Bump version to 0.0.33

.github/workflows/ci.yaml

@@ -2,16 +2,16 @@ name: CI
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
-    branches: [ main ]
+    branches: [main]
 
 jobs:
   cargo_build:
     name: "cargo build"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -33,7 +33,7 @@ jobs:
     name: "cargo fmt"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -55,7 +55,7 @@ jobs:
     name: "cargo clippy"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -77,7 +77,7 @@ jobs:
     name: "cargo test"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -99,13 +99,13 @@ jobs:
     name: "maturin build"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
       - uses: actions/setup-python@v4
         with:
-          python-version: '3.10'
+          python-version: "3.10"
       - run: pip install maturin
       - uses: actions/cache@v3
         env:

.github/workflows/release.yaml

@@ -1,6 +1,8 @@
 name: Release
 
 on:
+  pull_request:
+    branches: [main]
   create:
     tags:
       - v*
@@ -127,7 +129,7 @@ jobs:
         with:
           target: ${{ matrix.target }}
           manylinux: auto
-          args: --release --out dist
+          args: --no-default-features --release --out dist
           maturin-version: "v0.13.0"
       - uses: uraimo/run-on-arch-action@v2.0.5
         if: matrix.target != 'ppc64'
@@ -227,9 +229,9 @@ jobs:
         os: [ubuntu-latest, macos-latest]
         target: [x86_64, aarch64]
         python-version:
-          - '3.7'
-          - '3.8'
-          - '3.9'
+          - "3.7"
+          - "3.8"
+          - "3.9"
         exclude:
           - os: macos-latest
             target: aarch64

.gitignore

@@ -1,5 +1,5 @@
 # Local cache
-.cache
+.ruff_cache
 resources/test/cpython
 
 ###

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+  - repo: https://github.com/charliermarsh/ruff
+    rev: v0.0.33
+    hooks:
+      - id: lint

.pre-commit-hooks.yaml

@@ -0,0 +1,7 @@
+- id: lint
+  name: ruff lint
+  description: Run ruff to lint Python files.
+  entry: ruff
+  language: python
+  types_or: [python]
+  pass_filenames: true

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "adler"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
+
 [[package]]
 name = "ahash"
 version = "0.7.6"
@@ -197,6 +203,12 @@ dependencies = [
  "byteorder",
 ]
 
+[[package]]
+name = "base64"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
+
 [[package]]
 name = "bincode"
 version = "1.3.3"
@@ -362,6 +374,12 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "chunked_transfer"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fff857943da45f546682664a79488be82e69e43c1a7a2307679ab9afb3a66d2e"
+
 [[package]]
 name = "clap"
 version = "3.2.16"
@@ -465,6 +483,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crc32fast"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b540bd8bc810d3885c6ea91e2018302f68baba2129ab3e88f32389ee9370880d"
+dependencies = [
+ "cfg-if 1.0.0",
+]
+
 [[package]]
 name = "crossbeam-channel"
 version = "0.5.6"
@@ -550,6 +577,15 @@ dependencies = [
  "generic-array 0.14.6",
 ]
 
+[[package]]
+name = "directories"
+version = "4.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f51c5d4ddabd36886dd3e1438cb358cdcb0d7c499cb99cb4ac2e38e18b5cb210"
+dependencies = [
+ "dirs-sys",
+]
+
 [[package]]
 name = "dirs"
 version = "2.0.2"
@@ -664,12 +700,32 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
+[[package]]
+name = "flate2"
+version = "1.0.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f82b0f4c27ad9f8bfd1f3208d882da2b09c301bc1c828fd3a00d0216d2fbbff6"
+dependencies = [
+ "crc32fast",
+ "miniz_oxide",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
+[[package]]
+name = "form_urlencoded"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fc25a87fa4fd2094bffb06925852034d90a17f0d1e05197d4956d3555752191"
+dependencies = [
+ "matches",
+ "percent-encoding",
+]
+
 [[package]]
 name = "fsevent"
 version = "0.4.0"
@@ -914,6 +970,17 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "idna"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "418a0a6fab821475f634efe3ccc45c013f742efe03d853e8d3355d5cb850ecf8"
+dependencies = [
+ "matches",
+ "unicode-bidi",
+ "unicode-normalization",
+]
+
 [[package]]
 name = "indexmap"
 version = "1.9.1"
@@ -1084,6 +1151,12 @@ dependencies = [
  "twox-hash",
 ]
 
+[[package]]
+name = "matches"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3e378b66a060d48947b590737b30a1be76706c8dd7b8ba0f2fe3989c68a853f"
+
 [[package]]
 name = "memchr"
 version = "2.5.0"
@@ -1108,6 +1181,15 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "miniz_oxide"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f5c75688da582b8ffc1f1799e9db273f32133c49e048f614d22ec3256773ccc"
+dependencies = [
+ "adler",
+]
+
 [[package]]
 name = "mio"
 version = "0.6.23"
@@ -1260,9 +1342,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.13.0"
+version = "1.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18a6dbe30758c9f83eb00cbea4ac95966305f5a7772f3f42ebfc7fc7eddbd8e1"
+checksum = "074864da206b4973b84eb91683020dbefd6a8c3f0f38e054d93954e891935e4e"
 
 [[package]]
 name = "opaque-debug"
@@ -1311,6 +1393,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "percent-encoding"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4fd5641d01c8f18a23da7b6fe29298ff4b55afcccdf78973b24cf3175fee32e"
+
 [[package]]
 name = "petgraph"
 version = "0.6.2"
@@ -1639,9 +1727,24 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "ring"
+version = "0.16.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3053cf52e236a3ed746dfc745aa9cacf1b791d846bdaf412f60a8d7d6e17c8fc"
+dependencies = [
+ "cc",
+ "libc",
+ "once_cell",
+ "spin",
+ "untrusted",
+ "web-sys",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "ruff"
-version = "0.0.22"
+version = "0.0.33"
 dependencies = [
  "anyhow",
  "bincode",
@@ -1655,21 +1758,37 @@ dependencies = [
  "fern",
  "filetime",
  "glob",
+ "itertools",
+ "lazy_static",
  "log",
  "notify",
+ "once_cell",
  "rayon",
  "regex",
  "rustpython-parser",
  "serde",
  "serde_json",
  "toml",
+ "update-informer",
  "walkdir",
 ]
 
+[[package]]
+name = "rustls"
+version = "0.20.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5aab8ee6c7097ed6057f43c187a62418d0c05a4bd5f18b3571db50ee0f9ce033"
+dependencies = [
+ "log",
+ "ring",
+ "sct",
+ "webpki",
+]
+
 [[package]]
 name = "rustpython-ast"
 version = "0.1.0"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=1613f6c6990011a4bc559e79aaf28d715f9f729b#1613f6c6990011a4bc559e79aaf28d715f9f729b"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "num-bigint",
  "rustpython-compiler-core",
@@ -1678,7 +1797,7 @@ dependencies = [
 [[package]]
 name = "rustpython-compiler-core"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=1613f6c6990011a4bc559e79aaf28d715f9f729b#1613f6c6990011a4bc559e79aaf28d715f9f729b"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "bincode",
  "bitflags",
@@ -1695,7 +1814,7 @@ dependencies = [
 [[package]]
 name = "rustpython-parser"
 version = "0.1.2"
-source = "git+https://github.com/charliermarsh/RustPython.git?rev=1613f6c6990011a4bc559e79aaf28d715f9f729b#1613f6c6990011a4bc559e79aaf28d715f9f729b"
+source = "git+https://github.com/charliermarsh/RustPython.git?rev=7d21c6923a506e79cc041708d83cef925efd33f4#7d21c6923a506e79cc041708d83cef925efd33f4"
 dependencies = [
  "ahash",
  "anyhow",
@@ -1743,6 +1862,22 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
+[[package]]
+name = "sct"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d53dcdb7c9f8158937a7981b48accfd39a43af418591a5d008c7b22b5e1b7ca4"
+dependencies = [
+ "ring",
+ "untrusted",
+]
+
+[[package]]
+name = "semver"
+version = "1.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93f6841e709003d68bb2deee8c343572bf446003ec20a583e76f7b15cebf3711"
+
 [[package]]
 name = "serde"
 version = "1.0.143"
@@ -1874,13 +2009,19 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
 [[package]]
 name = "ssri"
 version = "7.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a9cec0d388f39fbe79d7aa600e8d38053bf97b1bc8d350da7c0ba800d0f423f2"
 dependencies = [
- "base64",
+ "base64 0.10.1",
  "digest 0.8.1",
  "hex 0.3.2",
  "serde",
@@ -2018,6 +2159,21 @@ dependencies = [
  "crunchy",
 ]
 
+[[package]]
+name = "tinyvec"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87cc5ceb3875bb20c2890005a4e226a4651264a5c75edb2421b52861a0a0cb50"
+dependencies = [
+ "tinyvec_macros",
+]
+
+[[package]]
+name = "tinyvec_macros"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
+
 [[package]]
 name = "toml"
 version = "0.5.9"
@@ -2095,12 +2251,27 @@ dependencies = [
  "unic-common",
 ]
 
+[[package]]
+name = "unicode-bidi"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "099b7128301d285f79ddd55b9a83d5e6b9e97c92e0ea0daebee7263e932de992"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c4f5b37a154999a8f3f98cc23a628d850e154479cd94decf3414696e12e31aaf"
 
+[[package]]
+name = "unicode-normalization"
+version = "0.1.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "854cbdc4f7bc6ae19c820d44abdc3277ac3e1b2b93db20a636825d9322fb60e6"
+dependencies = [
+ "tinyvec",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.3"
@@ -2113,6 +2284,56 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eec8e807a365e5c972debc47b8f06d361b37b94cfd18d48f7adc715fb86404dd"
 
+[[package]]
+name = "untrusted"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a156c684c91ea7d62626509bce3cb4e1d9ed5c4d978f7b4352658f96a4c26b4a"
+
+[[package]]
+name = "update-informer"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f154aee470c0882ea0f3b1cc2a46c5f4d24f282655f7b0cec065614fe24c447f"
+dependencies = [
+ "directories",
+ "semver",
+ "serde",
+ "serde_json",
+ "ureq",
+]
+
+[[package]]
+name = "ureq"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b97acb4c28a254fd7a4aeec976c46a7fa404eac4d7c134b30c75144846d7cb8f"
+dependencies = [
+ "base64 0.13.0",
+ "chunked_transfer",
+ "flate2",
+ "log",
+ "once_cell",
+ "rustls",
+ "serde",
+ "serde_json",
+ "url",
+ "webpki",
+ "webpki-roots",
+]
+
+[[package]]
+name = "url"
+version = "2.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a507c383b2d33b5fc35d1861e77e6b383d158b2da5e14fe51b83dfedf6fd578c"
+dependencies = [
+ "form_urlencoded",
+ "idna",
+ "matches",
+ "percent-encoding",
+]
+
 [[package]]
 name = "value-bag"
 version = "1.0.0-alpha.9"
@@ -2240,6 +2461,25 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "webpki"
+version = "0.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f095d78192e208183081cc07bc5515ef55216397af48b873e5edcd72637fa1bd"
+dependencies = [
+ "ring",
+ "untrusted",
+]
+
+[[package]]
+name = "webpki-roots"
+version = "0.22.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1c760f0d366a6c24a02ed7816e23e691f5d92291f94d15e836006fd11b04daf"
+dependencies = [
+ "webpki",
+]
+
 [[package]]
 name = "wepoll-ffi"
 version = "0.1.2"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruff"
-version = "0.0.22"
+version = "0.0.33"
 edition = "2021"
 
 [lib]
@@ -18,17 +18,25 @@ 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"}
+glob = { version = "0.3.0" }
+itertools = "0.10.3"
+lazy_static = "1.4.0"
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
+once_cell = { version = "1.13.1" }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "1613f6c6990011a4bc559e79aaf28d715f9f729b" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "7d21c6923a506e79cc041708d83cef925efd33f4" }
 serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }
+update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
 walkdir = { version = "2.3.2" }
 
+[features]
+default = ["update-informer"]
+update-informer = ["dep:update-informer"]
+
 [profile.release]
 panic = "abort"
 lto = "thin"

README.md

@@ -17,8 +17,9 @@ An extremely fast Python linter, written in Rust.
 - 🐍 Installable via `pip`
 - 🤝 Python 3.10 compatibility
 - 🛠️ `pyproject.toml` support
-- 📦 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired cache semantics
-- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` semantics
+- 📦 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired cache support
+- 🔧 [ESLint](https://eslint.org/docs/latest/user-guide/command-line-interface#caching)-inspired `--fix` support
+- 👀 [TypeScript](https://www.typescriptlang.org/docs/handbook/configuring-watch.html)-inspired `--watch` support
 
 _ruff is a proof-of-concept and not yet intended for production use. It supports only a small subset
 of the Flake8 rules, and may crash on your codebase._
@@ -51,6 +52,16 @@ You can run ruff in `--watch` mode to automatically re-run on-change:
 ruff path/to/code/ --watch
 ```
 
+ruff also works with [Pre-Commit](https://pre-commit.com) (requires Cargo on system):
+
+```yaml
+repos:
+- repo: https://github.com/charliermarsh/ruff
+  rev: v0.0.33
+  hooks:
+    - id: lint
+```
+
 ## Configuration
 
 ruff is configurable both via `pyproject.toml` and the command line.
@@ -75,7 +86,7 @@ ruff path/to/code/ --select F401 F403
 See `ruff --help` for more:
 
 ```shell
-ruff
+ruff (v0.0.33)
 An extremely fast Python linter.
 
 USAGE:
@@ -85,17 +96,85 @@ ARGS:
     <FILES>...
 
 OPTIONS:
-    -e, --exit-zero             Exit with status code "0", even upon detecting errors
-    -h, --help                  Print help information
-        --ignore <IGNORE>...    Comma-separated list of error codes to ignore
-    -n, --no-cache              Disable cache reads
-    -q, --quiet                 Disable all logging (but still exit with status code "1" upon
-                                detecting errors)
-        --select <SELECT>...    Comma-separated list of error codes to enable
-    -v, --verbose               Enable verbose logging
-    -w, --watch                 Run in watch mode by re-running whenever files change
+    -e, --exit-zero               Exit with status code "0", even upon detecting errors
+        --exclude <EXCLUDE>...    List of file and/or directory patterns to exclude from checks
+    -f, --fix                     Attempt to automatically fix lint errors
+    -h, --help                    Print help information
+        --ignore <IGNORE>...      List of error codes to ignore
+    -n, --no-cache                Disable cache reads
+    -q, --quiet                   Disable all logging (but still exit with status code "1" upon
+                                  detecting errors)
+        --select <SELECT>...      List of error codes to enable
+    -v, --verbose                 Enable verbose logging
+    -w, --watch                   Run in watch mode by re-running whenever files change
 ```
 
+### Compatibility with Black
+
+ruff is intended to be compatible with [Black](https://github.com/psf/black), and should be
+compatible out-of-the-box as long as the `line-length` setting is consistent between the two.
+
+As a project, ruff is designed to be used alongside Black and, as such, will defer implementing
+lint rules that are obviated by Black (e.g., stylistic rules).
+
+### Parity with Flake8
+
+ruff's goal is to achieve feature-parity with Flake8 when used (1) without any plugins,
+(2) alongside Black, and (3) on Python 3 code. (Using Black obviates the need for many of Flake8's
+stylistic checks; limiting to Python 3 obviates the need for certain compatibility checks.)
+
+Under those conditions, Flake8 implements about 58 rules, give or take. At time of writing, ruff
+implements 28 rules. (Note that these 28 rules likely cover a disproportionate share of errors:
+unused imports, undefined variables, etc.)
+
+Of the unimplemented rules, ruff is missing:
+
+- 15 rules related to string `.format` calls.
+- 6 rules related to misplaced `yield`, `break`, and `return` statements.
+- 3 rules related to syntax errors in doctests and annotations.
+- 2 rules related to redefining unused names.
+
+...along with a variety of others that don't fit neatly into any specific category.
+
+Beyond rule-set parity, ruff suffers from the following limitations vis-à-vis Flake8:
+
+1. Flake8 supports a wider range of `noqa` patterns, such as per-file ignores defined in `.flake8`.
+2. Flake8 has a plugin architecture and supports writing custom lint rules.
+3. ruff does not yet support parenthesized context managers.
+
+## Rules
+
+| Code | Name | Message |
+| ---- | ----- | ------- |
+| E402 | ModuleImportNotAtTopOfFile | Module level import not at top of file |
+| E501 | LineTooLong | Line too long |
+| E711 | NoneComparison | Comparison to `None` should be `cond is None` |
+| E712 | TrueFalseComparison | Comparison to `True` should be `cond is True` |
+| E713 | NotInTest | Test for membership should be `not in` |
+| E714 | NotIsTest | Test for object identity should be `is not` |
+| E731 | DoNotAssignLambda | Do not assign a lambda expression, use a def |
+| E902 | IOError | No such file or directory: `...` |
+| F401 | UnusedImport | `...` imported but unused |
+| F403 | ImportStarUsage | Unable to detect undefined names |
+| F541 | FStringMissingPlaceholders | f-string without any placeholders |
+| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |
+| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |
+| F621 | TooManyExpressionsInStarredAssignment | too many expressions in star-unpacking assignment |
+| F622 | TwoStarredExpressions | two starred expressions in assignment |
+| F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |
+| F634 | IfTuple | If test is a tuple, which is always `True` |
+| F704 | YieldOutsideFunction | a `yield` or `yield from` statement outside of a function/method |
+| F706 | ReturnOutsideFunction | a `return` statement outside of a function/method |
+| F707 | DefaultExceptNotLast | an `except:` block as not the last exception handler |
+| F821 | UndefinedName | Undefined name `...` |
+| F822 | UndefinedExport | Undefined name `...` in `__all__` |
+| F823 | UndefinedLocal | Local variable `...` referenced before assignment |
+| F831 | DuplicateArgumentName | Duplicate argument name in function definition |
+| F841 | UnusedVariable | Local variable `...` is assigned to but never used |
+| F901 | RaiseNotImplemented | `raise NotImplemented` should be `raise NotImplementedError` |
+| R001 | UselessObjectInheritance | Class `...` inherits from object |
+| R002 | NoAssertEquals | `assertEquals` is deprecated, use `assertEqual` instead |
+
 ## Development
 
 ruff is written in Rust (1.63.0). You'll need to install the [Rust toolchain](https://www.rust-lang.org/tools/install)
@@ -104,7 +183,7 @@ for development.
 Assuming you have `cargo` installed, you can run:
 
 ```shell
-cargo run resources/test/src
+cargo run resources/test/fixtures
 cargo fmt
 cargo clippy
 cargo test
@@ -128,49 +207,25 @@ git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpy
 Add this `pyproject.toml` to the CPython directory:
 
 ```toml
-[tool.linter]
+[tool.ruff]
 line-length = 88
 exclude = [
-    "Lib/ctypes/test/test_numbers.py",
-    "Lib/dataclasses.py",
     "Lib/lib2to3/tests/data/bom.py",
     "Lib/lib2to3/tests/data/crlf.py",
     "Lib/lib2to3/tests/data/different_encoding.py",
     "Lib/lib2to3/tests/data/false_encoding.py",
     "Lib/lib2to3/tests/data/py2_test_grammar.py",
-    "Lib/sqlite3/test/factory.py",
-    "Lib/sqlite3/test/hooks.py",
-    "Lib/sqlite3/test/regression.py",
-    "Lib/sqlite3/test/transactions.py",
-    "Lib/sqlite3/test/types.py",
     "Lib/test/bad_coding2.py",
     "Lib/test/badsyntax_3131.py",
     "Lib/test/badsyntax_pep3120.py",
     "Lib/test/encoded_modules/module_iso_8859_1.py",
     "Lib/test/encoded_modules/module_koi8_r.py",
-    "Lib/test/sortperf.py",
-    "Lib/test/test_email/torture_test.py",
     "Lib/test/test_fstring.py",
-    "Lib/test/test_genericpath.py",
-    "Lib/test/test_getopt.py",
     "Lib/test/test_grammar.py",
-    "Lib/test/test_htmlparser.py",
-    "Lib/test/test_importlib/stubs.py",
-    "Lib/test/test_importlib/test_files.py",
-    "Lib/test/test_importlib/test_metadata_api.py",
-    "Lib/test/test_importlib/test_open.py",
     "Lib/test/test_importlib/test_util.py",
     "Lib/test/test_named_expressions.py",
     "Lib/test/test_patma.py",
-    "Lib/test/test_peg_generator/__main__.py",
-    "Lib/test/test_pipes.py",
     "Lib/test/test_source_encoding.py",
-    "Lib/test/test_weakref.py",
-    "Lib/test/test_webbrowser.py",
-    "Lib/tkinter/__main__.py",
-    "Lib/tkinter/test/test_tkinter/test_variables.py",
-    "Modules/_decimal/libmpdec/literature/fnt.py",
-    "Modules/_decimal/tests/deccheck.py",
     "Tools/c-analyzer/c_parser/parser/_delim.py",
     "Tools/i18n/pygettext.py",
     "Tools/test2to3/maintest.py",
@@ -215,6 +270,7 @@ hyperfine --ignore-failure --warmup 5 \
 ```
 
 In order, these evaluate:
+
 - ruff
 - Pylint
 - PyFlakes

examples/generate_rules_table.rs

@@ -0,0 +1,47 @@
+/// Generate a Markdown-compatible table of supported lint rules.
+use ruff::checks::{CheckKind, RejectedCmpop};
+
+fn main() {
+    let mut check_kinds: Vec<CheckKind> = vec![
+        CheckKind::AssertTuple,
+        CheckKind::DefaultExceptNotLast,
+        CheckKind::DoNotAssignLambda,
+        CheckKind::DuplicateArgumentName,
+        CheckKind::FStringMissingPlaceholders,
+        CheckKind::IOError("...".to_string()),
+        CheckKind::IfTuple,
+        CheckKind::ImportStarUsage,
+        CheckKind::LineTooLong,
+        CheckKind::ModuleImportNotAtTopOfFile,
+        CheckKind::MultiValueRepeatedKeyLiteral,
+        CheckKind::MultiValueRepeatedKeyVariable("...".to_string()),
+        CheckKind::NoAssertEquals,
+        CheckKind::NoneComparison(RejectedCmpop::Eq),
+        CheckKind::NotInTest,
+        CheckKind::NotIsTest,
+        CheckKind::RaiseNotImplemented,
+        CheckKind::ReturnOutsideFunction,
+        CheckKind::TooManyExpressionsInStarredAssignment,
+        CheckKind::TrueFalseComparison(true, RejectedCmpop::Eq),
+        CheckKind::TwoStarredExpressions,
+        CheckKind::UndefinedExport("...".to_string()),
+        CheckKind::UndefinedLocal("...".to_string()),
+        CheckKind::UndefinedName("...".to_string()),
+        CheckKind::UnusedImport("...".to_string()),
+        CheckKind::UnusedVariable("...".to_string()),
+        CheckKind::UselessObjectInheritance("...".to_string()),
+        CheckKind::YieldOutsideFunction,
+    ];
+    check_kinds.sort_by_key(|check_kind| check_kind.code());
+
+    println!("| Code | Name | Message |");
+    println!("| ---- | ----- | ------- |");
+    for check_kind in check_kinds {
+        println!(
+            "| {} | {} | {} |",
+            check_kind.code().as_str(),
+            check_kind.name(),
+            check_kind.body()
+        );
+    }
+}

examples/print_ast.rs

@@ -0,0 +1,25 @@
+/// Print the AST for a given Python file.
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::{Parser, ValueHint};
+use rustpython_parser::parser;
+
+use ruff::fs;
+
+#[derive(Debug, Parser)]
+struct Cli {
+    #[clap(parse(from_os_str), value_hint = ValueHint::FilePath, required = true)]
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let contents = fs::read_file(&cli.file)?;
+    let python_ast = parser::parse_program(&contents, &cli.file.to_string_lossy())?;
+
+    println!("{:#?}", python_ast);
+
+    Ok(())
+}

examples/print_tokens.rs

@@ -0,0 +1,25 @@
+/// Print the token stream for a given Python file.
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::{Parser, ValueHint};
+use rustpython_parser::lexer;
+
+use ruff::fs;
+
+#[derive(Debug, Parser)]
+struct Cli {
+    #[clap(parse(from_os_str), value_hint = ValueHint::FilePath, required = true)]
+    file: PathBuf,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    let contents = fs::read_file(&cli.file)?;
+    for (_, tok, _) in lexer::make_tokenizer(&contents).flatten() {
+        println!("{:#?}", tok);
+    }
+
+    Ok(())
+}

resources/test/fixtures/E402.py

@@ -0,0 +1,28 @@
+"""Top-level docstring."""
+import a
+
+try:
+    import b
+except ImportError:
+    pass
+else:
+    pass
+
+import c
+
+if x > 0:
+    import d
+else:
+    import e
+
+y = x + 1
+
+import f
+
+
+def foo() -> None:
+    import e
+
+
+if __name__ == "__main__":
+    import g

resources/test/fixtures/E711.py

@@ -0,0 +1,11 @@
+if var == None:
+    pass
+
+if None != var:
+    pass
+
+if var is None:
+    pass
+
+if None is not var:
+    pass

resources/test/fixtures/E712.py

@@ -0,0 +1,14 @@
+if var == True:
+    pass
+
+if False != var:
+    pass
+
+if var != False != True:
+    pass
+
+if var is True:
+    pass
+
+if False is not var:
+    pass

resources/test/fixtures/E713.py

@@ -0,0 +1,7 @@
+my_list = [1, 2, 3]
+if not num in my_list:
+    print(num)
+
+my_list = [1, 2, 3]
+if num not in my_list:
+    print(num)

resources/test/fixtures/E714.py

@@ -0,0 +1,5 @@
+if not user is None:
+    print(user.name)
+
+if user is not None:
+    print(user.name)

resources/test/fixtures/E731.py

@@ -0,0 +1,6 @@
+from typing import Callable, Iterable
+
+a = lambda x: x**2
+b = map(lambda x: 2 * x, range(3))
+c: Callable = lambda x: x**2
+d: Iterable = map(lambda x: 2 * x, range(3))

resources/test/fixtures/F401.py

@@ -0,0 +1,41 @@
+from __future__ import all_feature_names
+import os
+import functools
+from datetime import datetime
+from collections import (
+    Counter,
+    OrderedDict,
+    namedtuple,
+)
+import multiprocessing.pool
+import multiprocessing.process
+import logging.config
+import logging.handlers
+from typing import TYPING_CHECK, NamedTuple, Dict, Type, TypeVar, List, Set, Union, cast
+
+from blah import ClassA, ClassB, ClassC
+
+if TYPING_CHECK:
+    from models import Fruit, Nut, Vegetable
+
+
+class X:
+    datetime: datetime
+    foo: Type["NamedTuple"]
+
+    def a(self) -> "namedtuple":
+        x = os.environ["1"]
+        y = Counter()
+        z = multiprocessing.pool.ThreadPool()
+
+
+__all__ = ["ClassA"] + ["ClassB"]
+__all__ += ["ClassC"]
+
+X = TypeVar("X")
+Y = TypeVar("Y", bound="Dict")
+Z = TypeVar("Z", "List", "Set")
+
+a = list["Fruit"]
+b = Union["Nut", None]
+c = cast("Vegetable", b)

resources/test/fixtures/F601.py

@@ -0,0 +1,12 @@
+x = {
+    "a": 1,
+    "a": 2,
+    "b": 3,
+    ("a", "b"): 3,
+    ("a", "b"): 4,
+    1.0: 2,
+    1: 0,
+    1: 3,
+    b"123": 1,
+    b"123": 4,
+}

resources/test/fixtures/F602.py

@@ -0,0 +1,7 @@
+a = 1
+b = 2
+x = {
+    a: 1,
+    a: 2,
+    b: 3,
+}

resources/test/fixtures/F622.py

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

resources/test/fixtures/F631.py

@@ -0,0 +1,4 @@
+assert (False, "x")
+assert (False,)
+assert ()
+assert True

resources/test/fixtures/F634.py

@@ -6,3 +6,5 @@ for _ in range(5):
         pass
     elif (3, 4):
         pass
+    elif ():
+        pass

resources/test/fixtures/F707.py

@@ -0,0 +1,46 @@
+try:
+    pass
+except:
+    pass
+except ValueError:
+    pass
+
+try:
+    pass
+except:
+    pass
+except ValueError:
+    pass
+finally:
+    pass
+
+try:
+    pass
+except:
+    pass
+except ValueError:
+    pass
+else:
+    pass
+
+try:
+    pass
+except:
+    pass
+
+try:
+    pass
+except ValueError:
+    pass
+except:
+    pass
+
+try:
+    pass
+except ValueError:
+    pass
+
+try:
+    pass
+finally:
+    pass

resources/test/fixtures/F821.py

@@ -33,14 +33,47 @@ def ternary_optarg(prec, exp_range, itr):
 class Foo:
     CLASS_VAR = 1
     REFERENCES_CLASS_VAR = {"CLASS_VAR": CLASS_VAR}
+    ANNOTATED_CLASS_VAR: int = 2
+
+
+from typing import Literal
 
 
 class Class:
+    copy_on_model_validation: Literal["none", "deep", "shallow"]
+    post_init_call: Literal["before_validation", "after_validation"]
+
     def __init__(self):
-        # TODO(charlie): This should be recognized as a defined variable.
-        Class  # noqa: F821
+        Class
+
 
 try:
     x = 1 / 0
 except Exception as e:
     print(e)
+
+
+y: int = 1
+
+x: "Bar" = 1
+
+[first] = ["yup"]
+
+
+from typing import List, TypedDict
+
+
+class Item(TypedDict):
+    nodes: List[TypedDict("Node", {"name": str})]
+
+
+from enum import Enum
+
+
+class Ticket:
+    class Status(Enum):
+        OPEN = "OPEN"
+        CLOSED = "CLOSED"
+
+    def set_status(self, status: Status):
+        self.status = status

resources/test/fixtures/F822.py

@@ -0,0 +1,3 @@
+a = 1
+
+__all__ = ["a", "b"]

resources/test/fixtures/F823.py

@@ -15,3 +15,13 @@ def baz():
     global my_var
     global my_dict
     my_dict[my_var] += 1
+
+
+def dec(x):
+    return x
+
+
+@dec
+def f():
+    dec = 1
+    return dec

resources/test/fixtures/R001.py

@@ -0,0 +1,141 @@
+class A:
+    ...
+
+
+class A(object):
+    ...
+
+
+class A(
+    object,
+):
+    ...
+
+
+class A(
+    object,
+    #
+):
+    ...
+
+
+class A(
+    #
+    object,
+):
+    ...
+
+
+class A(
+    #
+    object
+):
+    ...
+
+
+class A(
+    object
+    #
+):
+    ...
+
+
+class A(
+    #
+    object,
+    #
+):
+    ...
+
+
+class A(
+    #
+    object,
+    #
+):
+    ...
+
+
+class A(
+    #
+    object
+    #
+):
+    ...
+
+
+class A(
+    #
+    object
+    #
+):
+    ...
+
+
+class B(A, object):
+    ...
+
+
+class B(object, A):
+    ...
+
+
+class B(
+    object,
+    A,
+):
+    ...
+
+
+class B(
+    A,
+    object,
+):
+    ...
+
+
+class B(
+    object,
+    # Comment on A.
+    A,
+):
+    ...
+
+
+class B(
+    # Comment on A.
+    A,
+    object,
+):
+    ...
+
+
+def f():
+    class A(object):
+        ...
+
+
+class A(
+    object,
+):
+    ...
+
+
+class A(
+    object,  # )
+):
+    ...
+
+
+class A(
+    object  # )
+    ,
+):
+    ...
+
+
+object = A
+
+
+class B(object):
+    ...

resources/test/fixtures/R002.py

@@ -0,0 +1,3 @@
+self.assertEquals (1, 2)
+self.assertEquals(1, 2)
+self.assertEqual(3, 4)

resources/test/fixtures/pyproject.toml

@@ -2,16 +2,32 @@
 line-length = 88
 exclude = ["excluded.py", "**/migrations"]
 select = [
+    "E402",
     "E501",
+    "E711",
+    "E712",
+    "E713",
+    "E714",
+    "E731",
+    "E902",
     "F401",
     "F403",
     "F541",
+    "F601",
+    "F602",
+    "F621",
+    "F622",
+    "F631",
     "F634",
     "F704",
     "F706",
+    "F707",
     "F821",
+    "F822",
+    "F823",
     "F831",
-    "F832",
     "F841",
     "F901",
+    "R001",
+    "R002",
 ]

resources/test/src/F401.py

@@ -1,18 +0,0 @@
-import os
-import functools
-from collections import (
-    Counter,
-    OrderedDict,
-    namedtuple,
-)
-import multiprocessing.pool
-import multiprocessing.process
-import logging.config
-import logging.handlers
-
-
-class X:
-    def a(self) -> "namedtuple":
-        x = os.environ["1"]
-        y = Counter()
-        z = multiprocessing.pool.ThreadPool()

src/ast.rs

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

src/ast/checks.rs

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

src/ast/operations.rs

@@ -0,0 +1,132 @@
+use rustpython_parser::ast::{Constant, Expr, ExprKind, Location, Stmt, StmtKind};
+
+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 {
+                value: Constant::Str(value),
+                ..
+            } = &elt.node
+            {
+                names.push(value.to_string())
+            }
+        }
+    }
+
+    // Grab the existing bound __all__ values.
+    if let StmtKind::AugAssign { .. } = &stmt.node {
+        if let Some(binding) = scope.values.get("__all__") {
+            if let BindingKind::Export(existing) = &binding.kind {
+                names.extend(existing.clone());
+            }
+        }
+    }
+
+    if let Some(value) = match &stmt.node {
+        StmtKind::Assign { value, .. } => Some(value),
+        StmtKind::AnnAssign { value, .. } => value.as_ref(),
+        StmtKind::AugAssign { value, .. } => Some(value),
+        _ => None,
+    } {
+        match &value.node {
+            ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                add_to_names(&mut names, elts)
+            }
+            ExprKind::BinOp { left, right, .. } => {
+                let mut current_left = left;
+                let mut current_right = right;
+                while let Some(elts) = match &current_right.node {
+                    ExprKind::List { elts, .. } => Some(elts),
+                    ExprKind::Tuple { elts, .. } => Some(elts),
+                    _ => None,
+                } {
+                    add_to_names(&mut names, elts);
+                    match &current_left.node {
+                        ExprKind::BinOp { left, right, .. } => {
+                            current_left = left;
+                            current_right = right;
+                        }
+                        ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                            add_to_names(&mut names, elts);
+                            break;
+                        }
+                        _ => break,
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+
+    names
+}
+
+/// Check if a node is parent of a conditional branch.
+pub fn on_conditional_branch(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::If { .. })
+            || matches!(parent.node, StmtKind::While { .. })
+        {
+            return true;
+        }
+        if let StmtKind::Expr { value } = &parent.node {
+            if matches!(value.node, ExprKind::IfExp { .. }) {
+                return true;
+            }
+        }
+    }
+
+    false
+}
+
+/// Check if a node is in a nested block.
+pub fn in_nested_block(parent_stack: &[usize], parents: &[&Stmt]) -> bool {
+    for index in parent_stack.iter().rev() {
+        let parent = parents[*index];
+        if matches!(parent.node, StmtKind::Try { .. })
+            || matches!(parent.node, StmtKind::If { .. })
+            || matches!(parent.node, StmtKind::With { .. })
+        {
+            return true;
+        }
+    }
+
+    false
+}
+
+/// Struct used to efficiently slice source code at (row, column) Locations.
+pub struct SourceCodeLocator<'a> {
+    content: &'a str,
+    offsets: Vec<usize>,
+    initialized: bool,
+}
+
+impl<'a> SourceCodeLocator<'a> {
+    pub fn new(content: &'a str) -> Self {
+        SourceCodeLocator {
+            content,
+            offsets: vec![],
+            initialized: false,
+        }
+    }
+
+    pub fn slice_source_code(&mut self, location: &Location) -> &'a str {
+        if !self.initialized {
+            let mut offset = 0;
+            for i in self.content.lines() {
+                self.offsets.push(offset);
+                offset += i.len();
+                offset += 1;
+            }
+            self.initialized = true;
+        }
+        let offset = self.offsets[location.row() - 1] + location.column() - 1;
+        &self.content[offset..]
+    }
+}

src/ast/relocate.rs

@@ -0,0 +1,137 @@
+use rustpython_parser::ast::{Expr, ExprKind, Keyword, Location};
+
+fn relocate_keyword(keyword: &mut Keyword, location: Location) {
+    keyword.location = location;
+    relocate_expr(&mut keyword.node.value, location);
+}
+
+/// Change an expression's location (recursively) to match a desired, fixed location.
+pub fn relocate_expr(expr: &mut Expr, location: Location) {
+    expr.location = location;
+    match &mut expr.node {
+        ExprKind::BoolOp { values, .. } => {
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::NamedExpr { target, value } => {
+            relocate_expr(target, location);
+            relocate_expr(value, location);
+        }
+        ExprKind::BinOp { left, right, .. } => {
+            relocate_expr(left, location);
+            relocate_expr(right, location);
+        }
+        ExprKind::UnaryOp { operand, .. } => {
+            relocate_expr(operand, location);
+        }
+        ExprKind::Lambda { body, .. } => {
+            relocate_expr(body, location);
+        }
+        ExprKind::IfExp { test, body, orelse } => {
+            relocate_expr(test, location);
+            relocate_expr(body, location);
+            relocate_expr(orelse, location);
+        }
+        ExprKind::Dict { keys, values } => {
+            for expr in keys {
+                relocate_expr(expr, location);
+            }
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Set { elts } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::ListComp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::SetComp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::DictComp { key, value, .. } => {
+            relocate_expr(key, location);
+            relocate_expr(value, location);
+        }
+        ExprKind::GeneratorExp { elt, .. } => {
+            relocate_expr(elt, location);
+        }
+        ExprKind::Await { value } => relocate_expr(value, location),
+        ExprKind::Yield { value } => {
+            if let Some(expr) = value {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::YieldFrom { value } => relocate_expr(value, location),
+        ExprKind::Compare {
+            left, comparators, ..
+        } => {
+            relocate_expr(left, location);
+            for expr in comparators {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Call {
+            func,
+            args,
+            keywords,
+        } => {
+            relocate_expr(func, location);
+            for expr in args {
+                relocate_expr(expr, location);
+            }
+            for keyword in keywords {
+                relocate_keyword(keyword, location);
+            }
+        }
+        ExprKind::FormattedValue {
+            value, format_spec, ..
+        } => {
+            relocate_expr(value, location);
+            if let Some(expr) = format_spec {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::JoinedStr { values } => {
+            for expr in values {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Constant { .. } => {}
+        ExprKind::Attribute { value, .. } => {
+            relocate_expr(value, location);
+        }
+        ExprKind::Subscript { value, slice, .. } => {
+            relocate_expr(value, location);
+            relocate_expr(slice, location);
+        }
+        ExprKind::Starred { value, .. } => {
+            relocate_expr(value, location);
+        }
+        ExprKind::Name { .. } => {}
+        ExprKind::List { elts, .. } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Tuple { elts, .. } => {
+            for expr in elts {
+                relocate_expr(expr, location);
+            }
+        }
+        ExprKind::Slice { lower, upper, step } => {
+            if let Some(expr) = lower {
+                relocate_expr(expr, location);
+            }
+            if let Some(expr) = upper {
+                relocate_expr(expr, location);
+            }
+            if let Some(expr) = step {
+                relocate_expr(expr, location);
+            }
+        }
+    }
+}

src/ast/types.rs

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

src/ast/visitor.rs

@@ -4,64 +4,64 @@ use rustpython_parser::ast::{
     PatternKind, Stmt, StmtKind, Unaryop, Withitem,
 };
 
-pub trait Visitor {
-    fn visit_stmt(&mut self, stmt: &Stmt) {
+pub trait Visitor<'a> {
+    fn visit_stmt(&mut self, stmt: &'a Stmt) {
         walk_stmt(self, stmt);
     }
-    fn visit_annotation(&mut self, expr: &Expr) {
+    fn visit_annotation(&mut self, expr: &'a Expr) {
         walk_expr(self, expr);
     }
-    fn visit_expr(&mut self, expr: &Expr) {
+    fn visit_expr(&mut self, expr: &'a Expr) {
         walk_expr(self, expr);
     }
-    fn visit_constant(&mut self, constant: &Constant) {
+    fn visit_constant(&mut self, constant: &'a Constant) {
         walk_constant(self, constant);
     }
-    fn visit_expr_context(&mut self, expr_content: &ExprContext) {
+    fn visit_expr_context(&mut self, expr_content: &'a ExprContext) {
         walk_expr_context(self, expr_content);
     }
-    fn visit_boolop(&mut self, boolop: &Boolop) {
+    fn visit_boolop(&mut self, boolop: &'a Boolop) {
         walk_boolop(self, boolop);
     }
-    fn visit_operator(&mut self, operator: &Operator) {
+    fn visit_operator(&mut self, operator: &'a Operator) {
         walk_operator(self, operator);
     }
-    fn visit_unaryop(&mut self, unaryop: &Unaryop) {
+    fn visit_unaryop(&mut self, unaryop: &'a Unaryop) {
         walk_unaryop(self, unaryop);
     }
-    fn visit_cmpop(&mut self, cmpop: &Cmpop) {
+    fn visit_cmpop(&mut self, cmpop: &'a Cmpop) {
         walk_cmpop(self, cmpop);
     }
-    fn visit_comprehension(&mut self, comprehension: &Comprehension) {
+    fn visit_comprehension(&mut self, comprehension: &'a Comprehension) {
         walk_comprehension(self, comprehension);
     }
-    fn visit_excepthandler(&mut self, excepthandler: &Excepthandler) {
+    fn visit_excepthandler(&mut self, excepthandler: &'a Excepthandler) {
         walk_excepthandler(self, excepthandler);
     }
-    fn visit_arguments(&mut self, arguments: &Arguments) {
+    fn visit_arguments(&mut self, arguments: &'a Arguments) {
         walk_arguments(self, arguments);
     }
-    fn visit_arg(&mut self, arg: &Arg) {
+    fn visit_arg(&mut self, arg: &'a Arg) {
         walk_arg(self, arg);
     }
-    fn visit_keyword(&mut self, keyword: &Keyword) {
+    fn visit_keyword(&mut self, keyword: &'a Keyword) {
         walk_keyword(self, keyword);
     }
-    fn visit_alias(&mut self, alias: &Alias) {
+    fn visit_alias(&mut self, alias: &'a Alias) {
         walk_alias(self, alias);
     }
-    fn visit_withitem(&mut self, withitem: &Withitem) {
+    fn visit_withitem(&mut self, withitem: &'a Withitem) {
         walk_withitem(self, withitem);
     }
-    fn visit_match_case(&mut self, match_case: &MatchCase) {
+    fn visit_match_case(&mut self, match_case: &'a MatchCase) {
         walk_match_case(self, match_case);
     }
-    fn visit_pattern(&mut self, pattern: &Pattern) {
+    fn visit_pattern(&mut self, pattern: &'a Pattern) {
         walk_pattern(self, pattern);
     }
 }
 
-pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
+pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
     match &stmt.node {
         StmtKind::FunctionDef {
             args,
@@ -72,13 +72,13 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         } => {
             visitor.visit_arguments(args);
             for expr in decorator_list {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for expr in returns {
                 visitor.visit_annotation(expr);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncFunctionDef {
@@ -90,13 +90,13 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         } => {
             visitor.visit_arguments(args);
             for expr in decorator_list {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for expr in returns {
                 visitor.visit_annotation(expr);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::ClassDef {
@@ -107,33 +107,33 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             ..
         } => {
             for expr in bases {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for keyword in keywords {
-                visitor.visit_keyword(keyword)
-            }
-            for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_keyword(keyword);
             }
             for expr in decorator_list {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
+            }
+            for stmt in body {
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Return { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Delete { targets } => {
             for expr in targets {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Assign { targets, value, .. } => {
+            visitor.visit_expr(value);
             for expr in targets {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
-            visitor.visit_expr(value)
         }
         StmtKind::AugAssign { target, op, value } => {
             visitor.visit_expr(target);
@@ -146,11 +146,11 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             value,
             ..
         } => {
-            visitor.visit_expr(target);
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
+            visitor.visit_expr(target);
         }
         StmtKind::For {
             target,
@@ -162,10 +162,10 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             visitor.visit_expr(target);
             visitor.visit_expr(iter);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncFor {
@@ -178,28 +178,28 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             visitor.visit_expr(target);
             visitor.visit_expr(iter);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::While { test, body, orelse } => {
             visitor.visit_expr(test);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::If { test, body, orelse } => {
             visitor.visit_expr(test);
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::With { items, body, .. } => {
@@ -207,7 +207,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
                 visitor.visit_withitem(withitem);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::AsyncWith { items, body, .. } => {
@@ -215,7 +215,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
                 visitor.visit_withitem(withitem);
             }
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Match { subject, cases } => {
@@ -227,10 +227,10 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         }
         StmtKind::Raise { exc, cause } => {
             if let Some(expr) = exc {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             };
             if let Some(expr) = cause {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             };
         }
         StmtKind::Try {
@@ -240,22 +240,22 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             finalbody,
         } => {
             for stmt in body {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for excepthandler in handlers {
                 visitor.visit_excepthandler(excepthandler)
             }
             for stmt in orelse {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
             for stmt in finalbody {
-                visitor.visit_stmt(stmt)
+                visitor.visit_stmt(stmt);
             }
         }
         StmtKind::Assert { test, msg } => {
             visitor.visit_expr(test);
             if let Some(expr) = msg {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         StmtKind::Import { names } => {
@@ -277,12 +277,12 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
     }
 }
 
-pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
+pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
     match &expr.node {
         ExprKind::BoolOp { op, values } => {
             visitor.visit_boolop(op);
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::NamedExpr { target, value } => {
@@ -309,26 +309,26 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         }
         ExprKind::Dict { keys, values } => {
             for expr in keys {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Set { elts } => {
             for expr in elts {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::ListComp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(elt);
         }
         ExprKind::SetComp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(elt);
         }
@@ -338,21 +338,21 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
             generators,
         } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(key);
             visitor.visit_expr(value);
         }
         ExprKind::GeneratorExp { elt, generators } => {
             for comprehension in generators {
-                visitor.visit_comprehension(comprehension)
+                visitor.visit_comprehension(comprehension);
             }
             visitor.visit_expr(elt);
         }
         ExprKind::Await { value } => visitor.visit_expr(value),
         ExprKind::Yield { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::YieldFrom { value } => visitor.visit_expr(value),
@@ -366,7 +366,7 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
                 visitor.visit_cmpop(cmpop);
             }
             for expr in comparators {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Call {
@@ -387,12 +387,12 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         } => {
             visitor.visit_expr(value);
             if let Some(expr) = format_spec {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::JoinedStr { values } => {
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr);
             }
         }
         ExprKind::Constant { value, .. } => visitor.visit_constant(value),
@@ -438,7 +438,7 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
     }
 }
 
-pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant) {
+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)
@@ -446,7 +446,10 @@ pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant)
     }
 }
 
-pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &Comprehension) {
+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);
     for expr in &comprehension.ifs {
@@ -454,7 +457,10 @@ pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &
     }
 }
 
-pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &Excepthandler) {
+pub fn walk_excepthandler<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    excepthandler: &'a Excepthandler,
+) {
     match &excepthandler.node {
         ExcepthandlerKind::ExceptHandler { type_, body, .. } => {
             if let Some(expr) = type_ {
@@ -467,7 +473,7 @@ pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &
     }
 }
 
-pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Arguments) {
+pub fn walk_arguments<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, arguments: &'a Arguments) {
     for arg in &arguments.posonlyargs {
         visitor.visit_arg(arg);
     }
@@ -475,40 +481,40 @@ pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Argument
         visitor.visit_arg(arg);
     }
     if let Some(arg) = &arguments.vararg {
-        visitor.visit_arg(arg)
+        visitor.visit_arg(arg);
     }
     for arg in &arguments.kwonlyargs {
         visitor.visit_arg(arg);
     }
     for expr in &arguments.kw_defaults {
-        visitor.visit_expr(expr)
+        visitor.visit_expr(expr);
     }
     if let Some(arg) = &arguments.kwarg {
-        visitor.visit_arg(arg)
+        visitor.visit_arg(arg);
     }
     for expr in &arguments.defaults {
-        visitor.visit_expr(expr)
+        visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_arg<V: Visitor + ?Sized>(visitor: &mut V, arg: &Arg) {
+pub fn walk_arg<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, arg: &'a Arg) {
     if let Some(expr) = &arg.node.annotation {
-        visitor.visit_annotation(expr)
+        visitor.visit_annotation(expr);
     }
 }
 
-pub fn walk_keyword<V: Visitor + ?Sized>(visitor: &mut V, keyword: &Keyword) {
+pub fn walk_keyword<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, keyword: &'a Keyword) {
     visitor.visit_expr(&keyword.node.value);
 }
 
-pub fn walk_withitem<V: Visitor + ?Sized>(visitor: &mut V, withitem: &Withitem) {
+pub fn walk_withitem<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, withitem: &'a Withitem) {
     visitor.visit_expr(&withitem.context_expr);
     if let Some(expr) = &withitem.optional_vars {
         visitor.visit_expr(expr);
     }
 }
 
-pub fn walk_match_case<V: Visitor + ?Sized>(visitor: &mut V, match_case: &MatchCase) {
+pub fn walk_match_case<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, match_case: &'a MatchCase) {
     visitor.visit_pattern(&match_case.pattern);
     if let Some(expr) = &match_case.guard {
         visitor.visit_expr(expr);
@@ -518,13 +524,13 @@ pub fn walk_match_case<V: Visitor + ?Sized>(visitor: &mut V, match_case: &MatchC
     }
 }
 
-pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
+pub fn walk_pattern<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, pattern: &'a Pattern) {
     match &pattern.node {
         PatternKind::MatchValue { value } => visitor.visit_expr(value),
         PatternKind::MatchSingleton { value } => visitor.visit_constant(value),
         PatternKind::MatchSequence { patterns } => {
             for pattern in patterns {
-                visitor.visit_pattern(pattern)
+                visitor.visit_pattern(pattern);
             }
         }
         PatternKind::MatchMapping { keys, patterns, .. } => {
@@ -553,7 +559,7 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
         PatternKind::MatchStar { .. } => {}
         PatternKind::MatchAs { pattern, .. } => {
             if let Some(pattern) = pattern {
-                visitor.visit_pattern(pattern)
+                visitor.visit_pattern(pattern);
             }
         }
         PatternKind::MatchOr { patterns } => {
@@ -566,24 +572,28 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_expr_context<V: Visitor + ?Sized>(visitor: &mut V, expr_context: &ExprContext) {}
+pub fn walk_expr_context<'a, V: Visitor<'a> + ?Sized>(
+    visitor: &mut V,
+    expr_context: &'a ExprContext,
+) {
+}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_boolop<V: Visitor + ?Sized>(visitor: &mut V, boolop: &Boolop) {}
+pub fn walk_boolop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, boolop: &'a Boolop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_operator<V: Visitor + ?Sized>(visitor: &mut V, operator: &Operator) {}
+pub fn walk_operator<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, operator: &'a Operator) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_unaryop<V: Visitor + ?Sized>(visitor: &mut V, unaryop: &Unaryop) {}
+pub fn walk_unaryop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, unaryop: &'a Unaryop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_cmpop<V: Visitor + ?Sized>(visitor: &mut V, cmpop: &Cmpop) {}
+pub fn walk_cmpop<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, cmpop: &'a Cmpop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_alias<V: Visitor + ?Sized>(visitor: &mut V, alias: &Alias) {}
+pub fn walk_alias<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, alias: &'a Alias) {}

src/autofix.rs

@@ -0,0 +1,2 @@
+pub mod fixer;
+pub mod fixes;

src/autofix/fixer.rs

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

src/autofix/fixes.rs

@@ -0,0 +1,126 @@
+use rustpython_parser::ast::{Expr, Keyword, Location};
+use rustpython_parser::lexer;
+use rustpython_parser::token::Tok;
+
+use crate::ast::operations::SourceCodeLocator;
+use crate::checks::Fix;
+
+/// Convert a location within a file (relative to `base`) to an absolute position.
+fn to_absolute(relative: &Location, base: &Location) -> Location {
+    if relative.row() == 1 {
+        Location::new(
+            relative.row() + base.row() - 1,
+            relative.column() + base.column() - 1,
+        )
+    } else {
+        Location::new(relative.row() + base.row() - 1, relative.column())
+    }
+}
+
+/// Generate a fix to remove a base from a ClassDef statement.
+pub fn remove_class_def_base(
+    locator: &mut SourceCodeLocator,
+    stmt_at: &Location,
+    expr_at: Location,
+    bases: &[Expr],
+    keywords: &[Keyword],
+) -> Option<Fix> {
+    let content = locator.slice_source_code(stmt_at);
+
+    // Case 1: `object` is the only base.
+    if bases.len() == 1 && keywords.is_empty() {
+        let mut fix_start = None;
+        let mut fix_end = None;
+        let mut count: usize = 0;
+        for (start, tok, end) in lexer::make_tokenizer(content).flatten() {
+            if matches!(tok, Tok::Lpar) {
+                if count == 0 {
+                    fix_start = Some(to_absolute(&start, stmt_at));
+                }
+                count += 1;
+            }
+
+            if matches!(tok, Tok::Rpar) {
+                count -= 1;
+                if count == 0 {
+                    fix_end = Some(to_absolute(&end, stmt_at));
+                    break;
+                }
+            }
+        }
+
+        return match (fix_start, fix_end) {
+            (Some(start), Some(end)) => Some(Fix {
+                content: "".to_string(),
+                start,
+                end,
+                applied: false,
+            }),
+            _ => None,
+        };
+    }
+
+    if bases
+        .iter()
+        .map(|node| node.location)
+        .chain(keywords.iter().map(|node| node.location))
+        .any(|location| location > expr_at)
+    {
+        // Case 2: `object` is _not_ the last node.
+        let mut fix_start: Option<Location> = None;
+        let mut fix_end: Option<Location> = None;
+        let mut seen_comma = false;
+        for (start, tok, end) in lexer::make_tokenizer(content).flatten() {
+            let start = to_absolute(&start, stmt_at);
+            if seen_comma {
+                if matches!(tok, Tok::Newline) {
+                    fix_end = Some(end);
+                } else {
+                    fix_end = Some(start);
+                }
+                break;
+            }
+            if start == expr_at {
+                fix_start = Some(start);
+            }
+            if fix_start.is_some() && matches!(tok, Tok::Comma) {
+                seen_comma = true;
+            }
+        }
+
+        match (fix_start, fix_end) {
+            (Some(start), Some(end)) => Some(Fix {
+                content: "".to_string(),
+                start,
+                end,
+                applied: false,
+            }),
+            _ => None,
+        }
+    } else {
+        // Case 3: `object` is the last node, so we have to find the last token that isn't a comma.
+        let mut fix_start: Option<Location> = None;
+        let mut fix_end: Option<Location> = None;
+        for (start, tok, end) in lexer::make_tokenizer(content).flatten() {
+            let start = to_absolute(&start, stmt_at);
+            let end = to_absolute(&end, stmt_at);
+            if start == expr_at {
+                fix_end = Some(end);
+                break;
+            }
+            if matches!(tok, Tok::Comma) {
+                fix_start = Some(start);
+            }
+        }
+
+        match (fix_start, fix_end) {
+            (Some(start), Some(end)) => Some(Fix {
+                content: "".to_string(),
+                start,
+                end,
+                applied: false,
+            }),
+            _ => None,
+        }
+    }
+}

src/cache.rs

@@ -1,4 +1,5 @@
 use std::collections::hash_map::DefaultHasher;
+use std::fs::Metadata;
 use std::hash::{Hash, Hasher};
 use std::path::Path;
 
@@ -7,6 +8,7 @@ use filetime::FileTime;
 use log::error;
 use serde::{Deserialize, Serialize};
 
+use crate::autofix::fixer;
 use crate::message::Message;
 use crate::settings::Settings;
 
@@ -60,18 +62,19 @@ impl From<bool> for Mode {
     fn from(value: bool) -> Self {
         match value {
             true => Mode::ReadWrite,
-            false => Mode::WriteOnly,
+            false => Mode::None,
         }
     }
 }
 
 fn cache_dir() -> &'static str {
-    "./.cache"
+    "./.ruff_cache"
 }
 
-fn cache_key(path: &Path, settings: &Settings) -> String {
+fn cache_key(path: &Path, settings: &Settings, autofix: &fixer::Mode) -> String {
     let mut hasher = DefaultHasher::new();
     settings.hash(&mut hasher);
+    autofix.hash(&mut hasher);
     format!(
         "{}@{}@{}",
         path.canonicalize().unwrap().to_string_lossy(),
@@ -80,22 +83,28 @@ fn cache_key(path: &Path, settings: &Settings) -> String {
     )
 }
 
-pub fn get(path: &Path, settings: &Settings, mode: &Mode) -> Option<Vec<Message>> {
+pub fn get(
+    path: &Path,
+    metadata: &Metadata,
+    settings: &Settings,
+    autofix: &fixer::Mode,
+    mode: &Mode,
+) -> Option<Vec<Message>> {
     if !mode.allow_read() {
         return None;
     };
 
-    match cacache::read_sync(cache_dir(), cache_key(path, settings)) {
-        Ok(encoded) => match path.metadata() {
-            Ok(m) => match bincode::deserialize::<CheckResult>(&encoded[..]) {
-                Ok(CheckResult { metadata, messages }) => {
-                    if FileTime::from_last_modification_time(&m).unix_seconds() == metadata.mtime {
-                        return Some(messages);
-                    }
+    match cacache::read_sync(cache_dir(), cache_key(path, settings, autofix)) {
+        Ok(encoded) => match bincode::deserialize::<CheckResult>(&encoded[..]) {
+            Ok(CheckResult {
+                metadata: CacheMetadata { mtime },
+                messages,
+            }) => {
+                if FileTime::from_last_modification_time(metadata).unix_seconds() == mtime {
+                    return Some(messages);
                 }
-                Err(e) => error!("Failed to deserialize encoded cache entry: {e:?}"),
-            },
-            Err(e) => error!("Failed to read metadata from path: {e:?}"),
+            }
+            Err(e) => error!("Failed to deserialize encoded cache entry: {e:?}"),
         },
         Err(EntryNotFound(_, _)) => {}
         Err(e) => error!("Failed to read from cache: {e:?}"),
@@ -103,24 +112,29 @@ pub fn get(path: &Path, settings: &Settings, mode: &Mode) -> Option<Vec<Message>
     None
 }
 
-pub fn set(path: &Path, settings: &Settings, messages: &[Message], mode: &Mode) {
+pub fn set(
+    path: &Path,
+    metadata: &Metadata,
+    settings: &Settings,
+    autofix: &fixer::Mode,
+    messages: &[Message],
+    mode: &Mode,
+) {
     if !mode.allow_write() {
         return;
     };
 
-    if let Ok(metadata) = path.metadata() {
-        let check_result = CheckResultRef {
-            metadata: &CacheMetadata {
-                mtime: FileTime::from_last_modification_time(&metadata).unix_seconds(),
-            },
-            messages,
-        };
-        if let Err(e) = cacache::write_sync(
-            cache_dir(),
-            cache_key(path, settings),
-            bincode::serialize(&check_result).unwrap(),
-        ) {
-            error!("Failed to write to cache: {e:?}")
-        }
+    let check_result = CheckResultRef {
+        metadata: &CacheMetadata {
+            mtime: FileTime::from_last_modification_time(metadata).unix_seconds(),
+        },
+        messages,
+    };
+    if let Err(e) = cacache::write_sync(
+        cache_dir(),
+        cache_key(path, settings, autofix),
+        bincode::serialize(&check_result).unwrap(),
+    ) {
+        error!("Failed to write to cache: {e:?}")
     }
 }

src/check_lines.rs

@@ -3,8 +3,24 @@ use rustpython_parser::ast::Location;
 use crate::checks::{Check, CheckKind};
 use crate::settings::Settings;
 
+/// Whether the given line is too long and should be reported.
+fn should_enforce_line_length(line: &str, limit: usize) -> bool {
+    if line.len() > limit {
+        let mut chunks = line.split_whitespace();
+        if let (Some(first), Some(_)) = (chunks.next(), chunks.next()) {
+            // Do not enforce the line length for commented lines with a single word
+            !(first == "#" && chunks.next().is_none())
+        } else {
+            // Single word / no printable chars - no way to make the line shorter
+            false
+        }
+    } else {
+        false
+    }
+}
+
 pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings) {
-    let enforce_line_too_ling = settings.select.contains(CheckKind::LineTooLong.code());
+    let enforce_line_too_long = settings.select.contains(CheckKind::LineTooLong.code());
 
     let mut line_checks = vec![];
     let mut ignored = vec![];
@@ -18,16 +34,13 @@ pub fn check_lines(checks: &mut Vec<Check>, contents: &str, settings: &Settings)
         }
 
         // Enforce line length.
-        if enforce_line_too_ling && line.len() > settings.line_length {
-            let chunks: Vec<&str> = line.split_whitespace().collect();
-            if !(chunks.len() == 1 || (chunks.len() == 2 && chunks[0] == "#")) {
-                let check = Check {
-                    kind: CheckKind::LineTooLong,
-                    location: Location::new(row + 1, settings.line_length + 1),
-                };
-                if !check.is_inline_ignored(line) {
-                    line_checks.push(check);
-                }
+        if enforce_line_too_long && should_enforce_line_length(line, settings.line_length) {
+            let check = Check::new(
+                CheckKind::LineTooLong,
+                Location::new(row + 1, settings.line_length + 1),
+            );
+            if !check.is_inline_ignored(line) {
+                line_checks.push(check);
             }
         }
     }

src/checks.rs

@@ -1,24 +1,41 @@
 use std::str::FromStr;
 
 use anyhow::Result;
+use once_cell::sync::Lazy;
 use regex::Regex;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
 
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize, Hash, PartialOrd, Ord)]
 pub enum CheckCode {
+    E402,
     E501,
+    E711,
+    E712,
+    E713,
+    E714,
+    E731,
+    E902,
     F401,
     F403,
     F541,
+    F601,
+    F602,
+    F621,
+    F622,
+    F631,
     F634,
     F704,
     F706,
+    F707,
     F821,
+    F822,
+    F823,
     F831,
-    F832,
     F841,
     F901,
+    R001,
+    R002,
 }
 
 impl FromStr for CheckCode {
@@ -26,18 +43,34 @@ impl FromStr for CheckCode {
 
     fn from_str(s: &str) -> Result<Self> {
         match s {
+            "E402" => Ok(CheckCode::E402),
             "E501" => Ok(CheckCode::E501),
+            "E711" => Ok(CheckCode::E711),
+            "E712" => Ok(CheckCode::E712),
+            "E713" => Ok(CheckCode::E713),
+            "E714" => Ok(CheckCode::E714),
+            "E731" => Ok(CheckCode::E731),
+            "E902" => Ok(CheckCode::E902),
             "F401" => Ok(CheckCode::F401),
             "F403" => Ok(CheckCode::F403),
             "F541" => Ok(CheckCode::F541),
+            "F601" => Ok(CheckCode::F601),
+            "F602" => Ok(CheckCode::F602),
+            "F621" => Ok(CheckCode::F621),
+            "F622" => Ok(CheckCode::F622),
+            "F631" => Ok(CheckCode::F631),
             "F634" => Ok(CheckCode::F634),
             "F704" => Ok(CheckCode::F704),
             "F706" => Ok(CheckCode::F706),
+            "F707" => Ok(CheckCode::F707),
             "F821" => Ok(CheckCode::F821),
+            "F822" => Ok(CheckCode::F822),
+            "F823" => Ok(CheckCode::F823),
             "F831" => Ok(CheckCode::F831),
-            "F832" => Ok(CheckCode::F832),
             "F841" => Ok(CheckCode::F841),
             "F901" => Ok(CheckCode::F901),
+            "R001" => Ok(CheckCode::R001),
+            "R002" => Ok(CheckCode::R002),
             _ => Err(anyhow::anyhow!("Unknown check code: {s}")),
         }
     }
@@ -46,36 +79,68 @@ impl FromStr for CheckCode {
 impl CheckCode {
     pub fn as_str(&self) -> &str {
         match self {
+            CheckCode::E402 => "E402",
             CheckCode::E501 => "E501",
+            CheckCode::E711 => "E711",
+            CheckCode::E712 => "E712",
+            CheckCode::E713 => "E713",
+            CheckCode::E714 => "E714",
+            CheckCode::E731 => "E731",
+            CheckCode::E902 => "E902",
             CheckCode::F401 => "F401",
             CheckCode::F403 => "F403",
             CheckCode::F541 => "F541",
+            CheckCode::F601 => "F601",
+            CheckCode::F602 => "F602",
+            CheckCode::F621 => "F621",
+            CheckCode::F622 => "F622",
+            CheckCode::F631 => "F631",
             CheckCode::F634 => "F634",
             CheckCode::F704 => "F704",
             CheckCode::F706 => "F706",
+            CheckCode::F707 => "F707",
             CheckCode::F821 => "F821",
+            CheckCode::F822 => "F822",
+            CheckCode::F823 => "F823",
             CheckCode::F831 => "F831",
-            CheckCode::F832 => "F832",
             CheckCode::F841 => "F841",
             CheckCode::F901 => "F901",
+            CheckCode::R001 => "R001",
+            CheckCode::R002 => "R002",
         }
     }
 
     /// The source for the check (either the AST, or the physical lines).
     pub fn lint_source(&self) -> &'static LintSource {
         match self {
+            CheckCode::E402 => &LintSource::AST,
             CheckCode::E501 => &LintSource::Lines,
+            CheckCode::E711 => &LintSource::AST,
+            CheckCode::E712 => &LintSource::AST,
+            CheckCode::E713 => &LintSource::AST,
+            CheckCode::E714 => &LintSource::AST,
+            CheckCode::E731 => &LintSource::AST,
+            CheckCode::E902 => &LintSource::FileSystem,
             CheckCode::F401 => &LintSource::AST,
             CheckCode::F403 => &LintSource::AST,
             CheckCode::F541 => &LintSource::AST,
+            CheckCode::F601 => &LintSource::AST,
+            CheckCode::F602 => &LintSource::AST,
+            CheckCode::F621 => &LintSource::AST,
+            CheckCode::F622 => &LintSource::AST,
+            CheckCode::F631 => &LintSource::AST,
             CheckCode::F634 => &LintSource::AST,
             CheckCode::F704 => &LintSource::AST,
             CheckCode::F706 => &LintSource::AST,
+            CheckCode::F707 => &LintSource::AST,
             CheckCode::F821 => &LintSource::AST,
+            CheckCode::F822 => &LintSource::AST,
+            CheckCode::F823 => &LintSource::AST,
             CheckCode::F831 => &LintSource::AST,
-            CheckCode::F832 => &LintSource::AST,
             CheckCode::F841 => &LintSource::AST,
             CheckCode::F901 => &LintSource::AST,
+            CheckCode::R001 => &LintSource::AST,
+            CheckCode::R002 => &LintSource::AST,
         }
     }
 }
@@ -84,94 +149,285 @@ impl CheckCode {
 pub enum LintSource {
     AST,
     Lines,
+    FileSystem,
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum RejectedCmpop {
+    Eq,
+    NotEq,
 }
 
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum CheckKind {
+    AssertTuple,
+    DefaultExceptNotLast,
+    DoNotAssignLambda,
     DuplicateArgumentName,
     FStringMissingPlaceholders,
+    IOError(String),
     IfTuple,
     ImportStarUsage,
     LineTooLong,
+    ModuleImportNotAtTopOfFile,
+    MultiValueRepeatedKeyLiteral,
+    MultiValueRepeatedKeyVariable(String),
+    NoAssertEquals,
+    NoneComparison(RejectedCmpop),
+    NotInTest,
+    NotIsTest,
     RaiseNotImplemented,
-    YieldOutsideFunction,
     ReturnOutsideFunction,
-    UndefinedName(String),
+    TooManyExpressionsInStarredAssignment,
+    TrueFalseComparison(bool, RejectedCmpop),
+    TwoStarredExpressions,
+    UndefinedExport(String),
     UndefinedLocal(String),
-    UnusedVariable(String),
+    UndefinedName(String),
     UnusedImport(String),
+    UnusedVariable(String),
+    UselessObjectInheritance(String),
+    YieldOutsideFunction,
 }
 
 impl CheckKind {
+    /// The name of the check.
+    pub fn name(&self) -> &'static str {
+        match self {
+            CheckKind::AssertTuple => "AssertTuple",
+            CheckKind::DefaultExceptNotLast => "DefaultExceptNotLast",
+            CheckKind::DuplicateArgumentName => "DuplicateArgumentName",
+            CheckKind::FStringMissingPlaceholders => "FStringMissingPlaceholders",
+            CheckKind::IOError(_) => "IOError",
+            CheckKind::IfTuple => "IfTuple",
+            CheckKind::ImportStarUsage => "ImportStarUsage",
+            CheckKind::LineTooLong => "LineTooLong",
+            CheckKind::DoNotAssignLambda => "DoNotAssignLambda",
+            CheckKind::ModuleImportNotAtTopOfFile => "ModuleImportNotAtTopOfFile",
+            CheckKind::MultiValueRepeatedKeyLiteral => "MultiValueRepeatedKeyLiteral",
+            CheckKind::MultiValueRepeatedKeyVariable(_) => "MultiValueRepeatedKeyVariable",
+            CheckKind::NoAssertEquals => "NoAssertEquals",
+            CheckKind::NoneComparison(_) => "NoneComparison",
+            CheckKind::NotInTest => "NotInTest",
+            CheckKind::NotIsTest => "NotIsTest",
+            CheckKind::RaiseNotImplemented => "RaiseNotImplemented",
+            CheckKind::ReturnOutsideFunction => "ReturnOutsideFunction",
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "TooManyExpressionsInStarredAssignment"
+            }
+            CheckKind::TrueFalseComparison(_, _) => "TrueFalseComparison",
+            CheckKind::TwoStarredExpressions => "TwoStarredExpressions",
+            CheckKind::UndefinedExport(_) => "UndefinedExport",
+            CheckKind::UndefinedLocal(_) => "UndefinedLocal",
+            CheckKind::UndefinedName(_) => "UndefinedName",
+            CheckKind::UnusedImport(_) => "UnusedImport",
+            CheckKind::UnusedVariable(_) => "UnusedVariable",
+            CheckKind::UselessObjectInheritance(_) => "UselessObjectInheritance",
+            CheckKind::YieldOutsideFunction => "YieldOutsideFunction",
+        }
+    }
+
     /// A four-letter shorthand code for the check.
     pub fn code(&self) -> &'static CheckCode {
         match self {
+            CheckKind::AssertTuple => &CheckCode::F631,
+            CheckKind::DefaultExceptNotLast => &CheckCode::F707,
             CheckKind::DuplicateArgumentName => &CheckCode::F831,
             CheckKind::FStringMissingPlaceholders => &CheckCode::F541,
+            CheckKind::IOError(_) => &CheckCode::E902,
             CheckKind::IfTuple => &CheckCode::F634,
             CheckKind::ImportStarUsage => &CheckCode::F403,
             CheckKind::LineTooLong => &CheckCode::E501,
+            CheckKind::DoNotAssignLambda => &CheckCode::E731,
+            CheckKind::ModuleImportNotAtTopOfFile => &CheckCode::E402,
+            CheckKind::MultiValueRepeatedKeyLiteral => &CheckCode::F601,
+            CheckKind::MultiValueRepeatedKeyVariable(_) => &CheckCode::F602,
+            CheckKind::NoAssertEquals => &CheckCode::R002,
+            CheckKind::NoneComparison(_) => &CheckCode::E711,
+            CheckKind::NotInTest => &CheckCode::E713,
+            CheckKind::NotIsTest => &CheckCode::E714,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
-            CheckKind::YieldOutsideFunction => &CheckCode::F704,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
+            CheckKind::TooManyExpressionsInStarredAssignment => &CheckCode::F621,
+            CheckKind::TrueFalseComparison(_, _) => &CheckCode::E712,
+            CheckKind::TwoStarredExpressions => &CheckCode::F622,
+            CheckKind::UndefinedExport(_) => &CheckCode::F822,
+            CheckKind::UndefinedLocal(_) => &CheckCode::F823,
             CheckKind::UndefinedName(_) => &CheckCode::F821,
-            CheckKind::UndefinedLocal(_) => &CheckCode::F832,
-            CheckKind::UnusedVariable(_) => &CheckCode::F841,
             CheckKind::UnusedImport(_) => &CheckCode::F401,
+            CheckKind::UnusedVariable(_) => &CheckCode::F841,
+            CheckKind::UselessObjectInheritance(_) => &CheckCode::R001,
+            CheckKind::YieldOutsideFunction => &CheckCode::F704,
         }
     }
 
     /// The body text for the check.
     pub fn body(&self) -> String {
         match self {
+            CheckKind::AssertTuple => {
+                "Assert test is a non-empty tuple, which is always `True`".to_string()
+            }
+            CheckKind::DefaultExceptNotLast => {
+                "an `except:` block as not the last exception handler".to_string()
+            }
             CheckKind::DuplicateArgumentName => {
                 "Duplicate argument name in function definition".to_string()
             }
             CheckKind::FStringMissingPlaceholders => {
                 "f-string without any placeholders".to_string()
             }
-            CheckKind::IfTuple => {
-                "If test is a tuple.to_string(), which is always `True`".to_string()
+            CheckKind::IOError(name) => {
+                format!("No such file or directory: `{name}`")
             }
+            CheckKind::IfTuple => "If test is a tuple, which is always `True`".to_string(),
             CheckKind::ImportStarUsage => "Unable to detect undefined names".to_string(),
             CheckKind::LineTooLong => "Line too long".to_string(),
-            CheckKind::RaiseNotImplemented => {
-                "'raise NotImplemented' should be 'raise NotImplementedError".to_string()
+            CheckKind::DoNotAssignLambda => {
+                "Do not assign a lambda expression, use a def".to_string()
             }
-            CheckKind::YieldOutsideFunction => {
-                "a `yield` or `yield from` statement outside of a function/method".to_string()
+            CheckKind::ModuleImportNotAtTopOfFile => {
+                "Module level import not at top of file".to_string()
+            }
+            CheckKind::MultiValueRepeatedKeyLiteral => {
+                "Dictionary key literal repeated".to_string()
+            }
+            CheckKind::MultiValueRepeatedKeyVariable(name) => {
+                format!("Dictionary key `{name}` repeated")
+            }
+            CheckKind::NoAssertEquals => {
+                "`assertEquals` is deprecated, use `assertEqual` instead".to_string()
+            }
+            CheckKind::NoneComparison(op) => match op {
+                RejectedCmpop::Eq => "Comparison to `None` should be `cond is None`".to_string(),
+                RejectedCmpop::NotEq => {
+                    "Comparison to `None` should be `cond is not None`".to_string()
+                }
+            },
+            CheckKind::NotInTest => "Test for membership should be `not in`".to_string(),
+            CheckKind::NotIsTest => "Test for object identity should be `is not`".to_string(),
+            CheckKind::RaiseNotImplemented => {
+                "`raise NotImplemented` should be `raise NotImplementedError`".to_string()
             }
             CheckKind::ReturnOutsideFunction => {
                 "a `return` statement outside of a function/method".to_string()
             }
+            CheckKind::TooManyExpressionsInStarredAssignment => {
+                "too many expressions in star-unpacking assignment".to_string()
+            }
+            CheckKind::TrueFalseComparison(value, op) => match *value {
+                true => match op {
+                    RejectedCmpop::Eq => {
+                        "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::TwoStarredExpressions => "two starred expressions in assignment".to_string(),
+            CheckKind::UndefinedExport(name) => {
+                format!("Undefined name `{name}` in `__all__`")
+            }
             CheckKind::UndefinedName(name) => {
                 format!("Undefined name `{name}`")
             }
-            CheckKind::UnusedVariable(name) => {
-                format!("Local variable `{name}` is assigned to but never used")
-            }
             CheckKind::UndefinedLocal(name) => {
                 format!("Local variable `{name}` referenced before assignment")
             }
             CheckKind::UnusedImport(name) => format!("`{name}` imported but unused"),
+            CheckKind::UnusedVariable(name) => {
+                format!("Local variable `{name}` is assigned to but never used")
+            }
+            CheckKind::UselessObjectInheritance(name) => {
+                format!("Class `{name}` inherits from object")
+            }
+            CheckKind::YieldOutsideFunction => {
+                "a `yield` or `yield from` statement outside of a function/method".to_string()
+            }
+        }
+    }
+
+    /// Whether the check kind is (potentially) fixable.
+    pub fn fixable(&self) -> bool {
+        match self {
+            CheckKind::AssertTuple => false,
+            CheckKind::DefaultExceptNotLast => false,
+            CheckKind::DuplicateArgumentName => false,
+            CheckKind::FStringMissingPlaceholders => false,
+            CheckKind::IOError(_) => false,
+            CheckKind::IfTuple => false,
+            CheckKind::ImportStarUsage => false,
+            CheckKind::DoNotAssignLambda => false,
+            CheckKind::LineTooLong => false,
+            CheckKind::ModuleImportNotAtTopOfFile => false,
+            CheckKind::MultiValueRepeatedKeyLiteral => false,
+            CheckKind::MultiValueRepeatedKeyVariable(_) => false,
+            CheckKind::NoAssertEquals => true,
+            CheckKind::NotInTest => false,
+            CheckKind::NotIsTest => false,
+            CheckKind::NoneComparison(_) => false,
+            CheckKind::RaiseNotImplemented => false,
+            CheckKind::ReturnOutsideFunction => false,
+            CheckKind::TooManyExpressionsInStarredAssignment => false,
+            CheckKind::TrueFalseComparison(_, _) => false,
+            CheckKind::TwoStarredExpressions => false,
+            CheckKind::UndefinedExport(_) => false,
+            CheckKind::UndefinedLocal(_) => false,
+            CheckKind::UndefinedName(_) => false,
+            CheckKind::UnusedImport(_) => false,
+            CheckKind::UnusedVariable(_) => false,
+            CheckKind::UselessObjectInheritance(_) => true,
+            CheckKind::YieldOutsideFunction => false,
         }
     }
 }
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Fix {
+    pub content: String,
+    pub start: Location,
+    pub end: Location,
+    pub applied: bool,
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Check {
     pub kind: CheckKind,
     pub location: Location,
+    pub fix: Option<Fix>,
 }
 
+static NO_QA_REGEX: Lazy<Regex> = Lazy::new(|| {
+    Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").expect("Invalid regex")
+});
+static SPLIT_COMMA_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"[,\s]").expect("Invalid regex"));
+
 impl Check {
+    pub fn new(kind: CheckKind, location: Location) -> Self {
+        Self {
+            kind,
+            location,
+            fix: None,
+        }
+    }
+
+    pub fn amend(&mut self, fix: Fix) {
+        self.fix = Some(fix);
+    }
+
     pub fn is_inline_ignored(&self, line: &str) -> bool {
-        let re = Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").unwrap();
-        match re.captures(line) {
+        match NO_QA_REGEX.captures(line) {
             Some(caps) => match caps.name("codes") {
                 Some(codes) => {
-                    let re = Regex::new(r"[,\s]").unwrap();
-                    for code in re
+                    for code in SPLIT_COMMA_REGEX
                         .split(codes.as_str())
                         .map(|code| code.trim())
                         .filter(|code| !code.is_empty())

src/lib.rs

@@ -1,4 +1,7 @@
-mod builtins;
+extern crate core;
+
+mod ast;
+mod autofix;
 mod cache;
 pub mod check_ast;
 mod check_lines;
@@ -8,5 +11,5 @@ pub mod linter;
 pub mod logging;
 pub mod message;
 mod pyproject;
+mod python;
 pub mod settings;
-mod visitor;

src/main.rs

@@ -6,21 +6,26 @@ use std::time::Instant;
 use anyhow::Result;
 use clap::{Parser, ValueHint};
 use colored::Colorize;
+use glob::Pattern;
 use log::{debug, error};
 use notify::{raw_watcher, RecursiveMode, Watcher};
 use rayon::prelude::*;
 use walkdir::DirEntry;
 
 use ::ruff::checks::CheckCode;
+use ::ruff::checks::CheckKind;
 use ::ruff::fs::iter_python_files;
-use ::ruff::linter::check_path;
+use ::ruff::linter::lint_path;
 use ::ruff::logging::set_up_logging;
 use ::ruff::message::Message;
 use ::ruff::settings::Settings;
 use ::ruff::tell_user;
 
+const CARGO_PKG_NAME: &str = env!("CARGO_PKG_NAME");
+const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
+
 #[derive(Debug, Parser)]
-#[clap(name = "ruff")]
+#[clap(name = format!("{CARGO_PKG_NAME} (v{CARGO_PKG_VERSION})"))]
 #[clap(about = "An extremely fast Python linter.", long_about = None)]
 struct Cli {
     #[clap(parse(from_os_str), value_hint = ValueHint::AnyPath, required = true)]
@@ -37,21 +42,56 @@ struct Cli {
     /// Run in watch mode by re-running whenever files change.
     #[clap(short, long, action)]
     watch: bool,
+    /// Attempt to automatically fix lint errors.
+    #[clap(short, long, action)]
+    fix: bool,
     /// Disable cache reads.
     #[clap(short, long, action)]
     no_cache: bool,
-    /// Comma-separated list of error codes to enable.
+    /// List of error codes to enable.
     #[clap(long, multiple = true)]
     select: Vec<CheckCode>,
-    /// Comma-separated list of error codes to ignore.
+    /// List of error codes to ignore.
     #[clap(long, multiple = true)]
     ignore: Vec<CheckCode>,
+    /// List of file and/or directory patterns to exclude from checks.
+    #[clap(long, multiple = true)]
+    exclude: Vec<Pattern>,
 }
 
-fn run_once(files: &[PathBuf], settings: &Settings, cache: bool) -> Result<Vec<Message>> {
+#[cfg(feature = "update-informer")]
+fn check_for_updates() {
+    use update_informer::{registry, Check};
+
+    let informer = update_informer::new(registry::PyPI, CARGO_PKG_NAME, CARGO_PKG_VERSION);
+
+    if let Some(new_version) = informer.check_version().ok().flatten() {
+        let msg = format!(
+            "A new version of {pkg_name} is available: v{pkg_version} -> {new_version}",
+            pkg_name = CARGO_PKG_NAME.italic().cyan(),
+            pkg_version = CARGO_PKG_VERSION,
+            new_version = new_version.to_string().green()
+        );
+
+        let cmd = format!(
+            "Run to update: {cmd} {pkg_name}",
+            cmd = "pip3 install --upgrade".green(),
+            pkg_name = CARGO_PKG_NAME.green()
+        );
+
+        println!("\n{msg}\n{cmd}");
+    }
+}
+
+fn run_once(
+    files: &[PathBuf],
+    settings: &Settings,
+    cache: bool,
+    autofix: bool,
+) -> Result<Vec<Message>> {
     // Collect all the files to check.
     let start = Instant::now();
-    let files: Vec<DirEntry> = files
+    let paths: Vec<DirEntry> = files
         .iter()
         .flat_map(|path| iter_python_files(path, &settings.exclude))
         .collect();
@@ -59,16 +99,30 @@ fn run_once(files: &[PathBuf], settings: &Settings, cache: bool) -> Result<Vec<M
     debug!("Identified files to lint in: {:?}", duration);
 
     let start = Instant::now();
-    let mut messages: Vec<Message> = files
+    let mut messages: Vec<Message> = paths
         .par_iter()
         .map(|entry| {
-            check_path(entry.path(), settings, &cache.into()).unwrap_or_else(|e| {
+            lint_path(entry.path(), settings, &cache.into(), &autofix.into()).unwrap_or_else(|e| {
                 error!("Failed to check {}: {e:?}", entry.path().to_string_lossy());
                 vec![]
             })
         })
         .flatten()
         .collect();
+
+    if settings.select.contains(&CheckCode::E902) {
+        for file in files {
+            if !file.exists() {
+                messages.push(Message {
+                    kind: CheckKind::IOError(file.to_string_lossy().to_string()),
+                    fixed: false,
+                    location: Default::default(),
+                    filename: file.to_string_lossy().to_string(),
+                })
+            }
+        }
+    }
+
     messages.sort_unstable();
     let duration = start.elapsed();
     debug!("Checked files in: {:?}", duration);
@@ -77,13 +131,32 @@ fn run_once(files: &[PathBuf], settings: &Settings, cache: bool) -> Result<Vec<M
 }
 
 fn report_once(messages: &[Message]) -> Result<()> {
-    println!("Found {} error(s).", messages.len());
+    let (fixed, outstanding): (Vec<&Message>, Vec<&Message>) =
+        messages.iter().partition(|message| message.fixed);
+    let num_fixable = outstanding
+        .iter()
+        .filter(|message| message.kind.fixable())
+        .count();
 
-    if !messages.is_empty() {
-        println!();
-        for message in messages {
+    if !outstanding.is_empty() {
+        for message in &outstanding {
             println!("{}", message);
         }
+        println!();
+    }
+
+    if !fixed.is_empty() {
+        println!(
+            "Found {} error(s) ({} fixed).",
+            outstanding.len(),
+            fixed.len()
+        );
+    } else {
+        println!("Found {} error(s).", outstanding.len());
+    }
+
+    if num_fixable > 0 {
+        println!("{num_fixable} potentially fixable with the --fix option.");
     }
 
     Ok(())
@@ -119,13 +192,20 @@ fn inner_main() -> Result<ExitCode> {
     if !cli.ignore.is_empty() {
         settings.ignore(&cli.ignore);
     }
+    if !cli.exclude.is_empty() {
+        settings.exclude(cli.exclude);
+    }
 
     if cli.watch {
+        if cli.fix {
+            println!("Warning: --fix is not enabled in watch mode.")
+        }
+
         // Perform an initial run instantly.
         clearscreen::clear()?;
         tell_user!("Starting linter in watch mode...\n");
 
-        let messages = run_once(&cli.files, &settings, !cli.no_cache)?;
+        let messages = run_once(&cli.files, &settings, !cli.no_cache, false)?;
         if !cli.quiet {
             report_continuously(&messages)?;
         }
@@ -145,7 +225,7 @@ fn inner_main() -> Result<ExitCode> {
                             clearscreen::clear()?;
                             tell_user!("File change detected...\n");
 
-                            let messages = run_once(&cli.files, &settings, !cli.no_cache)?;
+                            let messages = run_once(&cli.files, &settings, !cli.no_cache, false)?;
                             if !cli.quiet {
                                 report_continuously(&messages)?;
                             }
@@ -156,11 +236,14 @@ fn inner_main() -> Result<ExitCode> {
             }
         }
     } else {
-        let messages = run_once(&cli.files, &settings, !cli.no_cache)?;
+        let messages = run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?;
         if !cli.quiet {
             report_once(&messages)?;
         }
 
+        #[cfg(feature = "update-informer")]
+        check_for_updates();
+
         if !messages.is_empty() && !cli.exit_zero {
             return Ok(ExitCode::FAILURE);
         }

src/message.rs

@@ -7,25 +7,10 @@ use serde::{Deserialize, Serialize};
 
 use crate::checks::CheckKind;
 
-#[derive(Serialize, Deserialize)]
-#[serde(remote = "Location")]
-struct LocationDef {
-    #[serde(getter = "Location::row")]
-    row: usize,
-    #[serde(getter = "Location::column")]
-    column: usize,
-}
-
-impl From<LocationDef> for Location {
-    fn from(def: LocationDef) -> Location {
-        Location::new(def.row, def.column)
-    }
-}
-
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Message {
     pub kind: CheckKind,
-    #[serde(with = "LocationDef")]
+    pub fixed: bool,
     pub location: Location,
     pub filename: String,
 }
@@ -35,7 +20,7 @@ impl Ord for Message {
         (&self.filename, self.location.row(), self.location.column()).cmp(&(
             &other.filename,
             other.location.row(),
-            self.location.column(),
+            other.location.column(),
         ))
     }
 }

src/pyproject.rs

@@ -1,4 +1,3 @@
-use std::collections::BTreeSet;
 use std::path::{Path, PathBuf};
 
 use anyhow::Result;
@@ -14,12 +13,20 @@ pub fn load_config<'a>(paths: impl IntoIterator<Item = &'a Path>) -> Result<(Pat
         Some(project_root) => match find_pyproject_toml(&project_root) {
             Some(path) => {
                 debug!("Found pyproject.toml at: {}", path.to_string_lossy());
-                let pyproject = parse_pyproject_toml(&path)?;
-                let config = pyproject
-                    .tool
-                    .and_then(|tool| tool.ruff)
-                    .unwrap_or_default();
-                Ok((project_root, config))
+                match parse_pyproject_toml(&path) {
+                    Ok(pyproject) => {
+                        let config = pyproject
+                            .tool
+                            .and_then(|tool| tool.ruff)
+                            .unwrap_or_default();
+                        Ok((project_root, config))
+                    }
+                    Err(e) => {
+                        println!("Failed to load pyproject.toml: {:?}", e);
+                        println!("Falling back to default configuration...");
+                        Ok(Default::default())
+                    }
+                }
             }
             None => Ok(Default::default()),
         },
@@ -32,7 +39,8 @@ pub fn load_config<'a>(paths: impl IntoIterator<Item = &'a Path>) -> Result<(Pat
 pub struct Config {
     pub line_length: Option<usize>,
     pub exclude: Option<Vec<PathBuf>>,
-    pub select: Option<BTreeSet<CheckCode>>,
+    pub select: Option<Vec<CheckCode>>,
+    pub ignore: Option<Vec<CheckCode>>,
 }
 
 #[derive(Debug, PartialEq, Eq, Deserialize)]
@@ -82,7 +90,6 @@ fn find_project_root<'a>(sources: impl IntoIterator<Item = &'a Path>) -> Option<
 
 #[cfg(test)]
 mod tests {
-    use std::collections::BTreeSet;
     use std::path::Path;
 
     use anyhow::Result;
@@ -117,6 +124,7 @@ mod tests {
                     line_length: None,
                     exclude: None,
                     select: None,
+                    ignore: None,
                 })
             })
         );
@@ -135,6 +143,7 @@ line-length = 79
                     line_length: Some(79),
                     exclude: None,
                     select: None,
+                    ignore: None,
                 })
             })
         );
@@ -153,6 +162,7 @@ exclude = ["foo.py"]
                     line_length: None,
                     exclude: Some(vec![Path::new("foo.py").to_path_buf()]),
                     select: None,
+                    ignore: None,
                 })
             })
         );
@@ -170,7 +180,27 @@ select = ["E501"]
                 ruff: Some(Config {
                     line_length: None,
                     exclude: None,
-                    select: Some(BTreeSet::from([CheckCode::E501])),
+                    select: Some(vec![CheckCode::E501]),
+                    ignore: None,
+                })
+            })
+        );
+
+        let pyproject: PyProject = toml::from_str(
+            r#"
+[tool.black]
+[tool.ruff]
+ignore = ["E501"]
+"#,
+        )?;
+        assert_eq!(
+            pyproject.tool,
+            Some(Tools {
+                ruff: Some(Config {
+                    line_length: None,
+                    exclude: None,
+                    select: None,
+                    ignore: Some(vec![CheckCode::E501]),
                 })
             })
         );
@@ -208,18 +238,17 @@ other-attribute = 1
 
     #[test]
     fn find_and_parse_pyproject_toml() -> Result<()> {
-        let project_root = find_project_root([Path::new("resources/test/src/__init__.py")])
+        let project_root = find_project_root([Path::new("resources/test/fixtures/__init__.py")])
             .expect("Unable to find project root.");
-        assert_eq!(project_root, Path::new("resources/test/src"));
+        assert_eq!(project_root, Path::new("resources/test/fixtures"));
 
         let path = find_pyproject_toml(&project_root).expect("Unable to find pyproject.toml.");
-        assert_eq!(path, Path::new("resources/test/src/pyproject.toml"));
+        assert_eq!(path, Path::new("resources/test/fixtures/pyproject.toml"));
 
         let pyproject = parse_pyproject_toml(&path)?;
         let config = pyproject
             .tool
-            .map(|tool| tool.ruff)
-            .flatten()
+            .and_then(|tool| tool.ruff)
             .expect("Unable to find tool.ruff.");
         assert_eq!(
             config,
@@ -229,20 +258,37 @@ other-attribute = 1
                     Path::new("excluded.py").to_path_buf(),
                     Path::new("**/migrations").to_path_buf()
                 ]),
-                select: Some(BTreeSet::from([
+                select: Some(vec![
+                    CheckCode::E402,
                     CheckCode::E501,
+                    CheckCode::E711,
+                    CheckCode::E712,
+                    CheckCode::E713,
+                    CheckCode::E714,
+                    CheckCode::E731,
+                    CheckCode::E902,
                     CheckCode::F401,
                     CheckCode::F403,
                     CheckCode::F541,
+                    CheckCode::F601,
+                    CheckCode::F602,
+                    CheckCode::F621,
+                    CheckCode::F622,
+                    CheckCode::F631,
                     CheckCode::F634,
                     CheckCode::F704,
                     CheckCode::F706,
+                    CheckCode::F707,
                     CheckCode::F821,
+                    CheckCode::F822,
+                    CheckCode::F823,
                     CheckCode::F831,
-                    CheckCode::F832,
                     CheckCode::F841,
                     CheckCode::F901,
-                ])),
+                    CheckCode::R001,
+                    CheckCode::R002,
+                ]),
+                ignore: None,
             }
         );
 

src/python.rs

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

src/python/builtins.rs

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

src/python/typing.rs

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

src/settings.rs

@@ -27,7 +27,7 @@ impl Hash for Settings {
 impl Settings {
     pub fn from_paths<'a>(paths: impl IntoIterator<Item = &'a Path>) -> Result<Self> {
         let (project_root, config) = load_config(paths)?;
-        Ok(Settings {
+        let mut settings = Settings {
             line_length: config.line_length.unwrap_or(88),
             exclude: config
                 .exclude
@@ -42,20 +42,44 @@ impl Settings {
                 })
                 .map(|path| Pattern::new(&path.to_string_lossy()).expect("Invalid pattern."))
                 .collect(),
-            select: config.select.unwrap_or_else(|| {
-                BTreeSet::from([
+            select: BTreeSet::from_iter(config.select.unwrap_or_else(|| {
+                vec![
+                    CheckCode::E402,
                     CheckCode::E501,
+                    CheckCode::E711,
+                    CheckCode::E712,
+                    CheckCode::E713,
+                    CheckCode::E714,
+                    CheckCode::E731,
+                    CheckCode::E902,
                     CheckCode::F401,
                     CheckCode::F403,
                     CheckCode::F541,
+                    CheckCode::F601,
+                    CheckCode::F602,
+                    CheckCode::F621,
+                    CheckCode::F622,
+                    CheckCode::F631,
                     CheckCode::F634,
+                    CheckCode::F704,
                     CheckCode::F706,
+                    CheckCode::F707,
+                    CheckCode::F821,
+                    CheckCode::F822,
+                    CheckCode::F823,
                     CheckCode::F831,
-                    CheckCode::F832,
+                    CheckCode::F841,
                     CheckCode::F901,
-                ])
-            }),
-        })
+                    // Disable refactoring codes by default.
+                    // CheckCode::R001,
+                    // CheckCode::R002,
+                ]
+            })),
+        };
+        if let Some(ignore) = &config.ignore {
+            settings.ignore(ignore);
+        }
+        Ok(settings)
     }
 
     pub fn select(&mut self, codes: Vec<CheckCode>) {
@@ -70,4 +94,8 @@ impl Settings {
             self.select.remove(code);
         }
     }
+
+    pub fn exclude(&mut self, exclude: Vec<Pattern>) {
+        self.exclude = exclude;
+    }
 }