Bump version to 0.0.143

This reverts commit bd08fc359d.

.cargo/config.toml

@@ -0,0 +1,2 @@
+[alias]
+dev = "run --package ruff_dev --bin ruff_dev"

.github/workflows/ci.yaml

@@ -6,6 +6,11 @@ on:
   pull_request:
     branches: [main]
 
+env:
+  CARGO_INCREMENTAL: 0
+  CARGO_NET_RETRY: 10
+  RUSTUP_MAX_RETRIES: 10
+
 jobs:
   cargo_build:
     name: "cargo build"
@@ -14,7 +19,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          profile: minimal
       - uses: actions/cache@v3
         env:
           cache-name: cache-cargo
@@ -27,7 +32,7 @@ jobs:
             ${{ runner.os }}-build-${{ env.cache-name }}-
             ${{ runner.os }}-build-
             ${{ runner.os }}-
-      - run: cargo build --release
+      - run: cargo build --all --release
 
   cargo_fmt:
     name: "cargo fmt"
@@ -36,7 +41,10 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          profile: minimal
+          toolchain: nightly-2022-11-01
+          override: true
+          components: rustfmt
       - uses: actions/cache@v3
         env:
           cache-name: cache-cargo
@@ -49,7 +57,7 @@ jobs:
             ${{ runner.os }}-build-${{ env.cache-name }}-
             ${{ runner.os }}-build-
             ${{ runner.os }}-
-      - run: cargo fmt --check
+      - run: cargo fmt --all --check
 
   cargo_clippy:
     name: "cargo clippy"
@@ -58,7 +66,10 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          profile: minimal
+          toolchain: nightly-2022-11-01
+          override: true
+          components: clippy
       - uses: actions/cache@v3
         env:
           cache-name: cache-cargo
@@ -71,7 +82,7 @@ jobs:
             ${{ runner.os }}-build-${{ env.cache-name }}-
             ${{ runner.os }}-build-
             ${{ runner.os }}-
-      - run: cargo clippy -- -D warnings
+      - run: cargo clippy --workspace --all-targets --all-features -- -D warnings -W clippy::pedantic
 
   cargo_test:
     name: "cargo test"
@@ -80,7 +91,9 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          profile: minimal
+          toolchain: nightly-2022-11-01
+          override: true
       - uses: actions/cache@v3
         env:
           cache-name: cache-cargo
@@ -93,7 +106,7 @@ jobs:
             ${{ runner.os }}-build-${{ env.cache-name }}-
             ${{ runner.os }}-build-
             ${{ runner.os }}-
-      - run: cargo test
+      - run: cargo test --all
 
   maturin_build:
     name: "maturin build"
@@ -102,7 +115,9 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          profile: minimal
+          toolchain: nightly-2022-11-01
+          override: true
       - uses: actions/setup-python@v4
         with:
           python-version: "3.10"

.github/workflows/flake8-to-ruff.yaml

@@ -0,0 +1,293 @@
+name: "[flake8-to-ruff] Release"
+
+on: workflow_dispatch
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  PACKAGE_NAME: flake8-to-ruff
+  CRATE_NAME: flake8_to_ruff
+  PYTHON_VERSION: "3.7" # to build abi3 wheels
+  CARGO_INCREMENTAL: 0
+  CARGO_NET_RETRY: 10
+  RUSTUP_MAX_RETRIES: 10
+
+jobs:
+  macos-x86_64:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          architecture: x64
+      - name: Install Rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          default: true
+      - name: Build wheels - x86_64
+        uses: messense/maturin-action@v1
+        with:
+          target: x86_64
+          args: --release --out dist --sdist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - name: Install built wheel - x86_64
+        run: |
+          pip install dist/${{ env.CRATE_NAME }}-*.whl --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+  macos-universal:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          architecture: x64
+      - name: Install Rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          default: true
+      - name: Build wheels - universal2
+        uses: messense/maturin-action@v1
+        with:
+          args: --release --universal2 --out dist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - name: Install built wheel - universal2
+        run: |
+          pip install dist/${{ env.CRATE_NAME }}-*universal2.whl --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  windows:
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        target: [x64, x86]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          architecture: ${{ matrix.target }}
+      - name: Install Rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          default: true
+      - name: Build wheels
+        uses: messense/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          args: --release --out dist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - name: Install built wheel
+        shell: bash
+        run: |
+          python -m pip install dist/${{ env.CRATE_NAME }}-*.whl --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  linux:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target: [x86_64, i686]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          architecture: x64
+      - name: Build wheels
+        uses: messense/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          manylinux: auto
+          args: --release --out dist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - name: Install built wheel
+        if: matrix.target == 'x86_64'
+        run: |
+          pip install dist/${{ env.CRATE_NAME }}-*.whl --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  linux-cross:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target: [aarch64, armv7, s390x, ppc64le, ppc64]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Build wheels
+        uses: messense/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          manylinux: auto
+          args: --no-default-features --release --out dist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - uses: uraimo/run-on-arch-action@v2.0.5
+        if: matrix.target != 'ppc64'
+        name: Install built wheel
+        with:
+          arch: ${{ matrix.target }}
+          distro: ubuntu20.04
+          githubToken: ${{ github.token }}
+          install: |
+            apt-get update
+            apt-get install -y --no-install-recommends python3 python3-pip
+            pip3 install -U pip
+          run: |
+            pip3 install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  musllinux:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - x86_64-unknown-linux-musl
+          - i686-unknown-linux-musl
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          architecture: x64
+      - name: Build wheels
+        uses: messense/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          manylinux: musllinux_1_2
+          args: --release --out dist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - name: Install built wheel
+        if: matrix.target == 'x86_64-unknown-linux-musl'
+        uses: addnab/docker-run-action@v3
+        with:
+          image: alpine:latest
+          options: -v ${{ github.workspace }}:/io -w /io
+          run: |
+            apk add py3-pip
+            pip3 install ${{ env.PACKAGE_NAME }} --no-index --find-links /io/dist/ --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  musllinux-cross:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        platform:
+          - target: aarch64-unknown-linux-musl
+            arch: aarch64
+          - target: armv7-unknown-linux-musleabihf
+            arch: armv7
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+      - name: Build wheels
+        uses: messense/maturin-action@v1
+        with:
+          target: ${{ matrix.platform.target }}
+          manylinux: musllinux_1_2
+          args: --release --out dist -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - uses: uraimo/run-on-arch-action@master
+        name: Install built wheel
+        with:
+          arch: ${{ matrix.platform.arch }}
+          distro: alpine_latest
+          githubToken: ${{ github.token }}
+          install: |
+            apk add py3-pip
+          run: |
+            pip3 install ${{ env.PACKAGE_NAME }} --no-index --find-links dist/ --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  pypy:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+        target: [x86_64, aarch64]
+        python-version:
+          - "3.7"
+          - "3.8"
+          - "3.9"
+        exclude:
+          - os: macos-latest
+            target: aarch64
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: pypy${{ matrix.python-version }}
+      - name: Build wheels
+        uses: messense/maturin-action@v1
+        with:
+          target: ${{ matrix.target }}
+          manylinux: auto
+          args: --release --out dist -i pypy${{ matrix.python-version }} -m ./${{ env.CRATE_NAME }}/Cargo.toml
+      - name: Install built wheel
+        if: matrix.target == 'x86_64'
+        run: |
+          pip install dist/${{ env.CRATE_NAME }}-*.whl --force-reinstall
+      - name: Upload wheels
+        uses: actions/upload-artifact@v2
+        with:
+          name: wheels
+          path: dist
+
+  release:
+    name: Release
+    runs-on: ubuntu-latest
+    needs:
+      - macos-universal
+      - macos-x86_64
+      - windows
+      - linux
+      - linux-cross
+      - musllinux
+      - musllinux-cross
+      - pypy
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+      - uses: actions/setup-python@v4
+      - name: Publish to PyPi
+        env:
+          TWINE_USERNAME: __token__
+          TWINE_PASSWORD: ${{ secrets.FLAKE8_TO_RUFF_TOKEN }}
+        run: |
+          pip install --upgrade twine
+          twine upload --skip-existing *

.github/workflows/ruff.yaml

@@ -1,8 +1,6 @@
-name: Release
+name: "[ruff] Release"
 
 on:
-  pull_request:
-    branches: [main]
   create:
     tags:
       - v*
@@ -14,6 +12,9 @@ concurrency:
 env:
   PACKAGE_NAME: ruff
   PYTHON_VERSION: "3.7" # to build abi3 wheels
+  CARGO_INCREMENTAL: 0
+  CARGO_NET_RETRY: 10
+  RUSTUP_MAX_RETRIES: 10
 
 jobs:
   macos-x86_64:
@@ -35,7 +36,6 @@ jobs:
         with:
           target: x86_64
           args: --release --out dist --sdist
-          maturin-version: "v0.13.0"
       - name: Install built wheel - x86_64
         run: |
           pip install dist/${{ env.PACKAGE_NAME }}-*.whl --force-reinstall
@@ -62,7 +62,6 @@ jobs:
         uses: messense/maturin-action@v1
         with:
           args: --release --universal2 --out dist
-          maturin-version: "v0.13.0"
       - name: Install built wheel - universal2
         run: |
           pip install dist/${{ env.PACKAGE_NAME }}-*universal2.whl --force-reinstall
@@ -94,7 +93,6 @@ jobs:
         with:
           target: ${{ matrix.target }}
           args: --release --out dist
-          maturin-version: "v0.13.0"
       - name: Install built wheel
         shell: bash
         run: |
@@ -122,7 +120,6 @@ jobs:
           target: ${{ matrix.target }}
           manylinux: auto
           args: --release --out dist
-          maturin-version: "v0.13.0"
       - name: Install built wheel
         if: matrix.target == 'x86_64'
         run: |
@@ -149,7 +146,6 @@ jobs:
           target: ${{ matrix.target }}
           manylinux: auto
           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'
         name: Install built wheel
@@ -188,7 +184,6 @@ jobs:
           target: ${{ matrix.target }}
           manylinux: musllinux_1_2
           args: --release --out dist
-          maturin-version: "v0.13.0"
       - name: Install built wheel
         if: matrix.target == 'x86_64-unknown-linux-musl'
         uses: addnab/docker-run-action@v3
@@ -224,7 +219,6 @@ jobs:
           target: ${{ matrix.platform.target }}
           manylinux: musllinux_1_2
           args: --release --out dist
-          maturin-version: "v0.13.0"
       - uses: uraimo/run-on-arch-action@master
         name: Install built wheel
         with:
@@ -262,7 +256,6 @@ jobs:
       - name: Build wheels
         uses: messense/maturin-action@v1
         with:
-          maturin-version: "v0.13.0"
           target: ${{ matrix.target }}
           manylinux: auto
           args: --release --out dist -i pypy${{ matrix.python-version }}
@@ -297,7 +290,7 @@ jobs:
       - name: Publish to PyPi
         env:
           TWINE_USERNAME: __token__
-          TWINE_PASSWORD: ${{ secrets.PYPI_TOKEN }}
+          TWINE_PASSWORD: ${{ secrets.RUFF_TOKEN }}
         run: |
           pip install --upgrade twine
           twine upload --skip-existing *

.pre-commit-config.yaml

@@ -1,8 +1,8 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.40
+    rev: v0.0.143
     hooks:
-      - id: lint
+      - id: ruff
 
   - repo: https://github.com/abravalheri/validate-pyproject
     rev: v0.10.1

CONTRIBUTING.md

@@ -1,17 +1,17 @@
-# Contributing to ruff
+# Contributing to Ruff
 
-Welcome! We're happy to have you here. Thank you in advance for your contribution to ruff.
+Welcome! We're happy to have you here. Thank you in advance for your contribution to Ruff.
 
 ## The basics
 
-ruff welcomes contributions in the form of Pull Requests. For small changes (e.g., bug fixes), feel
+Ruff welcomes contributions in the form of Pull Requests. For small changes (e.g., bug fixes), feel
 free to submit a PR. For larger changes (e.g., new lint rules, new functionality, new configuration
 options), consider submitting an [Issue](https://github.com/charliermarsh/ruff/issues) outlining
 your proposed change.
 
 ### Prerequisites
 
-ruff is written in Rust (1.63.0). You'll need to install the
+Ruff is written in Rust. You'll need to install the
 [Rust toolchain](https://www.rust-lang.org/tools/install) for development.
 
 You'll also need [Insta](https://insta.rs/docs/) to update snapshot tests:
@@ -22,7 +22,7 @@ cargo install cargo-insta
 
 ### Development
 
-After cloning the repository, run ruff locally with:
+After cloning the repository, run Ruff locally with:
 
 ```shell
 cargo run resources/test/fixtures --no-cache
@@ -32,9 +32,9 @@ Prior to opening a pull request, ensure that your code has been auto-formatted,
 both the lint and test validation checks:
 
 ```shell
-cargo fmt     # Auto-formatting...
-cargo clippy  # Linting...
-cargo test    # Testing...
+cargo +nightly fmt --all     # Auto-formatting...
+cargo +nightly clippy --all  # Linting...
+cargo +nightly test --all    # Testing...
 ```
 
 These checks will run on GitHub Actions when you open your Pull Request, but running them locally
@@ -45,12 +45,13 @@ prior to merging.
 
 ### Example: Adding a new lint rule
 
-There are three phases to adding a new lint rule:
+There are four phases to adding a new lint rule:
 
 1. Define the rule in `src/checks.rs`.
-2. Define the _logic_ for triggering the rule in `src/check_ast.rs` (for AST-based checks)
-   or `src/check_lines.rs` (for text-based checks).
+2. Define the _logic_ for triggering the rule in `src/check_ast.rs` (for AST-based checks),
+   `src/check_tokens.rs` (for token-based checks), or `src/check_lines.rs` (for text-based checks).
 3. Add a test fixture.
+4. Update the generated files (documentation and generated code).
 
 To define the rule, open up `src/checks.rs`. You'll need to define both a `CheckCode` and
 `CheckKind`. As an example, you can grep for `E402` and `ModuleImportNotAtTopOfFile`, and follow the
@@ -58,37 +59,33 @@ pattern implemented therein.
 
 To trigger the rule, you'll likely want to augment the logic in `src/check_ast.rs`, which defines
 the Python AST visitor, responsible for iterating over the abstract syntax tree and collecting
-lint-rule violations as it goes. Grep for the `Check::new` invocations to understand how other,
-similar rules are implemented.
+lint-rule violations as it goes. If you need to inspect the AST, you can run `cargo dev print-ast`
+with a Python file. Grep for the `Check::new` invocations to understand how other, similar rules
+are implemented.
 
 To add a test fixture, create a file under `resources/test/fixtures`, named to match the `CheckCode`
 you defined earlier (e.g., `E402.py`). This file should contain a variety of violations and
-non-violations designed to evaluate and demonstrate the behavior of your lint rule. Run ruff locally
-with (e.g.) `cargo run resources/test/fixtures/E402.py`. Once you're satisfied with the output,
-codify the behavior as a snapshot test by adding a new function to the `mod tests` section of
-`src/linter.rs`, like so:
+non-violations designed to evaluate and demonstrate the behavior of your lint rule. Run Ruff locally
+with (e.g.) `cargo run resources/test/fixtures/E402.py --no-cache`. Once you're satisfied with the
+output, codify the behavior as a snapshot test by adding a new `testcase` macro to the `mod tests`
+section of `src/linter.rs`, like so:
 
 ```rust
-#[test]
-fn e402() -> Result<()> {
-    let mut checks = check_path(
-        Path::new("./resources/test/fixtures/E402.py"),
-        &settings::Settings::for_rule(CheckCode::E402),
-        &fixer::Mode::Generate,
-    )?;
-    checks.sort_by_key(|check| check.location);
-    insta::assert_yaml_snapshot!(checks);
-    Ok(())
-}
+#[test_case(CheckCode::A001, Path::new("A001.py"); "A001")]
+...
 ```
 
 Then, run `cargo test`. Your test will fail, but you'll be prompted to follow-up with
 `cargo insta review`. Accept the generated snapshot, then commit the snapshot file alongside the
 rest of your changes.
 
+Finally, to update the documentation, run `cargo dev generate-rules-table` from the repo root. To
+update the generated prefix map, run `cargo dev generate-check-code-prefix`. Both of these commands
+should be run whenever a new check is added to the codebase.
+
 ### Example: Adding a new configuration option
 
-ruff's user-facing settings live in two places: first, the command-line options defined with
+Ruff's user-facing settings live in two places: first, the command-line options defined with
 [clap](https://docs.rs/clap/latest/clap/) via the `Cli` struct in `src/main.rs`; and second, the
 `Config` struct defined `src/pyproject.rs`, which is responsible for extracting user-defined
 settings from a `pyproject.toml` file.
@@ -101,11 +98,18 @@ _and_ a `pyproject.toml` parameter to `src/pyproject.rs`. If you want to pattern
 existing example, grep for `dummy_variable_rgx`, which defines a regular expression to match against
 acceptable unused variables (e.g., `_`).
 
+If the new plugin's configuration should be cached between runs, you'll need to add it to the
+`Hash` implementation for `Settings` in `src/settings/mod.rs`.
+
+You may also want to add the new configuration option to the `flake8-to-ruff` tool, which is
+responsible for converting `flake8` configuration files to Ruff's TOML format. This logic
+lives in `flake8_to_ruff/src/converter.rs`.
+
 ## Release process
 
-As of now, ruff has an ad hoc release process: releases are cut with high frequency via GitHub
+As of now, Ruff has an ad hoc release process: releases are cut with high frequency via GitHub
 Actions, which automatically generates the appropriate wheels across architectures and publishes
 them to [PyPI](https://pypi.org/project/ruff/).
 
-ruff follows the [semver](https://semver.org/) versioning standard. However, as pre-1.0 software,
+Ruff follows the [semver](https://semver.org/) versioning standard. However, as pre-1.0 software,
 even patch releases may contain [non-backwards-compatible changes](https://semver.org/#spec-item-4).

Cargo.toml

@@ -1,45 +1,72 @@
+[workspace]
+members = [
+  "flake8_to_ruff",
+  "ruff_dev",
+]
+
 [package]
 name = "ruff"
-version = "0.0.62"
+version = "0.0.143"
 edition = "2021"
+rust-version = "1.65.0"
 
 [lib]
 name = "ruff"
 
 [dependencies]
-anyhow = { version = "1.0.60" }
+annotate-snippets = { version = "0.9.1", features = ["color"] }
+anyhow = { version = "1.0.66" }
+atty = { version = "0.2.14" }
 bincode = { version = "1.3.3" }
-cacache = { version = "10.0.1" }
-chrono = { version = "0.4.21" }
+bitflags = { version = "1.3.2" }
+cachedir = { version = "0.3.0" }
+chrono = { version = "0.4.21", default-features = false, features = ["clock"] }
 clap = { version = "4.0.1", features = ["derive"] }
-clearscreen = { version = "1.0.10" }
+clap_complete_command = "0.4.0"
 colored = { version = "2.0.0" }
 common-path = { version = "1.0.0" }
 dirs = { version = "4.0.0" }
 fern = { version = "0.6.1" }
 filetime = { version = "0.2.17" }
-glob = { version = "0.3.0" }
+globset = {version = "0.4.9" }
 itertools = { version = "0.10.5" }
-libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "32a044c127668df44582f85699358e67803b0d73" }
+libcst = { git = "https://github.com/charliermarsh/LibCST", rev = "f2f0b7a487a8725d161fe8b3ed73a6758b21e177" }
 log = { version = "0.4.17" }
+nohash-hasher = { version = "0.2.0" }
 notify = { version = "4.0.17" }
-once_cell = { version = "1.13.1" }
-path-absolutize = { version = "3.0.13", features = ["once_cell_cache"] }
+num-bigint = { version = "0.4.3" }
+once_cell = { version = "1.16.0" }
+path-absolutize = { version = "3.0.14", features = ["once_cell_cache", "use_unix_paths_on_wasm"] }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
-rustpython-ast = { features = ["unparse"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
-rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
-rustpython-common = { git = "https://github.com/charliermarsh/RustPython.git", rev = "4f457893efc381ad5c432576b24bcc7e4a08c641" }
-serde = { version = "1.0.143", features = ["derive"] }
-serde_json = { version = "1.0.83" }
-toml = { version = "0.5.9" }
-update-informer = { version = "0.5.0", default_features = false, features = ["pypi"], optional = true }
-walkdir = { version = "2.3.2" }
+ropey = { version = "1.5.0", features = ["cr_lines", "simd"], default-features = false }
+rustc-hash = { version = "1.1.0" }
+rustpython-ast = { features = ["unparse"], git = "https://github.com/RustPython/RustPython.git", rev = "f885db8c61514f069979861f6b3bd83292086231" }
+rustpython-common = { git = "https://github.com/RustPython/RustPython.git", rev = "f885db8c61514f069979861f6b3bd83292086231" }
+rustpython-parser = { features = ["lalrpop"], git = "https://github.com/RustPython/RustPython.git", rev = "f885db8c61514f069979861f6b3bd83292086231" }
+serde = { version = "1.0.147", features = ["derive"] }
+serde_json = { version = "1.0.87" }
 strum = { version = "0.24.1", features = ["strum_macros"] }
-strum_macros = "0.24.3"
+strum_macros = { version = "0.24.3" }
+textwrap = { version = "0.16.0" }
+titlecase = { version = "2.2.1" }
+toml = { version = "0.5.9" }
+update-informer = { version = "0.5.0", default-features = false, features = ["pypi"], optional = true }
+walkdir = { version = "2.3.2" }
+
+[target.'cfg(not(target_family = "wasm"))'.dependencies]
+clearscreen = { version = "1.0.10" } # uses which
+
+# https://docs.rs/getrandom/0.2.7/getrandom/#webassembly-support
+# For (future) wasm-pack support
+[target.'cfg(all(target_family = "wasm", target_os = "unknown"))'.dependencies]
+getrandom = { version = "0.2.7", features = ["js"] }
 
 [dev-dependencies]
+assert_cmd = { version = "2.0.4" }
+criterion = { version = "0.4.0" }
 insta = { version = "1.19.1", features = ["yaml"] }
+test-case = { version = "2.2.2" }
 
 [features]
 default = ["update-informer"]
@@ -56,3 +83,7 @@ opt-level = 3
 
 [profile.dev.package.similar]
 opt-level = 3
+
+[[bench]]
+name = "source_code_locator"
+harness = false

LICENSE

@@ -19,3 +19,477 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+The externally maintained libraries from which parts of the Software is derived
+are:
+
+- Pyflakes, licensed as follows:
+  """
+    Copyright 2005-2011 Divmod, Inc.
+    Copyright 2013-2014 Florent Xicluna
+
+    Permission is hereby granted, free of charge, to any person obtaining
+    a copy of this software and associated documentation files (the
+    "Software"), to deal in the Software without restriction, including
+    without limitation the rights to use, copy, modify, merge, publish,
+    distribute, sublicense, and/or sell copies of the Software, and to
+    permit persons to whom the Software is furnished to do so, subject to
+    the following conditions:
+
+    The above copyright notice and this permission notice shall be
+    included in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+  """
+
+- autoflake, licensed as follows:
+  """
+    Copyright (C) 2012-2018 Steven Myint
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy of
+    this software and associated documentation files (the "Software"), to deal in
+    the Software without restriction, including without limitation the rights to
+    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+    of the Software, and to permit persons to whom the Software is furnished to do
+    so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- Flake8, licensed as follows:
+  """
+    == Flake8 License (MIT) ==
+
+    Copyright (C) 2011-2013 Tarek Ziade <tarek@ziade.org>
+    Copyright (C) 2012-2016 Ian Cordasco <graffatcolmingov@gmail.com>
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy of
+    this software and associated documentation files (the "Software"), to deal in
+    the Software without restriction, including without limitation the rights to
+    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+    of the Software, and to permit persons to whom the Software is furnished to do
+    so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-2020, licensed as follows:
+  """
+    Copyright (c) 2019 Anthony Sottile
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+  """
+
+- flake8-annotations, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2019 - Present S. Co1
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-bandit, licensed as follows:
+  """
+    Copyright (c) 2017 Tyler Wince
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+  """
+
+- flake8-blind-except, licensed as follows:
+  """
+    The MIT License (MIT)
+
+    Copyright (c) 2014 Elijah Andrews
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy of
+    this software and associated documentation files (the "Software"), to deal in
+    the Software without restriction, including without limitation the rights to
+    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+    the Software, and to permit persons to whom the Software is furnished to do so,
+    subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+    COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+  """
+
+- flake8-bugbear, licensed as follows:
+  """
+    The MIT License (MIT)
+
+    Copyright (c) 2016 Łukasz Langa
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-comprehensions, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2017 Adam Johnson
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-debugger, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2016 Joseph Kahn
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-tidy-imports, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2017 Adam Johnson
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-print, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2016 Joseph Kahn
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- flake8-quotes, licensed as follows:
+  """
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+  """
+
+- isort, licensed as follows:
+  """
+    The MIT License (MIT)
+
+    Copyright (c) 2013 Timothy Edmund Crosley
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+  """
+
+- pep8-naming, licensed as follows:
+  """
+    Copyright © 2013 Florent Xicluna <florent.xicluna@gmail.com>
+
+    Licensed under the terms of the Expat License
+
+    Permission is hereby granted, free of charge, to any person
+    obtaining a copy of this software and associated documentation files
+    (the "Software"), to deal in the Software without restriction,
+    including without limitation the rights to use, copy, modify, merge,
+    publish, distribute, sublicense, and/or sell copies of the Software,
+    and to permit persons to whom the Software is furnished to do so,
+    subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be
+    included in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+    BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+    ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- pycodestyle, licensed as follows:
+  """
+    Copyright © 2006-2009 Johann C. Rocholl <johann@rocholl.net>
+    Copyright © 2009-2014 Florent Xicluna <florent.xicluna@gmail.com>
+    Copyright © 2014-2020 Ian Lee <IanLee1521@gmail.com>
+
+    Licensed under the terms of the Expat License
+
+    Permission is hereby granted, free of charge, to any person
+    obtaining a copy of this software and associated documentation files
+    (the "Software"), to deal in the Software without restriction,
+    including without limitation the rights to use, copy, modify, merge,
+    publish, distribute, sublicense, and/or sell copies of the Software,
+    and to permit persons to whom the Software is furnished to do so,
+    subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be
+    included in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+    BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+    ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- pydocstyle, licensed as follows:
+  """
+    Copyright (c) 2012 GreenSteam, <http://greensteam.dk/>
+
+    Copyright (c) 2014-2020 Amir Rachum, <http://amir.rachum.com/>
+
+    Copyright (c) 2020 Sambhav Kothari, <https://github.com/samj1912>
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy of
+    this software and associated documentation files (the "Software"), to deal in
+    the Software without restriction, including without limitation the rights to
+    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+    of the Software, and to permit persons to whom the Software is furnished to do
+    so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """
+
+- pyupgrade, licensed as follows:
+  """
+    Copyright (c) 2017 Anthony Sottile
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+  """
+
+- RustPython, licensed as follows:
+  """
+    MIT License
+
+    Copyright (c) 2020 RustPython Team
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+  """

benches/source_code_locator.rs

@@ -0,0 +1,18 @@
+use std::fs;
+use std::path::Path;
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use ropey::Rope;
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let contents = fs::read_to_string(Path::new("resources/test/fixtures/D.py")).unwrap();
+    c.bench_function("rope", |b| {
+        b.iter(|| {
+            let rope = Rope::from_str(black_box(&contents));
+            rope.line_to_char(black_box(4));
+        });
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

examples/generate_rules_table.rs

@@ -1,26 +0,0 @@
-/// Generate a Markdown-compatible table of supported lint rules.
-use strum::IntoEnumIterator;
-
-use ruff::checks::{CheckCode, DEFAULT_CHECK_CODES};
-
-fn main() {
-    println!("| Code | Name | Message |     |     |");
-    println!("| ---- | ---- | ------- | --- | --- |");
-    for check_code in CheckCode::iter() {
-        let check_kind = check_code.kind();
-        let default_token = if DEFAULT_CHECK_CODES.contains(&check_code) {
-            "✅"
-        } else {
-            ""
-        };
-        let fix_token = if check_kind.fixable() { "🛠" } else { "" };
-        println!(
-            "| {} | {} | {} | {} | {} |",
-            check_kind.code().as_ref(),
-            check_kind.as_ref(),
-            check_kind.body(),
-            default_token,
-            fix_token
-        );
-    }
-}

examples/print_ast.rs

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

examples/print_tokens.rs

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

flake8_to_ruff/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "flake8-to-ruff"
+version = "0.0.143-dev.0"
+edition = "2021"
+
+[lib]
+name = "flake8_to_ruff"
+
+[dependencies]
+anyhow = { version = "1.0.66" }
+clap = { version = "4.0.1", features = ["derive"] }
+configparser = { version = "3.0.2" }
+once_cell = { version = "1.16.0" }
+regex = { version = "1.6.0" }
+ruff = { path = "..", default-features = false }
+rustc-hash = { version = "1.1.0" }
+serde = { version = "1.0.147", features = ["derive"] }
+serde_json = { version = "1.0.87" }
+toml = { version = "0.5.9" }
+
+[dev-dependencies]
+
+[features]

flake8_to_ruff/README.md

@@ -0,0 +1,98 @@
+# flake8-to-ruff
+
+Convert existing Flake8 configuration files (`setup.cfg`, `tox.ini`, or `.flake8`) for use with
+[Ruff](https://github.com/charliermarsh/ruff).
+
+Generates a Ruff-compatible `pyproject.toml` section.
+
+## Installation and Usage
+
+### Installation
+
+Available as [`flake8-to-ruff`](https://pypi.org/project/flake8-to-ruff/) on PyPI:
+
+```shell
+pip install flake8-to-ruff
+```
+
+### Usage
+
+To run `flake8-to-ruff`:
+
+```shell
+flake8-to-ruff path/to/setup.cfg
+flake8-to-ruff path/to/tox.ini
+flake8-to-ruff path/to/.flake8
+```
+
+`flake8-to-ruff` will print the relevant `pyproject.toml` sections to standard output, like so:
+
+```toml
+[tool.ruff]
+exclude = [
+    '.svn',
+    'CVS',
+    '.bzr',
+    '.hg',
+    '.git',
+    '__pycache__',
+    '.tox',
+    '.idea',
+    '.mypy_cache',
+    '.venv',
+    'node_modules',
+    '_state_machine.py',
+    'test_fstring.py',
+    'bad_coding2.py',
+    'badsyntax_*.py',
+]
+select = [
+    'A',
+    'E',
+    'F',
+    'Q',
+]
+ignore = []
+
+[tool.ruff.flake8-quotes]
+inline-quotes = 'single'
+
+[tool.ruff.pep8-naming]
+ignore-names = [
+    'foo',
+    'bar',
+]
+```
+
+### Plugins
+
+`flake8-to-ruff` will attempt to infer any activated plugins based on the settings provided in your
+configuration file.
+
+For example, if your `.flake8` file includes a `docstring-convention` property, `flake8-to-ruff`
+will enable the appropriate [`flake8-docstrings`](https://pypi.org/project/flake8-docstrings/)
+checks.
+
+Alternatively, you can manually specify plugins on the command-line:
+
+```shell
+flake8-to-ruff path/to/.flake8 --plugin flake8-builtins --plugin flake8-quotes
+```
+
+## Limitations
+
+1. Ruff only supports a subset of the Flake configuration options. `flake8-to-ruff` will warn on and
+   ignore unsupported options in the `.flake8` file (or equivalent). (Similarly, Ruff has a few
+   configuration options that don't exist in Flake8.)
+2. Ruff will omit any error codes that are unimplemented or unsupported by Ruff, including error
+   codes from unsupported plugins. (See the [Ruff README](https://github.com/charliermarsh/ruff#user-content-how-does-ruff-compare-to-flake8)
+   for the complete list of supported plugins.)
+
+## License
+
+MIT
+
+## Contributing
+
+Contributions are welcome and hugely appreciated. To get started, check out the
+[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTING.md).

flake8_to_ruff/examples/poetry.ini

@@ -0,0 +1,36 @@
+[flake8]
+min_python_version = 3.7.0
+max-line-length = 88
+ban-relative-imports = true
+# flake8-use-fstring: https://github.com/MichaelKim0407/flake8-use-fstring#--percent-greedy-and---format-greedy
+format-greedy = 1
+inline-quotes = double
+enable-extensions = TC, TC1
+type-checking-strict = true
+eradicate-whitelist-extend = ^-.*;
+extend-ignore =
+    # E203: Whitespace before ':' (pycqa/pycodestyle#373)
+    E203,
+    # SIM106: Handle error-cases first
+    SIM106,
+    # ANN101: Missing type annotation for self in method
+    ANN101,
+    # ANN102: Missing type annotation for cls in classmethod
+    ANN102,
+    # PIE781: assign-and-return
+    PIE781,
+    # PIE798 no-unnecessary-class: Consider using a module for namespacing instead
+    PIE798,
+per-file-ignores =
+    # TC002: Move third-party import '...' into a type-checking block
+    __init__.py:TC002,
+    # ANN201: Missing return type annotation for public function
+    tests/test_*:ANN201
+    tests/**/test_*:ANN201
+extend-exclude =
+    # Frozen and not subject to change in this repo:
+    get-poetry.py,
+    install-poetry.py,
+    # External to the project's coding standards:
+    tests/fixtures/*,
+    tests/**/fixtures/*,

flake8_to_ruff/examples/python-discord.ini

@@ -0,0 +1,19 @@
+[flake8]
+max-line-length=120
+docstring-convention=all
+import-order-style=pycharm
+application_import_names=bot,tests
+exclude=.cache,.venv,.git,constants.py
+extend-ignore=
+    B311,W503,E226,S311,T000,E731
+    # Missing Docstrings
+    D100,D104,D105,D107,
+    # Docstring Whitespace
+    D203,D212,D214,D215,
+    # Docstring Quotes
+    D301,D302,
+    # Docstring Content
+    D400,D401,D402,D404,D405,D406,D407,D408,D409,D410,D411,D412,D413,D414,D416,D417
+    # Type Annotations
+    ANN002,ANN003,ANN101,ANN102,ANN204,ANN206,ANN401
+per-file-ignores=tests/*:D,ANN

flake8_to_ruff/examples/requests.ini

@@ -0,0 +1,6 @@
+[flake8]
+ignore = E203, E501, W503
+per-file-ignores =
+    requests/__init__.py:E402, F401
+    requests/compat.py:E402, F401
+    tests/compat.py:F401

flake8_to_ruff/pyproject.toml

@@ -0,0 +1,33 @@
+[project]
+name = "flake8-to-ruff"
+keywords = ["automation", "flake8", "pycodestyle", "pyflakes", "pylint", "clippy"]
+classifiers = [
+    "Development Status :: 3 - Alpha",
+    "Environment :: Console",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: MIT License",
+    "Operating System :: OS Independent",
+    "Programming Language :: Python",
+    "Programming Language :: Python :: 3.7",
+    "Programming Language :: Python :: 3.8",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3 :: Only",
+    "Topic :: Software Development :: Libraries :: Python Modules",
+    "Topic :: Software Development :: Quality Assurance",
+]
+author = "Charlie Marsh"
+author_email = "charlie.r.marsh@gmail.com"
+description = "Convert existing Flake8 configuration to Ruff."
+requires-python = ">=3.7"
+
+[project.urls]
+repository = "https://github.com/charliermarsh/ruff#subdirectory=crates/flake8_to_ruff"
+
+[build-system]
+requires = ["maturin>=0.14,<0.15"]
+build-backend = "maturin"
+
+[tool.maturin]
+bindings = "bin"
+strip = true

flake8_to_ruff/src/converter.rs

@@ -0,0 +1,560 @@
+use std::collections::{BTreeSet, HashMap};
+
+use anyhow::Result;
+use ruff::checks_gen::CheckCodePrefix;
+use ruff::flake8_quotes::settings::Quote;
+use ruff::flake8_tidy_imports::settings::Strictness;
+use ruff::settings::options::Options;
+use ruff::settings::pyproject::Pyproject;
+use ruff::{
+    flake8_annotations, flake8_bugbear, flake8_quotes, flake8_tidy_imports, mccabe, pep8_naming,
+};
+
+use crate::plugin::Plugin;
+use crate::{parser, plugin};
+
+pub fn convert(
+    flake8: &HashMap<String, Option<String>>,
+    plugins: Option<Vec<Plugin>>,
+) -> Result<Pyproject> {
+    // Extract all referenced check code prefixes, to power plugin inference.
+    let mut referenced_codes: BTreeSet<CheckCodePrefix> = BTreeSet::default();
+    for (key, value) in flake8 {
+        if let Some(value) = value {
+            match key.as_str() {
+                "select" | "ignore" | "extend-select" | "extend_select" | "extend-ignore"
+                | "extend_ignore" => {
+                    referenced_codes.extend(parser::parse_prefix_codes(value.as_ref()));
+                }
+                "per-file-ignores" | "per_file_ignores" => {
+                    if let Ok(per_file_ignores) =
+                        parser::parse_files_to_codes_mapping(value.as_ref())
+                    {
+                        for (_, codes) in parser::collect_per_file_ignores(per_file_ignores) {
+                            referenced_codes.extend(codes);
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+
+    // Check if the user has specified a `select`. If not, we'll add our own
+    // default `select`, and populate it based on user plugins.
+    let mut select = flake8
+        .get("select")
+        .and_then(|value| {
+            value
+                .as_ref()
+                .map(|value| BTreeSet::from_iter(parser::parse_prefix_codes(value)))
+        })
+        .unwrap_or_else(|| {
+            plugin::resolve_select(
+                flake8,
+                &plugins.unwrap_or_else(|| {
+                    plugin::infer_plugins_from_options(flake8)
+                        .into_iter()
+                        .chain(plugin::infer_plugins_from_codes(&referenced_codes))
+                        .collect()
+                }),
+            )
+        });
+    let mut ignore = flake8
+        .get("ignore")
+        .and_then(|value| {
+            value
+                .as_ref()
+                .map(|value| BTreeSet::from_iter(parser::parse_prefix_codes(value)))
+        })
+        .unwrap_or_default();
+
+    // Parse each supported option.
+    let mut options = Options::default();
+    let mut flake8_annotations = flake8_annotations::settings::Options::default();
+    let mut flake8_bugbear = flake8_bugbear::settings::Options::default();
+    let mut flake8_quotes = flake8_quotes::settings::Options::default();
+    let mut flake8_tidy_imports = flake8_tidy_imports::settings::Options::default();
+    let mut mccabe = mccabe::settings::Options::default();
+    let mut pep8_naming = pep8_naming::settings::Options::default();
+    for (key, value) in flake8 {
+        if let Some(value) = value {
+            match key.as_str() {
+                // flake8
+                "max-line-length" | "max_line_length" => match value.clone().parse::<usize>() {
+                    Ok(line_length) => options.line_length = Some(line_length),
+                    Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                },
+                "select" => {
+                    // No-op (handled above).
+                    select.extend(parser::parse_prefix_codes(value.as_ref()));
+                }
+                "ignore" => {
+                    // No-op (handled above).
+                }
+                "extend-select" | "extend_select" => {
+                    // Unlike Flake8, use a single explicit `select`.
+                    select.extend(parser::parse_prefix_codes(value.as_ref()));
+                }
+                "extend-ignore" | "extend_ignore" => {
+                    // Unlike Flake8, use a single explicit `ignore`.
+                    ignore.extend(parser::parse_prefix_codes(value.as_ref()));
+                }
+                "exclude" => {
+                    options.exclude = Some(parser::parse_strings(value.as_ref()));
+                }
+                "extend-exclude" | "extend_exclude" => {
+                    options.extend_exclude = Some(parser::parse_strings(value.as_ref()));
+                }
+                "per-file-ignores" | "per_file_ignores" => {
+                    match parser::parse_files_to_codes_mapping(value.as_ref()) {
+                        Ok(per_file_ignores) => {
+                            options.per_file_ignores =
+                                Some(parser::collect_per_file_ignores(per_file_ignores));
+                        }
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                // flake8-bugbear
+                "extend-immutable-calls" | "extend_immutable_calls" => {
+                    flake8_bugbear.extend_immutable_calls =
+                        Some(parser::parse_strings(value.as_ref()));
+                }
+                // flake8-annotations
+                "suppress-none-returning" | "suppress_none_returning" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.suppress_none_returning = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                "suppress-dummy-args" | "suppress_dummy_args" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.suppress_dummy_args = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                "mypy-init-return" | "mypy_init_return" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.mypy_init_return = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                "allow-star-arg-any" | "allow_star_arg_any" => {
+                    match parser::parse_bool(value.as_ref()) {
+                        Ok(bool) => flake8_annotations.allow_star_arg_any = Some(bool),
+                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                    }
+                }
+                // flake8-quotes
+                "quotes" | "inline-quotes" | "inline_quotes" => match value.trim() {
+                    "'" | "single" => flake8_quotes.inline_quotes = Some(Quote::Single),
+                    "\"" | "double" => flake8_quotes.inline_quotes = Some(Quote::Single),
+                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                },
+                "multiline-quotes" | "multiline_quotes" => match value.trim() {
+                    "'" | "single" => flake8_quotes.multiline_quotes = Some(Quote::Single),
+                    "\"" | "double" => flake8_quotes.multiline_quotes = Some(Quote::Single),
+                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                },
+                "docstring-quotes" | "docstring_quotes" => match value.trim() {
+                    "'" | "single" => flake8_quotes.docstring_quotes = Some(Quote::Single),
+                    "\"" | "double" => flake8_quotes.docstring_quotes = Some(Quote::Single),
+                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                },
+                "avoid-escape" | "avoid_escape" => match parser::parse_bool(value.as_ref()) {
+                    Ok(bool) => flake8_quotes.avoid_escape = Some(bool),
+                    Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                },
+                // pep8-naming
+                "ignore-names" | "ignore_names" => {
+                    pep8_naming.ignore_names = Some(parser::parse_strings(value.as_ref()));
+                }
+                "classmethod-decorators" | "classmethod_decorators" => {
+                    pep8_naming.classmethod_decorators =
+                        Some(parser::parse_strings(value.as_ref()));
+                }
+                "staticmethod-decorators" | "staticmethod_decorators" => {
+                    pep8_naming.staticmethod_decorators =
+                        Some(parser::parse_strings(value.as_ref()));
+                }
+                // flake8-tidy-imports
+                "ban-relative-imports" | "ban_relative_imports" => match value.trim() {
+                    "true" => flake8_tidy_imports.ban_relative_imports = Some(Strictness::All),
+                    "parents" => {
+                        flake8_tidy_imports.ban_relative_imports = Some(Strictness::Parents);
+                    }
+                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                },
+                // flake8-docstrings
+                "docstring-convention" => {
+                    // No-op (handled above).
+                }
+                // mccabe
+                "max-complexity" | "max_complexity" => match value.clone().parse::<usize>() {
+                    Ok(max_complexity) => mccabe.max_complexity = Some(max_complexity),
+                    Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                },
+                // Unknown
+                _ => eprintln!("Skipping unsupported property: {key}"),
+            }
+        }
+    }
+
+    // Deduplicate and sort.
+    options.select = Some(Vec::from_iter(select));
+    options.ignore = Some(Vec::from_iter(ignore));
+    if flake8_annotations != flake8_annotations::settings::Options::default() {
+        options.flake8_annotations = Some(flake8_annotations);
+    }
+    if flake8_bugbear != flake8_bugbear::settings::Options::default() {
+        options.flake8_bugbear = Some(flake8_bugbear);
+    }
+    if flake8_quotes != flake8_quotes::settings::Options::default() {
+        options.flake8_quotes = Some(flake8_quotes);
+    }
+    if flake8_tidy_imports != flake8_tidy_imports::settings::Options::default() {
+        options.flake8_tidy_imports = Some(flake8_tidy_imports);
+    }
+    if mccabe != mccabe::settings::Options::default() {
+        options.mccabe = Some(mccabe);
+    }
+    if pep8_naming != pep8_naming::settings::Options::default() {
+        options.pep8_naming = Some(pep8_naming);
+    }
+
+    // Create the pyproject.toml.
+    Ok(Pyproject::new(options))
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use anyhow::Result;
+    use ruff::checks_gen::CheckCodePrefix;
+    use ruff::flake8_quotes;
+    use ruff::settings::options::Options;
+    use ruff::settings::pyproject::Pyproject;
+
+    use crate::converter::convert;
+    use crate::plugin::Plugin;
+
+    #[test]
+    fn it_converts_empty() -> Result<()> {
+        let actual = convert(&HashMap::from([]), None)?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: None,
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: None,
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn it_converts_dashes() -> Result<()> {
+        let actual = convert(
+            &HashMap::from([("max-line-length".to_string(), Some("100".to_string()))]),
+            Some(vec![]),
+        )?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: Some(100),
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: None,
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn it_converts_underscores() -> Result<()> {
+        let actual = convert(
+            &HashMap::from([("max_line_length".to_string(), Some("100".to_string()))]),
+            Some(vec![]),
+        )?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: Some(100),
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: None,
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn it_ignores_parse_errors() -> Result<()> {
+        let actual = convert(
+            &HashMap::from([("max_line_length".to_string(), Some("abc".to_string()))]),
+            Some(vec![]),
+        )?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: None,
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: None,
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn it_converts_plugin_options() -> Result<()> {
+        let actual = convert(
+            &HashMap::from([("inline-quotes".to_string(), Some("single".to_string()))]),
+            Some(vec![]),
+        )?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: None,
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: Some(flake8_quotes::settings::Options {
+                inline_quotes: Some(flake8_quotes::settings::Quote::Single),
+                multiline_quotes: None,
+                docstring_quotes: None,
+                avoid_escape: None,
+            }),
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn it_converts_docstring_conventions() -> Result<()> {
+        let actual = convert(
+            &HashMap::from([(
+                "docstring-convention".to_string(),
+                Some("numpy".to_string()),
+            )]),
+            Some(vec![Plugin::Flake8Docstrings]),
+        )?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: None,
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::D100,
+                CheckCodePrefix::D101,
+                CheckCodePrefix::D102,
+                CheckCodePrefix::D103,
+                CheckCodePrefix::D104,
+                CheckCodePrefix::D105,
+                CheckCodePrefix::D106,
+                CheckCodePrefix::D200,
+                CheckCodePrefix::D201,
+                CheckCodePrefix::D202,
+                CheckCodePrefix::D204,
+                CheckCodePrefix::D205,
+                CheckCodePrefix::D206,
+                CheckCodePrefix::D207,
+                CheckCodePrefix::D208,
+                CheckCodePrefix::D209,
+                CheckCodePrefix::D210,
+                CheckCodePrefix::D211,
+                CheckCodePrefix::D214,
+                CheckCodePrefix::D215,
+                CheckCodePrefix::D300,
+                CheckCodePrefix::D400,
+                CheckCodePrefix::D403,
+                CheckCodePrefix::D404,
+                CheckCodePrefix::D405,
+                CheckCodePrefix::D406,
+                CheckCodePrefix::D407,
+                CheckCodePrefix::D408,
+                CheckCodePrefix::D409,
+                CheckCodePrefix::D410,
+                CheckCodePrefix::D411,
+                CheckCodePrefix::D412,
+                CheckCodePrefix::D414,
+                CheckCodePrefix::D418,
+                CheckCodePrefix::D419,
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: None,
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+
+    #[test]
+    fn it_infers_plugins_if_omitted() -> Result<()> {
+        let actual = convert(
+            &HashMap::from([("inline-quotes".to_string(), Some("single".to_string()))]),
+            None,
+        )?;
+        let expected = Pyproject::new(Options {
+            dummy_variable_rgx: None,
+            exclude: None,
+            extend_exclude: None,
+            extend_ignore: None,
+            extend_select: None,
+            fix: None,
+            fixable: None,
+            ignore: Some(vec![]),
+            line_length: None,
+            per_file_ignores: None,
+            select: Some(vec![
+                CheckCodePrefix::E,
+                CheckCodePrefix::F,
+                CheckCodePrefix::Q,
+                CheckCodePrefix::W,
+            ]),
+            show_source: None,
+            src: None,
+            target_version: None,
+            unfixable: None,
+            flake8_annotations: None,
+            flake8_bugbear: None,
+            flake8_quotes: Some(flake8_quotes::settings::Options {
+                inline_quotes: Some(flake8_quotes::settings::Quote::Single),
+                multiline_quotes: None,
+                docstring_quotes: None,
+                avoid_escape: None,
+            }),
+            flake8_tidy_imports: None,
+            isort: None,
+            mccabe: None,
+            pep8_naming: None,
+        });
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+}

flake8_to_ruff/src/lib.rs

@@ -0,0 +1,16 @@
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
+
+pub mod converter;
+mod parser;
+pub mod plugin;

flake8_to_ruff/src/main.rs

@@ -0,0 +1,56 @@
+//! Utility to generate Ruff's pyproject.toml section from a Flake8 INI file.
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::collapsible_if,
+    clippy::implicit_hasher,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::too_many_lines
+)]
+
+use std::path::PathBuf;
+
+use anyhow::Result;
+use clap::Parser;
+use configparser::ini::Ini;
+use flake8_to_ruff::converter;
+use flake8_to_ruff::plugin::Plugin;
+
+#[derive(Parser)]
+#[command(
+    about = "Convert existing Flake8 configuration to Ruff.",
+    long_about = None
+)]
+struct Cli {
+    /// Path to the Flake8 configuration file (e.g., 'setup.cfg', 'tox.ini', or
+    /// '.flake8').
+    #[arg(required = true)]
+    file: PathBuf,
+    /// List of plugins to enable.
+    #[arg(long, value_delimiter = ',')]
+    plugin: Option<Vec<Plugin>>,
+}
+
+fn main() -> Result<()> {
+    let cli = Cli::parse();
+
+    // Read the INI file.
+    let mut ini = Ini::new_cs();
+    ini.set_multiline(true);
+    let config = ini.load(cli.file).map_err(|msg| anyhow::anyhow!(msg))?;
+
+    // Extract the Flake8 section.
+    let flake8 = config
+        .get("flake8")
+        .expect("Unable to find flake8 section in INI file.");
+
+    // Create the pyproject.toml.
+    let pyproject = converter::convert(flake8, cli.plugin)?;
+    println!("{}", toml::to_string_pretty(&pyproject)?);
+
+    Ok(())
+}

flake8_to_ruff/src/parser.rs

@@ -0,0 +1,382 @@
+use std::str::FromStr;
+
+use anyhow::Result;
+use once_cell::sync::Lazy;
+use regex::Regex;
+use ruff::checks_gen::CheckCodePrefix;
+use ruff::settings::types::PatternPrefixPair;
+use rustc_hash::FxHashMap;
+
+static COMMA_SEPARATED_LIST_RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"[,\s]").unwrap());
+
+/// Parse a comma-separated list of `CheckCodePrefix` values (e.g.,
+/// "F401,E501").
+pub fn parse_prefix_codes(value: &str) -> Vec<CheckCodePrefix> {
+    let mut codes: Vec<CheckCodePrefix> = vec![];
+    for code in COMMA_SEPARATED_LIST_RE.split(value) {
+        let code = code.trim();
+        if code.is_empty() {
+            continue;
+        }
+        if let Ok(code) = CheckCodePrefix::from_str(code) {
+            codes.push(code);
+        } else {
+            eprintln!("Unsupported prefix code: {code}");
+        }
+    }
+    codes
+}
+
+/// Parse a comma-separated list of strings (e.g., "__init__.py,__main__.py").
+pub fn parse_strings(value: &str) -> Vec<String> {
+    COMMA_SEPARATED_LIST_RE
+        .split(value)
+        .map(str::trim)
+        .filter(|part| !part.is_empty())
+        .map(String::from)
+        .collect()
+}
+
+/// Parse a boolean.
+pub fn parse_bool(value: &str) -> Result<bool> {
+    match value.trim() {
+        "true" => Ok(true),
+        "false" => Ok(false),
+        _ => Err(anyhow::anyhow!("Unexpected boolean value: {value}")),
+    }
+}
+
+#[derive(Debug)]
+struct Token {
+    token_name: TokenType,
+    src: String,
+}
+
+#[derive(Debug)]
+enum TokenType {
+    Code,
+    File,
+    Colon,
+    Comma,
+    Ws,
+    Eof,
+}
+
+struct State {
+    seen_sep: bool,
+    seen_colon: bool,
+    filenames: Vec<String>,
+    codes: Vec<String>,
+}
+
+impl State {
+    fn new() -> Self {
+        Self {
+            seen_sep: true,
+            seen_colon: false,
+            filenames: vec![],
+            codes: vec![],
+        }
+    }
+
+    /// Generate the list of `StrCheckCodePair` pairs for the current state.
+    fn parse(&self) -> Vec<PatternPrefixPair> {
+        let mut codes: Vec<PatternPrefixPair> = vec![];
+        for code in &self.codes {
+            match CheckCodePrefix::from_str(code) {
+                Ok(code) => {
+                    for filename in &self.filenames {
+                        codes.push(PatternPrefixPair {
+                            pattern: filename.clone(),
+                            prefix: code.clone(),
+                        });
+                    }
+                }
+                Err(_) => eprintln!("Skipping unrecognized prefix: {code}"),
+            }
+        }
+        codes
+    }
+}
+
+/// Tokenize the raw 'files-to-codes' mapping.
+fn tokenize_files_to_codes_mapping(value: &str) -> Vec<Token> {
+    let mut tokens = vec![];
+    let mut i = 0;
+    while i < value.len() {
+        for (token_re, token_name) in [
+            (
+                Regex::new(r"([A-Z]+[0-9]*)(?:$|\s|,)").unwrap(),
+                TokenType::Code,
+            ),
+            (Regex::new(r"([^\s:,]+)").unwrap(), TokenType::File),
+            (Regex::new(r"(\s*:\s*)").unwrap(), TokenType::Colon),
+            (Regex::new(r"(\s*,\s*)").unwrap(), TokenType::Comma),
+            (Regex::new(r"(\s+)").unwrap(), TokenType::Ws),
+        ] {
+            if let Some(cap) = token_re.captures(&value[i..]) {
+                let mat = cap.get(1).unwrap();
+                if mat.start() == 0 {
+                    tokens.push(Token {
+                        token_name,
+                        src: mat.as_str().to_string().trim().to_string(),
+                    });
+                    i += mat.end();
+                    break;
+                }
+            }
+        }
+    }
+    tokens.push(Token {
+        token_name: TokenType::Eof,
+        src: String::new(),
+    });
+    tokens
+}
+
+/// Parse a 'files-to-codes' mapping, mimicking Flake8's internal logic.
+///
+/// See: <https://github.com/PyCQA/flake8/blob/7dfe99616fc2f07c0017df2ba5fa884158f3ea8a/src/flake8/utils.py#L45>
+pub fn parse_files_to_codes_mapping(value: &str) -> Result<Vec<PatternPrefixPair>> {
+    if value.trim().is_empty() {
+        return Ok(vec![]);
+    }
+    let mut codes: Vec<PatternPrefixPair> = vec![];
+    let mut state = State::new();
+    for token in tokenize_files_to_codes_mapping(value) {
+        if matches!(token.token_name, TokenType::Comma | TokenType::Ws) {
+            state.seen_sep = true;
+        } else if !state.seen_colon {
+            if matches!(token.token_name, TokenType::Colon) {
+                state.seen_colon = true;
+                state.seen_sep = true;
+            } else if state.seen_sep && matches!(token.token_name, TokenType::File) {
+                state.filenames.push(token.src);
+                state.seen_sep = false;
+            } else {
+                return Err(anyhow::anyhow!("Unexpected token: {:?}", token.token_name));
+            }
+        } else {
+            if matches!(token.token_name, TokenType::Eof) {
+                codes.extend(state.parse());
+                state = State::new();
+            } else if state.seen_sep && matches!(token.token_name, TokenType::Code) {
+                state.codes.push(token.src);
+                state.seen_sep = false;
+            } else if state.seen_sep && matches!(token.token_name, TokenType::File) {
+                codes.extend(state.parse());
+                state = State::new();
+                state.filenames.push(token.src);
+                state.seen_sep = false;
+            } else {
+                return Err(anyhow::anyhow!("Unexpected token: {:?}", token.token_name));
+            }
+        }
+    }
+    Ok(codes)
+}
+
+/// Collect a list of `PatternPrefixPair` structs as a `BTreeMap`.
+pub fn collect_per_file_ignores(
+    pairs: Vec<PatternPrefixPair>,
+) -> FxHashMap<String, Vec<CheckCodePrefix>> {
+    let mut per_file_ignores: FxHashMap<String, Vec<CheckCodePrefix>> = FxHashMap::default();
+    for pair in pairs {
+        per_file_ignores
+            .entry(pair.pattern)
+            .or_insert_with(Vec::new)
+            .push(pair.prefix);
+    }
+    per_file_ignores
+}
+
+#[cfg(test)]
+mod tests {
+    use anyhow::Result;
+    use ruff::checks_gen::CheckCodePrefix;
+    use ruff::settings::types::PatternPrefixPair;
+
+    use crate::parser::{parse_files_to_codes_mapping, parse_prefix_codes, parse_strings};
+
+    #[test]
+    fn it_parses_prefix_codes() {
+        let actual = parse_prefix_codes("");
+        let expected: Vec<CheckCodePrefix> = vec![];
+        assert_eq!(actual, expected);
+
+        let actual = parse_prefix_codes(" ");
+        let expected: Vec<CheckCodePrefix> = vec![];
+        assert_eq!(actual, expected);
+
+        let actual = parse_prefix_codes("F401");
+        let expected = vec![CheckCodePrefix::F401];
+        assert_eq!(actual, expected);
+
+        let actual = parse_prefix_codes("F401,");
+        let expected = vec![CheckCodePrefix::F401];
+        assert_eq!(actual, expected);
+
+        let actual = parse_prefix_codes("F401,E501");
+        let expected = vec![CheckCodePrefix::F401, CheckCodePrefix::E501];
+        assert_eq!(actual, expected);
+
+        let actual = parse_prefix_codes("F401, E501");
+        let expected = vec![CheckCodePrefix::F401, CheckCodePrefix::E501];
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn it_parses_strings() {
+        let actual = parse_strings("");
+        let expected: Vec<String> = vec![];
+        assert_eq!(actual, expected);
+
+        let actual = parse_strings(" ");
+        let expected: Vec<String> = vec![];
+        assert_eq!(actual, expected);
+
+        let actual = parse_strings("__init__.py");
+        let expected = vec!["__init__.py".to_string()];
+        assert_eq!(actual, expected);
+
+        let actual = parse_strings("__init__.py,");
+        let expected = vec!["__init__.py".to_string()];
+        assert_eq!(actual, expected);
+
+        let actual = parse_strings("__init__.py,__main__.py");
+        let expected = vec!["__init__.py".to_string(), "__main__.py".to_string()];
+        assert_eq!(actual, expected);
+
+        let actual = parse_strings("__init__.py, __main__.py");
+        let expected = vec!["__init__.py".to_string(), "__main__.py".to_string()];
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn it_parse_files_to_codes_mapping() -> Result<()> {
+        let actual = parse_files_to_codes_mapping("")?;
+        let expected: Vec<PatternPrefixPair> = vec![];
+        assert_eq!(actual, expected);
+
+        let actual = parse_files_to_codes_mapping(" ")?;
+        let expected: Vec<PatternPrefixPair> = vec![];
+        assert_eq!(actual, expected);
+
+        // Ex) locust
+        let actual = parse_files_to_codes_mapping(
+            "per-file-ignores =
+    locust/test/*: F841
+    examples/*: F841
+    *.pyi: E302,E704"
+                .strip_prefix("per-file-ignores =")
+                .unwrap(),
+        )?;
+        let expected: Vec<PatternPrefixPair> = vec![
+            PatternPrefixPair {
+                pattern: "locust/test/*".to_string(),
+                prefix: CheckCodePrefix::F841,
+            },
+            PatternPrefixPair {
+                pattern: "examples/*".to_string(),
+                prefix: CheckCodePrefix::F841,
+            },
+        ];
+        assert_eq!(actual, expected);
+
+        // Ex) celery
+        let actual = parse_files_to_codes_mapping(
+            "per-file-ignores =
+   t/*,setup.py,examples/*,docs/*,extra/*:
+       D,"
+            .strip_prefix("per-file-ignores =")
+            .unwrap(),
+        )?;
+        let expected: Vec<PatternPrefixPair> = vec![
+            PatternPrefixPair {
+                pattern: "t/*".to_string(),
+                prefix: CheckCodePrefix::D,
+            },
+            PatternPrefixPair {
+                pattern: "setup.py".to_string(),
+                prefix: CheckCodePrefix::D,
+            },
+            PatternPrefixPair {
+                pattern: "examples/*".to_string(),
+                prefix: CheckCodePrefix::D,
+            },
+            PatternPrefixPair {
+                pattern: "docs/*".to_string(),
+                prefix: CheckCodePrefix::D,
+            },
+            PatternPrefixPair {
+                pattern: "extra/*".to_string(),
+                prefix: CheckCodePrefix::D,
+            },
+        ];
+        assert_eq!(actual, expected);
+
+        // Ex) scrapy
+        let actual = parse_files_to_codes_mapping(
+            "per-file-ignores =
+    scrapy/__init__.py:E402
+    scrapy/core/downloader/handlers/http.py:F401
+    scrapy/http/__init__.py:F401
+    scrapy/linkextractors/__init__.py:E402,F401
+    scrapy/selector/__init__.py:F401
+    scrapy/spiders/__init__.py:E402,F401
+    scrapy/utils/url.py:F403,F405
+    tests/test_loader.py:E741"
+                .strip_prefix("per-file-ignores =")
+                .unwrap(),
+        )?;
+        let expected: Vec<PatternPrefixPair> = vec![
+            PatternPrefixPair {
+                pattern: "scrapy/__init__.py".to_string(),
+                prefix: CheckCodePrefix::E402,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/core/downloader/handlers/http.py".to_string(),
+                prefix: CheckCodePrefix::F401,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/http/__init__.py".to_string(),
+                prefix: CheckCodePrefix::F401,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/linkextractors/__init__.py".to_string(),
+                prefix: CheckCodePrefix::E402,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/linkextractors/__init__.py".to_string(),
+                prefix: CheckCodePrefix::F401,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/selector/__init__.py".to_string(),
+                prefix: CheckCodePrefix::F401,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/spiders/__init__.py".to_string(),
+                prefix: CheckCodePrefix::E402,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/spiders/__init__.py".to_string(),
+                prefix: CheckCodePrefix::F401,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/utils/url.py".to_string(),
+                prefix: CheckCodePrefix::F403,
+            },
+            PatternPrefixPair {
+                pattern: "scrapy/utils/url.py".to_string(),
+                prefix: CheckCodePrefix::F405,
+            },
+            PatternPrefixPair {
+                pattern: "tests/test_loader.py".to_string(),
+                prefix: CheckCodePrefix::E741,
+            },
+        ];
+        assert_eq!(actual, expected);
+
+        Ok(())
+    }
+}

flake8_to_ruff/src/plugin.rs

@@ -0,0 +1,435 @@
+use std::collections::{BTreeSet, HashMap};
+use std::str::FromStr;
+
+use anyhow::anyhow;
+use ruff::checks_gen::CheckCodePrefix;
+
+#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub enum Plugin {
+    Flake8Bandit,
+    Flake8Bugbear,
+    Flake8Builtins,
+    Flake8Comprehensions,
+    Flake8Debugger,
+    Flake8Docstrings,
+    Flake8TidyImports,
+    Flake8Print,
+    Flake8Quotes,
+    Flake8Annotations,
+    McCabe,
+    Flake8BlindExcept,
+    PEP8Naming,
+    Pyupgrade,
+}
+
+impl FromStr for Plugin {
+    type Err = anyhow::Error;
+
+    fn from_str(string: &str) -> Result<Self, Self::Err> {
+        match string {
+            "flake8-bandit" => Ok(Plugin::Flake8Bandit),
+            "flake8-bugbear" => Ok(Plugin::Flake8Bugbear),
+            "flake8-builtins" => Ok(Plugin::Flake8Builtins),
+            "flake8-comprehensions" => Ok(Plugin::Flake8Comprehensions),
+            "flake8-debugger" => Ok(Plugin::Flake8Debugger),
+            "flake8-docstrings" => Ok(Plugin::Flake8Docstrings),
+            "flake8-tidy-imports" => Ok(Plugin::Flake8TidyImports),
+            "flake8-print" => Ok(Plugin::Flake8Print),
+            "flake8-quotes" => Ok(Plugin::Flake8Quotes),
+            "flake8-annotations" => Ok(Plugin::Flake8Annotations),
+            "flake8-blind-except" => Ok(Plugin::Flake8BlindExcept),
+            "mccabe" => Ok(Plugin::McCabe),
+            "pep8-naming" => Ok(Plugin::PEP8Naming),
+            "pyupgrade" => Ok(Plugin::Pyupgrade),
+            _ => Err(anyhow!("Unknown plugin: {}", string)),
+        }
+    }
+}
+
+impl Plugin {
+    pub fn default(&self) -> CheckCodePrefix {
+        match self {
+            Plugin::Flake8Bandit => CheckCodePrefix::S,
+            Plugin::Flake8Bugbear => CheckCodePrefix::B,
+            Plugin::Flake8Builtins => CheckCodePrefix::A,
+            Plugin::Flake8Comprehensions => CheckCodePrefix::C4,
+            Plugin::Flake8Debugger => CheckCodePrefix::T1,
+            Plugin::Flake8Docstrings => CheckCodePrefix::D,
+            Plugin::Flake8TidyImports => CheckCodePrefix::I25,
+            Plugin::Flake8Print => CheckCodePrefix::T2,
+            Plugin::Flake8Quotes => CheckCodePrefix::Q,
+            Plugin::Flake8Annotations => CheckCodePrefix::ANN,
+            Plugin::Flake8BlindExcept => CheckCodePrefix::BLE,
+            Plugin::McCabe => CheckCodePrefix::C9,
+            Plugin::PEP8Naming => CheckCodePrefix::N,
+            Plugin::Pyupgrade => CheckCodePrefix::U,
+        }
+    }
+
+    pub fn select(&self, flake8: &HashMap<String, Option<String>>) -> Vec<CheckCodePrefix> {
+        match self {
+            Plugin::Flake8Bandit => vec![CheckCodePrefix::S],
+            Plugin::Flake8Bugbear => vec![CheckCodePrefix::B],
+            Plugin::Flake8Builtins => vec![CheckCodePrefix::A],
+            Plugin::Flake8Comprehensions => vec![CheckCodePrefix::C4],
+            Plugin::Flake8Debugger => vec![CheckCodePrefix::T1],
+            Plugin::Flake8Docstrings => {
+                // Use the user-provided docstring.
+                for key in ["docstring-convention", "docstring_convention"] {
+                    if let Some(Some(value)) = flake8.get(key) {
+                        match DocstringConvention::from_str(value) {
+                            Ok(convention) => return convention.select(),
+                            Err(e) => {
+                                eprintln!("Unexpected '{key}' value: {value} ({e}");
+                                return vec![];
+                            }
+                        }
+                    }
+                }
+                // Default to PEP8.
+                DocstringConvention::PEP8.select()
+            }
+            Plugin::Flake8TidyImports => vec![CheckCodePrefix::I25],
+            Plugin::Flake8Print => vec![CheckCodePrefix::T2],
+            Plugin::Flake8Quotes => vec![CheckCodePrefix::Q],
+            Plugin::Flake8Annotations => vec![CheckCodePrefix::ANN],
+            Plugin::Flake8BlindExcept => vec![CheckCodePrefix::BLE],
+            Plugin::McCabe => vec![CheckCodePrefix::C9],
+            Plugin::PEP8Naming => vec![CheckCodePrefix::N],
+            Plugin::Pyupgrade => vec![CheckCodePrefix::U],
+        }
+    }
+}
+
+pub enum DocstringConvention {
+    All,
+    PEP8,
+    NumPy,
+    Google,
+}
+
+impl FromStr for DocstringConvention {
+    type Err = anyhow::Error;
+
+    fn from_str(string: &str) -> Result<Self, Self::Err> {
+        match string {
+            "all" => Ok(DocstringConvention::All),
+            "pep8" => Ok(DocstringConvention::PEP8),
+            "numpy" => Ok(DocstringConvention::NumPy),
+            "google" => Ok(DocstringConvention::Google),
+            _ => Err(anyhow!("Unknown docstring convention: {}", string)),
+        }
+    }
+}
+
+impl DocstringConvention {
+    fn select(&self) -> Vec<CheckCodePrefix> {
+        match self {
+            DocstringConvention::All => vec![CheckCodePrefix::D],
+            DocstringConvention::PEP8 => vec![
+                // All errors except D203, D212, D213, D214, D215, D404, D405, D406, D407, D408,
+                // D409, D410, D411, D413, D415, D416 and D417.
+                CheckCodePrefix::D100,
+                CheckCodePrefix::D101,
+                CheckCodePrefix::D102,
+                CheckCodePrefix::D103,
+                CheckCodePrefix::D104,
+                CheckCodePrefix::D105,
+                CheckCodePrefix::D106,
+                CheckCodePrefix::D107,
+                CheckCodePrefix::D200,
+                CheckCodePrefix::D201,
+                CheckCodePrefix::D202,
+                // CheckCodePrefix::D203,
+                CheckCodePrefix::D204,
+                CheckCodePrefix::D205,
+                CheckCodePrefix::D206,
+                CheckCodePrefix::D207,
+                CheckCodePrefix::D208,
+                CheckCodePrefix::D209,
+                CheckCodePrefix::D210,
+                CheckCodePrefix::D211,
+                // CheckCodePrefix::D212,
+                // CheckCodePrefix::D213,
+                // CheckCodePrefix::D214,
+                // CheckCodePrefix::D215,
+                CheckCodePrefix::D300,
+                CheckCodePrefix::D400,
+                CheckCodePrefix::D402,
+                CheckCodePrefix::D403,
+                // CheckCodePrefix::D404,
+                // CheckCodePrefix::D405,
+                // CheckCodePrefix::D406,
+                // CheckCodePrefix::D407,
+                // CheckCodePrefix::D408,
+                // CheckCodePrefix::D409,
+                // CheckCodePrefix::D410,
+                // CheckCodePrefix::D411,
+                CheckCodePrefix::D412,
+                // CheckCodePrefix::D413,
+                CheckCodePrefix::D414,
+                // CheckCodePrefix::D415,
+                // CheckCodePrefix::D416,
+                // CheckCodePrefix::D417,
+                CheckCodePrefix::D418,
+                CheckCodePrefix::D419,
+            ],
+            DocstringConvention::NumPy => vec![
+                // All errors except D107, D203, D212, D213, D402, D413, D415, D416, and D417.
+                CheckCodePrefix::D100,
+                CheckCodePrefix::D101,
+                CheckCodePrefix::D102,
+                CheckCodePrefix::D103,
+                CheckCodePrefix::D104,
+                CheckCodePrefix::D105,
+                CheckCodePrefix::D106,
+                // CheckCodePrefix::D107,
+                CheckCodePrefix::D200,
+                CheckCodePrefix::D201,
+                CheckCodePrefix::D202,
+                // CheckCodePrefix::D203,
+                CheckCodePrefix::D204,
+                CheckCodePrefix::D205,
+                CheckCodePrefix::D206,
+                CheckCodePrefix::D207,
+                CheckCodePrefix::D208,
+                CheckCodePrefix::D209,
+                CheckCodePrefix::D210,
+                CheckCodePrefix::D211,
+                // CheckCodePrefix::D212,
+                // CheckCodePrefix::D213,
+                CheckCodePrefix::D214,
+                CheckCodePrefix::D215,
+                CheckCodePrefix::D300,
+                CheckCodePrefix::D400,
+                // CheckCodePrefix::D402,
+                CheckCodePrefix::D403,
+                CheckCodePrefix::D404,
+                CheckCodePrefix::D405,
+                CheckCodePrefix::D406,
+                CheckCodePrefix::D407,
+                CheckCodePrefix::D408,
+                CheckCodePrefix::D409,
+                CheckCodePrefix::D410,
+                CheckCodePrefix::D411,
+                CheckCodePrefix::D412,
+                // CheckCodePrefix::D413,
+                CheckCodePrefix::D414,
+                // CheckCodePrefix::D415,
+                // CheckCodePrefix::D416,
+                // CheckCodePrefix::D417,
+                CheckCodePrefix::D418,
+                CheckCodePrefix::D419,
+            ],
+            DocstringConvention::Google => vec![
+                // All errors except D203, D204, D213, D215, D400, D401, D404, D406, D407, D408,
+                // D409 and D413.
+                CheckCodePrefix::D100,
+                CheckCodePrefix::D101,
+                CheckCodePrefix::D102,
+                CheckCodePrefix::D103,
+                CheckCodePrefix::D104,
+                CheckCodePrefix::D105,
+                CheckCodePrefix::D106,
+                CheckCodePrefix::D107,
+                CheckCodePrefix::D200,
+                CheckCodePrefix::D201,
+                CheckCodePrefix::D202,
+                // CheckCodePrefix::D203,
+                // CheckCodePrefix::D204,
+                CheckCodePrefix::D205,
+                CheckCodePrefix::D206,
+                CheckCodePrefix::D207,
+                CheckCodePrefix::D208,
+                CheckCodePrefix::D209,
+                CheckCodePrefix::D210,
+                CheckCodePrefix::D211,
+                CheckCodePrefix::D212,
+                // CheckCodePrefix::D213,
+                CheckCodePrefix::D214,
+                // CheckCodePrefix::D215,
+                CheckCodePrefix::D300,
+                // CheckCodePrefix::D400,
+                CheckCodePrefix::D402,
+                CheckCodePrefix::D403,
+                // CheckCodePrefix::D404,
+                CheckCodePrefix::D405,
+                // CheckCodePrefix::D406,
+                // CheckCodePrefix::D407,
+                // CheckCodePrefix::D408,
+                // CheckCodePrefix::D409,
+                CheckCodePrefix::D410,
+                CheckCodePrefix::D411,
+                CheckCodePrefix::D412,
+                // CheckCodePrefix::D413,
+                CheckCodePrefix::D414,
+                CheckCodePrefix::D415,
+                CheckCodePrefix::D416,
+                CheckCodePrefix::D417,
+                CheckCodePrefix::D418,
+                CheckCodePrefix::D419,
+            ],
+        }
+    }
+}
+
+/// Infer the enabled plugins based on user-provided options.
+///
+/// For example, if the user specified a `mypy-init-return` setting, we should
+/// infer that `flake8-annotations` is active.
+pub fn infer_plugins_from_options(flake8: &HashMap<String, Option<String>>) -> Vec<Plugin> {
+    let mut plugins = BTreeSet::new();
+    for key in flake8.keys() {
+        match key.as_str() {
+            // flake8-docstrings
+            "docstring-convention" | "docstring_convention" => {
+                plugins.insert(Plugin::Flake8Docstrings);
+            }
+            // flake8-bugbear
+            "extend-immutable-calls" | "extend_immutable_calls" => {
+                plugins.insert(Plugin::Flake8Bugbear);
+            }
+            // flake8-builtins
+            "builtins-ignorelist" | "builtins_ignorelist" => {
+                plugins.insert(Plugin::Flake8Builtins);
+            }
+            // flake8-quotes
+            "quotes" | "inline-quotes" | "inline_quotes" => {
+                plugins.insert(Plugin::Flake8Quotes);
+            }
+            "multiline-quotes" | "multiline_quotes" => {
+                plugins.insert(Plugin::Flake8Quotes);
+            }
+            "docstring-quotes" | "docstring_quotes" => {
+                plugins.insert(Plugin::Flake8Quotes);
+            }
+            "avoid-escape" | "avoid_escape" => {
+                plugins.insert(Plugin::Flake8Quotes);
+            }
+            // flake8-annotations
+            "suppress-none-returning" | "suppress_none_returning" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "suppress-dummy-args" | "suppress_dummy_args" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "allow-untyped-defs" | "allow_untyped_defs" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "allow-untyped-nested" | "allow_untyped_nested" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "mypy-init-return" | "mypy_init_return" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "dispatch-decorators" | "dispatch_decorators" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "overload-decorators" | "overload_decorators" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            "allow-star-arg-any" | "allow_star_arg_any" => {
+                plugins.insert(Plugin::Flake8Annotations);
+            }
+            // flake8-tidy-imports
+            "ban-relative-imports" | "ban_relative_imports" => {
+                plugins.insert(Plugin::Flake8TidyImports);
+            }
+            "banned-modules" | "banned_modules" => {
+                plugins.insert(Plugin::Flake8TidyImports);
+            }
+            // mccabe
+            "max-complexity" | "max_complexity" => {
+                plugins.insert(Plugin::McCabe);
+            }
+            // pep8-naming
+            "ignore-names" | "ignore_names" => {
+                plugins.insert(Plugin::PEP8Naming);
+            }
+            "classmethod-decorators" | "classmethod_decorators" => {
+                plugins.insert(Plugin::PEP8Naming);
+            }
+            "staticmethod-decorators" | "staticmethod_decorators" => {
+                plugins.insert(Plugin::PEP8Naming);
+            }
+            _ => {}
+        }
+    }
+    Vec::from_iter(plugins)
+}
+
+/// Infer the enabled plugins based on the referenced prefixes.
+///
+/// For example, if the user ignores `ANN101`, we should infer that
+/// `flake8-annotations` is active.
+pub fn infer_plugins_from_codes(codes: &BTreeSet<CheckCodePrefix>) -> Vec<Plugin> {
+    [
+        Plugin::Flake8Bandit,
+        Plugin::Flake8Bugbear,
+        Plugin::Flake8Builtins,
+        Plugin::Flake8Comprehensions,
+        Plugin::Flake8Debugger,
+        Plugin::Flake8Docstrings,
+        Plugin::Flake8TidyImports,
+        Plugin::Flake8Print,
+        Plugin::Flake8Quotes,
+        Plugin::Flake8Annotations,
+        Plugin::Flake8BlindExcept,
+        Plugin::PEP8Naming,
+        Plugin::Pyupgrade,
+    ]
+    .into_iter()
+    .filter(|plugin| {
+        for prefix in codes {
+            if prefix
+                .codes()
+                .iter()
+                .any(|code| plugin.default().codes().contains(code))
+            {
+                return true;
+            }
+        }
+        false
+    })
+    .collect()
+}
+
+/// Resolve the set of enabled `CheckCodePrefix` values for the given plugins.
+pub fn resolve_select(
+    flake8: &HashMap<String, Option<String>>,
+    plugins: &[Plugin],
+) -> BTreeSet<CheckCodePrefix> {
+    // Include default Pyflakes and pycodestyle checks.
+    let mut select = BTreeSet::from([CheckCodePrefix::E, CheckCodePrefix::F, CheckCodePrefix::W]);
+
+    // Add prefix codes for every plugin.
+    for plugin in plugins {
+        select.extend(plugin.select(flake8));
+    }
+
+    select
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use crate::plugin::{infer_plugins_from_options, Plugin};
+
+    #[test]
+    fn it_infers_plugins() {
+        let actual = infer_plugins_from_options(&HashMap::from([(
+            "inline-quotes".to_string(),
+            Some("single".to_string()),
+        )]));
+        let expected = vec![Plugin::Flake8Quotes];
+        assert_eq!(actual, expected);
+
+        let actual = infer_plugins_from_options(&HashMap::from([(
+            "staticmethod-decorators".to_string(),
+            Some("[]".to_string()),
+        )]));
+        let expected = vec![Plugin::PEP8Naming];
+        assert_eq!(actual, expected);
+    }
+}

pyproject.toml

@@ -25,10 +25,13 @@ requires-python = ">=3.7"
 repository = "https://github.com/charliermarsh/ruff"
 
 [build-system]
-requires = ["maturin>=0.13,<0.14"]
+requires = ["maturin>=0.14,<0.15"]
 build-backend = "maturin"
 
 [tool.maturin]
 bindings = "bin"
-sdist-include = ["Cargo.lock"]
 strip = true
+
+[tool.isort]
+profile = "black"
+known_third_party = ["fastapi", "pydantic", "starlette"]

resources/test/fixtures/B002.py

@@ -0,0 +1,20 @@
+"""
+Should emit:
+B002 - on lines 15 and 20
+"""
+
+
+def this_is_all_fine(n):
+    x = n + 1
+    y = 1 + n
+    z = +x + y
+    return +z
+
+
+def this_is_buggy(n):
+    x = ++n
+    return x
+
+
+def this_is_buggy_too(n):
+    return ++n

resources/test/fixtures/B003.py

@@ -0,0 +1,18 @@
+"""
+Should emit:
+B003 - on line 9
+"""
+
+import os
+from os import environ
+
+os.environ = {}
+environ = {}  # that's fine, assigning a new meaning to the module-level name
+
+
+class Object:
+    os = None
+
+
+o = Object()
+o.os.environ = {}

resources/test/fixtures/B004.py

@@ -0,0 +1,12 @@
+def this_is_a_bug():
+    o = object()
+    if hasattr(o, "__call__"):
+        print("Ooh, callable! Or is it?")
+    if getattr(o, "__call__", False):
+        print("Ooh, callable! Or is it?")
+
+
+def this_is_fine():
+    o = object()
+    if callable(o):
+        print("Ooh, this is actually callable.")

resources/test/fixtures/B005.py

@@ -0,0 +1,26 @@
+s = "qwe"
+s.strip(s)  # no warning
+s.strip("we")  # no warning
+s.strip(".facebook.com")  # warning
+s.strip("e")  # no warning
+s.strip("\n\t ")  # no warning
+s.strip(r"\n\t ")  # warning
+s.lstrip(s)  # no warning
+s.lstrip("we")  # no warning
+s.lstrip(".facebook.com")  # warning
+s.lstrip("e")  # no warning
+s.lstrip("\n\t ")  # no warning
+s.lstrip(r"\n\t ")  # warning
+s.rstrip(s)  # no warning
+s.rstrip("we")  # warning
+s.rstrip(".facebook.com")  # warning
+s.rstrip("e")  # no warning
+s.rstrip("\n\t ")  # no warning
+s.rstrip(r"\n\t ")  # warning
+
+from somewhere import other_type, strip
+
+strip("we")  # no warning
+other_type().lstrip()  # no warning
+other_type().rstrip(["a", "b", "c"])  # no warning
+other_type().strip("a", "b")  # no warning

resources/test/fixtures/B006_B008.py

@@ -0,0 +1,207 @@
+import collections
+import datetime as dt
+import logging
+import operator
+import random
+import re
+import time
+import types
+from operator import attrgetter, itemgetter, methodcaller
+from types import MappingProxyType
+
+
+# B006
+# Allow immutable literals/calls/comprehensions
+def this_is_okay(value=(1, 2, 3)):
+    ...
+
+
+async def and_this_also(value=tuple()):
+    pass
+
+
+def frozenset_also_okay(value=frozenset()):
+    pass
+
+
+def mappingproxytype_okay(
+    value=MappingProxyType({}), value2=types.MappingProxyType({})
+):
+    pass
+
+
+def re_compile_ok(value=re.compile("foo")):
+    pass
+
+
+def operators_ok(
+    v=operator.attrgetter("foo"),
+    v2=operator.itemgetter("foo"),
+    v3=operator.methodcaller("foo"),
+):
+    pass
+
+
+def operators_ok_unqualified(
+    v=attrgetter("foo"),
+    v2=itemgetter("foo"),
+    v3=methodcaller("foo"),
+):
+    pass
+
+
+def kwonlyargs_immutable(*, value=()):
+    ...
+
+
+# Flag mutable literals/comprehensions
+
+
+def this_is_wrong(value=[1, 2, 3]):
+    ...
+
+
+def this_is_also_wrong(value={}):
+    ...
+
+
+def and_this(value=set()):
+    ...
+
+
+def this_too(value=collections.OrderedDict()):
+    ...
+
+
+async def async_this_too(value=collections.defaultdict()):
+    ...
+
+
+def dont_forget_me(value=collections.deque()):
+    ...
+
+
+# N.B. we're also flagging the function call in the comprehension
+def list_comprehension_also_not_okay(default=[i**2 for i in range(3)]):
+    pass
+
+
+def dict_comprehension_also_not_okay(default={i: i**2 for i in range(3)}):
+    pass
+
+
+def set_comprehension_also_not_okay(default={i**2 for i in range(3)}):
+    pass
+
+
+def kwonlyargs_mutable(*, value=[]):
+    ...
+
+
+# Recommended approach for mutable defaults
+def do_this_instead(value=None):
+    if value is None:
+        value = set()
+
+
+# B008
+# Flag function calls as default args (including if they are part of a sub-expression)
+def in_fact_all_calls_are_wrong(value=time.time()):
+    ...
+
+
+def f(when=dt.datetime.now() + dt.timedelta(days=7)):
+    pass
+
+
+def can_even_catch_lambdas(a=(lambda x: x)()):
+    ...
+
+
+# Recommended approach for function calls as default args
+LOGGER = logging.getLogger(__name__)
+
+
+def do_this_instead_of_calls_in_defaults(logger=LOGGER):
+    # That makes it more obvious that this one value is reused.
+    ...
+
+
+# Handle inf/infinity/nan special case
+def float_inf_okay(value=float("inf")):
+    pass
+
+
+def float_infinity_okay(value=float("infinity")):
+    pass
+
+
+def float_plus_infinity_okay(value=float("+infinity")):
+    pass
+
+
+def float_minus_inf_okay(value=float("-inf")):
+    pass
+
+
+def float_nan_okay(value=float("nan")):
+    pass
+
+
+def float_minus_NaN_okay(value=float("-NaN")):
+    pass
+
+
+def float_infinity_literal(value=float("1e999")):
+    pass
+
+
+# But don't allow standard floats
+def float_int_is_wrong(value=float(3)):
+    pass
+
+
+def float_str_not_inf_or_nan_is_wrong(value=float("3.14")):
+    pass
+
+
+# B006 and B008
+# We should handle arbitrary nesting of these B008.
+def nested_combo(a=[float(3), dt.datetime.now()]):
+    pass
+
+
+# Don't flag nested B006 since we can't guarantee that
+# it isn't made mutable by the outer operation.
+def no_nested_b006(a=map(lambda s: s.upper(), ["a", "b", "c"])):
+    pass
+
+
+# B008-ception.
+def nested_b008(a=random.randint(0, dt.datetime.now().year)):
+    pass
+
+
+# Ignore lambda contents since they are evaluated at call time.
+def foo(f=lambda x: print(x)):
+    f(1)
+
+
+from collections import abc
+from typing import Annotated, Dict, Optional, Sequence, Union, Set
+
+
+def immutable_annotations(
+    a: Sequence[int] | None = [],
+    b: Optional[abc.Mapping[int, int]] = {},
+    c: Annotated[Union[abc.Set[str], abc.Sized], "annotation"] = set(),
+):
+    pass
+
+
+def mutable_annotations(
+    a: list[int] | None = [],
+    b: Optional[Dict[int, int]] = {},
+    c: Annotated[Union[Set[str], abc.Sized], "annotation"] = set(),
+):
+    pass

resources/test/fixtures/B007.py

@@ -0,0 +1,31 @@
+for i in range(10):
+    print(i)
+
+print(i)  # name no longer defined on Python 3; no warning yet
+
+for i in range(10):  # name not used within the loop; B007
+    print(10)
+
+print(i)  # name no longer defined on Python 3; no warning yet
+
+
+for _ in range(10):  # _ is okay for a throw-away variable
+    print(10)
+
+
+for i in range(10):
+    for j in range(10):
+        for k in range(10):  # k not used, i and j used transitively
+            print(i + j)
+
+
+def strange_generator():
+    for i in range(10):
+        for j in range(10):
+            for k in range(10):
+                for l in range(10):
+                    yield i, (j, (k, l))
+
+
+for i, (j, (k, l)) in strange_generator():  # i, k not used
+    print(j, l)

resources/test/fixtures/B008_extended.py

@@ -0,0 +1,20 @@
+from typing import List
+
+import fastapi
+from fastapi import Query
+
+
+def okay(db=fastapi.Depends(get_db)):
+    ...
+
+
+def okay(data: List[str] = fastapi.Query(None)):
+    ...
+
+
+def okay(data: List[str] = Query(None)):
+    ...
+
+
+def error_due_to_missing_import(data: List[str] = Depends(None)):
+    ...

resources/test/fixtures/B009_B010.py

@@ -0,0 +1,37 @@
+"""
+Should emit:
+B009 - Line 18, 19, 20, 21, 22
+B010 - Line 33, 34, 35, 36
+"""
+
+# Valid getattr usage
+getattr(foo, bar)
+getattr(foo, "bar", None)
+getattr(foo, "bar{foo}".format(foo="a"), None)
+getattr(foo, "bar{foo}".format(foo="a"))
+getattr(foo, bar, None)
+getattr(foo, "123abc")
+getattr(foo, r"123\abc")
+getattr(foo, "except")
+
+# Invalid usage
+getattr(foo, "bar")
+getattr(foo, "_123abc")
+getattr(foo, "abc123")
+getattr(foo, r"abc123")
+_ = lambda x: getattr(x, "bar")
+
+# Valid setattr usage
+setattr(foo, bar, None)
+setattr(foo, "bar{foo}".format(foo="a"), None)
+setattr(foo, "123abc", None)
+setattr(foo, r"123\abc", None)
+setattr(foo, "except", None)
+_ = lambda x: setattr(x, "bar", 1)
+
+# Invalid usage
+setattr(foo, "bar", None)
+setattr(foo, "_123abc", None)
+setattr(foo, "abc123", None)
+setattr(foo, r"abc123", None)
+setattr(foo.bar, r"baz", None)

resources/test/fixtures/B011.py

@@ -0,0 +1,10 @@
+"""
+Should emit:
+B011 - on line 8
+B011 - on line 10
+"""
+
+assert 1 != 2
+assert False
+assert 1 != 2, "message"
+assert False, "message"

resources/test/fixtures/B012.py

@@ -0,0 +1,107 @@
+def a():
+    try:
+        pass
+    finally:
+        return  # warning
+
+
+def b():
+    try:
+        pass
+    finally:
+        if 1 + 0 == 2 - 1:
+            return  # warning
+
+
+def c():
+    try:
+        pass
+    finally:
+        try:
+            return  # warning
+        except Exception:
+            pass
+
+
+def d():
+    try:
+        try:
+            pass
+        finally:
+            return  # warning
+    finally:
+        pass
+
+
+def e():
+    if 1 == 2 - 1:
+        try:
+
+            def f():
+                try:
+                    pass
+                finally:
+                    return  # warning
+
+        finally:
+            pass
+
+
+def g():
+    try:
+        pass
+    finally:
+
+        def h():
+            return  # no warning
+
+        e()
+
+
+def i():
+    while True:
+        try:
+            pass
+        finally:
+            break  # warning
+
+            def j():
+                while True:
+                    break  # no warning
+
+
+def h():
+    while True:
+        try:
+            pass
+        finally:
+            continue  # warning
+
+            def j():
+                while True:
+                    continue  # no warning
+
+
+def k():
+    try:
+        pass
+    finally:
+        while True:
+            break  # no warning
+        while True:
+            continue  # no warning
+        while True:
+            return  # warning
+
+
+while True:
+    try:
+        pass
+    finally:
+        continue  # warning
+
+while True:
+    try:
+        pass
+    finally:
+        break  # warning

resources/test/fixtures/B013.py

@@ -0,0 +1,8 @@
+try:
+    pass
+except (ValueError,):
+    pass
+except AttributeError:
+    pass
+except (ImportError, TypeError):
+    pass

resources/test/fixtures/B014.py

@@ -0,0 +1,76 @@
+"""
+Should emit:
+B014 - on lines 11, 17, 28, 42, 49, 56, and 74.
+"""
+
+import binascii
+import re
+
+try:
+    pass
+except (Exception, TypeError):
+    # TypeError is a subclass of Exception, so it doesn't add anything
+    pass
+
+try:
+    pass
+except (OSError, OSError) as err:
+    # Duplicate exception types are useless
+    pass
+
+
+class MyError(Exception):
+    pass
+
+
+try:
+    pass
+except (MyError, MyError):
+    # Detect duplicate non-builtin errors
+    pass
+
+
+try:
+    pass
+except (MyError, Exception) as e:
+    # Don't assume that we're all subclasses of Exception
+    pass
+
+
+try:
+    pass
+except (MyError, BaseException) as e:
+    # But we *can* assume that everything is a subclass of BaseException
+    pass
+
+
+try:
+    pass
+except (re.error, re.error):
+    # Duplicate exception types as attributes
+    pass
+
+
+try:
+    pass
+except (IOError, EnvironmentError, OSError):
+    # Detect if a primary exception and any its aliases are present.
+    #
+    # Since Python 3.3, IOError, EnvironmentError, WindowsError, mmap.error,
+    # socket.error and select.error are aliases of OSError. See PEP 3151 for
+    # more info.
+    pass
+
+
+try:
+    pass
+except (MyException, NotImplemented):
+    # NotImplemented is not an exception, let's not crash on it.
+    pass
+
+
+try:
+    pass
+except (ValueError, binascii.Error):
+    # binascii.Error is a subclass of ValueError.
+    pass

resources/test/fixtures/B015.py

@@ -0,0 +1,27 @@
+assert 1 == 1
+
+1 == 1
+
+assert 1 in (1, 2)
+
+1 in (1, 2)
+
+
+if 1 == 2:
+    pass
+
+
+def test():
+    assert 1 in (1, 2)
+
+    1 in (1, 2)
+
+
+data = [x for x in [1, 2, 3] if x in (1, 2)]
+
+
+class TestClass:
+    1 == 1
+
+
+print(1 == 1)

resources/test/fixtures/B016.py

@@ -0,0 +1,11 @@
+"""
+Should emit:
+B016 - on lines 6, 7, and 8
+"""
+
+raise False
+raise 1
+raise "string"
+raise Exception(False)
+raise Exception(1)
+raise Exception("string")

resources/test/fixtures/B017.py

@@ -0,0 +1,36 @@
+"""
+Should emit:
+B017 - on lines 20
+"""
+import asyncio
+import unittest
+
+CONSTANT = True
+
+
+def something_else() -> None:
+    for i in (1, 2, 3):
+        print(i)
+
+
+class Foo:
+    pass
+
+
+class Foobar(unittest.TestCase):
+    def evil_raises(self) -> None:
+        with self.assertRaises(Exception):
+            raise Exception("Evil I say!")
+
+    def context_manager_raises(self) -> None:
+        with self.assertRaises(Exception) as ex:
+            raise Exception("Context manager is good")
+        self.assertEqual("Context manager is good", str(ex.exception))
+
+    def regex_raises(self) -> None:
+        with self.assertRaisesRegex(Exception, "Regex is good"):
+            raise Exception("Regex is good")
+
+    def raises_with_absolute_reference(self):
+        with self.assertRaises(asyncio.CancelledError):
+            Foo()

resources/test/fixtures/B018.py

@@ -0,0 +1,59 @@
+class Foo1:
+    """abc"""
+
+
+class Foo2:
+    """abc"""
+
+    a = 2
+    "str"  # Str (no raise)
+    f"{int}"  # JoinedStr (no raise)
+    1j  # Number (complex)
+    1  # Number (int)
+    1.0  # Number (float)
+    b"foo"  # Binary
+    True  # NameConstant (True)
+    False  # NameConstant (False)
+    None  # NameConstant (None)
+    [1, 2]  # list
+    {1, 2}  # set
+    {"foo": "bar"}  # dict
+
+
+class Foo3:
+    123
+    a = 2
+    "str"
+    1
+
+
+def foo1():
+    """my docstring"""
+
+
+def foo2():
+    """my docstring"""
+    a = 2
+    "str"  # Str (no raise)
+    f"{int}"  # JoinedStr (no raise)
+    1j  # Number (complex)
+    1  # Number (int)
+    1.0  # Number (float)
+    b"foo"  # Binary
+    True  # NameConstant (True)
+    False  # NameConstant (False)
+    None  # NameConstant (None)
+    [1, 2]  # list
+    {1, 2}  # set
+    {"foo": "bar"}  # dict
+
+
+def foo3():
+    123
+    a = 2
+    "str"
+    3
+
+
+def foo4():
+    ...

resources/test/fixtures/B019.py

@@ -0,0 +1,108 @@
+"""
+Should emit:
+B019 - on lines 73, 77, 81, 85, 89, 93, 97, 101
+"""
+import functools
+from functools import cache, cached_property, lru_cache
+
+
+def some_other_cache():
+    ...
+
+
+@functools.cache
+def compute_func(self, y):
+    ...
+
+
+class Foo:
+    def __init__(self, x):
+        self.x = x
+
+    def compute_method(self, y):
+        ...
+
+    @some_other_cache
+    def user_cached_instance_method(self, y):
+        ...
+
+    @classmethod
+    @functools.cache
+    def cached_classmethod(cls, y):
+        ...
+
+    @classmethod
+    @cache
+    def other_cached_classmethod(cls, y):
+        ...
+
+    @classmethod
+    @functools.lru_cache
+    def lru_cached_classmethod(cls, y):
+        ...
+
+    @classmethod
+    @lru_cache
+    def other_lru_cached_classmethod(cls, y):
+        ...
+
+    @staticmethod
+    @functools.cache
+    def cached_staticmethod(y):
+        ...
+
+    @staticmethod
+    @cache
+    def other_cached_staticmethod(y):
+        ...
+
+    @staticmethod
+    @functools.lru_cache
+    def lru_cached_staticmethod(y):
+        ...
+
+    @staticmethod
+    @lru_cache
+    def other_lru_cached_staticmethod(y):
+        ...
+
+    @functools.cached_property
+    def some_cached_property(self):
+        ...
+
+    @cached_property
+    def some_other_cached_property(self):
+        ...
+
+    # Remaining methods should emit B019
+    @functools.cache
+    def cached_instance_method(self, y):
+        ...
+
+    @cache
+    def another_cached_instance_method(self, y):
+        ...
+
+    @functools.cache()
+    def called_cached_instance_method(self, y):
+        ...
+
+    @cache()
+    def another_called_cached_instance_method(self, y):
+        ...
+
+    @functools.lru_cache
+    def lru_cached_instance_method(self, y):
+        ...
+
+    @lru_cache
+    def another_lru_cached_instance_method(self, y):
+        ...
+
+    @functools.lru_cache()
+    def called_lru_cached_instance_method(self, y):
+        ...
+
+    @lru_cache()
+    def another_called_lru_cached_instance_method(self, y):
+        ...

resources/test/fixtures/B020.py

@@ -0,0 +1,40 @@
+"""
+Should emit:
+B020 - on lines 8, 21, and 36
+"""
+
+items = [1, 2, 3]
+
+for items in items:
+    print(items)
+
+items = [1, 2, 3]
+
+for item in items:
+    print(item)
+
+values = {"secret": 123}
+
+for key, value in values.items():
+    print(f"{key}, {value}")
+
+for key, values in values.items():
+    print(f"{key}, {values}")
+
+# Variables defined in a comprehension are local in scope
+# to that comprehension and are therefore allowed.
+for var in [var for var in range(10)]:
+    print(var)
+
+for var in (var for var in range(10)):
+    print(var)
+
+for k, v in {k: v for k, v in zip(range(10), range(10, 20))}.items():
+    print(k, v)
+
+# However we still call out reassigning the iterable in the comprehension.
+for vars in [i for i in vars]:
+    print(vars)
+
+for var in sorted(range(10), key=lambda var: var.real):
+    print(var)

resources/test/fixtures/B021.py

@@ -0,0 +1,76 @@
+f"""
+Should emit:
+B021 - on lines 14, 22, 30, 38, 46, 54, 62, 70, 73
+"""
+
+VARIABLE = "world"
+
+
+def foo1():
+    """hello world!"""
+
+
+def foo2():
+    f"""hello {VARIABLE}!"""
+
+
+class bar1:
+    """hello world!"""
+
+
+class bar2:
+    f"""hello {VARIABLE}!"""
+
+
+def foo1():
+    """hello world!"""
+
+
+def foo2():
+    f"""hello {VARIABLE}!"""
+
+
+class bar1:
+    """hello world!"""
+
+
+class bar2:
+    f"""hello {VARIABLE}!"""
+
+
+def foo1():
+    "hello world!"
+
+
+def foo2():
+    f"hello {VARIABLE}!"
+
+
+class bar1:
+    "hello world!"
+
+
+class bar2:
+    f"hello {VARIABLE}!"
+
+
+def foo1():
+    "hello world!"
+
+
+def foo2():
+    f"hello {VARIABLE}!"
+
+
+class bar1:
+    "hello world!"
+
+
+class bar2:
+    f"hello {VARIABLE}!"
+
+
+def baz():
+    f"""I'm probably a docstring: {VARIABLE}!"""
+    print(f"""I'm a normal string""")
+    f"""Don't detect me!"""

resources/test/fixtures/B022.py

@@ -0,0 +1,23 @@
+"""
+Should emit:
+B022 - on lines 8
+"""
+
+import contextlib
+from contextlib import suppress
+
+with contextlib.suppress():
+    raise ValueError
+
+with suppress():
+    raise ValueError
+
+with contextlib.suppress(ValueError):
+    raise ValueError
+
+exceptions_to_suppress = []
+if True:
+    exceptions_to_suppress.append(ValueError)
+
+with contextlib.suppress(*exceptions_to_suppress):
+    raise

resources/test/fixtures/B023.py

@@ -0,0 +1,82 @@
+"""
+Should emit:
+B023 - on lines 12, 13, 16, 28, 29, 30, 31, 40, 42, 50, 51, 52, 53, 61, 68.
+"""
+
+functions = []
+z = 0
+
+for x in range(3):
+    y = x + 1
+    # Subject to late-binding problems
+    functions.append(lambda: x)
+    functions.append(lambda: y)  # not just the loop var
+
+    def f_bad_1():
+        return x
+
+    # Actually OK
+    functions.append(lambda x: x * 2)
+    functions.append(lambda x=x: x)
+    functions.append(lambda: z)  # OK because not assigned in the loop
+
+    def f_ok_1(x):
+        return x * 2
+
+
+def check_inside_functions_too():
+    ls = [lambda: x for x in range(2)]
+    st = {lambda: x for x in range(2)}
+    gn = (lambda: x for x in range(2))
+    dt = {x: lambda: x for x in range(2)}
+
+
+async def pointless_async_iterable():
+    yield 1
+
+
+async def container_for_problems():
+    async for x in pointless_async_iterable():
+        functions.append(lambda: x)
+
+    [lambda: x async for x in pointless_async_iterable()]
+
+
+a = 10
+b = 0
+while True:
+    a = a_ = a - 1
+    b += 1
+    functions.append(lambda: a)
+    functions.append(lambda: a_)
+    functions.append(lambda: b)
+    functions.append(lambda: c)  # not a name error because of late binding!
+    c: bool = a > 3
+    if not c:
+        break
+
+# Nested loops should not duplicate reports
+for j in range(2):
+    for k in range(3):
+        lambda: j * k
+
+
+for j, k, l in [(1, 2, 3)]:
+
+    def f():
+        j = None  # OK because it's an assignment
+        [l for k in range(2)]  # error for l, not for k
+
+        assert a and functions
+
+    a.attribute = 1  # modifying an attribute doesn't make it a loop variable
+    functions[0] = lambda: None  # same for an element
+
+for var in range(2):
+
+    def explicit_capture(captured=var):
+        return captured
+
+
+for i in range(3):
+    lambda: f"{i}"

resources/test/fixtures/B024.py

@@ -0,0 +1,129 @@
+"""
+Should emit:
+B024 - on lines 17, 34, 52, 58, 69, 74, 79, 84, 89
+"""
+
+import abc
+import abc as notabc
+from abc import ABC, ABCMeta
+from abc import abstractmethod
+from abc import abstractmethod as abstract
+from abc import abstractmethod as abstractaoeuaoeuaoeu
+from abc import abstractmethod as notabstract
+
+import foo
+
+
+class Base_1(ABC):  # error
+    def method(self):
+        foo()
+
+
+class Base_2(ABC):
+    @abstractmethod
+    def method(self):
+        foo()
+
+
+class Base_3(ABC):
+    @abc.abstractmethod
+    def method(self):
+        foo()
+
+
+class Base_4(ABC):
+    @notabc.abstractmethod
+    def method(self):
+        foo()
+
+
+class Base_5(ABC):
+    @abstract
+    def method(self):
+        foo()
+
+
+class Base_6(ABC):
+    @abstractaoeuaoeuaoeu
+    def method(self):
+        foo()
+
+
+class Base_7(ABC):  # error
+    @notabstract
+    def method(self):
+        foo()
+
+
+class MetaBase_1(metaclass=ABCMeta):  # error
+    def method(self):
+        foo()
+
+
+class MetaBase_2(metaclass=ABCMeta):
+    @abstractmethod
+    def method(self):
+        foo()
+
+
+class abc_Base_1(abc.ABC):  # error
+    def method(self):
+        foo()
+
+
+class abc_Base_2(metaclass=abc.ABCMeta):  # error
+    def method(self):
+        foo()
+
+
+class notabc_Base_1(notabc.ABC):  # error
+    def method(self):
+        foo()
+
+
+class multi_super_1(notabc.ABC, abc.ABCMeta):  # safe
+    def method(self):
+        foo()
+
+
+class multi_super_2(notabc.ABC, metaclass=abc.ABCMeta):  # safe
+    def method(self):
+        foo()
+
+
+class non_keyword_abcmeta_1(ABCMeta):  # safe
+    def method(self):
+        foo()
+
+
+class non_keyword_abcmeta_2(abc.ABCMeta):  # safe
+    def method(self):
+        foo()
+
+
+# very invalid code, but that's up to mypy et al to check
+class keyword_abc_1(metaclass=ABC):  # safe
+    def method(self):
+        foo()
+
+
+class keyword_abc_2(metaclass=abc.ABC):  # safe
+    def method(self):
+        foo()
+
+
+class abc_set_class_variable_1(ABC):  # safe
+    foo: int
+
+
+class abc_set_class_variable_2(ABC):  # safe
+    foo = 2
+
+
+class abc_set_class_variable_3(ABC):  # safe
+    foo: int = 2
+
+
+# this doesn't actually declare a class variable, it's just an expression
+class abc_set_class_variable_4(ABC):  # error
+    foo

resources/test/fixtures/B025.py

@@ -0,0 +1,38 @@
+"""
+Should emit:
+B025 - on lines 15, 22, 31
+"""
+
+import pickle
+
+try:
+    a = 1
+except ValueError:
+    a = 2
+finally:
+    a = 3
+
+try:
+    a = 1
+except ValueError:
+    a = 2
+except ValueError:
+    a = 2
+
+try:
+    a = 1
+except pickle.PickleError:
+    a = 2
+except ValueError:
+    a = 2
+except pickle.PickleError:
+    a = 2
+
+try:
+    a = 1
+except (ValueError, TypeError):
+    a = 2
+except ValueError:
+    a = 2
+except (OSError, TypeError):
+    a = 2

resources/test/fixtures/B026.py

@@ -0,0 +1,21 @@
+"""
+Should emit:
+B026 - on lines 16, 17, 18, 19, 20, 21
+"""
+
+
+def foo(bar, baz, bam):
+    print(bar, baz, bam)
+
+
+bar_baz = ["bar", "baz"]
+
+foo("bar", "baz", bam="bam")
+foo("bar", baz="baz", bam="bam")
+foo(bar="bar", baz="baz", bam="bam")
+foo(bam="bam", *["bar", "baz"])
+foo(bam="bam", *bar_baz)
+foo(baz="baz", bam="bam", *["bar"])
+foo(bar="bar", baz="baz", bam="bam", *[])
+foo(bam="bam", *["bar"], *["baz"])
+foo(*["bar"], bam="bam", *["baz"])

resources/test/fixtures/B027.py

@@ -0,0 +1,88 @@
+"""
+Should emit:
+B027 - on lines 12, 15, 18, 22, 30
+"""
+import abc
+from abc import ABC
+from abc import abstractmethod
+from abc import abstractmethod as notabstract
+
+
+class AbstractClass(ABC):
+    def empty_1(self):  # error
+        ...
+
+    def empty_2(self):  # error
+        pass
+
+    def empty_3(self):  # error
+        """docstring"""
+        ...
+
+    def empty_4(self):  # error
+        """multiple ellipsis/pass"""
+        ...
+        pass
+        ...
+        pass
+
+    @notabstract
+    def abstract_0(self):
+        ...
+
+    @abstractmethod
+    def abstract_1(self):
+        ...
+
+    @abstractmethod
+    def abstract_2(self):
+        pass
+
+    @abc.abstractmethod
+    def abstract_3(self):
+        ...
+
+    def body_1(self):
+        print("foo")
+        ...
+
+    def body_2(self):
+        self.body_1()
+
+
+class NonAbstractClass:
+    def empty_1(self):  # safe
+        ...
+
+    def empty_2(self):  # safe
+        pass
+
+
+# ignore @overload, fixes issue #304
+# ignore overload with other imports, fixes #308
+import typing
+import typing as t
+import typing as anything
+from typing import Union, overload
+
+
+class AbstractClass(ABC):
+    @overload
+    def empty_1(self, foo: str):
+        ...
+
+    @typing.overload
+    def empty_1(self, foo: int):
+        ...
+
+    @t.overload
+    def empty_1(self, foo: list):
+        ...
+
+    @anything.overload
+    def empty_1(self, foo: float):
+        ...
+
+    @abstractmethod
+    def empty_1(self, foo: Union[str, int, list, float]):
+        ...

resources/test/fixtures/B904.py

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

resources/test/fixtures/BLE.py

@@ -0,0 +1,55 @@
+try:
+    pass
+except ValueError:
+    pass
+except Exception as e:
+    raise e
+finally:
+    pass
+
+
+try:
+    pass
+except BaseException as e:
+    raise e
+except TypeError:
+    pass
+else:
+    pass
+
+
+try:
+    pass
+except Exception as e:
+    raise e
+except BaseException:
+    pass
+
+
+try:
+    pass
+except Exception:
+    pass
+finally:
+    try:
+        pass
+    except BaseException as e:
+        raise e
+
+
+try:
+    pass
+except Exception as e:
+    try:
+        raise e
+    except BaseException:
+        pass
+
+
+try:
+    try:
+        pass
+    except BaseException as e:
+        raise e
+except Exception:
+    pass

resources/test/fixtures/C400.py

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

resources/test/fixtures/C401.py

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

resources/test/fixtures/C402.py

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

resources/test/fixtures/C403.py

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

resources/test/fixtures/C404.py

@@ -1 +1,2 @@
-d = dict([(i, i) for i in range(3)])
+dict([(i, i) for i in range(3)])
+dict([(i, i) for i in range(3)], z=4)

resources/test/fixtures/C409.py

@@ -0,0 +1,10 @@
+t1 = tuple([])
+t2 = tuple([1, 2])
+t3 = tuple((1, 2))
+t4 = tuple([
+    1,
+    2
+])
+t5 = tuple(
+    (1, 2)
+)

resources/test/fixtures/C410.py

@@ -0,0 +1,4 @@
+l1 = list([1, 2])
+l2 = list((1, 2))
+l3 = list([])
+l4 = list(())

resources/test/fixtures/C411.py

@@ -0,0 +1,2 @@
+x = [1, 2, 3]
+list([i for i in x])

resources/test/fixtures/C413.py

@@ -0,0 +1,6 @@
+x = [2, 3, 1]
+list(x)
+list(sorted(x))
+reversed(sorted(x))
+reversed(sorted(x, key=lambda e: e))
+reversed(sorted(x, reverse=True))

resources/test/fixtures/C414.py

@@ -0,0 +1,14 @@
+x = [1, 2, 3]
+list(list(x))
+list(tuple(x))
+tuple(list(x))
+tuple(tuple(x))
+set(set(x))
+set(list(x))
+set(tuple(x))
+set(sorted(x))
+set(reversed(x))
+sorted(list(x))
+sorted(tuple(x))
+sorted(sorted(x))
+sorted(reversed(x))

resources/test/fixtures/C415.py

@@ -0,0 +1,9 @@
+lst = [2, 1, 3]
+a = set(lst[::-1])
+b = reversed(lst[::-1])
+c = sorted(lst[::-1])
+d = sorted(lst[::-1], reverse=True)
+e = set(lst[2:-1])
+f = set(lst[:1:-1])
+g = set(lst[::1])
+h = set(lst[::-2])

resources/test/fixtures/C416.py

@@ -0,0 +1,6 @@
+x = [1, 2, 3]
+[i for i in x]
+{i for i in x}
+
+[i for i in x if i > 1]
+[i for i in x for j in x]

resources/test/fixtures/C417.py

@@ -0,0 +1,6 @@
+nums = [1, 2, 3]
+map(lambda x: x + 1, nums)
+map(lambda x: str(x), nums)
+list(map(lambda x: x * 2, nums))
+set(map(lambda x: x % 2 == 0, nums))
+dict(map(lambda v: (v, v**2), nums))

resources/test/fixtures/C901.py

@@ -0,0 +1,138 @@
+# Complexity = 1
+def trivial():
+    pass
+
+
+# Complexity = 1
+def expr_as_statement():
+    0xF00D
+
+
+# Complexity = 1
+def sequential(n):
+    k = n + 4
+    s = k + n
+    return s
+
+
+# Complexity = 3
+def if_elif_else_dead_path(n):
+    if n > 3:
+        return "bigger than three"
+    elif n > 4:
+        return "is never executed"
+    else:
+        return "smaller than or equal to three"
+
+
+# Complexity = 3
+def nested_ifs():
+    if n > 3:
+        if n > 4:
+            return "bigger than four"
+        else:
+            return "bigger than three"
+    else:
+        return "smaller than or equal to three"
+
+
+# Complexity = 2
+def for_loop():
+    for i in range(10):
+        print(i)
+
+
+# Complexity = 2
+def for_else(mylist):
+    for i in mylist:
+        print(i)
+    else:
+        print(None)
+
+
+# Complexity = 2
+def recursive(n):
+    if n > 4:
+        return f(n - 1)
+    else:
+        return n
+
+
+# Complexity = 3
+def nested_functions():
+    def a():
+        def b():
+            pass
+
+        b()
+
+    a()
+
+
+# Complexity = 4
+def try_else():
+    try:
+        print(1)
+    except TypeA:
+        print(2)
+    except TypeB:
+        print(3)
+    else:
+        print(4)
+
+
+# Complexity = 3
+def nested_try_finally():
+    try:
+        try:
+            print(1)
+        finally:
+            print(2)
+    finally:
+        print(3)
+
+
+# Complexity = 3
+async def foobar(a, b, c):
+    await whatever(a, b, c)
+    if await b:
+        pass
+    async with c:
+        pass
+    async for x in a:
+        pass
+
+
+# Complexity = 1
+def annotated_assign():
+    x: Any = None
+
+
+# Complexity = 9
+class Class:
+    def handle(self, *args, **options):
+        if args:
+            return
+
+        class ServiceProvider:
+            def a(self):
+                pass
+
+            def b(self, data):
+                if not args:
+                    pass
+
+        class Logger:
+            def c(*args, **kwargs):
+                pass
+
+            def error(self, message):
+                pass
+
+            def info(self, message):
+                pass
+
+            def exception(self):
+                pass
+
+        return ServiceProvider(Logger())

resources/test/fixtures/D.py

@@ -0,0 +1,573 @@
+# No docstring, so we can test D100
+from functools import wraps
+import os
+from .expected import Expectation
+from typing import overload
+from typing_extensions import override
+
+
+expectation = Expectation()
+expect = expectation.expect
+
+expect('class_', 'D101: Missing docstring in public class')
+
+
+class class_:
+
+    expect('meta', 'D419: Docstring is empty')
+
+    class meta:
+        """"""
+
+    @expect('D102: Missing docstring in public method')
+    def method(self=None):
+        pass
+
+    def _ok_since_private(self=None):
+        pass
+
+    @overload
+    def overloaded_method(self, a: int) -> str:
+        ...
+
+    @overload
+    def overloaded_method(self, a: str) -> str:
+        """Foo bar documentation."""
+        ...
+
+    def overloaded_method(a):
+        """Foo bar documentation."""
+        return str(a)
+
+    expect('overloaded_method',
+           "D418: Function/ Method decorated with @overload"
+           " shouldn't contain a docstring")
+
+    @override
+    def overridden_method(a):
+        return str(a)
+
+    @property
+    def foo(self):
+        """The foo of the thing, which isn't in imperative mood."""
+        return "hello"
+
+    @expect('D102: Missing docstring in public method')
+    def __new__(self=None):
+        pass
+
+    @expect('D107: Missing docstring in __init__')
+    def __init__(self=None):
+        pass
+
+    @expect('D105: Missing docstring in magic method')
+    def __str__(self=None):
+        pass
+
+    @expect('D102: Missing docstring in public method')
+    def __call__(self=None, x=None, y=None, z=None):
+        pass
+
+
+@expect('D419: Docstring is empty')
+def function():
+    """ """
+    def ok_since_nested():
+        pass
+
+    @expect('D419: Docstring is empty')
+    def nested():
+        ''
+
+
+def function_with_nesting():
+    """Foo bar documentation."""
+    @overload
+    def nested_overloaded_func(a: int) -> str:
+        ...
+
+    @overload
+    def nested_overloaded_func(a: str) -> str:
+        """Foo bar documentation."""
+        ...
+
+    def nested_overloaded_func(a):
+        """Foo bar documentation."""
+        return str(a)
+
+
+expect('nested_overloaded_func',
+       "D418: Function/ Method decorated with @overload"
+       " shouldn't contain a docstring")
+
+
+@overload
+def overloaded_func(a: int) -> str:
+    ...
+
+
+@overload
+def overloaded_func(a: str) -> str:
+    """Foo bar documentation."""
+    ...
+
+
+def overloaded_func(a):
+    """Foo bar documentation."""
+    return str(a)
+
+
+expect('overloaded_func',
+       "D418: Function/ Method decorated with @overload"
+       " shouldn't contain a docstring")
+
+
+@expect('D200: One-line docstring should fit on one line with quotes '
+        '(found 3)')
+@expect('D212: Multi-line docstring summary should start at the first line')
+def asdlkfasd():
+    """
+    Wrong.
+    """
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+def leading_space():
+
+    """Leading space."""
+
+
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+def trailing_space():
+    """Leading space."""
+
+    pass
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+def trailing_and_leading_space():
+
+    """Trailing and leading space."""
+
+    pass
+
+
+expect('LeadingSpaceMissing',
+       'D203: 1 blank line required before class docstring (found 0)')
+
+
+class LeadingSpaceMissing:
+    """Leading space missing."""
+
+
+expect('WithLeadingSpace',
+       'D211: No blank lines allowed before class docstring (found 1)')
+
+
+class WithLeadingSpace:
+
+    """With leading space."""
+
+
+expect('TrailingSpace',
+       'D204: 1 blank line required after class docstring (found 0)')
+expect('TrailingSpace',
+       'D211: No blank lines allowed before class docstring (found 1)')
+
+
+class TrailingSpace:
+
+    """TrailingSpace."""
+    pass
+
+
+expect('LeadingAndTrailingSpaceMissing',
+       'D203: 1 blank line required before class docstring (found 0)')
+expect('LeadingAndTrailingSpaceMissing',
+       'D204: 1 blank line required after class docstring (found 0)')
+
+
+class LeadingAndTrailingSpaceMissing:
+    """Leading and trailing space missing."""
+    pass
+
+
+@expect('D205: 1 blank line required between summary line and description '
+        '(found 0)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_zero_separating_blanks():
+    """Summary.
+    Description.
+
+    """
+
+
+@expect('D205: 1 blank line required between summary line and description '
+        '(found 2)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_two_separating_blanks():
+    """Summary.
+
+
+    Description.
+
+    """
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multi_line_one_separating_blanks():
+    """Summary.
+
+    Description.
+
+    """
+
+
+@expect('D207: Docstring is under-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdf():
+    """Summary.
+
+Description.
+
+    """
+
+
+@expect('D207: Docstring is under-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdsdfsdffsdf():
+    """Summary.
+
+    Description.
+
+"""
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdsdf24():
+    """Summary.
+
+       Description.
+
+    """
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdsdfsdf24():
+    """Summary.
+
+    Description.
+
+        """
+
+
+@expect('D208: Docstring is over-indented')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfsdfsdsdsdfsdf24():
+    """Summary.
+
+        Description.
+
+    """
+
+
+@expect('D209: Multi-line docstring closing quotes should be on a separate '
+        'line')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def asdfljdf24():
+    """Summary.
+
+    Description."""
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+def endswith():
+    """Whitespace at the end. """
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+def around():
+    """ Whitespace at everywhere. """
+
+
+@expect('D210: No whitespaces allowed surrounding docstring text')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multiline():
+    """ Whitespace at the beginning.
+
+    This is the end.
+    """
+
+
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw():
+    r'''Summary.'''
+
+
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw_uppercase():
+    R'''Summary.'''
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw():
+    r'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw_uppercase():
+    R'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+@expect('D301: Use r""" if any backslashes in a docstring')
+def single_quotes_raw_uppercase_backslash():
+    R'Sum\mary.'
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash():
+    """Sum\\mary."""
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash_uppercase():
+    R"""Sum\\mary."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def exceptions_of_D301():
+    """Exclude some backslashes from D301.
+
+    In particular, line continuations \
+    and unicode literals \u0394 and \N{GREEK CAPITAL LETTER DELTA}.
+    They are considered to be intentionally unescaped.
+    """
+
+
+@expect("D400: First line should end with a period (not 'y')")
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'y')")
+def lwnlkjl():
+    """Summary"""
+
+
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Return', not 'Returns')")
+def liouiwnlkjl():
+    """Returns foo."""
+
+
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'Constructor')")
+def sdgfsdg23245():
+    """Constructor for a foo."""
+
+
+@expect("D401: First line should be in imperative mood; try rephrasing "
+        "(found 'Constructor')")
+def sdgfsdg23245777():
+    """Constructor."""
+
+
+@expect('D402: First line should not be the function\'s "signature"')
+def foobar():
+    """Signature: foobar()."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def new_209():
+    """First line.
+
+    More lines.
+    """
+    pass
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def old_209():
+    """One liner.
+
+    Multi-line comments. OK to have extra blank line
+
+    """
+
+
+@expect("D103: Missing docstring in public function")
+def oneliner_d102(): return
+
+
+@expect("D400: First line should end with a period (not 'r')")
+@expect("D415: First line should end with a period, question mark,"
+        " or exclamation point (not 'r')")
+def oneliner_withdoc(): """One liner"""
+
+
+def ignored_decorator(func):   # noqa: D400,D401,D415
+    """Runs something"""
+    func()
+    pass
+
+
+def decorator_for_test(func):   # noqa: D400,D401,D415
+    """Runs something"""
+    func()
+    pass
+
+
+@ignored_decorator
+def oneliner_ignored_decorator(): """One liner"""
+
+
+@decorator_for_test
+@expect("D400: First line should end with a period (not 'r')")
+@expect("D415: First line should end with a period, question mark,"
+        " or exclamation point (not 'r')")
+def oneliner_with_decorator_expecting_errors(): """One liner"""
+
+
+@decorator_for_test
+def valid_oneliner_with_decorator(): """One liner."""
+
+
+@expect("D207: Docstring is under-indented")
+@expect('D213: Multi-line docstring summary should start at the second line')
+def docstring_start_in_same_line(): """First Line.
+
+    Second Line
+    """
+
+
+def function_with_lambda_arg(x=lambda y: y):
+    """Wrap the given lambda."""
+
+
+@expect('D213: Multi-line docstring summary should start at the second line')
+def a_following_valid_function(x=None):
+    """Check for a bug where the previous function caused an assertion.
+
+    The assertion was caused in the next function, so this one is necessary.
+
+    """
+
+
+def outer_function():
+    """Do something."""
+    def inner_function():
+        """Do inner something."""
+        return 0
+
+
+@expect("D400: First line should end with a period (not 'g')")
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Run', not 'Runs')")
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'g')")
+def docstring_bad():
+    """Runs something"""
+    pass
+
+
+def docstring_bad_ignore_all():  # noqa
+    """Runs something"""
+    pass
+
+
+def docstring_bad_ignore_one():  # noqa: D400,D401,D415
+    """Runs something"""
+    pass
+
+
+@expect("D401: First line should be in imperative mood "
+        "(perhaps 'Run', not 'Runs')")
+def docstring_ignore_some_violations_but_catch_D401():  # noqa: E501,D400,D415
+    """Runs something"""
+    pass
+
+
+@expect(
+    "D401: First line should be in imperative mood "
+    "(perhaps 'Initiate', not 'Initiates')"
+)
+def docstring_initiates():
+    """Initiates the process."""
+
+
+@expect(
+    "D401: First line should be in imperative mood "
+    "(perhaps 'Initialize', not 'Initializes')"
+)
+def docstring_initializes():
+    """Initializes the process."""
+
+
+@wraps(docstring_bad_ignore_one)
+def bad_decorated_function():
+    """Bad (E501) but decorated"""
+    pass
+
+
+def valid_google_string():  # noqa: D400
+    """Test a valid something!"""
+
+
+@expect("D415: First line should end with a period, question mark, "
+        "or exclamation point (not 'g')")
+def bad_google_string():  # noqa: D400
+    """Test a valid something"""
+
+
+# This is reproducing a bug where AttributeError is raised when parsing class
+# parameters as functions for Google / Numpy conventions.
+class Blah:  # noqa: D203,D213
+    """A Blah.
+
+    Parameters
+    ----------
+    x : int
+
+    """
+
+    def __init__(self, x):
+        pass
+
+
+expect(os.path.normcase(__file__ if __file__[-1] != 'c' else __file__[:-1]),
+       'D100: Missing docstring in public module')
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multiline_leading_space():
+
+    """Leading space.
+
+    More content.
+    """
+
+
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multiline_trailing_space():
+    """Leading space.
+
+    More content.
+    """
+
+    pass
+
+
+@expect('D201: No blank lines allowed before function docstring (found 1)')
+@expect('D202: No blank lines allowed after function docstring (found 1)')
+@expect('D213: Multi-line docstring summary should start at the second line')
+def multiline_trailing_and_leading_space():
+
+    """Trailing and leading space.
+
+    More content.
+    """
+
+    pass

resources/test/fixtures/E501.py

@@ -5,7 +5,7 @@
 Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
 """
 
-_ = """Lorem ipsum dolor sit amet.
+_ = """Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
 
     https://github.com/PyCQA/pycodestyle/pull/258/files#diff-841c622497a8033d10152bfdfb15b20b92437ecdea21a260944ea86b77b51533
 
@@ -14,3 +14,41 @@ Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor i
 
 _ = "---------------------------------------------------------------------------AAAAAAA"
 _ = "---------------------------------------------------------------------------亜亜亜亜亜亜亜"
+
+
+def caller(string: str) -> None:
+    assert string is not None
+
+
+caller(
+    """
+    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+    """,
+)
+
+
+caller(
+    """
+    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+    """,  # noqa: E501
+)
+
+multiple_strings_per_line = {
+    # OK
+    "Lorem ipsum dolor": "sit amet",
+    # E501 Line too long
+    "Lorem ipsum dolor": "sit amet consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
+    # E501 Line too long
+    "Lorem ipsum dolor": """
+sit amet  consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+""",
+    # OK
+    "Lorem ipsum dolor": "sit amet consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",  # noqa: E501
+    # OK
+    "Lorem ipsum dolor": """
+sit amet  consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+""",  # noqa: E501
+}
+
+# OK
+# A very long URL: https://loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong.url.com

resources/test/fixtures/E711.py

@@ -23,6 +23,9 @@ if None != res[1]:
 if None == res[1]:
     pass
 
+if x == None != None:
+    pass
+
 #: Okay
 if x not in y:
     pass

resources/test/fixtures/E712.py

@@ -22,6 +22,9 @@ var = 1 if cond == True else -1 if cond == False else cond
 if (True) == TrueElement or x == TrueElement:
     pass
 
+if res == True != False:
+    pass
+
 #: Okay
 if x not in y:
     pass

resources/test/fixtures/E731.py

@@ -8,14 +8,14 @@ while False:
 
 
 f = object()
-#: E731
 f.method = lambda: "Method"
 
 f = {}
-#: E731
 f["a"] = lambda x: x ** 2
 
 f = []
 f.append(lambda x: x ** 2)
 
+f = g = lambda x: x ** 2
+
 lambda: "no-op"

resources/test/fixtures/F401_0.py

@@ -28,7 +28,6 @@ from blah import ClassA, ClassB, ClassC
 if TYPE_CHECKING:
     from models import Fruit, Nut, Vegetable
 
-
 if TYPE_CHECKING:
     import shelve
     import importlib
@@ -61,7 +60,28 @@ Y = TypeVar("Y", bound="Dict")
 Z = TypeVar("Z", "List", "Set")
 
 a = list["Fruit"]
-b = Union["Nut", None]
+b = Union["""Nut""", None]
 c = cast("Vegetable", b)
 
 Field = lambda default=MISSING: field(default=default)
+
+
+# Test: access a sub-importation via an alias.
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))
+
+
+# Test: referencing an import via TypeAlias.
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_1.py

@@ -0,0 +1,5 @@
+"""Access a sub-importation via an alias."""
+import pyarrow as pa
+import pyarrow.csv
+
+print(pa.csv.read_csv("test.csv"))

resources/test/fixtures/F401_2.py

@@ -0,0 +1,12 @@
+"""Test: referencing an import via TypeAlias."""
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_3.py

@@ -0,0 +1,14 @@
+"""Test: referencing an import via TypeAlias (with future annotations)."""
+from __future__ import annotations
+
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = np.int8 | np.int16

resources/test/fixtures/F401_4.py

@@ -0,0 +1,14 @@
+"""Test: referencing an import via TypeAlias (with future annotations and quotes)."""
+from __future__ import annotations
+
+import sys
+
+import numpy as np
+
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
+
+CustomInt: TypeAlias = "np.int8 | np.int16"

resources/test/fixtures/F401_5.py

@@ -0,0 +1,5 @@
+"""Test: removal of multi-segment and aliases imports."""
+from a.b import c
+from d.e import f as g
+import h.i
+import j.k as l

resources/test/fixtures/F401_6.py

@@ -0,0 +1,20 @@
+"""Test: explicit re-export."""
+
+# OK
+from .applications import FastAPI as FastAPI
+
+# F401 `background.BackgroundTasks` imported but unused
+from .background import BackgroundTasks
+
+# F401 `datastructures.UploadFile` imported but unused
+from .datastructures import UploadFile as FileUpload
+
+
+# OK
+import applications as applications
+
+# F401 `background` imported but unused
+import background
+
+# F401 `datastructures` imported but unused
+import datastructures as structures

resources/test/fixtures/F404.py

@@ -1,4 +1,3 @@
-from __future__ import print_function
 """Docstring"""
 from __future__ import absolute_import
 

resources/test/fixtures/F502.py

@@ -0,0 +1,13 @@
+dog = {"bob": "bob"}
+
+"%(bob)s" % dog
+"%(bob)s" % {"bob": "bob"}
+"%(bob)s" % {**{"bob": "bob"}}
+"%(bob)s" % ["bob"]  # F202
+"%(bob)s" % ("bob",)  # F202
+"%(bob)s" % {"bob"}  # F202
+"%(bob)s" % [*["bob"]]  # F202
+"%(bob)s" % {"bob": "bob" for _ in range(1)}
+"%(bob)s" % ["bob" for _ in range(1)]  # F202
+"%(bob)s" % ("bob" for _ in range(1))  # F202
+"%(bob)s" % {"bob" for _ in range(1)}  # F202

resources/test/fixtures/F503.py

@@ -0,0 +1,26 @@
+dog = {"bob": "bob"}
+
+# Single placeholder always fine
+"%s" % dog
+"%s" % {"bob": "bob"}
+"%s" % {**{"bob": "bob"}}
+"%s" % ["bob"]
+"%s" % ("bob",)
+"%s" % {"bob"}
+"%s" % [*["bob"]]
+"%s" % {"bob": "bob" for _ in range(1)}
+"%s" % ["bob" for _ in range(1)]
+"%s" % ("bob" for _ in range(1))
+"%s" % {"bob" for _ in range(1)}
+# Multiple placeholders
+"%s %s" % dog
+"%s %s" % {"bob": "bob"}  # F503
+"%s %s" % {**{"bob": "bob"}}  # F503
+"%s %s" % ["bob"]
+"%s %s" % ("bob",)
+"%s %s" % {"bob"}
+"%s %s" % [*["bob"]]
+"%s %s" % {"bob": "bob" for _ in range(1)}  # F503
+"%s %s" % ["bob" for _ in range(1)]
+"%s %s" % ("bob" for _ in range(1))
+"%s %s" % {"bob" for _ in range(1)}

resources/test/fixtures/F504.py

@@ -0,0 +1,6 @@
+# Ruff has no way of knowing if the following are F505s
+a = "wrong"
+"%(a)s %(c)s" % {a: "?", "b": "!"}  # F504 ("b" not used)
+
+hidden = {"a": "!"}
+"%(a)s %(c)s" % {"x": 1, **hidden}  # Ok (cannot see through splat)

resources/test/fixtures/F50x.py

@@ -0,0 +1,25 @@
+'%(foo)' % {'foo': 'bar'}  # F501
+'%s %(foo)s' % {'foo': 'bar'}  # F506
+'%(foo)s %s' % {'foo': 'bar'}  # F506
+'%j' % (1,)  # F509
+'%s %s' % (1,)  # F507
+'%s %s' % (1, 2, 3)  # F507
+'%(bar)s' % {}  # F505
+'%(bar)s' % {'bar': 1, 'baz': 2}  # F504
+'%(bar)s' % (1, 2, 3)  # F502
+'%s %s' % {'k': 'v'}  # F503
+'%(bar)*s' % {'bar': 'baz'}  # F506, F508
+
+# ok: single %s with mapping
+'%s' % {'foo': 'bar', 'baz': 'womp'}
+# ok: %% should not count towards placeholder count
+'%% %s %% %s' % (1, 2)
+# ok: * consumes one positional argument
+'%.*f' % (2, 1.1234)
+'%*.*f' % (5, 2, 3.1234)
+# ok *args and **kwargs
+a = []
+'%s %s' % [*a]
+'%s %s' % (*a,)
+k = {}
+'%(k)s' % {**k}

resources/test/fixtures/F521.py

@@ -0,0 +1,21 @@
+"{".format(1)
+"}".format(1)
+"{foo[}".format(foo=1)
+# too much string recursion (placeholder-in-placeholder)
+"{:{:{}}}".format(1, 2, 3)
+# ruff picks these issues up, but flake8 doesn't
+"{foo[]}".format(foo={"": 1})
+"{foo..}".format(foo=1)
+"{foo..bar}".format(foo=1)
+
+# The following are all "good" uses of .format
+"{.__class__}".format("")
+"{foo[bar]}".format(foo={"bar": "barv"})
+"{[bar]}".format({"bar": "barv"})
+"{:{}} {}".format(1, 15, 2)
+"{:2}".format(1)
+"{foo}-{}".format(1, foo=2)
+a = ()
+"{}".format(*a)
+k = {}
+"{foo}".format(**k)

resources/test/fixtures/F522.py

@@ -0,0 +1,4 @@
+"{}".format(1, bar=2)  # F522
+"{bar}{}".format(1, bar=2, spam=3)  # F522
+"{bar:{spam}}".format(bar=2, spam=3)  # No issues
+"{bar:{spam}}".format(bar=2, spam=3, eggs=4, ham=5)  # F522

resources/test/fixtures/F523.py

@@ -0,0 +1,12 @@
+# With indexes
+"{0}".format(1, 2)  # F523
+"{1}".format(1, 2, 3)  # F523
+"{1:{0}}".format(1, 2)  # No issues
+"{1:{0}}".format(1, 2, 3)  # F523
+"{0}{2}".format(1, 2)  # F523, # F524
+
+# With no indexes
+"{}".format(1, 2)  # F523
+"{}".format(1, 2, 3)  # F523
+"{:{}}".format(1, 2)  # No issues
+"{:{}}".format(1, 2, 3)  # F523

resources/test/fixtures/F524.py

@@ -0,0 +1,6 @@
+"{} {}".format(1)  # F524
+"{2}".format()  # F524
+"{bar}".format()  # F524
+"{0} {bar}".format(1)  # F524
+"{0} {bar}".format()  # F524
+"{bar} {0}".format()  # F524

resources/test/fixtures/F525.py

@@ -0,0 +1,2 @@
+"{} {1}".format(1, 2)  # F525
+"{0} {}".format(1, 2)  # F523, F525

resources/test/fixtures/F632.py

@@ -3,3 +3,6 @@ if x is "abc":
 
 if 123 is not y:
     pass
+
+if "123" is x < 3:
+    pass

resources/test/fixtures/F821_0.py

@@ -122,3 +122,12 @@ class PEP593Test:
         dict["foo", "bar"],  # Expected to fail as undefined.
         123,
     ]
+
+
+def in_ipython_notebook() -> bool:
+    try:
+        # autoimported by notebooks
+        get_ipython()  # type: ignore[name-defined]
+    except NameError:
+        return False  # not in notebook
+    return True

resources/test/fixtures/F821_1.py

@@ -0,0 +1,30 @@
+"""Test: typing module imports."""
+from foo import cast
+
+# OK
+x = cast("Model")
+
+from typing import cast
+
+
+# F821 Undefined name `Model`
+x = cast("Model", x)
+
+
+import typing
+
+
+# F821 Undefined name `Model`
+x = typing.cast("Model", x)
+
+
+from typing import Pattern
+
+# F821 Undefined name `Model`
+x = Pattern["Model"]
+
+
+from typing.re import Match
+
+# F821 Undefined name `Model`
+x = Match["Model"]

resources/test/fixtures/F821_2.py

@@ -0,0 +1,18 @@
+"""Test: typing_extensions module imports."""
+from foo import Literal
+
+# F821 Undefined name `Model`
+x: Literal["Model"]
+
+from typing_extensions import Literal
+
+
+# OK
+x: Literal["Model"]
+
+
+import typing_extensions
+
+
+# OK
+x: typing_extensions.Literal["Model"]

resources/test/fixtures/F821_3.py

@@ -0,0 +1,24 @@
+"""Test (edge case): accesses of object named `dict`."""
+
+# OK
+dict = {"parameters": {}}
+dict["parameters"]["userId"] = "userId"
+dict["parameters"]["itemId"] = "itemId"
+del dict["parameters"]["itemId"]
+
+# F821 Undefined name `key`
+# F821 Undefined name `value`
+x: dict["key", "value"]
+
+# OK
+x: dict[str, str]
+
+# OK
+def unimportant(name):
+    pass
+
+
+def dang(dict, set, list):
+    unimportant(name=dict["name"])
+    unimportant(name=set["name"])
+    unimportant(name=list["name"])

resources/test/fixtures/F821_4.py

@@ -0,0 +1,24 @@
+"""Test: import alias tracking."""
+from typing import List
+
+_ = List["Model"]
+
+
+from typing import List as IList
+
+_ = IList["Model"]
+
+
+from collections.abc import ItemsView
+
+_ = ItemsView["Model"]
+
+
+import collections.abc
+
+_ = collections.abc.ItemsView["Model"]
+
+
+from collections import abc
+
+_ = abc.ItemsView["Model"]

resources/test/fixtures/F821_5.py

@@ -0,0 +1,14 @@
+"""Test: inner class annotation."""
+
+
+class RandomClass:
+    def random_func(self) -> "InnerClass":
+        pass
+
+
+class OuterClass:
+    class InnerClass:
+        pass
+
+    def failing_func(self) -> "InnerClass":
+        return self.InnerClass()

resources/test/fixtures/F841.py

@@ -35,3 +35,33 @@ def f4():
     _ = 1
     __ = 1
     _discarded = 1
+
+
+a = 1
+
+
+def f5():
+    global a
+
+    # Used in `f7` via `nonlocal`.
+    b = 1
+
+    def f6():
+        # F841
+        b = 1
+
+    def f7():
+        nonlocal b
+
+
+def f6():
+    annotations = []
+    assert len([annotations for annotations in annotations])
+
+
+def f7():
+    def connect():
+        return None, None
+
+    with connect() as (connection, cursor):
+        cursor.execute("SELECT * FROM users")

resources/test/fixtures/FBT.py

@@ -0,0 +1,42 @@
+def function(
+    posonly_nohint,
+    posonly_nonboolhint: int,
+    posonly_boolhint: bool,
+    posonly_boolstrhint: "bool",
+    /,
+    offset,
+    posorkw_nonvalued_nohint,
+    posorkw_nonvalued_nonboolhint: int,
+    posorkw_nonvalued_boolhint: bool,
+    posorkw_nonvalued_boolstrhint: "bool",
+    posorkw_boolvalued_nohint=True,
+    posorkw_boolvalued_nonboolhint: int = True,
+    posorkw_boolvalued_boolhint: bool = True,
+    posorkw_boolvalued_boolstrhint: "bool" = True,
+    posorkw_nonboolvalued_nohint=1,
+    posorkw_nonboolvalued_nonboolhint: int = 2,
+    posorkw_nonboolvalued_boolhint: bool = 3,
+    posorkw_nonboolvalued_boolstrhint: "bool" = 4,
+    *,
+    kwonly_nonvalued_nohint,
+    kwonly_nonvalued_nonboolhint: int,
+    kwonly_nonvalued_boolhint: bool,
+    kwonly_nonvalued_boolstrhint: "bool",
+    kwonly_boolvalued_nohint=True,
+    kwonly_boolvalued_nonboolhint: int = False,
+    kwonly_boolvalued_boolhint: bool = True,
+    kwonly_boolvalued_boolstrhint: "bool" = True,
+    kwonly_nonboolvalued_nohint=5,
+    kwonly_nonboolvalued_nonboolhint: int = 1,
+    kwonly_nonboolvalued_boolhint: bool = 1,
+    kwonly_nonboolvalued_boolstrhint: "bool" = 1,
+    **kw,
+):
+    ...
+
+
+def used(do):
+    return do
+
+used("a", True)
+used(do=True)

resources/test/fixtures/I252.py

@@ -0,0 +1,12 @@
+from . import sibling
+from .sibling import example
+
+from .. import parent
+from ..parent import example
+
+from ... import grandparent
+from ...grandparent import example
+
+import other
+import other.example
+from other import example