Run: brew install --build-from-source --verbose --debug ruff

File: /opt/homebrew/Library/Taps/homebrew/homebrew-core/Formula/ruff.rb

Docs: https://docs.brew.sh/Formula-Cookbook

Test: brew test ruff

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.135
+    rev: v0.0.137
     hooks:
       - id: ruff
 

Cargo.lock

@@ -670,7 +670,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8-to-ruff"
-version = "0.0.135-dev.0"
+version = "0.0.137-dev.0"
 dependencies = [
  "anyhow",
  "clap 4.0.22",
@@ -1768,7 +1768,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.135"
+version = "0.0.137"
 dependencies = [
  "annotate-snippets 0.9.1",
  "anyhow",
@@ -1818,7 +1818,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_dev"
-version = "0.0.135"
+version = "0.0.137"
 dependencies = [
  "anyhow",
  "clap 4.0.22",

Cargo.toml

@@ -6,8 +6,9 @@ members = [
 
 [package]
 name = "ruff"
-version = "0.0.135"
+version = "0.0.137"
 edition = "2021"
+rust-version = "1.65.0"
 
 [lib]
 name = "ruff"

README.md

@@ -107,7 +107,7 @@ Ruff also works with [pre-commit](https://pre-commit.com):
 ```yaml
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.135
+    rev: v0.0.137
     hooks:
       - id: ruff
 ```

flake8_to_ruff/Cargo.lock

@@ -771,7 +771,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8_to_ruff"
-version = "0.0.135"
+version = "0.0.137"
 dependencies = [
  "anyhow",
  "clap",
@@ -1975,7 +1975,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.135"
+version = "0.0.137"
 dependencies = [
  "anyhow",
  "bincode",

flake8_to_ruff/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "flake8-to-ruff"
-version = "0.0.135-dev.0"
+version = "0.0.137-dev.0"
 edition = "2021"
 
 [lib]

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.rb

@@ -0,0 +1,27 @@
+class Ruff < Formula
+  desc "An extremely fast Python linter, written in Rust."
+  homepage "https://github.com/charliermarsh/ruff"
+  url "https://github.com/charliermarsh/ruff/archive/refs/tags/v0.0.137.tar.gz"
+  sha256 "d5521f2ad9ee87ca8018bd23ea731fc05abd0fa4a01878880a8cc5119596f837"
+  license "MIT"
+  head "https://github.com/charliermarsh/ruff.git", branch: "main"
+
+  # STOPSHIP(charlie): Requires Rust 1.65.0.
+  # See: https://github.com/Homebrew/homebrew-core/pull/116480
+  depends_on "rust" => :build
+
+  def install
+    system "cargo", "install", "--no-default-features", *std_cargo_args
+    bin.install "target/release/ruff" => "ruff"
+  end
+
+  test do
+    (testpath/"test.py").write <<~EOS
+      import os
+    EOS
+    expected = <<~EOS
+      test.py:1:1: F401 `os` imported but unused
+    EOS
+    assert_equal expected, shell_output("#{bin}/ruff -- --quiet #{testpath}/test.py")
+  end
+end

ruff_dev/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff_dev"
-version = "0.0.135"
+version = "0.0.137"
 edition = "2021"
 
 [dependencies]

src/ast/visitor.rs

@@ -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);
     }

src/check_ast.rs

@@ -6,6 +6,7 @@ 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,
@@ -21,7 +22,7 @@ use crate::ast::types::{
     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::checks::{Check, CheckCode, CheckKind};
 use crate::docstrings::definition::{Definition, DefinitionKind, Documentable};
@@ -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,
@@ -120,6 +122,7 @@ impl<'a> Checker<'a> {
             in_deferred_string_annotation: false,
             in_literal: false,
             in_subscript: false,
+            in_withitem: false,
             seen_import_boundary: false,
             futures_allowed: true,
             annotations_future_enabled: false,
@@ -2080,6 +2083,13 @@ 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 {
@@ -2386,7 +2396,7 @@ 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 {

src/cli.rs

@@ -5,6 +5,7 @@ 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;
@@ -111,6 +112,9 @@ 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 {

src/main.rs

@@ -40,6 +40,7 @@ use notify::{raw_watcher, RecursiveMode, Watcher};
 use rayon::prelude::*;
 use ruff::linter::Diagnostics;
 use rustpython_ast::Location;
+use serde::Serialize;
 use walkdir::DirEntry;
 
 /// Shim that calls `par_iter` except for wasm because there's no wasm support
@@ -67,6 +68,37 @@ fn show_settings(
     );
 }
 
+#[derive(Serialize)]
+struct Explanation<'a> {
+    code: &'a str,
+    category: &'a str,
+    summary: &'a str,
+}
+
+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(())
+}
+
 fn show_files(files: &[PathBuf], settings: &Settings) {
     let mut entries: Vec<DirEntry> = files
         .iter()
@@ -294,6 +326,11 @@ fn inner_main() -> Result<ExitCode> {
         configuration.show_source = true;
     }
 
+    if let Some(code) = cli.explain {
+        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);