ast(&python_ast, locator, settings, autofix, path));
@@ -106,7 +100,7 @@ pub(crate) fn check_path(
                             location: parse_error.location,
                             end_location: parse_error.location,
                         },
-                    ))
+                    ));
                 }
             }
         }
@@ -135,132 +129,108 @@ pub(crate) fn check_path(
     Ok(checks)
 }
 
-pub fn lint_stdin(
-    path: &Path,
-    stdin: &str,
-    settings: &Settings,
-    autofix: &fixer::Mode,
-) -> Result<Vec<Message>> {
-    // Tokenize once.
-    let tokens: Vec<LexResult> = tokenize(stdin);
-
-    // Initialize the SourceCodeLocator (which computes offsets lazily).
-    let locator = SourceCodeLocator::new(stdin);
-
-    // Extract the `# noqa` and `# isort: skip` directives from the source.
-    let directives = directives::extract_directives(
-        &tokens,
-        &locator,
-        directives::Flags::from_settings(settings),
-    );
-
-    // Generate checks.
-    let mut checks = check_path(
-        path,
-        stdin,
-        tokens,
-        &locator,
-        &directives,
-        settings,
-        autofix,
-    )?;
-
-    // Apply autofix, write results to stdout.
-    if matches!(autofix, fixer::Mode::Apply) {
-        match fix_file(&mut checks, &locator) {
-            None => io::stdout().write_all(stdin.as_bytes()),
-            Some(contents) => io::stdout().write_all(contents.as_bytes()),
-        }?;
-    }
-
-    // Convert to messages.
-    Ok(checks
-        .into_iter()
-        .map(|check| {
-            let filename = path.to_string_lossy().to_string();
-            let source = if settings.show_source {
-                Some(Source::from_check(&check, &locator))
-            } else {
-                None
-            };
-            Message::from_check(check, filename, source)
-        })
-        .collect())
-}
+const MAX_ITERATIONS: usize = 100;
 
+/// Lint the source code at the given `Path`.
 pub fn lint_path(
     path: &Path,
     settings: &Settings,
     mode: &cache::Mode,
     autofix: &fixer::Mode,
-) -> Result<Vec<Message>> {
+) -> Result<Diagnostics> {
     let metadata = path.metadata()?;
 
     // Check the cache.
     if let Some(messages) = cache::get(path, &metadata, settings, autofix, mode) {
         debug!("Cache hit for: {}", path.to_string_lossy());
-        return Ok(messages);
+        return Ok(Diagnostics::new(messages));
     }
 
     // Read the file from disk.
-    let contents = fs::read_file(path)?;
+    let mut contents = fs::read_file(path)?;
 
-    // Tokenize once.
-    let tokens: Vec<LexResult> = tokenize(&contents);
+    // Track the number of fixed errors across iterations.
+    let mut fixed = 0;
 
-    // Initialize the SourceCodeLocator (which computes offsets lazily).
-    let locator = SourceCodeLocator::new(&contents);
+    // As an escape hatch, bail after 100 iterations.
+    let mut iterations = 0;
 
-    // Determine the noqa and isort exclusions.
-    let directives = directives::extract_directives(
-        &tokens,
-        &locator,
-        directives::Flags::from_settings(settings),
-    );
+    // Continuously autofix until the source code stabilizes.
+    let messages = loop {
+        // Tokenize once.
+        let tokens: Vec<LexResult> = rustpython_helpers::tokenize(&contents);
 
-    // Generate checks.
-    let mut checks = check_path(
-        path,
-        &contents,
-        tokens,
-        &locator,
-        &directives,
-        settings,
-        autofix,
-    )?;
+        // Initialize the SourceCodeLocator (which computes offsets lazily).
+        let locator = SourceCodeLocator::new(&contents);
 
-    // Apply autofix.
-    if matches!(autofix, fixer::Mode::Apply) {
-        if let Some(fixed_contents) = fix_file(&mut checks, &locator) {
-            write(path, fixed_contents.as_ref())?;
+        // Determine the noqa and isort exclusions.
+        let directives = directives::extract_directives(
+            &tokens,
+            &locator,
+            directives::Flags::from_settings(settings),
+        );
+
+        // Generate checks.
+        let checks = check_path(
+            path,
+            &contents,
+            tokens,
+            &locator,
+            &directives,
+            settings,
+            autofix.into(),
+        )?;
+
+        // Apply autofix.
+        if matches!(autofix, fixer::Mode::Apply) && iterations < MAX_ITERATIONS {
+            if let Some((fixed_contents, applied)) = fix_file(&checks, &locator) {
+                // Count the number of fixed errors.
+                fixed += applied;
+
+                // Store the fixed contents.
+                contents = fixed_contents.to_string();
+
+                // Increment the iteration count.
+                iterations += 1;
+
+                // Re-run the linter pass (by avoiding the break).
+                continue;
+            }
         }
+
+        // Convert to messages.
+        let filename = path.to_string_lossy().to_string();
+        break checks
+            .into_iter()
+            .map(|check| {
+                let source = if settings.show_source {
+                    Some(Source::from_check(&check, &locator))
+                } else {
+                    None
+                };
+                Message::from_check(check, filename.clone(), source)
+            })
+            .collect::<Vec<_>>();
     };
 
-    // Convert to messages.
-    let messages: Vec<Message> = checks
-        .into_iter()
-        .map(|check| {
-            let filename = path.to_string_lossy().to_string();
-            let source = if settings.show_source {
-                Some(Source::from_check(&check, &locator))
-            } else {
-                None
-            };
-            Message::from_check(check, filename, source)
-        })
-        .collect();
-
+    // Re-populate the cache.
     cache::set(path, &metadata, settings, autofix, &messages, mode);
 
-    Ok(messages)
+    // If we applied any fixes, write the contents back to disk.
+    if fixed > 0 {
+        write(path, &contents)?;
+    }
+
+    Ok(Diagnostics { messages, fixed })
 }
 
+/// Add any missing `#noqa` pragmas to the source code at the given `Path`.
 pub fn add_noqa_to_path(path: &Path, settings: &Settings) -> Result<usize> {
     // Read the file from disk.
     let contents = fs::read_file(path)?;
 
     // Tokenize once.
-    let tokens: Vec<LexResult> = tokenize(&contents);
+    let tokens: Vec<LexResult> = rustpython_helpers::tokenize(&contents);
 
     // Initialize the SourceCodeLocator (which computes offsets lazily).
     let locator = SourceCodeLocator::new(&contents);
@@ -280,32 +250,115 @@ pub fn add_noqa_to_path(path: &Path, settings: &Settings) -> Result<usize> {
         &locator,
         &directives,
         settings,
-        &fixer::Mode::None,
+        false,
     )?;
 
     add_noqa(&checks, &contents, &directives.noqa_line_for, path)
 }
 
+/// Apply autoformatting to the source code at the given `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);
+    let tokens: Vec<LexResult> = rustpython_helpers::tokenize(&contents);
 
     // Generate the AST.
-    let python_ast = parse_program_tokens(tokens, "<filename>")?;
-    let mut generator: SourceGenerator = Default::default();
-    generator.unparse_suite(&python_ast)?;
+    let python_ast = rustpython_helpers::parse_program_tokens(tokens, "<filename>")?;
+    let mut generator = SourceGenerator::default();
+    generator.unparse_suite(&python_ast);
     write(path, generator.generate()?)?;
 
     Ok(())
 }
 
+/// Generate a list of `Check` violations from source code content derived from
+/// stdin.
+pub fn lint_stdin(
+    path: &Path,
+    stdin: &str,
+    settings: &Settings,
+    autofix: &fixer::Mode,
+) -> Result<Diagnostics> {
+    // Read the file from disk.
+    let mut contents = stdin.to_string();
+
+    // Track the number of fixed errors across iterations.
+    let mut fixed = 0;
+
+    // As an escape hatch, bail after 100 iterations.
+    let mut iterations = 0;
+
+    let messages = loop {
+        // Tokenize once.
+        let tokens: Vec<LexResult> = rustpython_helpers::tokenize(&contents);
+
+        // Initialize the SourceCodeLocator (which computes offsets lazily).
+        let locator = SourceCodeLocator::new(&contents);
+
+        // Extract the `# noqa` and `# isort: skip` directives from the source.
+        let directives = directives::extract_directives(
+            &tokens,
+            &locator,
+            directives::Flags::from_settings(settings),
+        );
+
+        // Generate checks.
+        let checks = check_path(
+            path,
+            &contents,
+            tokens,
+            &locator,
+            &directives,
+            settings,
+            autofix.into(),
+        )?;
+
+        // Apply autofix.
+        if matches!(autofix, fixer::Mode::Apply) && iterations < MAX_ITERATIONS {
+            if let Some((fixed_contents, applied)) = fix_file(&checks, &locator) {
+                // Count the number of fixed errors.
+                fixed += applied;
+
+                // Store the fixed contents.
+                contents = fixed_contents.to_string();
+
+                // Increment the iteration count.
+                iterations += 1;
+
+                // Re-run the linter pass (by avoiding the break).
+                continue;
+            }
+        }
+
+        // Convert to messages.
+        let filename = path.to_string_lossy().to_string();
+        break checks
+            .into_iter()
+            .map(|check| {
+                let source = if settings.show_source {
+                    Some(Source::from_check(&check, &locator))
+                } else {
+                    None
+                };
+                Message::from_check(check, filename.clone(), source)
+            })
+            .collect();
+    };
+
+    // Write the fixed contents to stdout.
+    if matches!(autofix, fixer::Mode::Apply) {
+        io::stdout().write_all(contents.as_bytes())?;
+    }
+
+    Ok(Diagnostics { messages, fixed })
+}
+
 #[cfg(test)]
-pub fn test_path(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> Result<Vec<Check>> {
+pub fn test_path(path: &Path, settings: &Settings, autofix: bool) -> Result<Vec<Check>> {
     let contents = fs::read_file(path)?;
-    let tokens: Vec<LexResult> = tokenize(&contents);
+    let tokens: Vec<LexResult> = rustpython_helpers::tokenize(&contents);
     let locator = SourceCodeLocator::new(&contents);
     let directives = directives::extract_directives(
         &tokens,
@@ -332,7 +385,6 @@ mod tests {
     use regex::Regex;
     use test_case::test_case;
 
-    use crate::autofix::fixer;
     use crate::checks::CheckCode;
     use crate::linter::test_path;
     use crate::settings;
@@ -365,6 +417,7 @@ mod tests {
     #[test_case(CheckCode::B025, Path::new("B025.py"); "B025")]
     #[test_case(CheckCode::B026, Path::new("B026.py"); "B026")]
     #[test_case(CheckCode::B027, Path::new("B027.py"); "B027")]
+    #[test_case(CheckCode::B904, Path::new("B904.py"); "B904")]
     #[test_case(CheckCode::BLE001, Path::new("BLE.py"); "BLE001")]
     #[test_case(CheckCode::C400, Path::new("C400.py"); "C400")]
     #[test_case(CheckCode::C401, Path::new("C401.py"); "C401")]
@@ -453,6 +506,7 @@ mod tests {
     #[test_case(CheckCode::F405, Path::new("F405.py"); "F405")]
     #[test_case(CheckCode::F406, Path::new("F406.py"); "F406")]
     #[test_case(CheckCode::F407, Path::new("F407.py"); "F407")]
+    #[test_case(CheckCode::F521, Path::new("F521.py"); "F521")]
     #[test_case(CheckCode::F541, Path::new("F541.py"); "F541")]
     #[test_case(CheckCode::F601, Path::new("F601.py"); "F601")]
     #[test_case(CheckCode::F602, Path::new("F602.py"); "F602")]
@@ -552,7 +606,7 @@ mod tests {
         let mut checks = test_path(
             Path::new("./resources/test/fixtures").join(path).as_path(),
             &settings::Settings::for_rule(check_code),
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(snapshot, checks);
@@ -567,7 +621,7 @@ mod tests {
                 dummy_variable_rgx: Regex::new(r"^z$").unwrap(),
                 ..settings::Settings::for_rule(CheckCode::F841)
             },
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -579,7 +633,7 @@ mod tests {
         let mut checks = test_path(
             Path::new("./resources/test/fixtures/M001.py"),
             &settings::Settings::for_rules(vec![CheckCode::M001, CheckCode::E501, CheckCode::F841]),
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -591,7 +645,7 @@ mod tests {
         let mut checks = test_path(
             Path::new("./resources/test/fixtures/__init__.py"),
             &settings::Settings::for_rules(vec![CheckCode::F821, CheckCode::F822]),
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);
@@ -603,7 +657,7 @@ mod tests {
         let mut checks = test_path(
             Path::new("./resources/test/fixtures/future_annotations.py"),
             &settings::Settings::for_rules(vec![CheckCode::F401, CheckCode::F821]),
-            &fixer::Mode::Generate,
+            true,
         )?;
         checks.sort_by_key(|check| check.location);
         insta::assert_yaml_snapshot!(checks);

src/logging.rs

@@ -53,12 +53,12 @@ pub fn set_up_logging(level: &LogLevel) -> Result<()> {
                 record.target(),
                 record.level(),
                 message
-            ))
+            ));
         })
         .level(level.level_filter())
         .chain(std::io::stdout())
-        .apply()
-        .map_err(|e| e.into())
+        .apply()?;
+    Ok(())
 }
 
 #[cfg(test)]

src/main.rs

@@ -1,23 +1,34 @@
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
+
 use std::io::{self, Read};
 use std::path::{Path, PathBuf};
 use std::process::ExitCode;
 use std::sync::mpsc::channel;
 use std::time::Instant;
 
-use ::ruff::cache;
 use ::ruff::checks::{CheckCode, CheckKind};
 use ::ruff::cli::{collect_per_file_ignores, extract_log_level, Cli};
 use ::ruff::fs::iter_python_files;
-use ::ruff::linter::{add_noqa_to_path, autoformat_path, lint_path, lint_stdin};
+use ::ruff::linter::{add_noqa_to_path, autoformat_path, lint_path, lint_stdin, Diagnostics};
 use ::ruff::logging::{set_up_logging, LogLevel};
 use ::ruff::message::Message;
 use ::ruff::printer::{Printer, SerializationFormat};
 use ::ruff::settings::configuration::Configuration;
-use ::ruff::settings::types::FilePattern;
-use ::ruff::settings::user::UserConfiguration;
 use ::ruff::settings::{pyproject, Settings};
 #[cfg(feature = "update-informer")]
 use ::ruff::updates;
+use ::ruff::{cache, commands};
 use anyhow::Result;
 use clap::Parser;
 use colored::Colorize;
@@ -25,12 +36,13 @@ use log::{debug, error};
 use notify::{raw_watcher, RecursiveMode, Watcher};
 #[cfg(not(target_family = "wasm"))]
 use rayon::prelude::*;
+use rustpython_ast::Location;
 use walkdir::DirEntry;
 
-/// Shim that calls par_iter except for wasm because there's no wasm support in
-/// rayon yet (there is a shim to be used for the web, but it requires js
-/// cooperation) Unfortunately, ParallelIterator does not implement Iterator so
-/// the signatures diverge
+/// Shim that calls `par_iter` except for wasm because there's no wasm support
+/// in rayon yet (there is a shim to be used for the web, but it requires js
+/// cooperation) Unfortunately, `ParallelIterator` does not implement `Iterator`
+/// so the signatures diverge
 #[cfg(not(target_family = "wasm"))]
 fn par_iter<T: Sync>(iterable: &Vec<T>) -> impl ParallelIterator<Item = &T> {
     iterable.par_iter()
@@ -41,48 +53,20 @@ fn par_iter<T: Sync>(iterable: &Vec<T>) -> impl Iterator<Item = &T> {
     iterable.iter()
 }
 
-fn show_settings(
-    configuration: Configuration,
-    project_root: Option<PathBuf>,
-    pyproject: Option<PathBuf>,
-) {
-    println!(
-        "{:#?}",
-        UserConfiguration::from_configuration(configuration, project_root, pyproject)
-    );
-}
-
-fn show_files(files: &[PathBuf], settings: &Settings) {
-    let mut entries: Vec<DirEntry> = files
-        .iter()
-        .flat_map(|path| iter_python_files(path, &settings.exclude, &settings.extend_exclude))
-        .flatten()
-        .collect();
-    entries.sort_by(|a, b| a.path().cmp(b.path()));
-    for entry in entries {
-        println!("{}", entry.path().to_string_lossy());
-    }
-}
-
 fn read_from_stdin() -> Result<String> {
     let mut buffer = String::new();
     io::stdin().lock().read_to_string(&mut buffer)?;
     Ok(buffer)
 }
 
-fn run_once_stdin(settings: &Settings, filename: &Path, autofix: bool) -> Result<Vec<Message>> {
+fn run_once_stdin(settings: &Settings, filename: &Path, autofix: bool) -> Result<Diagnostics> {
     let stdin = read_from_stdin()?;
-    let mut messages = lint_stdin(filename, &stdin, settings, &autofix.into())?;
-    messages.sort_unstable();
-    Ok(messages)
+    let mut diagnostics = lint_stdin(filename, &stdin, settings, &autofix.into())?;
+    diagnostics.messages.sort_unstable();
+    Ok(diagnostics)
 }
 
-fn run_once(
-    files: &[PathBuf],
-    settings: &Settings,
-    cache: bool,
-    autofix: bool,
-) -> Result<Vec<Message>> {
+fn run_once(files: &[PathBuf], settings: &Settings, cache: bool, autofix: bool) -> Diagnostics {
     // Collect all the files to check.
     let start = Instant::now();
     let paths: Vec<Result<DirEntry, walkdir::Error>> = files
@@ -93,7 +77,7 @@ fn run_once(
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let mut messages: Vec<Message> = par_iter(&paths)
+    let mut diagnostics: Diagnostics = par_iter(&paths)
         .map(|entry| {
             match entry {
                 Ok(entry) => {
@@ -110,63 +94,67 @@ fn run_once(
             .unwrap_or_else(|(path, message)| {
                 if let Some(path) = path {
                     if settings.enabled.contains(&CheckCode::E902) {
-                        vec![Message {
+                        Diagnostics::new(vec![Message {
                             kind: CheckKind::IOError(message),
-                            fixed: false,
-                            location: Default::default(),
-                            end_location: Default::default(),
+                            location: Location::default(),
+                            end_location: Location::default(),
                             filename: path.to_string_lossy().to_string(),
                             source: None,
-                        }]
+                        }])
                     } else {
                         error!("Failed to check {}: {message}", path.to_string_lossy());
-                        vec![]
+                        Diagnostics::default()
                     }
                 } else {
                     error!("{message}");
-                    vec![]
+                    Diagnostics::default()
                 }
             })
         })
-        .flatten()
-        .collect();
+        .reduce(Diagnostics::default, |mut acc, item| {
+            acc += item;
+            acc
+        });
 
-    messages.sort_unstable();
+    diagnostics.messages.sort_unstable();
     let duration = start.elapsed();
     debug!("Checked files in: {:?}", duration);
 
-    Ok(messages)
+    diagnostics
 }
 
-fn add_noqa(files: &[PathBuf], settings: &Settings) -> Result<usize> {
+fn add_noqa(files: &[PathBuf], settings: &Settings) -> usize {
     // Collect all the files to check.
     let start = Instant::now();
-    let paths: Vec<Result<DirEntry, walkdir::Error>> = files
+    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: usize = par_iter(&paths)
-        .map(|entry| match entry {
-            Ok(entry) => {
-                let path = entry.path();
-                add_noqa_to_path(path, settings)
+        .filter_map(|entry| {
+            let path = entry.path();
+            match add_noqa_to_path(path, settings) {
+                Ok(count) => Some(count),
+                Err(e) => {
+                    error!("Failed to add noqa to {}: {e}", path.to_string_lossy());
+                    None
+                }
             }
-            Err(_) => Ok(0),
         })
-        .flatten()
         .sum();
 
     let duration = start.elapsed();
     debug!("Added noqa to files in: {:?}", duration);
 
-    Ok(modifications)
+    modifications
 }
 
-fn autoformat(files: &[PathBuf], settings: &Settings) -> Result<usize> {
+fn autoformat(files: &[PathBuf], settings: &Settings) -> usize {
     // Collect all the files to format.
     let start = Instant::now();
     let paths: Vec<DirEntry> = files
@@ -179,17 +167,22 @@ fn autoformat(files: &[PathBuf], settings: &Settings) -> Result<usize> {
 
     let start = Instant::now();
     let modifications = par_iter(&paths)
-        .map(|entry| {
+        .filter_map(|entry| {
             let path = entry.path();
-            autoformat_path(path)
+            match autoformat_path(path) {
+                Ok(()) => Some(()),
+                Err(e) => {
+                    error!("Failed to autoformat {}: {e}", path.to_string_lossy());
+                    None
+                }
+            }
         })
-        .flatten()
         .count();
 
     let duration = start.elapsed();
     debug!("Auto-formatted files in: {:?}", duration);
 
-    Ok(modifications)
+    modifications
 }
 
 fn inner_main() -> Result<ExitCode> {
@@ -215,28 +208,16 @@ fn inner_main() -> Result<ExitCode> {
     };
 
     // Reconcile configuration from pyproject.toml and command-line arguments.
-    let exclude: Vec<FilePattern> = cli
-        .exclude
-        .iter()
-        .map(|path| FilePattern::from_user(path, project_root.as_ref()))
-        .collect::<Result<_>>()?;
-    let extend_exclude: Vec<FilePattern> = cli
-        .extend_exclude
-        .iter()
-        .map(|path| FilePattern::from_user(path, project_root.as_ref()))
-        .collect::<Result<_>>()?;
-
     let mut configuration =
         Configuration::from_pyproject(pyproject.as_ref(), project_root.as_ref())?;
-    if !exclude.is_empty() {
-        configuration.exclude = exclude;
+    if !cli.exclude.is_empty() {
+        configuration.exclude = cli.exclude;
     }
-    if !extend_exclude.is_empty() {
-        configuration.extend_exclude = extend_exclude;
+    if !cli.extend_exclude.is_empty() {
+        configuration.extend_exclude = cli.extend_exclude;
     }
     if !cli.per_file_ignores.is_empty() {
-        configuration.per_file_ignores =
-            collect_per_file_ignores(cli.per_file_ignores, project_root.as_ref())?;
+        configuration.per_file_ignores = collect_per_file_ignores(cli.per_file_ignores);
     }
     if !cli.select.is_empty() {
         configuration.select = cli.select;
@@ -275,21 +256,26 @@ fn inner_main() -> Result<ExitCode> {
         configuration.show_source = true;
     }
 
+    if let Some(code) = cli.explain {
+        commands::explain(&code, cli.format)?;
+        return Ok(ExitCode::SUCCESS);
+    }
+
     if cli.show_settings && cli.show_files {
         eprintln!("Error: specify --show-settings or show-files (not both).");
         return Ok(ExitCode::FAILURE);
     }
     if cli.show_settings {
-        show_settings(configuration, project_root, pyproject);
+        commands::show_settings(&configuration, project_root.as_ref(), pyproject.as_ref());
         return Ok(ExitCode::SUCCESS);
     }
 
     // Extract settings for internal use.
     let fix_enabled: bool = configuration.fix;
-    let settings = Settings::from_configuration(configuration);
+    let settings = Settings::from_configuration(configuration, project_root.as_ref())?;
 
     if cli.show_files {
-        show_files(&cli.files, &settings);
+        commands::show_files(&cli.files, &settings);
         return Ok(ExitCode::SUCCESS);
     }
 
@@ -322,7 +308,7 @@ fn inner_main() -> Result<ExitCode> {
         printer.clear_screen()?;
         printer.write_to_user("Starting linter in watch mode...\n");
 
-        let messages = run_once(&cli.files, &settings, cache_enabled, false)?;
+        let messages = run_once(&cli.files, &settings, cache_enabled, false);
         printer.write_continuously(&messages)?;
 
         // Configure the file watcher.
@@ -340,7 +326,7 @@ fn inner_main() -> Result<ExitCode> {
                             printer.clear_screen()?;
                             printer.write_to_user("File change detected...\n");
 
-                            let messages = run_once(&cli.files, &settings, cache_enabled, false)?;
+                            let messages = run_once(&cli.files, &settings, cache_enabled, false);
                             printer.write_continuously(&messages)?;
                         }
                     }
@@ -349,12 +335,12 @@ fn inner_main() -> Result<ExitCode> {
             }
         }
     } else if cli.add_noqa {
-        let modifications = add_noqa(&cli.files, &settings)?;
+        let modifications = add_noqa(&cli.files, &settings);
         if modifications > 0 && log_level >= LogLevel::Default {
             println!("Added {modifications} noqa directives.");
         }
     } else if cli.autoformat {
-        let modifications = autoformat(&cli.files, &settings)?;
+        let modifications = autoformat(&cli.files, &settings);
         if modifications > 0 && log_level >= LogLevel::Default {
             println!("Formatted {modifications} files.");
         }
@@ -362,28 +348,28 @@ fn inner_main() -> Result<ExitCode> {
         let is_stdin = cli.files == vec![PathBuf::from("-")];
 
         // Generate lint violations.
-        let messages = if is_stdin {
+        let diagnostics = if is_stdin {
             let filename = cli.stdin_filename.unwrap_or_else(|| "-".to_string());
             let path = Path::new(&filename);
             run_once_stdin(&settings, path, fix_enabled)?
         } else {
-            run_once(&cli.files, &settings, cache_enabled, fix_enabled)?
+            run_once(&cli.files, &settings, cache_enabled, fix_enabled)
         };
 
         // Always try to print violations (the printer itself may suppress output),
         // unless we're writing fixes via stdin (in which case, the transformed
         // source code goes to stdout).
         if !(is_stdin && fix_enabled) {
-            printer.write_once(&messages)?;
+            printer.write_once(&diagnostics)?;
         }
 
         // Check for updates if we're in a non-silent log level.
         #[cfg(feature = "update-informer")]
         if !is_stdin && log_level >= LogLevel::Default && atty::is(atty::Stream::Stdout) {
-            let _ = updates::check_for_updates();
+            drop(updates::check_for_updates());
         }
 
-        if messages.iter().any(|message| !message.fixed) && !cli.exit_zero {
+        if !diagnostics.messages.is_empty() && !cli.exit_zero {
             return Ok(ExitCode::FAILURE);
         }
     }
@@ -395,7 +381,7 @@ fn main() -> ExitCode {
     match inner_main() {
         Ok(code) => code,
         Err(err) => {
-            eprintln!("{} {:?}", "error".red().bold(), err);
+            eprintln!("{} {err:?}", "error".red().bold());
             ExitCode::FAILURE
         }
     }