Bump version to 0.0.220

Note that the _annotation path_ is absolute, while the path encoded in
the message remains relative.

![Screen Shot 2023-01-12 at 5 54 11
PM](https://user-images.githubusercontent.com/1309177/212198531-63f15445-0f6a-471c-a64c-18ad2b6df0c7.png)

Closes #1835.

.github/ISSUE_TEMPLATE.md

@@ -4,7 +4,7 @@ Thank you for taking the time to report an issue! We're glad to have you involve
 If you're filing a bug report, please consider including the following information:
 
 - A minimal code snippet that reproduces the bug.
-- The command you invoked (e.g., `ruff /path/to/file.py --fix`).
+- The command you invoked (e.g., `ruff /path/to/file.py --fix`), ideally including the `--isolated` flag.
 - The current Ruff settings (any relevant sections from your `pyproject.toml`).
 - The current Ruff version (`ruff --version`).
 -->

.github/workflows/ci.yaml

@@ -26,21 +26,9 @@ jobs:
           profile: minimal
           toolchain: nightly-2022-11-01
           override: true
-          components: rustfmt
-      - uses: actions/cache@v3
-        env:
-          cache-name: cache-cargo
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache-name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
-      - run: cargo build --all --release
-      - run: ./target/release/ruff_dev generate-all
+      - uses: Swatinem/rust-cache@v1
+      - run: cargo build --all
+      - run: ./target/debug/ruff_dev generate-all
       - run: git diff --quiet README.md || echo "::error file=README.md::This file is outdated. Run 'cargo +nightly dev generate-all'."
       - run: git diff --quiet ruff.schema.json || echo "::error file=ruff.schema.json::This file is outdated. Run 'cargo +nightly dev generate-all'."
       - run: git diff --exit-code -- README.md ruff.schema.json
@@ -56,18 +44,6 @@ jobs:
           toolchain: nightly-2022-11-01
           override: true
           components: rustfmt
-      - uses: actions/cache@v3
-        env:
-          cache-name: cache-cargo
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache-name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
       - run: cargo fmt --all --check
 
   cargo_clippy:
@@ -82,18 +58,7 @@ jobs:
           override: true
           components: clippy
           target: wasm32-unknown-unknown
-      - uses: actions/cache@v3
-        env:
-          cache-name: cache-cargo
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache-name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
+      - uses: Swatinem/rust-cache@v1
       - run: cargo clippy --workspace --all-targets --all-features -- -D warnings -W clippy::pedantic
       - run: cargo clippy --workspace --target wasm32-unknown-unknown --all-features -- -D warnings -W clippy::pedantic
 
@@ -107,18 +72,7 @@ jobs:
           profile: minimal
           toolchain: nightly-2022-11-01
           override: true
-      - uses: actions/cache@v3
-        env:
-          cache-name: cache-cargo
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache-name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
+      - uses: Swatinem/rust-cache@v1
       - run: cargo install cargo-insta
       - run: pip install black[d]==22.12.0
       - name: Run tests
@@ -167,22 +121,11 @@ jobs:
           profile: minimal
           toolchain: nightly-2022-11-01
           override: true
+      - uses: Swatinem/rust-cache@v1
       - uses: actions/setup-python@v4
         with:
           python-version: "3.11"
       - run: pip install maturin
-      - uses: actions/cache@v3
-        env:
-          cache-name: cache-cargo
-        with:
-          path: |
-            ~/.cargo/registry
-            ~/.cargo/git
-          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/Cargo.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache-name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
       - run: maturin build -b bin
 
   typos:

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: v0.0.214
+    rev: v0.0.220
     hooks:
       - id: ruff
 

CONTRIBUTING.md

@@ -56,9 +56,9 @@ prior to merging.
 
 There are four phases to adding a new lint rule:
 
-1. Define the violation in `src/violations.rs` (e.g., `ModuleImportNotAtTopOfFile`).
-2. Map the violation to a code in `src/registry.rs` (e.g., `E402`).
-3. Define the _logic_ for triggering the violation in `src/checkers/ast.rs` (for AST-based checks),
+1. Define the violation struct in `src/violations.rs` (e.g., `ModuleImportNotAtTopOfFile`).
+2. Map the violation struct to a rule code in `src/registry.rs` (e.g., `E402`).
+3. Define the logic for triggering the violation in `src/checkers/ast.rs` (for AST-based checks),
    `src/checkers/tokens.rs` (for token-based checks), or `src/checkers/lines.rs` (for text-based checks).
 4. Add a test fixture.
 5. Update the generated files (documentation and generated code).
@@ -74,15 +74,16 @@ collecting diagnostics as it goes.
 If you need to inspect the AST, you can run `cargo +nightly 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/[plugin-name]`, named to match
-the code 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.
+To add a test fixture, create a file under `resources/test/fixtures/[origin]`, named to match
+the code you defined earlier (e.g., `resources/test/fixtures/pycodestyle/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 `cargo +nightly dev generate-all` to generate the code for your new fixture. Then run Ruff
 locally with (e.g.) `cargo run resources/test/fixtures/pycodestyle/E402.py --no-cache --select E402`.
 
 Once you're satisfied with the output, codify the behavior as a snapshot test by adding a new
-`test_case` macro in the relevant `src/[plugin-name]/mod.rs` file. Then, run `cargo test --all`.
+`test_case` macro in the relevant `src/[origin]/mod.rs` file. Then, run `cargo test --all`.
 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.
 

Cargo.lock

@@ -735,10 +735,11 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8-to-ruff"
-version = "0.0.214-dev.0"
+version = "0.0.220-dev.0"
 dependencies = [
  "anyhow",
  "clap 4.0.32",
+ "colored",
  "configparser",
  "once_cell",
  "regex",
@@ -1873,7 +1874,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.214"
+version = "0.0.220"
 dependencies = [
  "annotate-snippets 0.9.1",
  "anyhow",
@@ -1941,7 +1942,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_dev"
-version = "0.0.214"
+version = "0.0.220"
 dependencies = [
  "anyhow",
  "clap 4.0.32",
@@ -1961,7 +1962,7 @@ dependencies = [
 
 [[package]]
 name = "ruff_macros"
-version = "0.0.214"
+version = "0.0.220"
 dependencies = [
  "once_cell",
  "proc-macro2",

Cargo.toml

@@ -6,7 +6,7 @@ members = [
 
 [package]
 name = "ruff"
-version = "0.0.214"
+version = "0.0.220"
 authors = ["Charlie Marsh <charlie.r.marsh@gmail.com>"]
 edition = "2021"
 rust-version = "1.65.0"
@@ -19,6 +19,7 @@ license = "MIT"
 [lib]
 name = "ruff"
 crate-type = ["cdylib", "rlib"]
+doctest = false
 
 [dependencies]
 annotate-snippets = { version = "0.9.1", features = ["color"] }
@@ -29,7 +30,7 @@ bitflags = { version = "1.3.2" }
 cachedir = { version = "0.3.0" }
 cfg-if = { version = "1.0.0" }
 chrono = { version = "0.4.21", default-features = false, features = ["clock"] }
-clap = { version = "4.0.1", features = ["derive"] }
+clap = { version = "4.0.1", features = ["derive", "env"] }
 clap_complete_command = { version = "0.4.0" }
 colored = { version = "2.0.0" }
 dirs = { version = "4.0.0" }
@@ -51,7 +52,7 @@ path-absolutize = { version = "3.0.14", features = ["once_cell_cache", "use_unix
 quick-junit = { version = "0.3.2" }
 regex = { version = "1.6.0" }
 ropey = { version = "1.5.0", features = ["cr_lines", "simd"], default-features = false }
-ruff_macros = { version = "0.0.214", path = "ruff_macros" }
+ruff_macros = { version = "0.0.220", path = "ruff_macros" }
 rustc-hash = { version = "1.1.0" }
 rustpython-ast = { features = ["unparse"], git = "https://github.com/RustPython/RustPython.git", rev = "d532160333ffeb6dbeca2c2728c2391cd1e53b7f" }
 rustpython-common = { git = "https://github.com/RustPython/RustPython.git", rev = "d532160333ffeb6dbeca2c2728c2391cd1e53b7f" }

README.md

@@ -46,7 +46,9 @@ imports, and more.
 
 Ruff is extremely actively developed and used in major open-source projects like:
 
+- [pandas](https://github.com/pandas-dev/pandas)
 - [FastAPI](https://github.com/tiangolo/fastapi)
+- [Apache Airflow](https://github.com/apache/airflow)
 - [Bokeh](https://github.com/bokeh/bokeh)
 - [Zulip](https://github.com/zulip/zulip)
 - [Pydantic](https://github.com/pydantic/pydantic)
@@ -164,9 +166,9 @@ pacman -S ruff
 To run Ruff, try any of the following:
 
 ```shell
-ruff path/to/code/to/check.py  # Run Ruff over `check.py`
-ruff path/to/code/             # Run Ruff over all files in `/path/to/code` (and any subdirectories)
-ruff path/to/code/*.py         # Run Ruff over all `.py` files in `/path/to/code`
+ruff path/to/code/to/lint.py  # Run Ruff over `lint.py`
+ruff path/to/code/            # Run Ruff over all files in `/path/to/code` (and any subdirectories)
+ruff path/to/code/*.py        # Run Ruff over all `.py` files in `/path/to/code`
 ```
 
 You can run Ruff in `--watch` mode to automatically re-run on-change:
@@ -180,7 +182,7 @@ Ruff also works with [pre-commit](https://pre-commit.com):
 ```yaml
 - repo: https://github.com/charliermarsh/ruff-pre-commit
   # Ruff version.
-  rev: 'v0.0.214'
+  rev: 'v0.0.220'
   hooks:
     - id: ruff
       # Respect `exclude` and `extend-exclude` settings.
@@ -237,9 +239,9 @@ target-version = "py310"
 max-complexity = 10
 ```
 
-As an example, the following would configure Ruff to: (1) avoid checking for line-length
-violations (`E501`); (2) never remove unused imports (`F401`); and (3) ignore import-at-top-of-file
-errors (`E402`) in `__init__.py` files:
+As an example, the following would configure Ruff to: (1) avoid enforcing line-length violations
+(`E501`); (2) never remove unused imports (`F401`); and (3) ignore import-at-top-of-file violations
+(`E402`) in `__init__.py` files:
 
 ```toml
 [tool.ruff]
@@ -269,16 +271,16 @@ select = ["E", "F", "Q"]
 docstring-quotes = "double"
 ```
 
-Ruff mirrors Flake8's error code system, in which each error code consists of a one-to-three letter
-prefix, followed by three digits (e.g., `F401`). The prefix indicates that "source" of the error
-code (e.g., `F` for Pyflakes, `E` for `pycodestyle`, `ANN` for `flake8-annotations`). The set of
-enabled errors is determined by the `select` and `ignore` options, which support both the full
-error code (e.g., `F401`) and the prefix (e.g., `F`).
+Ruff mirrors Flake8's rule code system, in which each rule code consists of a one-to-three letter
+prefix, followed by three digits (e.g., `F401`). The prefix indicates that "source" of the rule
+(e.g., `F` for Pyflakes, `E` for `pycodestyle`, `ANN` for `flake8-annotations`). The set of enabled
+rules is determined by the `select` and `ignore` options, which support both the full code (e.g.,
+`F401`) and the prefix (e.g., `F`).
 
-As a special-case, Ruff also supports the `ALL` error code, which enables all error codes. Note that
-some of the `pydocstyle` error codes are conflicting (e.g., `D203` and `D211`) as they represent
-alternative docstring formats. Enabling `ALL` without further configuration may result in suboptimal
-behavior, especially for the `pydocstyle` plugin.
+As a special-case, Ruff also supports the `ALL` code, which enables all rules. Note that some of the
+`pydocstyle` rules conflict (e.g., `D203` and `D211`) as they represent alternative docstring
+formats. Enabling `ALL` without further configuration may result in suboptimal behavior, especially
+for the `pydocstyle` plugin.
 
 As an alternative to `pyproject.toml`, Ruff will also respect a `ruff.toml` file, which implements
 an equivalent schema (though the `[tool.ruff]` hierarchy can be omitted). For example, the
@@ -326,45 +328,47 @@ Options:
   -v, --verbose
           Enable verbose logging
   -q, --quiet
-          Only log errors
+          Print lint violations, but nothing else
   -s, --silent
-          Disable all logging (but still exit with status code "1" upon detecting errors)
+          Disable all logging (but still exit with status code "1" upon detecting lint violations)
   -e, --exit-zero
-          Exit with status code "0", even upon detecting errors
+          Exit with status code "0", even upon detecting lint violations
   -w, --watch
           Run in watch mode by re-running whenever files change
       --fix
-          Attempt to automatically fix lint errors
+          Attempt to automatically fix lint violations
       --fix-only
-          Fix any fixable lint errors, but don't report on leftover violations. Implies `--fix`
+          Fix any fixable lint violations, but don't report on leftover violations. Implies `--fix`
       --diff
           Avoid writing any fixed files back; instead, output a diff for each changed file to stdout
   -n, --no-cache
           Disable cache reads
-      --select <SELECT>
-          Comma-separated list of error codes to enable (or ALL, to enable all checks)
-      --extend-select <EXTEND_SELECT>
-          Like --select, but adds additional error codes on top of the selected ones
-      --ignore <IGNORE>
-          Comma-separated list of error codes to disable
-      --extend-ignore <EXTEND_IGNORE>
-          Like --ignore, but adds additional error codes on top of the ignored ones
-      --exclude <EXCLUDE>
-          List of paths, used to exclude files and/or directories from checks
-      --extend-exclude <EXTEND_EXCLUDE>
-          Like --exclude, but adds additional files and directories on top of the excluded ones
-      --fixable <FIXABLE>
-          List of error codes to treat as eligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
-      --unfixable <UNFIXABLE>
-          List of error codes to treat as ineligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
+      --isolated
+          Ignore all configuration files
+      --select <RULE_CODE>
+          Comma-separated list of rule codes to enable (or ALL, to enable all rules)
+      --extend-select <RULE_CODE>
+          Like --select, but adds additional rule codes on top of the selected ones
+      --ignore <RULE_CODE>
+          Comma-separated list of rule codes to disable
+      --extend-ignore <RULE_CODE>
+          Like --ignore, but adds additional rule codes on top of the ignored ones
+      --exclude <FILE_PATTERN>
+          List of paths, used to omit files and/or directories from analysis
+      --extend-exclude <FILE_PATTERN>
+          Like --exclude, but adds additional files and directories on top of those already excluded
+      --fixable <RULE_CODE>
+          List of rule codes to treat as eligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
+      --unfixable <RULE_CODE>
+          List of rule codes to treat as ineligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
       --per-file-ignores <PER_FILE_IGNORES>
           List of mappings from file pattern to code to exclude
       --format <FORMAT>
-          Output serialization format for error messages [possible values: text, json, junit, grouped, github, gitlab]
+          Output serialization format for violations [env: RUFF_FORMAT=] [possible values: text, json, junit, grouped, github, gitlab]
       --stdin-filename <STDIN_FILENAME>
           The name of the file when passing it through stdin
       --cache-dir <CACHE_DIR>
-          Path to the cache directory
+          Path to the cache directory [env: RUFF_CACHE_DIR=]
       --show-source
           Show violations with source code
       --respect-gitignore
@@ -378,7 +382,7 @@ Options:
       --target-version <TARGET_VERSION>
           The minimum Python version that should be supported
       --line-length <LINE_LENGTH>
-          Set the line-length for length-associated checks and automatic formatting
+          Set the line-length for length-associated rules and automatic formatting
       --max-complexity <MAX_COMPLEXITY>
           Maximum McCabe complexity allowed for a given function
       --add-noqa
@@ -390,7 +394,7 @@ Options:
       --show-files
           See the files Ruff will be run against with the current settings
       --show-settings
-          See the settings Ruff will use to check a given Python file
+          See the settings Ruff will use to lint a given Python file
   -h, --help
           Print help information
   -V, --version
@@ -447,16 +451,16 @@ in each directory's `pyproject.toml` file.
 By default, Ruff will also skip any files that are omitted via `.ignore`, `.gitignore`,
 `.git/info/exclude`, and global `gitignore` files (see: [`respect-gitignore`](#respect-gitignore)).
 
-Files that are passed to `ruff` directly are always checked, regardless of the above criteria.
-For example, `ruff /path/to/excluded/file.py` will always check `file.py`.
+Files that are passed to `ruff` directly are always linted, regardless of the above criteria.
+For example, `ruff /path/to/excluded/file.py` will always lint `file.py`.
 
 ### Ignoring errors
 
-To omit a lint check entirely, add it to the "ignore" list via [`ignore`](#ignore) or
+To omit a lint rule entirely, add it to the "ignore" list via [`ignore`](#ignore) or
 [`extend-ignore`](#extend-ignore), either on the command-line or in your `pyproject.toml` file.
 
-To ignore an error inline, Ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
-To ignore an individual error, add `# noqa: {code}` to the end of the line, like so:
+To ignore a violation inline, Ruff uses a `noqa` system similar to [Flake8](https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html).
+To ignore an individual violation, add `# noqa: {code}` to the end of the line, like so:
 
 ```python
 # Ignore F841.
@@ -465,7 +469,7 @@ x = 1  # noqa: F841
 # Ignore E741 and F841.
 i = 1  # noqa: E741, F841
 
-# Ignore _all_ errors.
+# Ignore _all_ violations.
 x = 1  # noqa
 ```
 
@@ -479,9 +483,9 @@ Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor i
 """  # noqa: E501
 ```
 
-To ignore all errors across an entire file, Ruff supports Flake8's `# flake8: noqa` directive (or,
-equivalently, `# ruff: noqa`). Adding either of those directives to any part of a file will disable
-error reporting for the entire file.
+To ignore all violations across an entire file, Ruff supports Flake8's `# flake8: noqa` directive
+(or, equivalently, `# ruff: noqa`). Adding either of those directives to any part of a file will
+disable enforcement across the entire file.
 
 For targeted exclusions across entire files (e.g., "Ignore all F841 violations in
 `/path/to/file.py`"), see the [`per-file-ignores`](#per-file-ignores) configuration setting.
@@ -500,8 +504,8 @@ for more.
 
 Ruff supports several workflows to aid in `noqa` management.
 
-First, Ruff provides a special error code, `RUF100`, to enforce that your `noqa` directives are
-"valid", in that the errors they _say_ they ignore are actually being triggered on that line (and
+First, Ruff provides a special rule code, `RUF100`, to enforce that your `noqa` directives are
+"valid", in that the violations they _say_ they ignore are actually being triggered on that line (and
 thus suppressed). You can run `ruff /path/to/file.py --extend-select RUF100` to flag unused `noqa`
 directives.
 
@@ -511,13 +515,13 @@ You can run `ruff /path/to/file.py --extend-select RUF100 --fix` to automaticall
 
 Third, Ruff can _automatically add_ `noqa` directives to all failing lines. This is useful when
 migrating a new codebase to Ruff. You can run `ruff /path/to/file.py --add-noqa` to automatically
-add `noqa` directives to all failing lines, with the appropriate error codes.
+add `noqa` directives to all failing lines, with the appropriate rule codes.
 
 ## Supported Rules
 
 Regardless of the rule's origin, Ruff re-implements every rule in Rust as a first-party feature.
 
-By default, Ruff enables all `E` and `F` error codes, which correspond to those built-in to Flake8.
+By default, Ruff enables all `E` and `F` rule codes, which correspond to those built-in to Flake8.
 
 The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` command-line option.
 
@@ -551,8 +555,8 @@ For more, see [Pyflakes](https://pypi.org/project/pyflakes/2.5.0/) on PyPI.
 | F524 | StringDotFormatMissingArguments | '...'.format(...) is missing argument(s) for placeholder(s): ... |  |
 | F525 | StringDotFormatMixingAutomatic | '...'.format(...) mixes automatic and manual numbering |  |
 | F541 | FStringMissingPlaceholders | f-string without any placeholders | 🛠 |
-| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal repeated |  |
-| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated |  |
+| F601 | MultiValueRepeatedKeyLiteral | Dictionary key literal `...` repeated | 🛠 |
+| F602 | MultiValueRepeatedKeyVariable | Dictionary key `...` repeated | 🛠 |
 | F621 | ExpressionsInStarAssignment | Too many expressions in star-unpacking assignment |  |
 | F622 | TwoStarredExpressions | Two starred expressions in assignment |  |
 | F631 | AssertTuple | Assert test is a non-empty tuple, which is always `True` |  |
@@ -595,6 +599,7 @@ For more, see [pycodestyle](https://pypi.org/project/pycodestyle/2.9.1/) on PyPI
 | E902 | IOError | IOError: `...` |  |
 | E999 | SyntaxError | SyntaxError: `...` |  |
 | W292 | NoNewLineAtEndOfFile | No newline at end of file | 🛠 |
+| W505 | DocLineTooLong | Doc line too long (89 > 88 characters) |  |
 | W605 | InvalidEscapeSequence | Invalid escape sequence: '\c' | 🛠 |
 
 ### mccabe (C90)
@@ -612,6 +617,7 @@ For more, see [isort](https://pypi.org/project/isort/5.10.1/) on PyPI.
 | Code | Name | Message | Fix |
 | ---- | ---- | ------- | --- |
 | I001 | UnsortedImports | Import block is un-sorted or un-formatted | 🛠 |
+| I002 | MissingRequiredImport | Missing required import: `from __future__ import ...` | 🛠 |
 
 ### pydocstyle (D)
 
@@ -699,6 +705,7 @@ For more, see [pyupgrade](https://pypi.org/project/pyupgrade/3.2.0/) on PyPI.
 | UP027 | RewriteListComprehension | Replace unpacked list comprehension with a generator expression | 🛠 |
 | UP028 | RewriteYieldFrom | Replace `yield` over `for` loop with `yield from` | 🛠 |
 | UP029 | UnnecessaryBuiltinImport | Unnecessary builtin import: `...` | 🛠 |
+| UP030 | FormatLiterals | Use implicit references for positional format fields | 🛠 |
 
 ### pep8-naming (N)
 
@@ -775,6 +782,9 @@ For more, see [flake8-bandit](https://pypi.org/project/flake8-bandit/4.1.1/) on
 | S324 | HashlibInsecureHashFunction | Probable use of insecure hash functions in `hashlib`: "..." |  |
 | S501 | RequestWithNoCertValidation | Probable use of `...` call with `verify=False` disabling SSL certificate checks |  |
 | S506 | UnsafeYAMLLoad | Probable use of unsafe `yaml.load`. Allows instantiation of arbitrary objects. Consider `yaml.safe_load`. |  |
+| S508 | SnmpInsecureVersion | The use of SNMPv1 and SNMPv2 is insecure. Use SNMPv3 if able. |  |
+| S509 | SnmpWeakCryptography | You should not use SNMPv3 without encryption. `noAuthNoPriv` & `authNoPriv` is insecure. |  |
+| S701 | Jinja2AutoescapeFalse | By default, jinja2 sets `autoescape` to `False`. Consider using `autoescape=True` or the `select_autoescape` function to mitigate XSS vulnerabilities. |  |
 
 ### flake8-blind-except (BLE)
 
@@ -933,8 +943,8 @@ For more, see [flake8-pytest-style](https://pypi.org/project/flake8-pytest-style
 | PT021 | FixtureFinalizerCallback | Use `yield` instead of `request.addfinalizer` |  |
 | PT022 | UselessYieldFixture | No teardown in fixture `...`, use `return` instead of `yield` | 🛠 |
 | PT023 | IncorrectMarkParenthesesStyle | Use `@pytest.mark....` over `@pytest.mark....()` | 🛠 |
-| PT024 | UnnecessaryAsyncioMarkOnFixture | `pytest.mark.asyncio` is unnecessary for fixtures |  |
-| PT025 | ErroneousUseFixturesOnFixture | `pytest.mark.usefixtures` has no effect on fixtures |  |
+| PT024 | UnnecessaryAsyncioMarkOnFixture | `pytest.mark.asyncio` is unnecessary for fixtures | 🛠 |
+| PT025 | ErroneousUseFixturesOnFixture | `pytest.mark.usefixtures` has no effect on fixtures | 🛠 |
 | PT026 | UseFixturesWithoutParameters | Useless `pytest.mark.usefixtures` without parameters | 🛠 |
 
 ### flake8-quotes (Q)
@@ -943,10 +953,10 @@ For more, see [flake8-quotes](https://pypi.org/project/flake8-quotes/3.3.1/) on
 
 | Code | Name | Message | Fix |
 | ---- | ---- | ------- | --- |
-| Q000 | BadQuotesInlineString | Single quotes found but double quotes preferred |  |
-| Q001 | BadQuotesMultilineString | Single quote multiline found but double quotes preferred |  |
-| Q002 | BadQuotesDocstring | Single quote docstring found but double quotes preferred |  |
-| Q003 | AvoidQuoteEscape | Change outer quotes to avoid escaping inner quotes |  |
+| Q000 | BadQuotesInlineString | Single quotes found but double quotes preferred | 🛠 |
+| Q001 | BadQuotesMultilineString | Single quote multiline found but double quotes preferred | 🛠 |
+| Q002 | BadQuotesDocstring | Single quote docstring found but double quotes preferred | 🛠 |
+| Q003 | AvoidQuoteEscape | Change outer quotes to avoid escaping inner quotes | 🛠 |
 
 ### flake8-return (RET)
 
@@ -969,6 +979,7 @@ For more, see [flake8-simplify](https://pypi.org/project/flake8-simplify/0.19.3/
 
 | Code | Name | Message | Fix |
 | ---- | ---- | ------- | --- |
+| SIM115 | OpenFileWithContextHandler | Use context handler for opening files |  |
 | SIM101 | DuplicateIsinstanceCall | Multiple `isinstance` calls for `...`, merge into a single call | 🛠 |
 | SIM102 | NestedIfStatements | Use a single `if` statement instead of nested `if` statements |  |
 | SIM103 | ReturnBoolConditionDirectly | Return the condition `...` directly | 🛠 |
@@ -978,6 +989,7 @@ For more, see [flake8-simplify](https://pypi.org/project/flake8-simplify/0.19.3/
 | SIM109 | CompareWithTuple | Use `value in (..., ...)` instead of `value == ... or value == ...` | 🛠 |
 | SIM110 | ConvertLoopToAny | Use `return any(x for x in y)` instead of `for` loop | 🛠 |
 | SIM111 | ConvertLoopToAll | Use `return all(x for x in y)` instead of `for` loop | 🛠 |
+| SIM112 | UseCapitalEnvironmentVariables | Use capitalized environment variable `...` instead of `...` | 🛠 |
 | SIM117 | MultipleWithStatements | Use a single `with` statement with multiple contexts instead of nested `with` statements |  |
 | SIM118 | KeyInDict | Use `key in dict` instead of `key in dict.keys()` | 🛠 |
 | SIM201 | NegateEqualOp | Use `left != right` instead of `not left == right` | 🛠 |
@@ -991,6 +1003,7 @@ For more, see [flake8-simplify](https://pypi.org/project/flake8-simplify/0.19.3/
 | SIM222 | OrTrue | Use `True` instead of `... or True` | 🛠 |
 | SIM223 | AndFalse | Use `False` instead of `... and False` | 🛠 |
 | SIM300 | YodaConditions | Yoda conditions are discouraged, use `left == right` instead | 🛠 |
+| SIM401 | DictGetWithDefault | Use `var = dict.get(key, "default")` instead of an `if` block | 🛠 |
 
 ### flake8-tidy-imports (TID)
 
@@ -1064,8 +1077,8 @@ For more, see [pygrep-hooks](https://github.com/pre-commit/pygrep-hooks) on GitH
 | ---- | ---- | ------- | --- |
 | PGH001 | NoEval | No builtin `eval()` allowed |  |
 | PGH002 | DeprecatedLogWarn | `warn` is deprecated in favor of `warning` |  |
-| PGH003 | BlanketTypeIgnore | Use specific error codes when ignoring type issues |  |
-| PGH004 | BlanketNOQA | Use specific error codes when using `noqa` |  |
+| PGH003 | BlanketTypeIgnore | Use specific rule codes when ignoring type issues |  |
+| PGH004 | BlanketNOQA | Use specific rule codes when using `noqa` |  |
 
 ### Pylint (PLC, PLE, PLR, PLW)
 
@@ -1391,7 +1404,7 @@ natively, including:
 - [`pyupgrade`](https://pypi.org/project/pyupgrade/) ([#827](https://github.com/charliermarsh/ruff/issues/827))
 - [`yesqa`](https://github.com/asottile/yesqa)
 
-Note that, in some cases, Ruff uses different error code prefixes than would be found in the
+Note that, in some cases, Ruff uses different rule codes and prefixes than would be found in the
 originating Flake8 plugins. For example, Ruff uses `TID252` to represent the `I252` rule from
 `flake8-tidy-imports`. This helps minimize conflicts across plugins and allows any individual plugin
 to be toggled on or off with a single (e.g.) `--select TID`, as opposed to `--select I2` (to avoid
@@ -1416,9 +1429,9 @@ At time of writing, Pylint implements 409 total rules, while Ruff implements 224
 at least 60 overlap with the Pylint rule set. Subjectively, Pylint tends to implement more rules
 based on type inference (e.g., validating the number of arguments in a function call).
 
-Like Flake8, Pylint supports plugins (called "checkers"), while Ruff implements all checks natively.
+Like Flake8, Pylint supports plugins (called "checkers"), while Ruff implements all rules natively.
 
-Unlike Pylint, Ruff is capable of automatically fixing its own lint errors.
+Unlike Pylint, Ruff is capable of automatically fixing its own lint violations.
 
 Pylint parity is being tracked in [#689](https://github.com/charliermarsh/ruff/issues/689).
 
@@ -1531,7 +1544,7 @@ For example, if you're coming from `flake8-docstrings`, and your originating con
 `--docstring-convention=numpy`, you'd instead set `convention = "numpy"` in your `pyproject.toml`,
 as above.
 
-Alongside `convention`, you'll want to explicitly enable the `D` error code class, like so:
+Alongside `convention`, you'll want to explicitly enable the `D` rule code prefix, like so:
 
 ```toml
 [tool.ruff]
@@ -1737,6 +1750,24 @@ allowed-confusables = ["−", "ρ", "∗"]
 
 ---
 
+#### [`builtins`](#builtins)
+
+A list of builtins to treat as defined references, in addition to the
+system builtins.
+
+**Default value**: `[]`
+
+**Type**: `Vec<String>`
+
+**Example usage**:
+
+```toml
+[tool.ruff]
+builtins = ["_"]
+```
+
+---
+
 #### [`cache-dir`](#cache-dir)
 
 A path to the cache directory.
@@ -1766,7 +1797,7 @@ cache-dir = "~/.cache/ruff"
 #### [`dummy-variable-rgx`](#dummy-variable-rgx)
 
 A regular expression used to identify "dummy" variables, or those which
-should be ignored when evaluating (e.g.) unused-variable checks. The
+should be ignored when enforcing (e.g.) unused-variable rules. The
 default expression matches `_`, `__`, and `_var`, but not `_var_`.
 
 **Default value**: `"^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"`
@@ -1797,6 +1828,8 @@ Exclusions are based on globs, and can be either:
   `directory`). Note that these paths are relative to the project root
   (e.g., the directory containing your `pyproject.toml`).
 
+For more information on the glob syntax, refer to the [`globset` documentation](https://docs.rs/globset/latest/globset/#syntax).
+
 Note that you'll typically want to use
 [`extend-exclude`](#extend-exclude) to modify the excluded paths.
 
@@ -1844,6 +1877,18 @@ line-length = 100
 A list of file patterns to omit from linting, in addition to those
 specified by `exclude`.
 
+Exclusions are based on globs, and can be either:
+
+- Single-path patterns, like `.mypy_cache` (to exclude any directory
+  named `.mypy_cache` in the tree), `foo.py` (to exclude any file named
+  `foo.py`), or `foo_*.py` (to exclude any file matching `foo_*.py` ).
+- Relative patterns, like `directory/foo.py` (to exclude that specific
+  file) or `directory/*.py` (to exclude any Python files in
+  `directory`). Note that these paths are relative to the project root
+  (e.g., the directory containing your `pyproject.toml`).
+
+For more information on the glob syntax, refer to the [`globset` documentation](https://docs.rs/globset/latest/globset/#syntax).
+
 **Default value**: `[]`
 
 **Type**: `Vec<FilePattern>`
@@ -1860,18 +1905,18 @@ extend-exclude = ["tests", "src/bad.py"]
 
 #### [`extend-ignore`](#extend-ignore)
 
-A list of check code prefixes to ignore, in addition to those specified
-by `ignore`.
+A list of rule codes or prefixes to ignore, in addition to those
+specified by `ignore`.
 
 **Default value**: `[]`
 
-**Type**: `Vec<CheckCodePrefix>`
+**Type**: `Vec<RuleCodePrefix>`
 
 **Example usage**:
 
 ```toml
 [tool.ruff]
-# Skip unused variable checks (`F841`).
+# Skip unused variable rules (`F841`).
 extend-ignore = ["F841"]
 ```
 
@@ -1879,12 +1924,12 @@ extend-ignore = ["F841"]
 
 #### [`extend-select`](#extend-select)
 
-A list of check code prefixes to enable, in addition to those specified
-by `select`.
+A list of rule codes or prefixes to enable, in addition to those
+specified by `select`.
 
 **Default value**: `[]`
 
-**Type**: `Vec<CheckCodePrefix>`
+**Type**: `Vec<RuleCodePrefix>`
 
 **Example usage**:
 
@@ -1898,10 +1943,10 @@ extend-select = ["B", "Q"]
 
 #### [`external`](#external)
 
-A list of check codes that are unsupported by Ruff, but should be
+A list of rule codes that are unsupported by Ruff, but should be
 preserved when (e.g.) validating `# noqa` directives. Useful for
 retaining `# noqa` directives that cover plugins not yet implemented
-in Ruff.
+by Ruff.
 
 **Default value**: `[]`
 
@@ -1955,17 +2000,17 @@ fix-only = true
 
 #### [`fixable`](#fixable)
 
-A list of check code prefixes to consider autofix-able.
+A list of rule codes or prefixes to consider autofixable.
 
 **Default value**: `["A", "ANN", "ARG", "B", "BLE", "C", "D", "E", "ERA", "F", "FBT", "I", "ICN", "N", "PGH", "PLC", "PLE", "PLR", "PLW", "Q", "RET", "RUF", "S", "T", "TID", "UP", "W", "YTT"]`
 
-**Type**: `Vec<CheckCodePrefix>`
+**Type**: `Vec<RuleCodePrefix>`
 
 **Example usage**:
 
 ```toml
 [tool.ruff]
-# Only allow autofix behavior for `E` and `F` checks.
+# Only allow autofix behavior for `E` and `F` rules.
 fixable = ["E", "F"]
 ```
 
@@ -2021,23 +2066,23 @@ format = "grouped"
 
 #### [`ignore`](#ignore)
 
-A list of check code prefixes to ignore. Prefixes can specify exact
-checks (like `F841`), entire categories (like `F`), or anything in
+A list of rule codes or prefixes to ignore. Prefixes can specify exact
+rules (like `F841`), entire categories (like `F`), or anything in
 between.
 
-When breaking ties between enabled and disabled checks (via `select` and
+When breaking ties between enabled and disabled rules (via `select` and
 `ignore`, respectively), more specific prefixes override less
 specific prefixes.
 
 **Default value**: `[]`
 
-**Type**: `Vec<CheckCodePrefix>`
+**Type**: `Vec<RuleCodePrefix>`
 
 **Example usage**:
 
 ```toml
 [tool.ruff]
-# Skip unused variable checks (`F841`).
+# Skip unused variable rules (`F841`).
 ignore = ["F841"]
 ```
 
@@ -2085,12 +2130,12 @@ line-length = 120
 
 #### [`per-file-ignores`](#per-file-ignores)
 
-A list of mappings from file pattern to check code prefixes to exclude,
-when considering any matching files.
+A list of mappings from file pattern to rule codes or prefixes to
+exclude, when considering any matching files.
 
 **Default value**: `{}`
 
-**Type**: `HashMap<String, Vec<CheckCodePrefix>>`
+**Type**: `HashMap<String, Vec<RuleCodePrefix>>`
 
 **Example usage**:
 
@@ -2144,17 +2189,17 @@ respect_gitignore = false
 
 #### [`select`](#select)
 
-A list of check code prefixes to enable. Prefixes can specify exact
-checks (like `F841`), entire categories (like `F`), or anything in
+A list of rule codes or prefixes to enable. Prefixes can specify exact
+rules (like `F841`), entire categories (like `F`), or anything in
 between.
 
-When breaking ties between enabled and disabled checks (via `select` and
+When breaking ties between enabled and disabled rules (via `select` and
 `ignore`, respectively), more specific prefixes override less
 specific prefixes.
 
 **Default value**: `["E", "F"]`
 
-**Type**: `Vec<CheckCodePrefix>`
+**Type**: `Vec<RuleCodePrefix>`
 
 **Example usage**:
 
@@ -2168,8 +2213,8 @@ select = ["E", "F", "B", "Q"]
 
 #### [`show-source`](#show-source)
 
-Whether to show source code snippets when reporting lint error
-violations (overridden by the `--show-source` command-line flag).
+Whether to show source code snippets when reporting lint violations
+(overridden by the `--show-source` command-line flag).
 
 **Default value**: `false`
 
@@ -2252,7 +2297,7 @@ target-version = "py37"
 A list of task tags to recognize (e.g., "TODO", "FIXME", "XXX").
 
 Comments starting with these tags will be ignored by commented-out code
-detection (`ERA`), and skipped by line-length checks (`E501`) if
+detection (`ERA`), and skipped by line-length rules (`E501`) if
 `ignore-overlong-task-comments` is set to `true`.
 
 **Default value**: `["TODO", "FIXME", "XXX"]`
@@ -2268,13 +2313,37 @@ task-tags = ["HACK"]
 
 ---
 
-#### [`unfixable`](#unfixable)
+#### [`typing-modules`](#typing-modules)
 
-A list of check code prefixes to consider un-autofix-able.
+A list of modules whose imports should be treated equivalently to
+members of the `typing` module.
+
+This is useful for ensuring proper type annotation inference for
+projects that re-export `typing` and `typing_extensions` members
+from a compatibility module. If omitted, any members imported from
+modules apart from `typing` and `typing_extensions` will be treated
+as ordinary Python objects.
 
 **Default value**: `[]`
 
-**Type**: `Vec<CheckCodePrefix>`
+**Type**: `Vec<String>`
+
+**Example usage**:
+
+```toml
+[tool.ruff]
+typing-modules = ["airflow.typing_compat"]
+```
+
+---
+
+#### [`unfixable`](#unfixable)
+
+A list of rule codes or prefixes to consider non-autofix-able.
+
+**Default value**: `[]`
+
+**Type**: `Vec<RuleCodePrefix>`
 
 **Example usage**:
 
@@ -2291,7 +2360,7 @@ unfixable = ["F401"]
 Enable or disable automatic update checks (overridden by the
 `--update-check` and `--no-update-check` command-line flags).
 
-**Default value**: `true`
+**Default value**: `false`
 
 **Type**: `bool`
 
@@ -2299,7 +2368,7 @@ Enable or disable automatic update checks (overridden by the
 
 ```toml
 [tool.ruff]
-update-check = false
+update-check = true
 ```
 
 ---
@@ -2344,7 +2413,7 @@ mypy-init-return = true
 
 #### [`suppress-dummy-args`](#suppress-dummy-args)
 
-Whether to suppress `ANN000`-level errors for arguments matching the
+Whether to suppress `ANN000`-level violations for arguments matching the
 "dummy" variable regex (like `_`).
 
 **Default value**: `false`
@@ -2362,8 +2431,8 @@ suppress-dummy-args = true
 
 #### [`suppress-none-returning`](#suppress-none-returning)
 
-Whether to suppress `ANN200`-level errors for functions that meet either
-of the following criteria:
+Whether to suppress `ANN200`-level violations for functions that meet
+either of the following criteria:
 
 - Contain no `return` statement.
 - Explicit `return` statement(s) all return `None` (explicitly or
@@ -2424,7 +2493,7 @@ extend-hardcoded-tmp-directory = ["/foo/bar"]
 #### [`extend-immutable-calls`](#extend-immutable-calls)
 
 Additional callable functions to consider "immutable" when evaluating,
-e.g., `no-mutable-default-argument` checks (`B006`).
+e.g., the `no-mutable-default-argument` rule (`B006`).
 
 **Default value**: `[]`
 
@@ -2511,9 +2580,9 @@ will be added to the `aliases` mapping.
 
 Boolean flag specifying whether `@pytest.fixture()` without parameters
 should have parentheses. If the option is set to `true` (the
-default), `@pytest.fixture()` is valid and `@pytest.fixture` is an
-error. If set to `false`, `@pytest.fixture` is valid and
-`@pytest.fixture()` is an error.
+default), `@pytest.fixture()` is valid and `@pytest.fixture` is
+invalid. If set to `false`, `@pytest.fixture` is valid and
+`@pytest.fixture()` is invalid.
 
 **Default value**: `true`
 
@@ -2532,9 +2601,9 @@ fixture-parentheses = true
 
 Boolean flag specifying whether `@pytest.mark.foo()` without parameters
 should have parentheses. If the option is set to `true` (the
-default), `@pytest.mark.foo()` is valid and `@pytest.mark.foo` is an
-error. If set to `false`, `@pytest.fixture` is valid and
-`@pytest.mark.foo()` is an error.
+default), `@pytest.mark.foo()` is valid and `@pytest.mark.foo` is
+invalid. If set to `false`, `@pytest.fixture` is valid and
+`@pytest.mark.foo()` is invalid.
 
 **Default value**: `true`
 
@@ -2756,7 +2825,7 @@ ban-relative-imports = "all"
 #### [`banned-api`](#banned-api)
 
 Specific modules or module members that may not be imported or accessed.
-Note that this check is only meant to flag accidental uses,
+Note that this rule is only meant to flag accidental uses,
 and can be circumvented via `eval` or `importlib`.
 
 **Default value**: `{}`
@@ -2848,6 +2917,25 @@ force-single-line = true
 
 ---
 
+#### [`force-sort-within-sections`](#force-sort-within-sections)
+
+Don't sort straight-style imports (like `import sys`) before from-style
+imports (like `from itertools import groupby`). Instead, sort the
+imports by module, independent of import style.
+
+**Default value**: `false`
+
+**Type**: `bool`
+
+**Example usage**:
+
+```toml
+[tool.ruff.isort]
+force-sort-within-sections = true
+```
+
+---
+
 #### [`force-wrap-aliases`](#force-wrap-aliases)
 
 Force `import from` statements with multiple members and at least one
@@ -2935,6 +3023,47 @@ order-by-type = true
 
 ---
 
+#### [`relative-imports-order`](#relative-imports-order)
+
+Whether to place "closer" imports (fewer `.` characters, most local)
+before "further" imports (more `.` characters, least local), or vice
+versa.
+
+The default ("furthest-to-closest") is equivalent to isort's
+`reverse-relative` default (`reverse-relative = false`); setting
+this to "closest-to-furthest" is equivalent to isort's `reverse-relative
+= true`.
+
+**Default value**: `furthest-to-closest`
+
+**Type**: `RelatveImportsOrder`
+
+**Example usage**:
+
+```toml
+[tool.ruff.isort]
+relative-imports-order = "closest-to-furthest"
+```
+
+---
+
+#### [`required-imports`](#required-imports)
+
+Add the specified import line to all files.
+
+**Default value**: `[]`
+
+**Type**: `Vec<String>`
+
+**Example usage**:
+
+```toml
+[tool.ruff.isort]
+required-imports = ["from __future__ import annotations"]
+```
+
+---
+
 #### [`single-line-exclusions`](#single-line-exclusions)
 
 One or more modules to exclude from the single line rule.
@@ -3057,7 +3186,7 @@ staticmethod-decorators = ["staticmethod", "stcmthd"]
 
 #### [`ignore-overlong-task-comments`](#ignore-overlong-task-comments)
 
-Whether or not line-length checks (`E501`) should be triggered for
+Whether or not line-length violations (`E501`) should be triggered for
 comments starting with `task-tags` (by default: ["TODO", "FIXME",
 and "XXX"]).
 
@@ -3074,6 +3203,24 @@ ignore-overlong-task-comments = true
 
 ---
 
+#### [`max-doc-length`](#max-doc-length)
+
+The maximum line length to allow for line-length violations within
+documentation (`W505`), including standalone comments.
+
+**Default value**: `None`
+
+**Type**: `usize`
+
+**Example usage**:
+
+```toml
+[tool.ruff.pycodestyle]
+max-doc-length = 88
+```
+
+---
+
 ### `pydocstyle`
 
 #### [`convention`](#convention)
@@ -3128,4 +3275,4 @@ MIT
 ## Contributing
 
 Contributions are welcome and hugely appreciated. To get started, check out the
-[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/.github/CONTRIBUTING.md).
+[contributing guidelines](https://github.com/charliermarsh/ruff/blob/main/CONTRIBUTING.md).

flake8_to_ruff/Cargo.lock

@@ -771,7 +771,7 @@ checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
 [[package]]
 name = "flake8_to_ruff"
-version = "0.0.214"
+version = "0.0.220"
 dependencies = [
  "anyhow",
  "clap",
@@ -1975,7 +1975,7 @@ dependencies = [
 
 [[package]]
 name = "ruff"
-version = "0.0.214"
+version = "0.0.220"
 dependencies = [
  "anyhow",
  "bincode",

flake8_to_ruff/Cargo.toml

@@ -1,14 +1,16 @@
 [package]
 name = "flake8-to-ruff"
-version = "0.0.214-dev.0"
+version = "0.0.220-dev.0"
 edition = "2021"
 
 [lib]
 name = "flake8_to_ruff"
+doctest = false
 
 [dependencies]
 anyhow = { version = "1.0.66" }
 clap = { version = "4.0.1", features = ["derive"] }
+colored = { version = "2.0.0" }
 configparser = { version = "3.0.2" }
 once_cell = { version = "1.16.0" }
 regex = { version = "1.6.0" }

flake8_to_ruff/README.md

@@ -84,7 +84,7 @@ flake8-to-ruff path/to/.flake8 --plugin flake8-builtins --plugin flake8-quotes
 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
+2. Ruff will omit any rule codes that are unimplemented or unsupported by Ruff, including rule
    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.)
 

flake8_to_ruff/examples/jupyterhub.ini

@@ -0,0 +1,19 @@
+[flake8]
+# Ignore style and complexity
+# E: style errors
+# W: style warnings
+# C: complexity
+# D: docstring warnings (unused pydocstyle extension)
+# F841: local variable assigned but never used
+ignore = E, C, W, D, F841
+builtins = c, get_config
+exclude =
+    .cache,
+    .github,
+    docs,
+    jupyterhub/alembic*,
+    onbuild,
+    scripts,
+    share,
+    tools,
+    setup.py

flake8_to_ruff/src/converter.rs

@@ -1,18 +1,19 @@
 use std::collections::{BTreeSet, HashMap};
 
 use anyhow::Result;
+use colored::Colorize;
 use ruff::flake8_pytest_style::types::{
     ParametrizeNameType, ParametrizeValuesRowType, ParametrizeValuesType,
 };
 use ruff::flake8_quotes::settings::Quote;
 use ruff::flake8_tidy_imports::settings::Strictness;
 use ruff::pydocstyle::settings::Convention;
-use ruff::registry::CheckCodePrefix;
+use ruff::registry::RuleCodePrefix;
 use ruff::settings::options::Options;
 use ruff::settings::pyproject::Pyproject;
 use ruff::{
     flake8_annotations, flake8_bugbear, flake8_errmsg, flake8_pytest_style, flake8_quotes,
-    flake8_tidy_imports, mccabe, pep8_naming, pydocstyle,
+    flake8_tidy_imports, mccabe, pep8_naming, pydocstyle, warn_user,
 };
 
 use crate::black::Black;
@@ -29,8 +30,8 @@ pub fn convert(
         .get("flake8")
         .expect("Unable to find flake8 section in INI file");
 
-    // Extract all referenced check code prefixes, to power plugin inference.
-    let mut referenced_codes: BTreeSet<CheckCodePrefix> = BTreeSet::default();
+    // Extract all referenced rule code prefixes, to power plugin inference.
+    let mut referenced_codes: BTreeSet<RuleCodePrefix> = BTreeSet::default();
     for (key, value) in flake8 {
         if let Some(value) = value {
             match key.as_str() {
@@ -60,7 +61,7 @@ pub fn convert(
         }
         let from_codes = plugin::infer_plugins_from_codes(&referenced_codes);
         if !from_codes.is_empty() {
-            eprintln!("Inferred plugins from referenced check codes: {from_codes:#?}");
+            eprintln!("Inferred plugins from referenced codes: {from_codes:#?}");
         }
         from_options.into_iter().chain(from_codes).collect()
     });
@@ -99,9 +100,14 @@ pub fn convert(
         if let Some(value) = value {
             match key.as_str() {
                 // flake8
+                "builtins" => {
+                    options.builtins = Some(parser::parse_strings(value.as_ref()));
+                }
                 "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}"),
+                    Err(e) => {
+                        warn_user!("Unable to parse '{key}' property: {e}");
+                    }
                 },
                 "select" => {
                     // No-op (handled above).
@@ -130,7 +136,9 @@ pub fn convert(
                             options.per_file_ignores =
                                 Some(parser::collect_per_file_ignores(per_file_ignores));
                         }
-                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                        Err(e) => {
+                            warn_user!("Unable to parse '{key}' property: {e}");
+                        }
                     }
                 }
                 // flake8-bugbear
@@ -142,46 +150,62 @@ pub fn convert(
                 "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}"),
+                        Err(e) => {
+                            warn_user!("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}"),
+                        Err(e) => {
+                            warn_user!("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}"),
+                        Err(e) => {
+                            warn_user!("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}"),
+                        Err(e) => {
+                            warn_user!("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::Double),
-                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                    _ => {
+                        warn_user!("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::Double),
-                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                    _ => {
+                        warn_user!("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::Double),
-                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                    _ => {
+                        warn_user!("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}"),
+                    Err(e) => {
+                        warn_user!("Unable to parse '{key}' property: {e}");
+                    }
                 },
                 // pep8-naming
                 "ignore-names" | "ignore_names" => {
@@ -201,7 +225,9 @@ pub fn convert(
                     "parents" => {
                         flake8_tidy_imports.ban_relative_imports = Some(Strictness::Parents);
                     }
-                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                    _ => {
+                        warn_user!("Unexpected '{key}' value: {value}");
+                    }
                 },
                 // flake8-docstrings
                 "docstring-convention" => match value.trim() {
@@ -209,12 +235,16 @@ pub fn convert(
                     "numpy" => pydocstyle.convention = Some(Convention::Numpy),
                     "pep257" => pydocstyle.convention = Some(Convention::Pep257),
                     "all" => pydocstyle.convention = None,
-                    _ => eprintln!("Unexpected '{key}' value: {value}"),
+                    _ => {
+                        warn_user!("Unexpected '{key}' value: {value}");
+                    }
                 },
                 // 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}"),
+                    Err(e) => {
+                        warn_user!("Unable to parse '{key}' property: {e}");
+                    }
                 },
                 // flake8-errmsg
                 "errmsg-max-string-length" | "errmsg_max_string_length" => {
@@ -222,14 +252,18 @@ pub fn convert(
                         Ok(max_string_length) => {
                             flake8_errmsg.max_string_length = Some(max_string_length);
                         }
-                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                        Err(e) => {
+                            warn_user!("Unable to parse '{key}' property: {e}");
+                        }
                     }
                 }
                 // flake8-pytest-style
                 "pytest-fixture-no-parentheses" | "pytest_fixture_no_parentheses " => {
                     match parser::parse_bool(value.as_ref()) {
                         Ok(bool) => flake8_pytest_style.fixture_parentheses = Some(!bool),
-                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                        Err(e) => {
+                            warn_user!("Unable to parse '{key}' property: {e}");
+                        }
                     }
                 }
                 "pytest-parametrize-names-type" | "pytest_parametrize_names_type" => {
@@ -246,7 +280,9 @@ pub fn convert(
                             flake8_pytest_style.parametrize_names_type =
                                 Some(ParametrizeNameType::List);
                         }
-                        _ => eprintln!("Unexpected '{key}' value: {value}"),
+                        _ => {
+                            warn_user!("Unexpected '{key}' value: {value}");
+                        }
                     }
                 }
                 "pytest-parametrize-values-type" | "pytest_parametrize_values_type" => {
@@ -259,7 +295,9 @@ pub fn convert(
                             flake8_pytest_style.parametrize_values_type =
                                 Some(ParametrizeValuesType::List);
                         }
-                        _ => eprintln!("Unexpected '{key}' value: {value}"),
+                        _ => {
+                            warn_user!("Unexpected '{key}' value: {value}");
+                        }
                     }
                 }
                 "pytest-parametrize-values-row-type" | "pytest_parametrize_values_row_type" => {
@@ -272,7 +310,9 @@ pub fn convert(
                             flake8_pytest_style.parametrize_values_row_type =
                                 Some(ParametrizeValuesRowType::List);
                         }
-                        _ => eprintln!("Unexpected '{key}' value: {value}"),
+                        _ => {
+                            warn_user!("Unexpected '{key}' value: {value}");
+                        }
                     }
                 }
                 "pytest-raises-require-match-for" | "pytest_raises_require_match_for" => {
@@ -282,11 +322,15 @@ pub fn convert(
                 "pytest-mark-no-parentheses" | "pytest_mark_no_parentheses" => {
                     match parser::parse_bool(value.as_ref()) {
                         Ok(bool) => flake8_pytest_style.mark_parentheses = Some(!bool),
-                        Err(e) => eprintln!("Unable to parse '{key}' property: {e}"),
+                        Err(e) => {
+                            warn_user!("Unable to parse '{key}' property: {e}");
+                        }
                     }
                 }
                 // Unknown
-                _ => eprintln!("Skipping unsupported property: {key}"),
+                _ => {
+                    warn_user!("Skipping unsupported property: {}", key);
+                }
             }
         }
     }
@@ -345,7 +389,7 @@ mod tests {
 
     use anyhow::Result;
     use ruff::pydocstyle::settings::Convention;
-    use ruff::registry::CheckCodePrefix;
+    use ruff::registry::RuleCodePrefix;
     use ruff::settings::options::Options;
     use ruff::settings::pyproject::Pyproject;
     use ruff::{flake8_quotes, pydocstyle};
@@ -362,6 +406,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -382,14 +427,15 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::W,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,
@@ -425,6 +471,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -445,14 +492,15 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::W,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,
@@ -488,6 +536,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -508,14 +557,15 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::W,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,
@@ -551,6 +601,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -571,14 +622,15 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::W,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,
@@ -614,6 +666,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -634,14 +687,15 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::W,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,
@@ -685,6 +739,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -705,15 +760,16 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::D,
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::W,
+                RuleCodePrefix::D,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,
@@ -751,6 +807,7 @@ mod tests {
         )?;
         let expected = Pyproject::new(Options {
             allowed_confusables: None,
+            builtins: None,
             cache_dir: None,
             dummy_variable_rgx: None,
             exclude: None,
@@ -771,15 +828,16 @@ mod tests {
             required_version: None,
             respect_gitignore: None,
             select: Some(vec![
-                CheckCodePrefix::E,
-                CheckCodePrefix::F,
-                CheckCodePrefix::Q,
-                CheckCodePrefix::W,
+                RuleCodePrefix::E,
+                RuleCodePrefix::F,
+                RuleCodePrefix::Q,
+                RuleCodePrefix::W,
             ]),
             show_source: None,
             src: None,
             target_version: None,
             unfixable: None,
+            typing_modules: None,
             task_tags: None,
             update_check: None,
             flake8_annotations: None,

flake8_to_ruff/src/parser.rs

@@ -1,18 +1,20 @@
 use std::str::FromStr;
 
 use anyhow::{bail, Result};
+use colored::Colorize;
 use once_cell::sync::Lazy;
 use regex::Regex;
-use ruff::registry::{CheckCodePrefix, PREFIX_REDIRECTS};
+use ruff::registry::{RuleCodePrefix, PREFIX_REDIRECTS};
 use ruff::settings::types::PatternPrefixPair;
+use ruff::warn_user;
 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.,
+/// Parse a comma-separated list of `RuleCodePrefix` values (e.g.,
 /// "F401,E501").
-pub fn parse_prefix_codes(value: &str) -> Vec<CheckCodePrefix> {
-    let mut codes: Vec<CheckCodePrefix> = vec![];
+pub fn parse_prefix_codes(value: &str) -> Vec<RuleCodePrefix> {
+    let mut codes: Vec<RuleCodePrefix> = vec![];
     for code in COMMA_SEPARATED_LIST_RE.split(value) {
         let code = code.trim();
         if code.is_empty() {
@@ -20,10 +22,10 @@ pub fn parse_prefix_codes(value: &str) -> Vec<CheckCodePrefix> {
         }
         if let Some(code) = PREFIX_REDIRECTS.get(code) {
             codes.push(code.clone());
-        } else if let Ok(code) = CheckCodePrefix::from_str(code) {
+        } else if let Ok(code) = RuleCodePrefix::from_str(code) {
             codes.push(code);
         } else {
-            eprintln!("Unsupported prefix code: {code}");
+            warn_user!("Unsupported prefix code: {code}");
         }
     }
     codes
@@ -81,7 +83,8 @@ impl State {
         }
     }
 
-    /// Generate the list of `StrCheckCodePair` pairs for the current state.
+    /// Generate the list of `StrRuleCodePair` pairs for the current
+    /// state.
     fn parse(&self) -> Vec<PatternPrefixPair> {
         let mut codes: Vec<PatternPrefixPair> = vec![];
         for code in &self.codes {
@@ -92,7 +95,7 @@ impl State {
                         prefix: code.clone(),
                     });
                 }
-            } else if let Ok(code) = CheckCodePrefix::from_str(code) {
+            } else if let Ok(code) = RuleCodePrefix::from_str(code) {
                 for filename in &self.filenames {
                     codes.push(PatternPrefixPair {
                         pattern: filename.clone(),
@@ -100,7 +103,7 @@ impl State {
                     });
                 }
             } else {
-                eprintln!("Unsupported prefix code: {code}");
+                warn_user!("Unsupported prefix code: {code}");
             }
         }
         codes
@@ -186,8 +189,8 @@ pub fn parse_files_to_codes_mapping(value: &str) -> Result<Vec<PatternPrefixPair
 /// 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();
+) -> FxHashMap<String, Vec<RuleCodePrefix>> {
+    let mut per_file_ignores: FxHashMap<String, Vec<RuleCodePrefix>> = FxHashMap::default();
     for pair in pairs {
         per_file_ignores
             .entry(pair.pattern)
@@ -200,7 +203,7 @@ pub fn collect_per_file_ignores(
 #[cfg(test)]
 mod tests {
     use anyhow::Result;
-    use ruff::registry::CheckCodePrefix;
+    use ruff::registry::RuleCodePrefix;
     use ruff::settings::types::PatternPrefixPair;
 
     use crate::parser::{parse_files_to_codes_mapping, parse_prefix_codes, parse_strings};
@@ -208,27 +211,27 @@ mod tests {
     #[test]
     fn it_parses_prefix_codes() {
         let actual = parse_prefix_codes("");
-        let expected: Vec<CheckCodePrefix> = vec![];
+        let expected: Vec<RuleCodePrefix> = vec![];
         assert_eq!(actual, expected);
 
         let actual = parse_prefix_codes(" ");
-        let expected: Vec<CheckCodePrefix> = vec![];
+        let expected: Vec<RuleCodePrefix> = vec![];
         assert_eq!(actual, expected);
 
         let actual = parse_prefix_codes("F401");
-        let expected = vec![CheckCodePrefix::F401];
+        let expected = vec![RuleCodePrefix::F401];
         assert_eq!(actual, expected);
 
         let actual = parse_prefix_codes("F401,");
-        let expected = vec![CheckCodePrefix::F401];
+        let expected = vec![RuleCodePrefix::F401];
         assert_eq!(actual, expected);
 
         let actual = parse_prefix_codes("F401,E501");
-        let expected = vec![CheckCodePrefix::F401, CheckCodePrefix::E501];
+        let expected = vec![RuleCodePrefix::F401, RuleCodePrefix::E501];
         assert_eq!(actual, expected);
 
         let actual = parse_prefix_codes("F401, E501");
-        let expected = vec![CheckCodePrefix::F401, CheckCodePrefix::E501];
+        let expected = vec![RuleCodePrefix::F401, RuleCodePrefix::E501];
         assert_eq!(actual, expected);
     }
 
@@ -281,11 +284,11 @@ mod tests {
         let expected: Vec<PatternPrefixPair> = vec![
             PatternPrefixPair {
                 pattern: "locust/test/*".to_string(),
-                prefix: CheckCodePrefix::F841,
+                prefix: RuleCodePrefix::F841,
             },
             PatternPrefixPair {
                 pattern: "examples/*".to_string(),
-                prefix: CheckCodePrefix::F841,
+                prefix: RuleCodePrefix::F841,
             },
         ];
         assert_eq!(actual, expected);
@@ -301,23 +304,23 @@ mod tests {
         let expected: Vec<PatternPrefixPair> = vec![
             PatternPrefixPair {
                 pattern: "t/*".to_string(),
-                prefix: CheckCodePrefix::D,
+                prefix: RuleCodePrefix::D,
             },
             PatternPrefixPair {
                 pattern: "setup.py".to_string(),
-                prefix: CheckCodePrefix::D,
+                prefix: RuleCodePrefix::D,
             },
             PatternPrefixPair {
                 pattern: "examples/*".to_string(),
-                prefix: CheckCodePrefix::D,
+                prefix: RuleCodePrefix::D,
             },
             PatternPrefixPair {
                 pattern: "docs/*".to_string(),
-                prefix: CheckCodePrefix::D,
+                prefix: RuleCodePrefix::D,
             },
             PatternPrefixPair {
                 pattern: "extra/*".to_string(),
-                prefix: CheckCodePrefix::D,
+                prefix: RuleCodePrefix::D,
             },
         ];
         assert_eq!(actual, expected);
@@ -339,47 +342,47 @@ mod tests {
         let expected: Vec<PatternPrefixPair> = vec![
             PatternPrefixPair {
                 pattern: "scrapy/__init__.py".to_string(),
-                prefix: CheckCodePrefix::E402,
+                prefix: RuleCodePrefix::E402,
             },
             PatternPrefixPair {
                 pattern: "scrapy/core/downloader/handlers/http.py".to_string(),
-                prefix: CheckCodePrefix::F401,
+                prefix: RuleCodePrefix::F401,
             },
             PatternPrefixPair {
                 pattern: "scrapy/http/__init__.py".to_string(),
-                prefix: CheckCodePrefix::F401,
+                prefix: RuleCodePrefix::F401,
             },
             PatternPrefixPair {
                 pattern: "scrapy/linkextractors/__init__.py".to_string(),
-                prefix: CheckCodePrefix::E402,
+                prefix: RuleCodePrefix::E402,
             },
             PatternPrefixPair {
                 pattern: "scrapy/linkextractors/__init__.py".to_string(),
-                prefix: CheckCodePrefix::F401,
+                prefix: RuleCodePrefix::F401,
             },
             PatternPrefixPair {
                 pattern: "scrapy/selector/__init__.py".to_string(),
-                prefix: CheckCodePrefix::F401,
+                prefix: RuleCodePrefix::F401,
             },
             PatternPrefixPair {
                 pattern: "scrapy/spiders/__init__.py".to_string(),
-                prefix: CheckCodePrefix::E402,
+                prefix: RuleCodePrefix::E402,
             },
             PatternPrefixPair {
                 pattern: "scrapy/spiders/__init__.py".to_string(),
-                prefix: CheckCodePrefix::F401,
+                prefix: RuleCodePrefix::F401,
             },
             PatternPrefixPair {
                 pattern: "scrapy/utils/url.py".to_string(),
-                prefix: CheckCodePrefix::F403,
+                prefix: RuleCodePrefix::F403,
             },
             PatternPrefixPair {
                 pattern: "scrapy/utils/url.py".to_string(),
-                prefix: CheckCodePrefix::F405,
+                prefix: RuleCodePrefix::F405,
             },
             PatternPrefixPair {
                 pattern: "tests/test_loader.py".to_string(),
-                prefix: CheckCodePrefix::E741,
+                prefix: RuleCodePrefix::E741,
             },
         ];
         assert_eq!(actual, expected);

flake8_to_ruff/src/plugin.rs

@@ -3,7 +3,7 @@ use std::fmt;
 use std::str::FromStr;
 
 use anyhow::anyhow;
-use ruff::registry::CheckCodePrefix;
+use ruff::registry::RuleCodePrefix;
 
 #[derive(Clone, Ord, PartialOrd, Eq, PartialEq)]
 pub enum Plugin {
@@ -97,53 +97,32 @@ impl fmt::Debug for Plugin {
 }
 
 impl Plugin {
-    pub fn prefix(&self) -> CheckCodePrefix {
+    pub fn prefix(&self) -> RuleCodePrefix {
         match self {
-            Plugin::Flake8Annotations => CheckCodePrefix::ANN,
-            Plugin::Flake8Bandit => CheckCodePrefix::S,
+            Plugin::Flake8Annotations => RuleCodePrefix::ANN,
+            Plugin::Flake8Bandit => RuleCodePrefix::S,
             // TODO(charlie): Handle rename of `B` to `BLE`.
-            Plugin::Flake8BlindExcept => CheckCodePrefix::BLE,
-            Plugin::Flake8Bugbear => CheckCodePrefix::B,
-            Plugin::Flake8Builtins => CheckCodePrefix::A,
-            Plugin::Flake8Comprehensions => CheckCodePrefix::C4,
-            Plugin::Flake8Datetimez => CheckCodePrefix::DTZ,
-            Plugin::Flake8Debugger => CheckCodePrefix::T1,
-            Plugin::Flake8Docstrings => CheckCodePrefix::D,
+            Plugin::Flake8BlindExcept => RuleCodePrefix::BLE,
+            Plugin::Flake8Bugbear => RuleCodePrefix::B,
+            Plugin::Flake8Builtins => RuleCodePrefix::A,
+            Plugin::Flake8Comprehensions => RuleCodePrefix::C4,
+            Plugin::Flake8Datetimez => RuleCodePrefix::DTZ,
+            Plugin::Flake8Debugger => RuleCodePrefix::T1,
+            Plugin::Flake8Docstrings => RuleCodePrefix::D,
             // TODO(charlie): Handle rename of `E` to `ERA`.
-            Plugin::Flake8Eradicate => CheckCodePrefix::ERA,
-            Plugin::Flake8ErrMsg => CheckCodePrefix::EM,
-            Plugin::Flake8ImplicitStrConcat => CheckCodePrefix::ISC,
-            Plugin::Flake8Print => CheckCodePrefix::T2,
-            Plugin::Flake8PytestStyle => CheckCodePrefix::PT,
-            Plugin::Flake8Quotes => CheckCodePrefix::Q,
-            Plugin::Flake8Return => CheckCodePrefix::RET,
-            Plugin::Flake8Simplify => CheckCodePrefix::SIM,
-            Plugin::Flake8TidyImports => CheckCodePrefix::TID25,
-            Plugin::McCabe => CheckCodePrefix::C9,
-            Plugin::PandasVet => CheckCodePrefix::PD,
-            Plugin::PEP8Naming => CheckCodePrefix::N,
-            Plugin::Pyupgrade => CheckCodePrefix::UP,
-        }
-    }
-}
-
-pub enum DocstringConvention {
-    All,
-    Pep257,
-    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),
-            "pep257" => Ok(DocstringConvention::Pep257),
-            "numpy" => Ok(DocstringConvention::Numpy),
-            "google" => Ok(DocstringConvention::Google),
-            _ => Err(anyhow!("Unknown docstring convention: {string}")),
+            Plugin::Flake8Eradicate => RuleCodePrefix::ERA,
+            Plugin::Flake8ErrMsg => RuleCodePrefix::EM,
+            Plugin::Flake8ImplicitStrConcat => RuleCodePrefix::ISC,
+            Plugin::Flake8Print => RuleCodePrefix::T2,
+            Plugin::Flake8PytestStyle => RuleCodePrefix::PT,
+            Plugin::Flake8Quotes => RuleCodePrefix::Q,
+            Plugin::Flake8Return => RuleCodePrefix::RET,
+            Plugin::Flake8Simplify => RuleCodePrefix::SIM,
+            Plugin::Flake8TidyImports => RuleCodePrefix::TID25,
+            Plugin::McCabe => RuleCodePrefix::C9,
+            Plugin::PandasVet => RuleCodePrefix::PD,
+            Plugin::PEP8Naming => RuleCodePrefix::N,
+            Plugin::Pyupgrade => RuleCodePrefix::UP,
         }
     }
 }
@@ -269,7 +248,7 @@ pub fn infer_plugins_from_options(flake8: &HashMap<String, Option<String>>) -> V
 ///
 /// 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> {
+pub fn infer_plugins_from_codes(codes: &BTreeSet<RuleCodePrefix>) -> Vec<Plugin> {
     [
         Plugin::Flake8Annotations,
         Plugin::Flake8Bandit,
@@ -307,9 +286,10 @@ pub fn infer_plugins_from_codes(codes: &BTreeSet<CheckCodePrefix>) -> Vec<Plugin
     .collect()
 }
 
-/// Resolve the set of enabled `CheckCodePrefix` values for the given plugins.
-pub fn resolve_select(plugins: &[Plugin]) -> BTreeSet<CheckCodePrefix> {
-    let mut select = BTreeSet::from([CheckCodePrefix::F, CheckCodePrefix::E, CheckCodePrefix::W]);
+/// Resolve the set of enabled `RuleCodePrefix` values for the given
+/// plugins.
+pub fn resolve_select(plugins: &[Plugin]) -> BTreeSet<RuleCodePrefix> {
+    let mut select = BTreeSet::from([RuleCodePrefix::F, RuleCodePrefix::E, RuleCodePrefix::W]);
     select.extend(plugins.iter().map(Plugin::prefix));
     select
 }

playground/src/Editor/Editor.tsx

@@ -1,6 +1,11 @@
 import { useCallback, useEffect, useState } from "react";
 import { DEFAULT_PYTHON_SOURCE } from "../constants";
-import init, { check, Check, currentVersion, defaultSettings } from "../pkg";
+import init, {
+  check,
+  Diagnostic,
+  currentVersion,
+  defaultSettings,
+} from "../pkg";
 import { ErrorMessage } from "./ErrorMessage";
 import Header from "./Header";
 import { useTheme } from "./theme";
@@ -18,7 +23,7 @@ export default function Editor() {
   const [edit, setEdit] = useState<number>(0);
   const [settingsSource, setSettingsSource] = useState<string | null>(null);
   const [pythonSource, setPythonSource] = useState<string | null>(null);
-  const [checks, setChecks] = useState<Check[]>([]);
+  const [diagnostics, setDiagnostics] = useState<Diagnostic[]>([]);
   const [error, setError] = useState<string | null>(null);
   const [theme, setTheme] = useTheme();
 
@@ -32,25 +37,25 @@ export default function Editor() {
     }
 
     let config: any;
-    let checks: Check[];
+    let diagnostics: Diagnostic[];
 
     try {
       config = JSON.parse(settingsSource);
     } catch (e) {
-      setChecks([]);
+      setDiagnostics([]);
       setError((e as Error).message);
       return;
     }
 
     try {
-      checks = check(pythonSource, config);
+      diagnostics = check(pythonSource, config);
     } catch (e) {
       setError(e as string);
       return;
     }
 
     setError(null);
-    setChecks(checks);
+    setDiagnostics(diagnostics);
   }, [initialized, settingsSource, pythonSource]);
 
   useEffect(() => {
@@ -122,7 +127,7 @@ export default function Editor() {
               visible={tab === "Source"}
               source={pythonSource}
               theme={theme}
-              checks={checks}
+              diagnostics={diagnostics}
               onChange={handlePythonSourceChange}
             />
             <SettingsEditor

playground/src/Editor/SourceEditor.tsx

@@ -5,19 +5,19 @@
 import Editor, { useMonaco } from "@monaco-editor/react";
 import { MarkerSeverity, MarkerTag } from "monaco-editor";
 import { useCallback, useEffect } from "react";
-import { Check } from "../pkg";
+import { Diagnostic } from "../pkg";
 import { Theme } from "./theme";
 
 export default function SourceEditor({
   visible,
   source,
   theme,
-  checks,
+  diagnostics,
   onChange,
 }: {
   visible: boolean;
   source: string;
-  checks: Check[];
+  diagnostics: Diagnostic[];
   theme: Theme;
   onChange: (pythonSource: string) => void;
 }) {
@@ -33,15 +33,15 @@ export default function SourceEditor({
     editor.setModelMarkers(
       model,
       "owner",
-      checks.map((check) => ({
-        startLineNumber: check.location.row,
-        startColumn: check.location.column + 1,
-        endLineNumber: check.end_location.row,
-        endColumn: check.end_location.column + 1,
-        message: `${check.code}: ${check.message}`,
+      diagnostics.map((diagnostic) => ({
+        startLineNumber: diagnostic.location.row,
+        startColumn: diagnostic.location.column + 1,
+        endLineNumber: diagnostic.end_location.row,
+        endColumn: diagnostic.end_location.column + 1,
+        message: `${diagnostic.code}: ${diagnostic.message}`,
         severity: MarkerSeverity.Error,
         tags:
-          check.code === "F401" || check.code === "F841"
+          diagnostic.code === "F401" || diagnostic.code === "F841"
             ? [MarkerTag.Unnecessary]
             : [],
       })),
@@ -52,7 +52,7 @@ export default function SourceEditor({
       {
         // @ts-expect-error: The type definition is wrong.
         provideCodeActions: function (model, position) {
-          const actions = checks
+          const actions = diagnostics
             .filter((check) => position.startLineNumber === check.location.row)
             .filter((check) => check.fix)
             .map((check) => ({
@@ -89,7 +89,7 @@ export default function SourceEditor({
     return () => {
       codeActionProvider?.dispose();
     };
-  }, [checks, monaco]);
+  }, [diagnostics, monaco]);
 
   const handleChange = useCallback(
     (value: string | undefined) => {

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "maturin"
 
 [project]
 name = "ruff"
-version = "0.0.214"
+version = "0.0.220"
 description = "An extremely fast Python linter, written in Rust."
 authors = [
   { name = "Charlie Marsh", email = "charlie.r.marsh@gmail.com" },
@@ -35,6 +35,7 @@ urls = { repository = "https://github.com/charliermarsh/ruff" }
 
 [tool.maturin]
 bindings = "bin"
+python-source = "python"
 strip = true
 
 [tool.setuptools]

resources/test/fixtures/flake8_bandit/S508.py

@@ -0,0 +1,6 @@
+from pysnmp.hlapi import CommunityData
+
+CommunityData("public", mpModel=0)  # S508
+CommunityData("public", mpModel=1)  # S508
+
+CommunityData("public", mpModel=2)  # OK

resources/test/fixtures/flake8_bandit/S509.py

@@ -0,0 +1,7 @@
+from pysnmp.hlapi import UsmUserData
+
+
+insecure = UsmUserData("securityName")  # S509
+auth_no_priv = UsmUserData("securityName", "authName")  # S509
+
+less_insecure = UsmUserData("securityName", "authName", "privName")  # OK

resources/test/fixtures/flake8_bandit/S701.py

@@ -0,0 +1,29 @@
+import jinja2
+from jinja2 import Environment, select_autoescape
+templateLoader = jinja2.FileSystemLoader( searchpath="/" )
+something = ''
+
+Environment(loader=templateLoader, load=templateLoader, autoescape=True)
+templateEnv = jinja2.Environment(autoescape=True,
+        loader=templateLoader )
+Environment(loader=templateLoader, load=templateLoader, autoescape=something)  # S701
+templateEnv = jinja2.Environment(autoescape=False, loader=templateLoader )  # S701
+Environment(loader=templateLoader,
+            load=templateLoader,
+            autoescape=False)  # S701
+
+Environment(loader=templateLoader,  # S701
+            load=templateLoader)
+
+Environment(loader=templateLoader, autoescape=select_autoescape())
+
+Environment(loader=templateLoader,
+            autoescape=select_autoescape(['html', 'htm', 'xml']))
+
+Environment(loader=templateLoader,
+            autoescape=jinja2.select_autoescape(['html', 'htm', 'xml']))
+
+
+def fake_func():
+    return 'foobar'
+Environment(loader=templateLoader, autoescape=fake_func())  # S701

resources/test/fixtures/flake8_bugbear/B023.py

@@ -25,10 +25,10 @@ for x in range(3):
 
 
 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)}
+    ls = [lambda: x for x in range(2)]  # error
+    st = {lambda: x for x in range(2)}  # error
+    gn = (lambda: x for x in range(2))  # error
+    dt = {x: lambda: x for x in range(2)}  # error
 
 
 async def pointless_async_iterable():
@@ -37,9 +37,9 @@ async def pointless_async_iterable():
 
 async def container_for_problems():
     async for x in pointless_async_iterable():
-        functions.append(lambda: x)
+        functions.append(lambda: x)  # error
 
-    [lambda: x async for x in pointless_async_iterable()]
+    [lambda: x async for x in pointless_async_iterable()]  # error
 
 
 a = 10
@@ -47,10 +47,10 @@ 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!
+    functions.append(lambda: a)  # error
+    functions.append(lambda: a_)  # error
+    functions.append(lambda: b)  # error
+    functions.append(lambda: c)  # error, but not a name error due to late binding
     c: bool = a > 3
     if not c:
         break
@@ -58,7 +58,7 @@ while True:
 # Nested loops should not duplicate reports
 for j in range(2):
     for k in range(3):
-        lambda: j * k
+        lambda: j * k  # error
 
 
 for j, k, l in [(1, 2, 3)]:
@@ -80,3 +80,95 @@ for var in range(2):
 
 for i in range(3):
     lambda: f"{i}"
+
+
+# `query` is defined in the function, so also defining it in the loop should be OK.
+for name in ["a", "b"]:
+    query = name
+
+    def myfunc(x):
+        query = x
+        query_post = x
+        _ = query
+        _ = query_post
+
+    query_post = name  # in case iteration order matters
+
+
+# Bug here because two dict comprehensions reference `name`, one of which is inside
+# the lambda.  This should be totally fine, of course.
+_ = {
+    k: v
+    for k, v in reduce(
+        lambda data, event: merge_mappings(
+            [data, {name: f(caches, data, event) for name, f in xx}]
+        ),
+        events,
+        {name: getattr(group, name) for name in yy},
+    ).items()
+    if k in backfill_fields
+}
+
+
+# OK to define lambdas if they're immediately consumed, typically as the `key=`
+# argument or in a consumed `filter()` (even if a comprehension is better style)
+for x in range(2):
+    # It's not a complete get-out-of-linting-free construct - these should fail:
+    min([None, lambda: x], key=repr)
+    sorted([None, lambda: x], key=repr)
+    any(filter(bool, [None, lambda: x]))
+    list(filter(bool, [None, lambda: x]))
+    all(reduce(bool, [None, lambda: x]))
+
+    # But all these should be OK:
+    min(range(3), key=lambda y: x * y)
+    max(range(3), key=lambda y: x * y)
+    sorted(range(3), key=lambda y: x * y)
+
+    any(map(lambda y: x < y, range(3)))
+    all(map(lambda y: x < y, range(3)))
+    set(map(lambda y: x < y, range(3)))
+    list(map(lambda y: x < y, range(3)))
+    tuple(map(lambda y: x < y, range(3)))
+    sorted(map(lambda y: x < y, range(3)))
+    frozenset(map(lambda y: x < y, range(3)))
+
+    any(filter(lambda y: x < y, range(3)))
+    all(filter(lambda y: x < y, range(3)))
+    set(filter(lambda y: x < y, range(3)))
+    list(filter(lambda y: x < y, range(3)))
+    tuple(filter(lambda y: x < y, range(3)))
+    sorted(filter(lambda y: x < y, range(3)))
+    frozenset(filter(lambda y: x < y, range(3)))
+
+    any(reduce(lambda y: x | y, range(3)))
+    all(reduce(lambda y: x | y, range(3)))
+    set(reduce(lambda y: x | y, range(3)))
+    list(reduce(lambda y: x | y, range(3)))
+    tuple(reduce(lambda y: x | y, range(3)))
+    sorted(reduce(lambda y: x | y, range(3)))
+    frozenset(reduce(lambda y: x | y, range(3)))
+
+    import functools
+
+    any(functools.reduce(lambda y: x | y, range(3)))
+    all(functools.reduce(lambda y: x | y, range(3)))
+    set(functools.reduce(lambda y: x | y, range(3)))
+    list(functools.reduce(lambda y: x | y, range(3)))
+    tuple(functools.reduce(lambda y: x | y, range(3)))
+    sorted(functools.reduce(lambda y: x | y, range(3)))
+    frozenset(functools.reduce(lambda y: x | y, range(3)))
+
+# OK because the lambda which references a loop variable is defined in a `return`
+# statement, and after we return the loop variable can't be redefined.
+# In principle we could do something fancy with `break`, but it's not worth it.
+def iter_f(names):
+    for name in names:
+        if exists(name):
+            return lambda: name if exists(name) else None
+
+        if foo(name):
+            return [lambda: name]  # known false alarm
+
+        if False:
+            return [lambda: i for i in range(3)]  # error

resources/test/fixtures/flake8_comprehensions/C400.py

@@ -2,3 +2,10 @@ x = list(x for x in range(3))
 x = list(
     x for x in range(3)
 )
+
+
+def list(*args, **kwargs):
+    return None
+
+
+list(x for x in range(3))

resources/test/fixtures/flake8_comprehensions/C401.py

@@ -2,3 +2,10 @@ x = set(x for x in range(3))
 x = set(
     x for x in range(3)
 )
+
+
+def set(*args, **kwargs):
+    return None
+
+
+set(x for x in range(3))

resources/test/fixtures/flake8_comprehensions/C408.py

@@ -3,3 +3,10 @@ l = list()
 d1 = dict()
 d2 = dict(a=1)
 d3 = dict(**d2)
+
+
+def list():
+    return [1, 2, 3]
+
+
+a = list()

resources/test/fixtures/flake8_comprehensions/C413.py

@@ -4,3 +4,10 @@ list(sorted(x))
 reversed(sorted(x))
 reversed(sorted(x, key=lambda e: e))
 reversed(sorted(x, reverse=True))
+
+
+def reversed(*args, **kwargs):
+    return None
+
+
+reversed(sorted(x, reverse=True))

resources/test/fixtures/flake8_pie/PIE794.py

@@ -31,3 +31,10 @@ class User(BaseModel):
     @buzz.setter
     def buzz(self, value: str | int) -> None:
         ...
+
+
+class User:
+    bar: str = StringField()
+    foo: bool = BooleanField()
+    # ...
+    bar = StringField()  # PIE794

resources/test/fixtures/flake8_quotes/docstring_doubles_function.py

@@ -17,6 +17,15 @@ def fun_with_params_no_docstring(a, b="""
 """ """docstring"""):
     pass
 
+
 def fun_with_params_no_docstring2(a, b=c[foo():], c=\
     """ not a docstring """):
     pass
+
+
+def function_with_single_docstring(a):
+    "Single line docstring"
+
+
+def double_inside_single(a):
+    'Double inside "single "'

resources/test/fixtures/flake8_quotes/docstring_singles_function.py

@@ -13,11 +13,19 @@ def foo2():
 
 
 def fun_with_params_no_docstring(a, b='''
-    not a 
+    not a
 ''' '''docstring'''):
     pass
 
+
 def fun_with_params_no_docstring2(a, b=c[foo():], c=\
     ''' not a docstring '''):
     pass
 
+
+def function_with_single_docstring(a):
+    'Single line docstring'
+
+
+def double_inside_single(a):
+    "Double inside 'single '"

resources/test/fixtures/flake8_quotes/doubles_escaped.py

@@ -1,4 +1,5 @@
 this_should_raise_Q003 = 'This is a \'string\''
+this_should_raise_Q003 = 'This is \\ a \\\'string\''
 this_is_fine = '"This" is a \'string\''
 this_is_fine = "This is a 'string'"
 this_is_fine = "\"This\" is a 'string'"

resources/test/fixtures/flake8_simplify/SIM108.py

@@ -1,13 +1,13 @@
-# Bad
+# SIM108
 if a:
     b = c
 else:
     b = d
 
-# Good
+# OK
 b = c if a else d
 
-# https://github.com/MartinThoma/flake8-simplify/issues/115
+# OK
 if a:
     b = c
 elif c:
@@ -15,6 +15,7 @@ elif c:
 else:
     b = d
 
+# OK
 if True:
     pass
 elif a:
@@ -22,6 +23,7 @@ elif a:
 else:
     b = 2
 
+# OK (false negative)
 if True:
     pass
 else:
@@ -29,3 +31,63 @@ else:
         b = 1
     else:
         b = 2
+
+
+import sys
+
+# OK
+if sys.version_info >= (3, 9):
+    randbytes = random.randbytes
+else:
+    randbytes = _get_random_bytes
+
+# OK
+if sys.platform == "darwin":
+    randbytes = random.randbytes
+else:
+    randbytes = _get_random_bytes
+
+# OK
+if sys.platform.startswith("linux"):
+    randbytes = random.randbytes
+else:
+    randbytes = _get_random_bytes
+
+
+# OK (includes comments)
+if x > 0:
+    # test test
+    abc = x
+else:
+    # test test test
+    abc = -x
+
+
+# OK (too long)
+if parser.errno == BAD_FIRST_LINE:
+    req = wrappers.Request(sock, server=self._server)
+else:
+    req = wrappers.Request(
+        sock,
+        parser.get_method(),
+        parser.get_scheme() or _scheme,
+        parser.get_path(),
+        parser.get_version(),
+        parser.get_query_string(),
+        server=self._server,
+    )
+
+
+# SIM108
+if a:
+    b = cccccccccccccccccccccccccccccccccccc
+else:
+    b = ddddddddddddddddddddddddddddddddddddd
+
+
+# OK (too long)
+if True:
+    if a:
+        b = cccccccccccccccccccccccccccccccccccc
+    else:
+        b = ddddddddddddddddddddddddddddddddddddd

resources/test/fixtures/flake8_simplify/SIM110.py

@@ -1,5 +1,6 @@
 def f():
-    for x in iterable:  # SIM110
+    # SIM110
+    for x in iterable:
         if check(x):
             return True
     return False
@@ -20,14 +21,16 @@ def f():
 
 
 def f():
-    for x in iterable:  # SIM111
+    # SIM111
+    for x in iterable:
         if check(x):
             return False
     return True
 
 
 def f():
-    for x in iterable:  # SIM111
+    # SIM111
+    for x in iterable:
         if not x.is_empty():
             return False
     return True
@@ -45,3 +48,70 @@ def f():
         if check(x):
             return "foo"
     return "bar"
+
+
+def f():
+    # SIM110
+    for x in iterable:
+        if check(x):
+            return True
+    else:
+        return False
+
+
+def f():
+    # SIM111
+    for x in iterable:
+        if check(x):
+            return False
+    else:
+        return True
+
+
+def f():
+    # SIM110
+    for x in iterable:
+        if check(x):
+            return True
+    else:
+        return False
+    return True
+
+
+def f():
+    # SIM111
+    for x in iterable:
+        if check(x):
+            return False
+    else:
+        return True
+    return False
+
+
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+        elif x.is_empty():
+            return True
+    return False
+
+
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+        else:
+            return True
+    return False
+
+
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+        elif x.is_empty():
+            return True
+    else:
+        return True
+    return False

resources/test/fixtures/flake8_simplify/SIM111.py

@@ -1,10 +1,18 @@
 def f():
-    for x in iterable:  # SIM110
+    # SIM110
+    for x in iterable:
         if check(x):
             return True
     return False
 
 
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+    return True
+
+
 def f():
     for el in [1, 2, 3]:
         if is_true(el):
@@ -13,21 +21,97 @@ def f():
 
 
 def f():
-    for x in iterable:  # SIM111
+    # SIM111
+    for x in iterable:
         if check(x):
             return False
     return True
 
 
 def f():
-    for x in iterable:  # SIM 111
+    # SIM111
+    for x in iterable:
         if not x.is_empty():
             return False
     return True
 
 
+def f():
+    for x in iterable:
+        if check(x):
+            return False
+    return False
+
+
 def f():
     for x in iterable:
         if check(x):
             return "foo"
     return "bar"
+
+
+def f():
+    # SIM110
+    for x in iterable:
+        if check(x):
+            return True
+    else:
+        return False
+
+
+def f():
+    # SIM111
+    for x in iterable:
+        if check(x):
+            return False
+    else:
+        return True
+
+
+def f():
+    # SIM110
+    for x in iterable:
+        if check(x):
+            return True
+    else:
+        return False
+    return True
+
+
+def f():
+    # SIM111
+    for x in iterable:
+        if check(x):
+            return False
+    else:
+        return True
+    return False
+
+
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+        elif x.is_empty():
+            return True
+    return False
+
+
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+        else:
+            return True
+    return False
+
+
+def f():
+    for x in iterable:
+        if check(x):
+            return True
+        elif x.is_empty():
+            return True
+    else:
+        return True
+    return False

resources/test/fixtures/flake8_simplify/SIM112.py

@@ -0,0 +1,19 @@
+import os
+
+# Bad
+os.environ['foo']
+
+os.environ.get('foo')
+
+os.environ.get('foo', 'bar')
+
+os.getenv('foo')
+
+# Good
+os.environ['FOO']
+
+os.environ.get('FOO')
+
+os.environ.get('FOO', 'bar')
+
+os.getenv('FOO')

resources/test/fixtures/flake8_simplify/SIM115.py

@@ -0,0 +1,6 @@
+f = open('foo.txt')  # SIM115
+data = f.read()
+f.close()
+
+with open('foo.txt') as f:  # OK
+    data = f.read()

resources/test/fixtures/flake8_simplify/SIM401.py

@@ -0,0 +1,87 @@
+###
+# Positive cases
+###
+
+# SIM401 (pattern-1)
+if key in a_dict:
+    var = a_dict[key]
+else:
+    var = "default1"
+
+# SIM401 (pattern-2)
+if key not in a_dict:
+    var = "default2"
+else:
+    var = a_dict[key]
+
+# SIM401 (default with a complex expression)
+if key in a_dict:
+    var = a_dict[key]
+else:
+    var = val1 + val2
+
+# SIM401 (complex expression in key)
+if keys[idx] in a_dict:
+    var = a_dict[keys[idx]]
+else:
+    var = "default"
+
+# SIM401 (complex expression in dict)
+if key in dicts[idx]:
+    var = dicts[idx][key]
+else:
+    var = "default"
+
+# SIM401 (complex expression in var)
+if key in a_dict:
+    vars[idx] = a_dict[key]
+else:
+    vars[idx] = "default"
+
+###
+# Negative cases
+###
+
+# OK (false negative)
+if not key in a_dict:
+    var = "default"
+else:
+    var = a_dict[key]
+
+# OK (different dict)
+if key in a_dict:
+    var = other_dict[key]
+else:
+    var = "default"
+
+# OK (different key)
+if key in a_dict:
+    var = a_dict[other_key]
+else:
+    var = "default"
+
+# OK (different var)
+if key in a_dict:
+    var = a_dict[key]
+else:
+    other_var = "default"
+
+# OK (extra vars in body)
+if key in a_dict:
+    var = a_dict[key]
+    var2 = value2
+else:
+    var = "default"
+
+# OK (extra vars in orelse)
+if key in a_dict:
+    var = a_dict[key]
+else:
+    var2 = value2
+    var = "default"
+
+# OK (complex default value)
+if key in a_dict:
+    var = a_dict[key]
+else:
+    var = foo()

resources/test/fixtures/flake8_unused_arguments/ARG.py

@@ -77,6 +77,34 @@ class C:
     def f(x):
         ...
 
+    def f(self, x):
+        """Docstring."""
+
+    def f(self, x):
+        """Docstring."""
+        ...
+
+    def f(self, x):
+        pass
+
+    def f(self, x):
+        raise NotImplementedError
+
+    def f(self, x):
+        raise NotImplementedError()
+
+    def f(self, x):
+        raise NotImplementedError("...")
+
+    def f(self, x):
+        raise NotImplemented
+
+    def f(self, x):
+        raise NotImplemented()
+
+    def f(self, x):
+        raise NotImplemented("...")
+
     ###
     # Unused functions attached to abstract methods (OK).
     ###
@@ -153,3 +181,17 @@ def f(a: int, b: int) -> str:
 
 def f(a, b):
     return f"{a}{b}"
+
+
+###
+# Unused arguments on magic methods.
+###
+class C:
+    def __init__(self, x) -> None:
+        print("Hello, world!")
+
+    def __str__(self) -> str:
+        return "Hello, world!"
+
+    def __exit__(self, exc_type, exc_value, traceback) -> None:
+        print("Hello, world!")

resources/test/fixtures/isort/force_sort_within_sections.py

@@ -0,0 +1,11 @@
+from a import a1  # import_from
+from c import * # import_from_star
+import a  # import
+import c.d
+import b as b1  # import_as
+
+from ..parent import *
+from .my import fn
+from . import my
+from .my.nested import fn2
+from ...grandparent import fn3

resources/test/fixtures/isort/relative_imports_order.py

@@ -0,0 +1,3 @@
+from ... import a
+from .. import b
+from . import c

resources/test/fixtures/isort/required_imports/comment.py

@@ -0,0 +1,3 @@
+#!/usr/bin/env python3
+
+x = 1

resources/test/fixtures/isort/required_imports/docstring.py

@@ -0,0 +1,3 @@
+"""Hello, world!"""
+
+x = 1

resources/test/fixtures/isort/required_imports/docstring_only.py

@@ -0,0 +1 @@
+"""Hello, world!"""

resources/test/fixtures/isort/required_imports/docstring_with_continuation.py

@@ -0,0 +1,2 @@
+"""Hello, world!"""; x = \
+    1; y = 2

resources/test/fixtures/isort/required_imports/docstring_with_semicolon.py

@@ -0,0 +1 @@
+"""Hello, world!"""; x = 1

resources/test/fixtures/isort/required_imports/existing_import.py

@@ -0,0 +1,2 @@
+from __future__ import generator_stop
+import os

resources/test/fixtures/isort/skip.py

@@ -1,10 +1,20 @@
-# isort: off
-import sys
-import os
-import collections
-# isort: on
+def f():
+    # isort: off
+    import sys
+    import os
+    import collections
+    # isort: on
 
-import sys
-import os  # isort: skip
-import collections
-import abc
+
+def f():
+    import sys
+    import os  # isort: skip
+    import collections
+    import abc
+
+
+def f():
+    import sys
+    import os  # isort:skip
+    import collections
+    import abc

resources/test/fixtures/pycodestyle/W505.py

@@ -0,0 +1,15 @@
+#!/usr/bin/env python3
+"""Here's a top-level docstring that's over the limit."""
+
+
+def f():
+    """Here's a docstring that's also over the limit."""
+
+    x = 1  # Here's a comment that's over the limit, but it's not standalone.
+
+    # Here's a standalone comment that's over the limit.
+
+    print("Here's a string that's over the limit, but it's not a docstring.")
+
+
+"This is also considered a docstring, and is over the limit."

resources/test/fixtures/pyflakes/F601.py

@@ -10,3 +10,41 @@ x = {
     b"123": 1,
     b"123": 4,
 }
+
+x = {
+    "a": 1,
+    "a": 2,
+    "a": 3,
+    "a": 3,
+}
+
+x = {
+    "a": 1,
+    "a": 2,
+    "a": 3,
+    "a": 3,
+    "a": 4,
+}
+
+x = {
+    "a": 1,
+    "a": 1,
+    "a": 2,
+    "a": 3,
+    "a": 4,
+}
+
+x = {
+    a: 1,
+    "a": 1,
+    a: 1,
+    "a": 2,
+    a: 2,
+    "a": 3,
+    a: 3,
+    "a": 3,
+    a: 4,
+}
+
+x = {"a": 1, "a": 1}
+x = {"a": 1, "b": 2, "a": 1}

resources/test/fixtures/pyflakes/F602.py

@@ -5,3 +5,41 @@ x = {
     a: 2,
     b: 3,
 }
+
+x = {
+    a: 1,
+    a: 2,
+    a: 3,
+    a: 3,
+}
+
+x = {
+    a: 1,
+    a: 2,
+    a: 3,
+    a: 3,
+    a: 4,
+}
+
+x = {
+    a: 1,
+    a: 1,
+    a: 2,
+    a: 3,
+    a: 4,
+}
+
+x = {
+    a: 1,
+    "a": 1,
+    a: 1,
+    "a": 2,
+    a: 2,
+    "a": 3,
+    a: 3,
+    "a": 3,
+    a: 4,
+}
+
+x = {a: 1, a: 1}
+x = {a: 1, b: 2, a: 1}

resources/test/fixtures/pyflakes/builtins.py

@@ -0,0 +1 @@
+_("Translations")

resources/test/fixtures/pyflakes/typing_modules.py

@@ -0,0 +1,7 @@
+from typing import Union
+
+from airflow.typing_compat import Literal, Optional
+
+
+X = Union[Literal[False], Literal["db"]]
+y = Optional["Class"]

resources/test/fixtures/pyupgrade/UP024_3.py

@@ -0,0 +1,8 @@
+class SocketError(Exception):
+    pass
+
+
+try:
+    raise SocketError()
+except SocketError:
+    pass

resources/test/fixtures/pyupgrade/UP030_0.py

@@ -0,0 +1,36 @@
+# Invalid calls; errors expected.
+
+"{0}" "{1}" "{2}".format(1, 2, 3)
+
+"a {3} complicated {1} string with {0} {2}".format(
+    "first", "second", "third", "fourth"
+)
+
+'{0}'.format(1)
+
+'{0:x}'.format(30)
+
+x = '{0}'.format(1)
+
+'''{0}\n{1}\n'''.format(1, 2)
+
+x = "foo {0}" \
+    "bar {1}".format(1, 2)
+
+("{0}").format(1)
+
+"\N{snowman} {0}".format(1)
+
+'{' '0}'.format(1)
+
+# These will not change because we are waiting for libcst to fix this issue:
+# https://github.com/Instagram/LibCST/issues/846
+print(
+    'foo{0}'
+    'bar{1}'.format(1, 2)
+)
+
+print(
+    'foo{0}'  # ohai\n"
+    'bar{1}'.format(1, 2)
+)

resources/test/fixtures/pyupgrade/UP030_1.py

@@ -0,0 +1,23 @@
+# Valid calls; no errors expected.
+
+'{}'.format(1)
+
+
+x = ('{0} {1}',)
+
+'{0} {0}'.format(1)
+
+'{0:<{1}}'.format(1, 4)
+
+f"{0}".format(a)
+
+f"{0}".format(1)
+
+print(f"{0}".format(1))
+
+# I did not include the following tests because ruff does not seem to work with
+# invalid python syntax (which is a good thing)
+
+# "{0}"format(1)
+# '{'.format(1)", "'}'.format(1)
+# ("{0}" # {1}\n"{2}").format(1, 2, 3)

resources/test/project/README.md

@@ -17,7 +17,7 @@ resources/test/project/examples/docs/docs/file.py:8:5: F841 Local variable `x` i
 resources/test/project/project/file.py:1:8: F401 `os` imported but unused
 resources/test/project/project/import_file.py:1:1: I001 Import block is un-sorted or un-formatted
 Found 7 error(s).
-6 potentially fixable with the --fix option.
+7 potentially fixable with the --fix option.
 ```
 
 Running from the project directory itself should exhibit the same behavior:
@@ -32,7 +32,7 @@ examples/docs/docs/file.py:8:5: F841 Local variable `x` is assigned to but never
 project/file.py:1:8: F401 `os` imported but unused
 project/import_file.py:1:1: I001 Import block is un-sorted or un-formatted
 Found 7 error(s).
-6 potentially fixable with the --fix option.
+7 potentially fixable with the --fix option.
 ```
 
 Running from the sub-package directory should exhibit the same behavior, but omit the top-level
@@ -43,7 +43,7 @@ files:
 docs/file.py:1:1: I001 Import block is un-sorted or un-formatted
 docs/file.py:8:5: F841 Local variable `x` is assigned to but never used
 Found 2 error(s).
-1 potentially fixable with the --fix option.
+2 potentially fixable with the --fix option.
 ```
 
 `--config` should force Ruff to use the specified `pyproject.toml` for all files, and resolve
@@ -74,7 +74,7 @@ docs/docs/file.py:1:1: I001 Import block is un-sorted or un-formatted
 docs/docs/file.py:8:5: F841 Local variable `x` is assigned to but never used
 excluded/script.py:5:5: F841 Local variable `x` is assigned to but never used
 Found 4 error(s).
-1 potentially fixable with the --fix option.
+4 potentially fixable with the --fix option.
 ```
 
 Passing an excluded directory directly should report errors in the contained files:

ruff_dev/Cargo.toml

@@ -1,8 +1,12 @@
 [package]
 name = "ruff_dev"
-version = "0.0.214"
+version = "0.0.220"
 edition = "2021"
 
+[lib]
+name = "ruff_dev"
+doctest = false
+
 [dependencies]
 anyhow = { version = "1.0.66" }
 clap = { version = "4.0.1", features = ["derive"] }

ruff_dev/src/generate_rules_table.rs

@@ -3,7 +3,7 @@
 use anyhow::Result;
 use clap::Args;
 use itertools::Itertools;
-use ruff::registry::{CheckCategory, CheckCode};
+use ruff::registry::{RuleCode, RuleOrigin};
 use strum::IntoEnumIterator;
 
 use crate::utils::replace_readme_section;
@@ -25,24 +25,24 @@ pub fn main(cli: &Cli) -> Result<()> {
     // Generate the table string.
     let mut table_out = String::new();
     let mut toc_out = String::new();
-    for check_category in CheckCategory::iter() {
-        let codes_csv: String = check_category.codes().iter().map(AsRef::as_ref).join(", ");
-        table_out.push_str(&format!("### {} ({codes_csv})", check_category.title()));
+    for origin in RuleOrigin::iter() {
+        let codes_csv: String = origin.codes().iter().map(AsRef::as_ref).join(", ");
+        table_out.push_str(&format!("### {} ({codes_csv})", origin.title()));
         table_out.push('\n');
         table_out.push('\n');
 
         toc_out.push_str(&format!(
             "   1. [{} ({})](#{}-{})\n",
-            check_category.title(),
+            origin.title(),
             codes_csv,
-            check_category.title().to_lowercase().replace(' ', "-"),
+            origin.title().to_lowercase().replace(' ', "-"),
             codes_csv.to_lowercase().replace(',', "-").replace(' ', "")
         ));
 
-        if let Some((url, platform)) = check_category.url() {
+        if let Some((url, platform)) = origin.url() {
             table_out.push_str(&format!(
                 "For more, see [{}]({}) on {}.",
-                check_category.title(),
+                origin.title(),
                 url,
                 platform
             ));
@@ -55,15 +55,15 @@ pub fn main(cli: &Cli) -> Result<()> {
         table_out.push_str("| ---- | ---- | ------- | --- |");
         table_out.push('\n');
 
-        for check_code in CheckCode::iter() {
-            if check_code.category() == check_category {
-                let check_kind = check_code.kind();
-                let fix_token = if check_kind.fixable() { "🛠" } else { "" };
+        for rule_code in RuleCode::iter() {
+            if rule_code.origin() == origin {
+                let kind = rule_code.kind();
+                let fix_token = if kind.fixable() { "🛠" } else { "" };
                 table_out.push_str(&format!(
                     "| {} | {} | {} | {} |",
-                    check_kind.code().as_ref(),
-                    check_kind.as_ref(),
-                    check_kind.summary().replace('|', r"\|"),
+                    kind.code().as_ref(),
+                    kind.as_ref(),
+                    kind.summary().replace('|', r"\|"),
                     fix_token
                 ));
                 table_out.push('\n');

ruff_dev/src/round_trip.rs

@@ -5,9 +5,7 @@ use std::path::PathBuf;
 
 use anyhow::Result;
 use clap::Args;
-use ruff::source_code_generator::SourceCodeGenerator;
-use ruff::source_code_locator::SourceCodeLocator;
-use ruff::source_code_style::SourceCodeStyleDetector;
+use ruff::source_code::{Generator, Locator, Stylist};
 use rustpython_parser::parser;
 
 #[derive(Args)]
@@ -20,9 +18,9 @@ pub struct Cli {
 pub fn main(cli: &Cli) -> Result<()> {
     let contents = fs::read_to_string(&cli.file)?;
     let python_ast = parser::parse_program(&contents, &cli.file.to_string_lossy())?;
-    let locator = SourceCodeLocator::new(&contents);
-    let stylist = SourceCodeStyleDetector::from_contents(&contents, &locator);
-    let mut generator: SourceCodeGenerator = (&stylist).into();
+    let locator = Locator::new(&contents);
+    let stylist = Stylist::from_contents(&contents, &locator);
+    let mut generator: Generator = (&stylist).into();
     generator.unparse_suite(&python_ast);
     println!("{}", generator.generate());
     Ok(())

ruff_macros/Cargo.toml

@@ -1,10 +1,11 @@
 [package]
 name = "ruff_macros"
-version = "0.0.214"
+version = "0.0.220"
 edition = "2021"
 
 [lib]
 proc-macro = true
+doctest = false
 
 [dependencies]
 once_cell = { version = "1.17.0" }

ruff_macros/src/lib.rs

@@ -12,10 +12,13 @@
 )]
 #![forbid(unsafe_code)]
 
-use syn::{parse_macro_input, DeriveInput};
+use proc_macro2::Span;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput, Ident};
 
-mod check_code_prefix;
 mod config;
+mod prefixes;
+mod rule_code_prefix;
 
 #[proc_macro_derive(ConfigurationOptions, attributes(option, doc, option_group))]
 pub fn derive_config(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
@@ -26,11 +29,31 @@ pub fn derive_config(input: proc_macro::TokenStream) -> proc_macro::TokenStream
         .into()
 }
 
-#[proc_macro_derive(CheckCodePrefix)]
-pub fn derive_check_code_prefix(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+#[proc_macro_derive(RuleCodePrefix)]
+pub fn derive_rule_code_prefix(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
 
-    check_code_prefix::derive_impl(input)
+    rule_code_prefix::derive_impl(input)
         .unwrap_or_else(syn::Error::into_compile_error)
         .into()
 }
+
+#[proc_macro]
+pub fn origin_by_code(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let ident = parse_macro_input!(item as Ident).to_string();
+    let mut iter = prefixes::PREFIX_TO_ORIGIN.iter();
+    let origin = loop {
+        let (prefix, origin) = iter
+            .next()
+            .unwrap_or_else(|| panic!("code doesn't start with any recognized prefix: {ident}"));
+        if ident.starts_with(prefix) {
+            break origin;
+        }
+    };
+    let prefix = Ident::new(origin, Span::call_site());
+
+    quote! {
+        RuleOrigin::#prefix
+    }
+    .into()
+}

ruff_macros/src/prefixes.rs

@@ -0,0 +1,53 @@
+// Longer prefixes should come first so that you can find an origin for a code
+// by simply picking the first entry that starts with the given prefix.
+
+pub const PREFIX_TO_ORIGIN: &[(&str, &str)] = &[
+    ("ANN", "Flake8Annotations"),
+    ("ARG", "Flake8UnusedArguments"),
+    ("A", "Flake8Builtins"),
+    ("BLE", "Flake8BlindExcept"),
+    ("B", "Flake8Bugbear"),
+    ("C4", "Flake8Comprehensions"),
+    ("C9", "McCabe"),
+    ("DTZ", "Flake8Datetimez"),
+    ("D", "Pydocstyle"),
+    ("ERA", "Eradicate"),
+    ("EM", "Flake8ErrMsg"),
+    ("E", "Pycodestyle"),
+    ("FBT", "Flake8BooleanTrap"),
+    ("F", "Pyflakes"),
+    ("ICN", "Flake8ImportConventions"),
+    ("ISC", "Flake8ImplicitStrConcat"),
+    ("I", "Isort"),
+    ("N", "PEP8Naming"),
+    ("PD", "PandasVet"),
+    ("PGH", "PygrepHooks"),
+    ("PL", "Pylint"),
+    ("PT", "Flake8PytestStyle"),
+    ("Q", "Flake8Quotes"),
+    ("RET", "Flake8Return"),
+    ("SIM", "Flake8Simplify"),
+    ("S", "Flake8Bandit"),
+    ("T10", "Flake8Debugger"),
+    ("T20", "Flake8Print"),
+    ("TID", "Flake8TidyImports"),
+    ("UP", "Pyupgrade"),
+    ("W", "Pycodestyle"),
+    ("YTT", "Flake82020"),
+    ("PIE", "Flake8Pie"),
+    ("RUF", "Ruff"),
+];
+
+#[cfg(test)]
+mod tests {
+    use super::PREFIX_TO_ORIGIN;
+
+    #[test]
+    fn order() {
+        for (idx, (prefix, _)) in PREFIX_TO_ORIGIN.iter().enumerate() {
+            for (prior_prefix, _) in PREFIX_TO_ORIGIN[..idx].iter() {
+                assert!(!prefix.starts_with(prior_prefix));
+            }
+        }
+    }
+}

ruff_macros/src/rule_code_prefix.rs

@@ -9,7 +9,8 @@ use syn::{DataEnum, DeriveInput, Ident, Variant};
 
 const ALL: &str = "ALL";
 
-/// A hash map from deprecated `CheckCodePrefix` to latest `CheckCodePrefix`.
+/// A hash map from deprecated `RuleCodePrefix` to latest
+/// `RuleCodePrefix`.
 pub static PREFIX_REDIRECTS: Lazy<HashMap<&'static str, &'static str>> = Lazy::new(|| {
     HashMap::from_iter([
         // TODO(charlie): Remove by 2023-01-01.
@@ -90,7 +91,7 @@ pub fn derive_impl(input: DeriveInput) -> syn::Result<proc_macro2::TokenStream>
     let syn::Data::Enum(DataEnum { variants, .. }) = data else {
         return Err(syn::Error::new(
             ident.span(),
-            "Can only derive `CheckCodePrefix` from enums.",
+            "Can only derive `RuleCodePrefix` from enums.",
         ));
     };
 
@@ -117,7 +118,7 @@ fn expand(
     prefix_ident: &Ident,
     variants: &Punctuated<Variant, Comma>,
 ) -> proc_macro2::TokenStream {
-    // Build up a map from prefix to matching CheckCodes.
+    // Build up a map from prefix to matching RuleCodes.
     let mut prefix_to_codes: BTreeMap<Ident, BTreeSet<String>> = BTreeMap::default();
     for variant in variants {
         let span = variant.ident.span();
@@ -141,12 +142,12 @@ fn expand(
     }
 
     // Add any prefix aliases (e.g., "U" to "UP").
-    for (alias, check_code) in PREFIX_REDIRECTS.iter() {
+    for (alias, rule_code) in PREFIX_REDIRECTS.iter() {
         prefix_to_codes.insert(
             Ident::new(alias, Span::call_site()),
             prefix_to_codes
-                .get(&Ident::new(check_code, Span::call_site()))
-                .unwrap_or_else(|| panic!("Unknown CheckCode: {alias:?}"))
+                .get(&Ident::new(rule_code, Span::call_site()))
+                .unwrap_or_else(|| panic!("Unknown RuleCode: {alias:?}"))
                 .clone(),
         );
     }
@@ -159,8 +160,8 @@ fn expand(
 
     let prefix_impl = generate_impls(ident, prefix_ident, &prefix_to_codes);
 
-    let prefix_redirects = PREFIX_REDIRECTS.iter().map(|(alias, check_code)| {
-        let code = Ident::new(check_code, Span::call_site());
+    let prefix_redirects = PREFIX_REDIRECTS.iter().map(|(alias, rule_code)| {
+        let code = Ident::new(rule_code, Span::call_site());
         quote! {
             (#alias, #prefix_ident::#code)
         }
@@ -186,7 +187,7 @@ fn expand(
 
         #prefix_impl
 
-        /// A hash map from deprecated `CheckCodePrefix` to latest `CheckCodePrefix`.
+        /// A hash map from deprecated `RuleCodePrefix` to latest `RuleCodePrefix`.
         pub static PREFIX_REDIRECTS: ::once_cell::sync::Lazy<::rustc_hash::FxHashMap<&'static str, #prefix_ident>> = ::once_cell::sync::Lazy::new(|| {
             ::rustc_hash::FxHashMap::from_iter([
                 #(#prefix_redirects),*
@@ -211,11 +212,8 @@ fn generate_impls(
         if let Some(target) = PREFIX_REDIRECTS.get(prefix_str.as_str()) {
             quote! {
                 #prefix_ident::#prefix => {
-                    crate::one_time_warning!(
-                        "{}{} {}",
-                        "warning".yellow().bold(),
-                        ":".bold(),
-                        format!("`{}` has been remapped to `{}`", #prefix_str, #target).bold()
+                    crate::warn_user_once!(
+                        "`{}` has been remapped to `{}`", #prefix_str, #target
                     );
                     vec![#(#codes),*]
                 }

scripts/add_check.py

@@ -1,139 +0,0 @@
-#!/usr/bin/env python3
-"""Generate boilerplate for a new check.
-
-Example usage:
-
-    python scripts/add_check.py \
-        --name PreferListBuiltin \
-        --code PIE807 \
-        --plugin flake8-pie
-"""
-
-import argparse
-import os
-
-ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-
-
-def dir_name(plugin: str) -> str:
-    return plugin.replace("-", "_")
-
-
-def pascal_case(plugin: str) -> str:
-    """Convert from snake-case to PascalCase."""
-    return "".join(word.title() for word in plugin.split("-"))
-
-
-def snake_case(name: str) -> str:
-    """Convert from PascalCase to snake_case."""
-    return "".join(f"_{word.lower()}" if word.isupper() else word for word in name).lstrip("_")
-
-
-def main(*, name: str, code: str, plugin: str) -> None:
-    # Create a test fixture.
-    with open(
-        os.path.join(ROOT_DIR, f"resources/test/fixtures/{dir_name(plugin)}/{code}.py"),
-        "a",
-    ):
-        pass
-
-    # Add the relevant `#testcase` macro.
-    with open(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}/mod.rs"), "r") as fp:
-        content = fp.read()
-
-    with open(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}/mod.rs"), "w") as fp:
-        for line in content.splitlines():
-            if line.strip() == "fn checks(check_code: CheckCode, path: &Path) -> Result<()> {":
-                indent = line.split("fn checks(check_code: CheckCode, path: &Path) -> Result<()> {")[0]
-                fp.write(f'{indent}#[test_case(CheckCode::{code}, Path::new("{code}.py"); "{code}")]')
-                fp.write("\n")
-
-            fp.write(line)
-            fp.write("\n")
-
-    # Add the relevant plugin function.
-    with open(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}/plugins.rs"), "a") as fp:
-        fp.write(
-            f"""
-/// {code}
-pub fn {snake_case(name)}(checker: &mut Checker) {{}}
-"""
-        )
-        fp.write("\n")
-
-    # Add the relevant sections to `src/registry.rs`.
-    with open(os.path.join(ROOT_DIR, "src/registry.rs"), "r") as fp:
-        content = fp.read()
-
-    index = 0
-    with open(os.path.join(ROOT_DIR, "src/registry.rs"), "w") as fp:
-        for line in content.splitlines():
-            fp.write(line)
-            fp.write("\n")
-
-            if line.strip() == f"// {plugin}":
-                if index == 0:
-                    # `CheckCode` definition
-                    indent = line.split(f"// {plugin}")[0]
-                    fp.write(f"{indent}{code},")
-                    fp.write("\n")
-
-                elif index == 1:
-                    # `CheckKind` definition
-                    indent = line.split(f"// {plugin}")[0]
-                    fp.write(f"{indent}{name},")
-                    fp.write("\n")
-
-                elif index == 2:
-                    # `CheckCode#kind()`
-                    indent = line.split(f"// {plugin}")[0]
-                    fp.write(f"{indent}CheckCode::{code} => CheckKind::{name},")
-                    fp.write("\n")
-
-                elif index == 3:
-                    # `CheckCode#category()`
-                    indent = line.split(f"// {plugin}")[0]
-                    fp.write(f"{indent}CheckCode::{code} => CheckCategory::{pascal_case(plugin)},")
-                    fp.write("\n")
-
-                elif index == 4:
-                    # `CheckKind#code()`
-                    indent = line.split(f"// {plugin}")[0]
-                    fp.write(f"{indent}CheckKind::{name} => &CheckCode::{code},")
-                    fp.write("\n")
-
-                elif index == 5:
-                    # `CheckCode#body`
-                    indent = line.split(f"// {plugin}")[0]
-                    fp.write(f'{indent}CheckKind::{name} => todo!("Write message body for {code}"),')
-                    fp.write("\n")
-
-                index += 1
-
-
-if __name__ == "__main__":
-    parser = argparse.ArgumentParser(
-        description="Generate boilerplate for a new check.",
-        epilog="python scripts/add_check.py --name PreferListBuiltin --code PIE807 --plugin flake8-pie",
-    )
-    parser.add_argument(
-        "--name",
-        type=str,
-        required=True,
-        help="The name of the check to generate, in PascalCase (e.g., 'LineTooLong').",
-    )
-    parser.add_argument(
-        "--code",
-        type=str,
-        required=True,
-        help="The code of the check to generate (e.g., 'A001').",
-    )
-    parser.add_argument(
-        "--plugin",
-        type=str,
-        required=True,
-        help="The plugin with which the check is associated (e.g., 'flake8-builtins').",
-    )
-    args = parser.parse_args()
-
-    main(name=args.name, code=args.code, plugin=args.plugin)

scripts/add_plugin.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Generate boilerplate for a new plugin.
+"""Generate boilerplate for a new Flake8 plugin.
 
 Example usage:
 
@@ -31,10 +31,10 @@ def main(*, plugin: str, url: str) -> None:
 
     # Create the Rust module.
     os.makedirs(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}"), exist_ok=True)
-    with open(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}/plugins.rs"), "a"):
-        pass
+    with open(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}/rules.rs"), "w+") as fp:
+        fp.write("use crate::checkers::ast::Checker;\n")
     with open(os.path.join(ROOT_DIR, f"src/{dir_name(plugin)}/mod.rs"), "w+") as fp:
-        fp.write("pub mod plugins;\n")
+        fp.write("pub(crate) mod rules;\n")
         fp.write("\n")
         fp.write(
             """#[cfg(test)]
@@ -45,19 +45,19 @@ mod tests {
     use anyhow::Result;
     use test_case::test_case;
 
-    use crate::registry::CheckCode;
+    use crate::registry::RuleCode;
     use crate::linter::test_path;
     use crate::settings;
 
-    fn checks(check_code: CheckCode, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", check_code.as_ref(), path.to_string_lossy());
-        let checks = test_path(
+    fn rules(rule_code: RuleCode, path: &Path) -> Result<()> {
+        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let diagnostics =test_path(
             Path::new("./resources/test/fixtures/%s")
                 .join(path)
                 .as_path(),
-            &settings::Settings::for_rule(check_code),
+            &settings::Settings::for_rule(rule_code),
         )?;
-        insta::assert_yaml_snapshot!(snapshot, checks);
+        insta::assert_yaml_snapshot!(snapshot, diagnostics);
         Ok(())
     }
 }
@@ -67,10 +67,10 @@ mod tests {
 
     # Add the plugin to `lib.rs`.
     with open(os.path.join(ROOT_DIR, "src/lib.rs"), "a") as fp:
-        fp.write(f"pub mod {dir_name(plugin)};")
+        fp.write(f"mod {dir_name(plugin)};")
 
     # Add the relevant sections to `src/registry.rs`.
-    with open(os.path.join(ROOT_DIR, "src/registry.rs"), "r") as fp:
+    with open(os.path.join(ROOT_DIR, "src/registry.rs")) as fp:
         content = fp.read()
 
     with open(os.path.join(ROOT_DIR, "src/registry.rs"), "w") as fp:
@@ -85,23 +85,37 @@ mod tests {
                 fp.write(f"{indent}{pascal_case(plugin)},")
                 fp.write("\n")
 
-            elif line.strip() == 'CheckCategory::Ruff => "Ruff-specific rules",':
-                indent = line.split('CheckCategory::Ruff => "Ruff-specific rules",')[0]
-                fp.write(f'{indent}CheckCategory::{pascal_case(plugin)} => "{plugin}",')
+            elif line.strip() == 'RuleOrigin::Ruff => "Ruff-specific rules",':
+                indent = line.split('RuleOrigin::Ruff => "Ruff-specific rules",')[0]
+                fp.write(f'{indent}RuleOrigin::{pascal_case(plugin)} => "{plugin}",')
                 fp.write("\n")
 
-            elif line.strip() == "CheckCategory::Ruff => vec![CheckCodePrefix::RUF],":
-                indent = line.split("CheckCategory::Ruff => vec![CheckCodePrefix::RUF],")[0]
+            elif line.strip() == "RuleOrigin::Ruff => vec![RuleCodePrefix::RUF],":
+                indent = line.split("RuleOrigin::Ruff => vec![RuleCodePrefix::RUF],")[0]
                 fp.write(
-                    f"{indent}CheckCategory::{pascal_case(plugin)} => vec![\n"
+                    f"{indent}RuleOrigin::{pascal_case(plugin)} => vec![\n"
                     f'{indent}    todo!("Fill-in prefix after generating codes")\n'
                     f"{indent}],"
                 )
                 fp.write("\n")
 
-            elif line.strip() == "CheckCategory::Ruff => None,":
-                indent = line.split("CheckCategory::Ruff => None,")[0]
-                fp.write(f"{indent}CheckCategory::{pascal_case(plugin)} => " f'Some(("{url}", &Platform::PyPI)),')
+            elif line.strip() == "RuleOrigin::Ruff => None,":
+                indent = line.split("RuleOrigin::Ruff => None,")[0]
+                fp.write(f"{indent}RuleOrigin::{pascal_case(plugin)} => " f'Some(("{url}", &Platform::PyPI)),')
+                fp.write("\n")
+
+            fp.write(line)
+            fp.write("\n")
+
+    # Add the relevant section to `src/violations.rs`.
+    with open(os.path.join(ROOT_DIR, "src/violations.rs")) as fp:
+        content = fp.read()
+
+    with open(os.path.join(ROOT_DIR, "src/violations.rs"), "w") as fp:
+        for line in content.splitlines():
+            if line.strip() == "// Ruff":
+                indent = line.split("// Ruff")[0]
+                fp.write(f"{indent}// {plugin}")
                 fp.write("\n")
 
             fp.write(line)
@@ -110,7 +124,7 @@ mod tests {
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(
-        description="Generate boilerplate for a new plugin.",
+        description="Generate boilerplate for a new Flake8 plugin.",
         epilog=(
             "Example usage: python scripts/add_plugin.py flake8-pie "
             "--url https://pypi.org/project/flake8-pie/0.16.0/"
@@ -118,7 +132,6 @@ if __name__ == "__main__":
     )
     parser.add_argument(
         "plugin",
-        required=True,
         type=str,
         help="The name of the plugin to generate.",
     )

scripts/add_rule.py

@@ -0,0 +1,145 @@
+#!/usr/bin/env python3
+"""Generate boilerplate for a new rule.
+
+Example usage:
+
+    python scripts/add_rule.py \
+        --name PreferListBuiltin \
+        --code PIE807 \
+        --origin flake8-pie
+"""
+
+import argparse
+import os
+
+ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+
+def dir_name(origin: str) -> str:
+    return origin.replace("-", "_")
+
+
+def pascal_case(origin: str) -> str:
+    """Convert from snake-case to PascalCase."""
+    return "".join(word.title() for word in origin.split("-"))
+
+
+def snake_case(name: str) -> str:
+    """Convert from PascalCase to snake_case."""
+    return "".join(f"_{word.lower()}" if word.isupper() else word for word in name).lstrip("_")
+
+
+def main(*, name: str, code: str, origin: str) -> None:
+    # Create a test fixture.
+    with open(
+        os.path.join(ROOT_DIR, f"resources/test/fixtures/{dir_name(origin)}/{code}.py"),
+        "a",
+    ):
+        pass
+
+    # Add the relevant `#testcase` macro.
+    with open(os.path.join(ROOT_DIR, f"src/{dir_name(origin)}/mod.rs")) as fp:
+        content = fp.read()
+
+    with open(os.path.join(ROOT_DIR, f"src/{dir_name(origin)}/mod.rs"), "w") as fp:
+        for line in content.splitlines():
+            if line.strip() == "fn rules(rule_code: RuleCode, path: &Path) -> Result<()> {":
+                indent = line.split("fn rules(rule_code: RuleCode, path: &Path) -> Result<()> {")[0]
+                fp.write(f'{indent}#[test_case(RuleCode::{code}, Path::new("{code}.py"); "{code}")]')
+                fp.write("\n")
+
+            fp.write(line)
+            fp.write("\n")
+
+    # Add the relevant rule function.
+    with open(os.path.join(ROOT_DIR, f"src/{dir_name(origin)}/rules.rs"), "a") as fp:
+        fp.write(
+            f"""
+/// {code}
+pub fn {snake_case(name)}(checker: &mut Checker) {{}}
+"""
+        )
+        fp.write("\n")
+
+    # Add the relevant struct to `src/violations.rs`.
+    with open(os.path.join(ROOT_DIR, "src/violations.rs")) as fp:
+        content = fp.read()
+
+    with open(os.path.join(ROOT_DIR, "src/violations.rs"), "w") as fp:
+        for line in content.splitlines():
+            fp.write(line)
+            fp.write("\n")
+
+            if line.startswith(f"// {origin}"):
+                fp.write(
+                    """define_violation!(
+    pub struct %s;
+);
+impl Violation for %s {
+    fn message(&self) -> String {
+        todo!("Implement message")
+    }
+
+    fn placeholder() -> Self {
+        %s
+    }
+}
+"""
+                    % (name, name, name)
+                )
+                fp.write("\n")
+
+    # Add the relevant code-to-violation pair to `src/registry.rs`.
+    with open(os.path.join(ROOT_DIR, "src/registry.rs")) as fp:
+        content = fp.read()
+
+    seen_macro = False
+    has_written = False
+    with open(os.path.join(ROOT_DIR, "src/registry.rs"), "w") as fp:
+        for line in content.splitlines():
+            fp.write(line)
+            fp.write("\n")
+
+            if has_written:
+                continue
+
+            if line.startswith("define_rule_mapping!"):
+                seen_macro = True
+                continue
+
+            if not seen_macro:
+                continue
+
+            if line.strip() == f"// {origin}":
+                indent = line.split("//")[0]
+                fp.write(f"{indent}{code} => violations::{name},")
+                fp.write("\n")
+                has_written = True
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Generate boilerplate for a new rule.",
+        epilog="python scripts/add_rule.py --name PreferListBuiltin --code PIE807 --origin flake8-pie",
+    )
+    parser.add_argument(
+        "--name",
+        type=str,
+        required=True,
+        help="The name of the check to generate, in PascalCase (e.g., 'LineTooLong').",
+    )
+    parser.add_argument(
+        "--code",
+        type=str,
+        required=True,
+        help="The code of the check to generate (e.g., 'A001').",
+    )
+    parser.add_argument(
+        "--origin",
+        type=str,
+        required=True,
+        help="The source with which the check originated (e.g., 'flake8-builtins').",
+    )
+    args = parser.parse_args()
+
+    main(name=args.name, code=args.code, origin=args.origin)

src/ast/cast.rs

@@ -1,5 +1,12 @@
 use rustpython_ast::{Expr, Stmt, StmtKind};
 
+pub fn name(stmt: &Stmt) -> &str {
+    match &stmt.node {
+        StmtKind::FunctionDef { name, .. } | StmtKind::AsyncFunctionDef { name, .. } => name,
+        _ => panic!("Expected StmtKind::FunctionDef | StmtKind::AsyncFunctionDef"),
+    }
+}
+
 pub fn decorator_list(stmt: &Stmt) -> &Vec<Expr> {
     match &stmt.node {
         StmtKind::FunctionDef { decorator_list, .. }

src/ast/comparable.rs

@@ -0,0 +1,530 @@
+//! An equivalent object hierarchy to the `Expr` hierarchy, but with the ability
+//! to compare expressions for equality (via `Eq` and `Hash`).
+
+use num_bigint::BigInt;
+use rustpython_ast::{
+    Arg, Arguments, Boolop, Cmpop, Comprehension, Constant, Expr, ExprContext, ExprKind, Keyword,
+    Operator, Unaryop,
+};
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableExprContext {
+    Load,
+    Store,
+    Del,
+}
+
+impl From<&ExprContext> for ComparableExprContext {
+    fn from(ctx: &ExprContext) -> Self {
+        match ctx {
+            ExprContext::Load => Self::Load,
+            ExprContext::Store => Self::Store,
+            ExprContext::Del => Self::Del,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableBoolop {
+    And,
+    Or,
+}
+
+impl From<&Boolop> for ComparableBoolop {
+    fn from(op: &Boolop) -> Self {
+        match op {
+            Boolop::And => Self::And,
+            Boolop::Or => Self::Or,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableOperator {
+    Add,
+    Sub,
+    Mult,
+    MatMult,
+    Div,
+    Mod,
+    Pow,
+    LShift,
+    RShift,
+    BitOr,
+    BitXor,
+    BitAnd,
+    FloorDiv,
+}
+
+impl From<&Operator> for ComparableOperator {
+    fn from(op: &Operator) -> Self {
+        match op {
+            Operator::Add => Self::Add,
+            Operator::Sub => Self::Sub,
+            Operator::Mult => Self::Mult,
+            Operator::MatMult => Self::MatMult,
+            Operator::Div => Self::Div,
+            Operator::Mod => Self::Mod,
+            Operator::Pow => Self::Pow,
+            Operator::LShift => Self::LShift,
+            Operator::RShift => Self::RShift,
+            Operator::BitOr => Self::BitOr,
+            Operator::BitXor => Self::BitXor,
+            Operator::BitAnd => Self::BitAnd,
+            Operator::FloorDiv => Self::FloorDiv,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableUnaryop {
+    Invert,
+    Not,
+    UAdd,
+    USub,
+}
+
+impl From<&Unaryop> for ComparableUnaryop {
+    fn from(op: &Unaryop) -> Self {
+        match op {
+            Unaryop::Invert => Self::Invert,
+            Unaryop::Not => Self::Not,
+            Unaryop::UAdd => Self::UAdd,
+            Unaryop::USub => Self::USub,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableCmpop {
+    Eq,
+    NotEq,
+    Lt,
+    LtE,
+    Gt,
+    GtE,
+    Is,
+    IsNot,
+    In,
+    NotIn,
+}
+
+impl From<&Cmpop> for ComparableCmpop {
+    fn from(op: &Cmpop) -> Self {
+        match op {
+            Cmpop::Eq => Self::Eq,
+            Cmpop::NotEq => Self::NotEq,
+            Cmpop::Lt => Self::Lt,
+            Cmpop::LtE => Self::LtE,
+            Cmpop::Gt => Self::Gt,
+            Cmpop::GtE => Self::GtE,
+            Cmpop::Is => Self::Is,
+            Cmpop::IsNot => Self::IsNot,
+            Cmpop::In => Self::In,
+            Cmpop::NotIn => Self::NotIn,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableConstant<'a> {
+    None,
+    Bool(&'a bool),
+    Str(&'a str),
+    Bytes(&'a [u8]),
+    Int(&'a BigInt),
+    Tuple(Vec<ComparableConstant<'a>>),
+    Float(u64),
+    Complex { real: u64, imag: u64 },
+    Ellipsis,
+}
+
+impl<'a> From<&'a Constant> for ComparableConstant<'a> {
+    fn from(constant: &'a Constant) -> Self {
+        match constant {
+            Constant::None => Self::None,
+            Constant::Bool(value) => Self::Bool(value),
+            Constant::Str(value) => Self::Str(value),
+            Constant::Bytes(value) => Self::Bytes(value),
+            Constant::Int(value) => Self::Int(value),
+            Constant::Tuple(value) => {
+                Self::Tuple(value.iter().map(std::convert::Into::into).collect())
+            }
+            Constant::Float(value) => Self::Float(value.to_bits()),
+            Constant::Complex { real, imag } => Self::Complex {
+                real: real.to_bits(),
+                imag: imag.to_bits(),
+            },
+            Constant::Ellipsis => Self::Ellipsis,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ComparableArguments<'a> {
+    pub posonlyargs: Vec<ComparableArg<'a>>,
+    pub args: Vec<ComparableArg<'a>>,
+    pub vararg: Option<ComparableArg<'a>>,
+    pub kwonlyargs: Vec<ComparableArg<'a>>,
+    pub kw_defaults: Vec<ComparableExpr<'a>>,
+    pub kwarg: Option<ComparableArg<'a>>,
+    pub defaults: Vec<ComparableExpr<'a>>,
+}
+
+impl<'a> From<&'a Arguments> for ComparableArguments<'a> {
+    fn from(arguments: &'a Arguments) -> Self {
+        Self {
+            posonlyargs: arguments
+                .posonlyargs
+                .iter()
+                .map(std::convert::Into::into)
+                .collect(),
+            args: arguments
+                .args
+                .iter()
+                .map(std::convert::Into::into)
+                .collect(),
+            vararg: arguments.vararg.as_ref().map(std::convert::Into::into),
+            kwonlyargs: arguments
+                .kwonlyargs
+                .iter()
+                .map(std::convert::Into::into)
+                .collect(),
+            kw_defaults: arguments
+                .kw_defaults
+                .iter()
+                .map(std::convert::Into::into)
+                .collect(),
+            kwarg: arguments.vararg.as_ref().map(std::convert::Into::into),
+            defaults: arguments
+                .defaults
+                .iter()
+                .map(std::convert::Into::into)
+                .collect(),
+        }
+    }
+}
+
+impl<'a> From<&'a Box<Arg>> for ComparableArg<'a> {
+    fn from(arg: &'a Box<Arg>) -> Self {
+        (&**arg).into()
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ComparableArg<'a> {
+    pub arg: &'a str,
+    pub annotation: Option<Box<ComparableExpr<'a>>>,
+    pub type_comment: Option<&'a str>,
+}
+
+impl<'a> From<&'a Arg> for ComparableArg<'a> {
+    fn from(arg: &'a Arg) -> Self {
+        Self {
+            arg: &arg.node.arg,
+            annotation: arg.node.annotation.as_ref().map(std::convert::Into::into),
+            type_comment: arg.node.type_comment.as_deref(),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ComparableKeyword<'a> {
+    pub arg: Option<&'a str>,
+    pub value: ComparableExpr<'a>,
+}
+
+impl<'a> From<&'a Keyword> for ComparableKeyword<'a> {
+    fn from(keyword: &'a Keyword) -> Self {
+        Self {
+            arg: keyword.node.arg.as_deref(),
+            value: (&keyword.node.value).into(),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ComparableComprehension<'a> {
+    pub target: ComparableExpr<'a>,
+    pub iter: ComparableExpr<'a>,
+    pub ifs: Vec<ComparableExpr<'a>>,
+    pub is_async: &'a usize,
+}
+
+impl<'a> From<&'a Comprehension> for ComparableComprehension<'a> {
+    fn from(comprehension: &'a Comprehension) -> Self {
+        Self {
+            target: (&comprehension.target).into(),
+            iter: (&comprehension.iter).into(),
+            ifs: comprehension
+                .ifs
+                .iter()
+                .map(std::convert::Into::into)
+                .collect(),
+            is_async: &comprehension.is_async,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub enum ComparableExpr<'a> {
+    BoolOp {
+        op: ComparableBoolop,
+        values: Vec<ComparableExpr<'a>>,
+    },
+    NamedExpr {
+        target: Box<ComparableExpr<'a>>,
+        value: Box<ComparableExpr<'a>>,
+    },
+    BinOp {
+        left: Box<ComparableExpr<'a>>,
+        op: ComparableOperator,
+        right: Box<ComparableExpr<'a>>,
+    },
+    UnaryOp {
+        op: ComparableUnaryop,
+        operand: Box<ComparableExpr<'a>>,
+    },
+    Lambda {
+        args: ComparableArguments<'a>,
+        body: Box<ComparableExpr<'a>>,
+    },
+    IfExp {
+        test: Box<ComparableExpr<'a>>,
+        body: Box<ComparableExpr<'a>>,
+        orelse: Box<ComparableExpr<'a>>,
+    },
+    Dict {
+        keys: Vec<ComparableExpr<'a>>,
+        values: Vec<ComparableExpr<'a>>,
+    },
+    Set {
+        elts: Vec<ComparableExpr<'a>>,
+    },
+    ListComp {
+        elt: Box<ComparableExpr<'a>>,
+        generators: Vec<ComparableComprehension<'a>>,
+    },
+    SetComp {
+        elt: Box<ComparableExpr<'a>>,
+        generators: Vec<ComparableComprehension<'a>>,
+    },
+    DictComp {
+        key: Box<ComparableExpr<'a>>,
+        value: Box<ComparableExpr<'a>>,
+        generators: Vec<ComparableComprehension<'a>>,
+    },
+    GeneratorExp {
+        elt: Box<ComparableExpr<'a>>,
+        generators: Vec<ComparableComprehension<'a>>,
+    },
+    Await {
+        value: Box<ComparableExpr<'a>>,
+    },
+    Yield {
+        value: Option<Box<ComparableExpr<'a>>>,
+    },
+    YieldFrom {
+        value: Box<ComparableExpr<'a>>,
+    },
+    Compare {
+        left: Box<ComparableExpr<'a>>,
+        ops: Vec<ComparableCmpop>,
+        comparators: Vec<ComparableExpr<'a>>,
+    },
+    Call {
+        func: Box<ComparableExpr<'a>>,
+        args: Vec<ComparableExpr<'a>>,
+        keywords: Vec<ComparableKeyword<'a>>,
+    },
+    FormattedValue {
+        value: Box<ComparableExpr<'a>>,
+        conversion: &'a usize,
+        format_spec: Option<Box<ComparableExpr<'a>>>,
+    },
+    JoinedStr {
+        values: Vec<ComparableExpr<'a>>,
+    },
+    Constant {
+        value: ComparableConstant<'a>,
+        kind: Option<&'a str>,
+    },
+    Attribute {
+        value: Box<ComparableExpr<'a>>,
+        attr: &'a str,
+        ctx: ComparableExprContext,
+    },
+    Subscript {
+        value: Box<ComparableExpr<'a>>,
+        slice: Box<ComparableExpr<'a>>,
+        ctx: ComparableExprContext,
+    },
+    Starred {
+        value: Box<ComparableExpr<'a>>,
+        ctx: ComparableExprContext,
+    },
+    Name {
+        id: &'a str,
+        ctx: ComparableExprContext,
+    },
+    List {
+        elts: Vec<ComparableExpr<'a>>,
+        ctx: ComparableExprContext,
+    },
+    Tuple {
+        elts: Vec<ComparableExpr<'a>>,
+        ctx: ComparableExprContext,
+    },
+    Slice {
+        lower: Option<Box<ComparableExpr<'a>>>,
+        upper: Option<Box<ComparableExpr<'a>>>,
+        step: Option<Box<ComparableExpr<'a>>>,
+    },
+}
+
+impl<'a> From<&'a Box<Expr>> for Box<ComparableExpr<'a>> {
+    fn from(expr: &'a Box<Expr>) -> Self {
+        Box::new((&**expr).into())
+    }
+}
+
+impl<'a> From<&'a Box<Expr>> for ComparableExpr<'a> {
+    fn from(expr: &'a Box<Expr>) -> Self {
+        (&**expr).into()
+    }
+}
+
+impl<'a> From<&'a Expr> for ComparableExpr<'a> {
+    fn from(expr: &'a Expr) -> Self {
+        match &expr.node {
+            ExprKind::BoolOp { op, values } => Self::BoolOp {
+                op: op.into(),
+                values: values.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::NamedExpr { target, value } => Self::NamedExpr {
+                target: target.into(),
+                value: value.into(),
+            },
+            ExprKind::BinOp { left, op, right } => Self::BinOp {
+                left: left.into(),
+                op: op.into(),
+                right: right.into(),
+            },
+            ExprKind::UnaryOp { op, operand } => Self::UnaryOp {
+                op: op.into(),
+                operand: operand.into(),
+            },
+            ExprKind::Lambda { args, body } => Self::Lambda {
+                args: (&**args).into(),
+                body: body.into(),
+            },
+            ExprKind::IfExp { test, body, orelse } => Self::IfExp {
+                test: test.into(),
+                body: body.into(),
+                orelse: orelse.into(),
+            },
+            ExprKind::Dict { keys, values } => Self::Dict {
+                keys: keys.iter().map(std::convert::Into::into).collect(),
+                values: values.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::Set { elts } => Self::Set {
+                elts: elts.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::ListComp { elt, generators } => Self::ListComp {
+                elt: elt.into(),
+                generators: generators.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::SetComp { elt, generators } => Self::SetComp {
+                elt: elt.into(),
+                generators: generators.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::DictComp {
+                key,
+                value,
+                generators,
+            } => Self::DictComp {
+                key: key.into(),
+                value: value.into(),
+                generators: generators.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::GeneratorExp { elt, generators } => Self::GeneratorExp {
+                elt: elt.into(),
+                generators: generators.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::Await { value } => Self::Await {
+                value: value.into(),
+            },
+            ExprKind::Yield { value } => Self::Yield {
+                value: value.as_ref().map(std::convert::Into::into),
+            },
+            ExprKind::YieldFrom { value } => Self::YieldFrom {
+                value: value.into(),
+            },
+            ExprKind::Compare {
+                left,
+                ops,
+                comparators,
+            } => Self::Compare {
+                left: left.into(),
+                ops: ops.iter().map(std::convert::Into::into).collect(),
+                comparators: comparators.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::Call {
+                func,
+                args,
+                keywords,
+            } => Self::Call {
+                func: func.into(),
+                args: args.iter().map(std::convert::Into::into).collect(),
+                keywords: keywords.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::FormattedValue {
+                value,
+                conversion,
+                format_spec,
+            } => Self::FormattedValue {
+                value: value.into(),
+                conversion,
+                format_spec: format_spec.as_ref().map(std::convert::Into::into),
+            },
+            ExprKind::JoinedStr { values } => Self::JoinedStr {
+                values: values.iter().map(std::convert::Into::into).collect(),
+            },
+            ExprKind::Constant { value, kind } => Self::Constant {
+                value: value.into(),
+                kind: kind.as_ref().map(String::as_str),
+            },
+            ExprKind::Attribute { value, attr, ctx } => Self::Attribute {
+                value: value.into(),
+                attr,
+                ctx: ctx.into(),
+            },
+            ExprKind::Subscript { value, slice, ctx } => Self::Subscript {
+                value: value.into(),
+                slice: slice.into(),
+                ctx: ctx.into(),
+            },
+            ExprKind::Starred { value, ctx } => Self::Starred {
+                value: value.into(),
+                ctx: ctx.into(),
+            },
+            ExprKind::Name { id, ctx } => Self::Name {
+                id,
+                ctx: ctx.into(),
+            },
+            ExprKind::List { elts, ctx } => Self::List {
+                elts: elts.iter().map(std::convert::Into::into).collect(),
+                ctx: ctx.into(),
+            },
+            ExprKind::Tuple { elts, ctx } => Self::Tuple {
+                elts: elts.iter().map(std::convert::Into::into).collect(),
+                ctx: ctx.into(),
+            },
+            ExprKind::Slice { lower, upper, step } => Self::Slice {
+                lower: lower.as_ref().map(std::convert::Into::into),
+                upper: upper.as_ref().map(std::convert::Into::into),
+                step: step.as_ref().map(std::convert::Into::into),
+            },
+        }
+    }
+}

src/ast/helpers.rs

@@ -12,9 +12,7 @@ use rustpython_parser::lexer::Tok;
 use rustpython_parser::token::StringKind;
 
 use crate::ast::types::{Binding, BindingKind, Range};
-use crate::source_code_generator::SourceCodeGenerator;
-use crate::source_code_style::SourceCodeStyleDetector;
-use crate::SourceCodeLocator;
+use crate::source_code::{Generator, Locator, Stylist};
 
 /// Create an `Expr` with default location from an `ExprKind`.
 pub fn create_expr(node: ExprKind) -> Expr {
@@ -27,15 +25,15 @@ pub fn create_stmt(node: StmtKind) -> Stmt {
 }
 
 /// Generate source code from an `Expr`.
-pub fn unparse_expr(expr: &Expr, stylist: &SourceCodeStyleDetector) -> String {
-    let mut generator: SourceCodeGenerator = stylist.into();
+pub fn unparse_expr(expr: &Expr, stylist: &Stylist) -> String {
+    let mut generator: Generator = stylist.into();
     generator.unparse_expr(expr, 0);
     generator.generate()
 }
 
 /// Generate source code from an `Stmt`.
-pub fn unparse_stmt(stmt: &Stmt, stylist: &SourceCodeStyleDetector) -> String {
-    let mut generator: SourceCodeGenerator = stylist.into();
+pub fn unparse_stmt(stmt: &Stmt, stylist: &Stylist) -> String {
+    let mut generator: Generator = stylist.into();
     generator.unparse_stmt(stmt);
     generator.generate()
 }
@@ -179,6 +177,131 @@ pub fn match_call_path(
     }
 }
 
+/// Return `true` if the `Expr` contains a reference to `${module}.${target}`.
+pub fn contains_call_path(
+    expr: &Expr,
+    module: &str,
+    member: &str,
+    import_aliases: &FxHashMap<&str, &str>,
+    from_imports: &FxHashMap<&str, FxHashSet<&str>>,
+) -> bool {
+    any_over_expr(expr, &|expr| {
+        let call_path = collect_call_paths(expr);
+        if !call_path.is_empty() {
+            if match_call_path(
+                &dealias_call_path(call_path, import_aliases),
+                module,
+                member,
+                from_imports,
+            ) {
+                return true;
+            }
+        }
+        false
+    })
+}
+
+/// Call `func` over every `Expr` in `expr`, returning `true` if any expression
+/// returns `true`..
+pub fn any_over_expr<F>(expr: &Expr, func: &F) -> bool
+where
+    F: Fn(&Expr) -> bool,
+{
+    if func(expr) {
+        return true;
+    }
+    match &expr.node {
+        ExprKind::BoolOp { values, .. } | ExprKind::JoinedStr { values } => {
+            values.iter().any(|expr| any_over_expr(expr, func))
+        }
+        ExprKind::NamedExpr { target, value } => {
+            any_over_expr(target, func) || any_over_expr(value, func)
+        }
+        ExprKind::BinOp { left, right, .. } => {
+            any_over_expr(left, func) || any_over_expr(right, func)
+        }
+        ExprKind::UnaryOp { operand, .. } => any_over_expr(operand, func),
+        ExprKind::Lambda { body, .. } => any_over_expr(body, func),
+        ExprKind::IfExp { test, body, orelse } => {
+            any_over_expr(test, func) || any_over_expr(body, func) || any_over_expr(orelse, func)
+        }
+        ExprKind::Dict { keys, values } => values
+            .iter()
+            .chain(keys.iter())
+            .any(|expr| any_over_expr(expr, func)),
+        ExprKind::Set { elts } | ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+            elts.iter().any(|expr| any_over_expr(expr, func))
+        }
+        ExprKind::ListComp { elt, generators }
+        | ExprKind::SetComp { elt, generators }
+        | ExprKind::GeneratorExp { elt, generators } => {
+            any_over_expr(elt, func)
+                || generators.iter().any(|generator| {
+                    any_over_expr(&generator.target, func)
+                        || any_over_expr(&generator.iter, func)
+                        || generator.ifs.iter().any(|expr| any_over_expr(expr, func))
+                })
+        }
+        ExprKind::DictComp {
+            key,
+            value,
+            generators,
+        } => {
+            any_over_expr(key, func)
+                || any_over_expr(value, func)
+                || generators.iter().any(|generator| {
+                    any_over_expr(&generator.target, func)
+                        || any_over_expr(&generator.iter, func)
+                        || generator.ifs.iter().any(|expr| any_over_expr(expr, func))
+                })
+        }
+        ExprKind::Await { value }
+        | ExprKind::YieldFrom { value }
+        | ExprKind::Attribute { value, .. }
+        | ExprKind::Starred { value, .. } => any_over_expr(value, func),
+        ExprKind::Yield { value } => value
+            .as_ref()
+            .map_or(false, |value| any_over_expr(value, func)),
+        ExprKind::Compare {
+            left, comparators, ..
+        } => any_over_expr(left, func) || comparators.iter().any(|expr| any_over_expr(expr, func)),
+        ExprKind::Call {
+            func: call_func,
+            args,
+            keywords,
+        } => {
+            any_over_expr(call_func, func)
+                || args.iter().any(|expr| any_over_expr(expr, func))
+                || keywords
+                    .iter()
+                    .any(|keyword| any_over_expr(&keyword.node.value, func))
+        }
+        ExprKind::FormattedValue {
+            value, format_spec, ..
+        } => {
+            any_over_expr(value, func)
+                || format_spec
+                    .as_ref()
+                    .map_or(false, |value| any_over_expr(value, func))
+        }
+        ExprKind::Subscript { value, slice, .. } => {
+            any_over_expr(value, func) || any_over_expr(slice, func)
+        }
+        ExprKind::Slice { lower, upper, step } => {
+            lower
+                .as_ref()
+                .map_or(false, |value| any_over_expr(value, func))
+                || upper
+                    .as_ref()
+                    .map_or(false, |value| any_over_expr(value, func))
+                || step
+                    .as_ref()
+                    .map_or(false, |value| any_over_expr(value, func))
+        }
+        ExprKind::Name { .. } | ExprKind::Constant { .. } => false,
+    }
+}
+
 static DUNDER_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"__[^\s]+__").unwrap());
 
 /// Return `true` if the `Stmt` is an assignment to a dunder (like `__all__`).
@@ -191,12 +314,12 @@ pub fn is_assignment_to_a_dunder(stmt: &Stmt) -> bool {
                 return false;
             }
             match &targets[0].node {
-                ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+                ExprKind::Name { id, .. } => DUNDER_REGEX.is_match(id),
                 _ => false,
             }
         }
         StmtKind::AnnAssign { target, .. } => match &target.node {
-            ExprKind::Name { id, ctx: _ } => DUNDER_REGEX.is_match(id),
+            ExprKind::Name { id, .. } => DUNDER_REGEX.is_match(id),
             _ => false,
         },
         _ => false,
@@ -305,6 +428,13 @@ pub fn collect_arg_names<'a>(arguments: &'a Arguments) -> FxHashSet<&'a str> {
     arg_names
 }
 
+/// Returns `true` if a statement or expression includes at least one comment.
+pub fn has_comments<T>(located: &Located<T>, locator: &Locator) -> bool {
+    lexer::make_tokenizer(&locator.slice_source_code_range(&Range::from_located(located)))
+        .flatten()
+        .any(|(_, tok, _)| matches!(tok, Tok::Comment(..)))
+}
+
 /// Returns `true` if a call is an argumented `super` invocation.
 pub fn is_super_call_with_arguments(func: &Expr, args: &[Expr]) -> bool {
     if let ExprKind::Name { id, .. } = &func.node {
@@ -351,14 +481,14 @@ pub fn to_absolute(relative: Location, base: Location) -> Location {
 }
 
 /// Return `true` if a `Stmt` has leading content.
-pub fn match_leading_content(stmt: &Stmt, locator: &SourceCodeLocator) -> bool {
+pub fn match_leading_content(stmt: &Stmt, locator: &Locator) -> bool {
     let range = Range::new(Location::new(stmt.location.row(), 0), stmt.location);
     let prefix = locator.slice_source_code_range(&range);
     prefix.chars().any(|char| !char.is_whitespace())
 }
 
 /// Return `true` if a `Stmt` has trailing content.
-pub fn match_trailing_content(stmt: &Stmt, locator: &SourceCodeLocator) -> bool {
+pub fn match_trailing_content(stmt: &Stmt, locator: &Locator) -> bool {
     let range = Range::new(
         stmt.end_location.unwrap(),
         Location::new(stmt.end_location.unwrap().row() + 1, 0),
@@ -376,7 +506,7 @@ pub fn match_trailing_content(stmt: &Stmt, locator: &SourceCodeLocator) -> bool
 }
 
 /// Return the number of trailing empty lines following a statement.
-pub fn count_trailing_lines(stmt: &Stmt, locator: &SourceCodeLocator) -> usize {
+pub fn count_trailing_lines(stmt: &Stmt, locator: &Locator) -> usize {
     let suffix =
         locator.slice_source_code_at(&Location::new(stmt.end_location.unwrap().row() + 1, 0));
     suffix
@@ -388,7 +518,7 @@ pub fn count_trailing_lines(stmt: &Stmt, locator: &SourceCodeLocator) -> usize {
 /// Return the appropriate visual `Range` for any message that spans a `Stmt`.
 /// Specifically, this method returns the range of a function or class name,
 /// rather than that of the entire function or class body.
-pub fn identifier_range(stmt: &Stmt, locator: &SourceCodeLocator) -> Range {
+pub fn identifier_range(stmt: &Stmt, locator: &Locator) -> Range {
     if matches!(
         stmt.node,
         StmtKind::ClassDef { .. }
@@ -407,7 +537,7 @@ pub fn identifier_range(stmt: &Stmt, locator: &SourceCodeLocator) -> Range {
 }
 
 /// Like `identifier_range`, but accepts a `Binding`.
-pub fn binding_range(binding: &Binding, locator: &SourceCodeLocator) -> Range {
+pub fn binding_range(binding: &Binding, locator: &Locator) -> Range {
     if matches!(
         binding.kind,
         BindingKind::ClassDefinition | BindingKind::FunctionDefinition
@@ -423,7 +553,7 @@ pub fn binding_range(binding: &Binding, locator: &SourceCodeLocator) -> Range {
 }
 
 // Return the ranges of `Name` tokens within a specified node.
-pub fn find_names<T>(located: &Located<T>, locator: &SourceCodeLocator) -> Vec<Range> {
+pub fn find_names<T>(located: &Located<T>, locator: &Locator) -> Vec<Range> {
     let contents = locator.slice_source_code_range(&Range::from_located(located));
     lexer::make_tokenizer_located(&contents, located.location)
         .flatten()
@@ -436,10 +566,7 @@ pub fn find_names<T>(located: &Located<T>, locator: &SourceCodeLocator) -> Vec<R
 }
 
 /// Return the `Range` of `name` in `Excepthandler`.
-pub fn excepthandler_name_range(
-    handler: &Excepthandler,
-    locator: &SourceCodeLocator,
-) -> Option<Range> {
+pub fn excepthandler_name_range(handler: &Excepthandler, locator: &Locator) -> Option<Range> {
     let ExcepthandlerKind::ExceptHandler {
         name, type_, body, ..
     } = &handler.node;
@@ -462,7 +589,7 @@ pub fn excepthandler_name_range(
 }
 
 /// Return the `Range` of `except` in `Excepthandler`.
-pub fn except_range(handler: &Excepthandler, locator: &SourceCodeLocator) -> Range {
+pub fn except_range(handler: &Excepthandler, locator: &Locator) -> Range {
     let ExcepthandlerKind::ExceptHandler { body, type_, .. } = &handler.node;
     let end = if let Some(type_) = type_ {
         type_.location
@@ -487,7 +614,7 @@ pub fn except_range(handler: &Excepthandler, locator: &SourceCodeLocator) -> Ran
 }
 
 /// Find f-strings that don't contain any formatted values in a `JoinedStr`.
-pub fn find_useless_f_strings(expr: &Expr, locator: &SourceCodeLocator) -> Vec<(Range, Range)> {
+pub fn find_useless_f_strings(expr: &Expr, locator: &Locator) -> Vec<(Range, Range)> {
     let contents = locator.slice_source_code_range(&Range::from_located(expr));
     lexer::make_tokenizer_located(&contents, expr.location)
         .flatten()
@@ -524,7 +651,7 @@ pub fn find_useless_f_strings(expr: &Expr, locator: &SourceCodeLocator) -> Vec<(
 }
 
 /// Return the `Range` of `else` in `For`, `AsyncFor`, and `While` statements.
-pub fn else_range(stmt: &Stmt, locator: &SourceCodeLocator) -> Option<Range> {
+pub fn else_range(stmt: &Stmt, locator: &Locator) -> Option<Range> {
     match &stmt.node {
         StmtKind::For { body, orelse, .. }
         | StmtKind::AsyncFor { body, orelse, .. }
@@ -558,7 +685,7 @@ pub fn else_range(stmt: &Stmt, locator: &SourceCodeLocator) -> Option<Range> {
 
 /// Return `true` if a `Stmt` appears to be part of a multi-statement line, with
 /// other statements preceding it.
-pub fn preceded_by_continuation(stmt: &Stmt, locator: &SourceCodeLocator) -> bool {
+pub fn preceded_by_continuation(stmt: &Stmt, locator: &Locator) -> bool {
     // Does the previous line end in a continuation? This will have a specific
     // false-positive, which is that if the previous line ends in a comment, it
     // will be treated as a continuation. So we should only use this information to
@@ -579,16 +706,31 @@ pub fn preceded_by_continuation(stmt: &Stmt, locator: &SourceCodeLocator) -> boo
 
 /// Return `true` if a `Stmt` appears to be part of a multi-statement line, with
 /// other statements preceding it.
-pub fn preceded_by_multi_statement_line(stmt: &Stmt, locator: &SourceCodeLocator) -> bool {
+pub fn preceded_by_multi_statement_line(stmt: &Stmt, locator: &Locator) -> bool {
     match_leading_content(stmt, locator) || preceded_by_continuation(stmt, locator)
 }
 
 /// Return `true` if a `Stmt` appears to be part of a multi-statement line, with
 /// other statements following it.
-pub fn followed_by_multi_statement_line(stmt: &Stmt, locator: &SourceCodeLocator) -> bool {
+pub fn followed_by_multi_statement_line(stmt: &Stmt, locator: &Locator) -> bool {
     match_trailing_content(stmt, locator)
 }
 
+/// Return `true` if a `Stmt` is a docstring.
+pub fn is_docstring_stmt(stmt: &Stmt) -> bool {
+    if let StmtKind::Expr { value } = &stmt.node {
+        matches!(
+            value.node,
+            ExprKind::Constant {
+                value: Constant::Str { .. },
+                ..
+            }
+        )
+    } else {
+        false
+    }
+}
+
 #[derive(Default)]
 /// A simple representation of a call's positional and keyword arguments.
 pub struct SimpleCallArgs<'a> {
@@ -634,6 +776,11 @@ impl<'a> SimpleCallArgs<'a> {
         }
         None
     }
+
+    /// Get the number of positional and keyword arguments used.
+    pub fn len(&self) -> usize {
+        self.args.len() + self.kwargs.len()
+    }
 }
 
 #[cfg(test)]
@@ -647,7 +794,7 @@ mod tests {
         else_range, identifier_range, match_module_member, match_trailing_content,
     };
     use crate::ast::types::Range;
-    use crate::source_code_locator::SourceCodeLocator;
+    use crate::source_code::Locator;
 
     #[test]
     fn builtin() -> Result<()> {
@@ -797,25 +944,25 @@ mod tests {
         let contents = "x = 1";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert!(!match_trailing_content(stmt, &locator));
 
         let contents = "x = 1; y = 2";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert!(match_trailing_content(stmt, &locator));
 
         let contents = "x = 1  ";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert!(!match_trailing_content(stmt, &locator));
 
         let contents = "x = 1  # Comment";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert!(!match_trailing_content(stmt, &locator));
 
         let contents = r#"
@@ -825,7 +972,7 @@ y = 2
         .trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert!(!match_trailing_content(stmt, &locator));
 
         Ok(())
@@ -836,7 +983,7 @@ y = 2
         let contents = "def f(): pass".trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             identifier_range(stmt, &locator),
             Range::new(Location::new(1, 4), Location::new(1, 5),)
@@ -850,7 +997,7 @@ def \
         .trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             identifier_range(stmt, &locator),
             Range::new(Location::new(2, 2), Location::new(2, 3),)
@@ -859,7 +1006,7 @@ def \
         let contents = "class Class(): pass".trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             identifier_range(stmt, &locator),
             Range::new(Location::new(1, 6), Location::new(1, 11),)
@@ -868,7 +1015,7 @@ def \
         let contents = "class Class: pass".trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             identifier_range(stmt, &locator),
             Range::new(Location::new(1, 6), Location::new(1, 11),)
@@ -882,7 +1029,7 @@ class Class():
         .trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             identifier_range(stmt, &locator),
             Range::new(Location::new(2, 6), Location::new(2, 11),)
@@ -891,7 +1038,7 @@ class Class():
         let contents = r#"x = y + 1"#.trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             identifier_range(stmt, &locator),
             Range::new(Location::new(1, 0), Location::new(1, 9),)
@@ -911,7 +1058,7 @@ else:
         .trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         let range = else_range(stmt, &locator).unwrap();
         assert_eq!(range.location.row(), 3);
         assert_eq!(range.location.column(), 0);

src/ast/mod.rs

@@ -1,5 +1,6 @@
 pub mod branch_detection;
 pub mod cast;
+pub mod comparable;
 pub mod function_type;
 pub mod helpers;
 pub mod operations;

src/ast/operations.rs

@@ -4,6 +4,7 @@ use rustpython_parser::ast::{Constant, Expr, ExprKind, Stmt, StmtKind};
 use rustpython_parser::lexer;
 use rustpython_parser::lexer::Tok;
 
+use crate::ast::helpers::any_over_expr;
 use crate::ast::types::{Binding, BindingKind, Scope};
 use crate::ast::visitor;
 use crate::ast::visitor::Visitor;
@@ -129,76 +130,13 @@ pub fn in_nested_block<'a>(mut parents: impl Iterator<Item = &'a Stmt>) -> bool
     })
 }
 
-/// Returns `true` if `parent` contains `child`.
-fn contains(parent: &Expr, child: &Expr) -> bool {
-    match &parent.node {
-        ExprKind::BoolOp { values, .. } => values.iter().any(|parent| contains(parent, child)),
-        ExprKind::NamedExpr { target, value } => contains(target, child) || contains(value, child),
-        ExprKind::BinOp { left, right, .. } => contains(left, child) || contains(right, child),
-        ExprKind::UnaryOp { operand, .. } => contains(operand, child),
-        ExprKind::Lambda { body, .. } => contains(body, child),
-        ExprKind::IfExp { test, body, orelse } => {
-            contains(test, child) || contains(body, child) || contains(orelse, child)
-        }
-        ExprKind::Dict { keys, values } => keys
-            .iter()
-            .chain(values.iter())
-            .any(|parent| contains(parent, child)),
-        ExprKind::Set { elts } => elts.iter().any(|parent| contains(parent, child)),
-        ExprKind::ListComp { elt, .. } => contains(elt, child),
-        ExprKind::SetComp { elt, .. } => contains(elt, child),
-        ExprKind::DictComp { key, value, .. } => contains(key, child) || contains(value, child),
-        ExprKind::GeneratorExp { elt, .. } => contains(elt, child),
-        ExprKind::Await { value } => contains(value, child),
-        ExprKind::Yield { value } => value.as_ref().map_or(false, |value| contains(value, child)),
-        ExprKind::YieldFrom { value } => contains(value, child),
-        ExprKind::Compare {
-            left, comparators, ..
-        } => contains(left, child) || comparators.iter().any(|parent| contains(parent, child)),
-        ExprKind::Call {
-            func,
-            args,
-            keywords,
-        } => {
-            contains(func, child)
-                || args.iter().any(|parent| contains(parent, child))
-                || keywords
-                    .iter()
-                    .any(|keyword| contains(&keyword.node.value, child))
-        }
-        ExprKind::FormattedValue {
-            value, format_spec, ..
-        } => {
-            contains(value, child)
-                || format_spec
-                    .as_ref()
-                    .map_or(false, |value| contains(value, child))
-        }
-        ExprKind::JoinedStr { values } => values.iter().any(|parent| contains(parent, child)),
-        ExprKind::Constant { .. } => false,
-        ExprKind::Attribute { value, .. } => contains(value, child),
-        ExprKind::Subscript { value, slice, .. } => {
-            contains(value, child) || contains(slice, child)
-        }
-        ExprKind::Starred { value, .. } => contains(value, child),
-        ExprKind::Name { .. } => parent == child,
-        ExprKind::List { elts, .. } => elts.iter().any(|parent| contains(parent, child)),
-        ExprKind::Tuple { elts, .. } => elts.iter().any(|parent| contains(parent, child)),
-        ExprKind::Slice { lower, upper, step } => {
-            lower.as_ref().map_or(false, |value| contains(value, child))
-                || upper.as_ref().map_or(false, |value| contains(value, child))
-                || step.as_ref().map_or(false, |value| contains(value, child))
-        }
-    }
-}
-
 /// Check if a node represents an unpacking assignment.
 pub fn is_unpacking_assignment(parent: &Stmt, child: &Expr) -> bool {
     match &parent.node {
         StmtKind::With { items, .. } => items.iter().any(|item| {
             if let Some(optional_vars) = &item.optional_vars {
                 if matches!(optional_vars.node, ExprKind::Tuple { .. }) {
-                    if contains(optional_vars, child) {
+                    if any_over_expr(optional_vars, &|expr| expr == child) {
                         return true;
                     }
                 }
@@ -227,7 +165,7 @@ pub fn is_unpacking_assignment(parent: &Stmt, child: &Expr) -> bool {
                     matches!(
                         item.node,
                         ExprKind::Set { .. } | ExprKind::List { .. } | ExprKind::Tuple { .. }
-                    ) && contains(item, child)
+                    ) && any_over_expr(item, &|expr| expr == child)
                 });
 
             // If our child is a tuple, and value is not, it's always an unpacking

src/ast/types.rs

@@ -74,7 +74,6 @@ pub enum ScopeKind<'a> {
     Function(FunctionDef<'a>),
     Generator,
     Module,
-    Arg,
     Lambda(Lambda<'a>),
 }
 

src/autofix/fixer.rs

@@ -1,225 +1 @@
-use std::borrow::Cow;
-use std::collections::BTreeSet;
 
-use itertools::Itertools;
-use ropey::RopeBuilder;
-use rustpython_parser::ast::Location;
-
-use crate::ast::types::Range;
-use crate::autofix::Fix;
-use crate::registry::Check;
-use crate::source_code_locator::SourceCodeLocator;
-
-#[derive(Debug, Copy, Clone, Hash)]
-pub enum Mode {
-    Generate,
-    Apply,
-    Diff,
-    None,
-}
-
-impl From<bool> for Mode {
-    fn from(value: bool) -> Self {
-        if value {
-            Mode::Apply
-        } else {
-            Mode::None
-        }
-    }
-}
-
-/// Auto-fix errors in a file, and write the fixed source code to disk.
-pub fn fix_file<'a>(
-    checks: &'a [Check],
-    locator: &'a SourceCodeLocator<'a>,
-) -> Option<(Cow<'a, str>, usize)> {
-    if checks.iter().all(|check| check.fix.is_none()) {
-        return None;
-    }
-
-    Some(apply_fixes(
-        checks.iter().filter_map(|check| check.fix.as_ref()),
-        locator,
-    ))
-}
-
-/// Apply a series of fixes.
-fn apply_fixes<'a>(
-    fixes: impl Iterator<Item = &'a Fix>,
-    locator: &'a SourceCodeLocator<'a>,
-) -> (Cow<'a, str>, usize) {
-    let mut output = RopeBuilder::new();
-    let mut last_pos: Location = Location::new(1, 0);
-    let mut applied: BTreeSet<&Fix> = BTreeSet::default();
-    let mut num_fixed: usize = 0;
-
-    for fix in fixes.sorted_by_key(|fix| fix.location) {
-        // If we already applied an identical fix as part of another correction, skip
-        // any re-application.
-        if applied.contains(&fix) {
-            num_fixed += 1;
-            continue;
-        }
-
-        // Best-effort approach: if this fix overlaps with a fix we've already applied,
-        // skip it.
-        if last_pos > fix.location {
-            continue;
-        }
-
-        // Add all contents from `last_pos` to `fix.location`.
-        let slice = locator.slice_source_code_range(&Range::new(last_pos, fix.location));
-        output.append(&slice);
-
-        // Add the patch itself.
-        output.append(&fix.content);
-
-        // Track that the fix was applied.
-        last_pos = fix.end_location;
-        applied.insert(fix);
-        num_fixed += 1;
-    }
-
-    // Add the remaining content.
-    let slice = locator.slice_source_code_at(&last_pos);
-    output.append(&slice);
-
-    (Cow::from(output.finish()), num_fixed)
-}
-
-#[cfg(test)]
-mod tests {
-    use rustpython_parser::ast::Location;
-
-    use crate::autofix::fixer::apply_fixes;
-    use crate::autofix::Fix;
-    use crate::SourceCodeLocator;
-
-    #[test]
-    fn empty_file() {
-        let fixes = vec![];
-        let locator = SourceCodeLocator::new(r#""#);
-        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
-        assert_eq!(contents, "");
-        assert_eq!(fixed, 0);
-    }
-
-    #[test]
-    fn apply_single_replacement() {
-        let fixes = vec![Fix {
-            content: "Bar".to_string(),
-            location: Location::new(1, 8),
-            end_location: Location::new(1, 14),
-        }];
-        let locator = SourceCodeLocator::new(
-            r#"
-class A(object):
-    ...
-"#
-            .trim(),
-        );
-        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
-        assert_eq!(
-            contents,
-            r#"
-class A(Bar):
-    ...
-"#
-            .trim(),
-        );
-        assert_eq!(fixed, 1);
-    }
-
-    #[test]
-    fn apply_single_removal() {
-        let fixes = vec![Fix {
-            content: String::new(),
-            location: Location::new(1, 7),
-            end_location: Location::new(1, 15),
-        }];
-        let locator = SourceCodeLocator::new(
-            r#"
-class A(object):
-    ...
-"#
-            .trim(),
-        );
-        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
-        assert_eq!(
-            contents,
-            r#"
-class A:
-    ...
-"#
-            .trim()
-        );
-        assert_eq!(fixed, 1);
-    }
-
-    #[test]
-    fn apply_double_removal() {
-        let fixes = vec![
-            Fix {
-                content: String::new(),
-                location: Location::new(1, 7),
-                end_location: Location::new(1, 16),
-            },
-            Fix {
-                content: String::new(),
-                location: Location::new(1, 16),
-                end_location: Location::new(1, 23),
-            },
-        ];
-        let locator = SourceCodeLocator::new(
-            r#"
-class A(object, object):
-    ...
-"#
-            .trim(),
-        );
-        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
-
-        assert_eq!(
-            contents,
-            r#"
-class A:
-    ...
-"#
-            .trim()
-        );
-        assert_eq!(fixed, 2);
-    }
-
-    #[test]
-    fn ignore_overlapping_fixes() {
-        let fixes = vec![
-            Fix {
-                content: String::new(),
-                location: Location::new(1, 7),
-                end_location: Location::new(1, 15),
-            },
-            Fix {
-                content: "ignored".to_string(),
-                location: Location::new(1, 9),
-                end_location: Location::new(1, 11),
-            },
-        ];
-        let locator = SourceCodeLocator::new(
-            r#"
-class A(object):
-    ...
-"#
-            .trim(),
-        );
-        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
-        assert_eq!(
-            contents,
-            r#"
-class A:
-    ...
-"#
-            .trim(),
-        );
-        assert_eq!(fixed, 1);
-    }
-}

src/autofix/helpers.rs

@@ -9,10 +9,10 @@ use crate::ast::helpers;
 use crate::ast::helpers::to_absolute;
 use crate::ast::types::Range;
 use crate::ast::whitespace::LinesWithTrailingNewline;
-use crate::autofix::Fix;
 use crate::cst::helpers::compose_module_path;
 use crate::cst::matchers::match_module;
-use crate::source_code_locator::SourceCodeLocator;
+use crate::fix::Fix;
+use crate::source_code::Locator;
 
 /// Determine if a body contains only a single statement, taking into account
 /// deleted.
@@ -78,7 +78,7 @@ fn is_lone_child(child: &Stmt, parent: &Stmt, deleted: &[&Stmt]) -> Result<bool>
 
 /// Return the location of a trailing semicolon following a `Stmt`, if it's part
 /// of a multi-statement line.
-fn trailing_semicolon(stmt: &Stmt, locator: &SourceCodeLocator) -> Option<Location> {
+fn trailing_semicolon(stmt: &Stmt, locator: &Locator) -> Option<Location> {
     let contents = locator.slice_source_code_at(&stmt.end_location.unwrap());
     for (row, line) in LinesWithTrailingNewline::from(&contents).enumerate() {
         let trimmed = line.trim();
@@ -100,7 +100,7 @@ fn trailing_semicolon(stmt: &Stmt, locator: &SourceCodeLocator) -> Option<Locati
 }
 
 /// Find the next valid break for a `Stmt` after a semicolon.
-fn next_stmt_break(semicolon: Location, locator: &SourceCodeLocator) -> Location {
+fn next_stmt_break(semicolon: Location, locator: &Locator) -> Location {
     let start_location = Location::new(semicolon.row(), semicolon.column() + 1);
     let contents = locator.slice_source_code_at(&start_location);
     for (row, line) in LinesWithTrailingNewline::from(&contents).enumerate() {
@@ -133,7 +133,7 @@ fn next_stmt_break(semicolon: Location, locator: &SourceCodeLocator) -> Location
 }
 
 /// Return `true` if a `Stmt` occurs at the end of a file.
-fn is_end_of_file(stmt: &Stmt, locator: &SourceCodeLocator) -> bool {
+fn is_end_of_file(stmt: &Stmt, locator: &Locator) -> bool {
     let contents = locator.slice_source_code_at(&stmt.end_location.unwrap());
     contents.is_empty()
 }
@@ -155,7 +155,7 @@ pub fn delete_stmt(
     stmt: &Stmt,
     parent: Option<&Stmt>,
     deleted: &[&Stmt],
-    locator: &SourceCodeLocator,
+    locator: &Locator,
 ) -> Result<Fix> {
     if parent
         .map(|parent| is_lone_child(stmt, parent, deleted))
@@ -197,7 +197,7 @@ pub fn remove_unused_imports<'a>(
     stmt: &Stmt,
     parent: Option<&Stmt>,
     deleted: &[&Stmt],
-    locator: &SourceCodeLocator,
+    locator: &Locator,
 ) -> Result<Fix> {
     let module_text = locator.slice_source_code_range(&Range::from_located(stmt));
     let mut tree = match_module(&module_text)?;
@@ -299,20 +299,20 @@ mod tests {
     use rustpython_parser::parser;
 
     use crate::autofix::helpers::{next_stmt_break, trailing_semicolon};
-    use crate::source_code_locator::SourceCodeLocator;
+    use crate::source_code::Locator;
 
     #[test]
     fn find_semicolon() -> Result<()> {
         let contents = "x = 1";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(trailing_semicolon(stmt, &locator), None);
 
         let contents = "x = 1; y = 1";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             trailing_semicolon(stmt, &locator),
             Some(Location::new(1, 5))
@@ -321,7 +321,7 @@ mod tests {
         let contents = "x = 1 ; y = 1";
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             trailing_semicolon(stmt, &locator),
             Some(Location::new(1, 6))
@@ -334,7 +334,7 @@ x = 1 \
         .trim();
         let program = parser::parse_program(contents, "<filename>")?;
         let stmt = program.first().unwrap();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             trailing_semicolon(stmt, &locator),
             Some(Location::new(2, 2))
@@ -346,14 +346,14 @@ x = 1 \
     #[test]
     fn find_next_stmt_break() {
         let contents = "x = 1; y = 1";
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             next_stmt_break(Location::new(1, 4), &locator),
             Location::new(1, 5)
         );
 
         let contents = "x = 1 ; y = 1";
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             next_stmt_break(Location::new(1, 5), &locator),
             Location::new(1, 6)
@@ -364,7 +364,7 @@ x = 1 \
   ; y = 1
 "#
         .trim();
-        let locator = SourceCodeLocator::new(contents);
+        let locator = Locator::new(contents);
         assert_eq!(
             next_stmt_break(Location::new(2, 2), &locator),
             Location::new(2, 4)

src/autofix/mod.rs

@@ -1,38 +1,210 @@
+use std::borrow::Cow;
+use std::collections::BTreeSet;
+
+use itertools::Itertools;
+use ropey::RopeBuilder;
 use rustpython_ast::Location;
-use serde::{Deserialize, Serialize};
+
+use crate::ast::types::Range;
+use crate::fix::Fix;
+use crate::registry::Diagnostic;
+use crate::source_code::Locator;
 
 pub mod fixer;
 pub mod helpers;
 
-#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
-pub struct Fix {
-    pub content: String,
-    pub location: Location,
-    pub end_location: Location,
+/// Auto-fix errors in a file, and write the fixed source code to disk.
+pub fn fix_file<'a>(
+    diagnostics: &'a [Diagnostic],
+    locator: &'a Locator<'a>,
+) -> Option<(Cow<'a, str>, usize)> {
+    if diagnostics.iter().all(|check| check.fix.is_none()) {
+        return None;
+    }
+
+    Some(apply_fixes(
+        diagnostics.iter().filter_map(|check| check.fix.as_ref()),
+        locator,
+    ))
 }
 
-impl Fix {
-    pub fn deletion(start: Location, end: Location) -> Self {
-        Self {
+/// Apply a series of fixes.
+fn apply_fixes<'a>(
+    fixes: impl Iterator<Item = &'a Fix>,
+    locator: &'a Locator<'a>,
+) -> (Cow<'a, str>, usize) {
+    let mut output = RopeBuilder::new();
+    let mut last_pos: Location = Location::new(1, 0);
+    let mut applied: BTreeSet<&Fix> = BTreeSet::default();
+    let mut num_fixed: usize = 0;
+
+    for fix in fixes.sorted_by_key(|fix| fix.location) {
+        // If we already applied an identical fix as part of another correction, skip
+        // any re-application.
+        if applied.contains(&fix) {
+            num_fixed += 1;
+            continue;
+        }
+
+        // Best-effort approach: if this fix overlaps with a fix we've already applied,
+        // skip it.
+        if last_pos > fix.location {
+            continue;
+        }
+
+        // Add all contents from `last_pos` to `fix.location`.
+        let slice = locator.slice_source_code_range(&Range::new(last_pos, fix.location));
+        output.append(&slice);
+
+        // Add the patch itself.
+        output.append(&fix.content);
+
+        // Track that the fix was applied.
+        last_pos = fix.end_location;
+        applied.insert(fix);
+        num_fixed += 1;
+    }
+
+    // Add the remaining content.
+    let slice = locator.slice_source_code_at(&last_pos);
+    output.append(&slice);
+
+    (Cow::from(output.finish()), num_fixed)
+}
+
+#[cfg(test)]
+mod tests {
+    use rustpython_parser::ast::Location;
+
+    use crate::autofix::apply_fixes;
+    use crate::fix::Fix;
+    use crate::source_code::Locator;
+
+    #[test]
+    fn empty_file() {
+        let fixes = vec![];
+        let locator = Locator::new(r#""#);
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(contents, "");
+        assert_eq!(fixed, 0);
+    }
+
+    #[test]
+    fn apply_single_replacement() {
+        let fixes = vec![Fix {
+            content: "Bar".to_string(),
+            location: Location::new(1, 8),
+            end_location: Location::new(1, 14),
+        }];
+        let locator = Locator::new(
+            r#"
+class A(object):
+    ...
+"#
+            .trim(),
+        );
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(
+            contents,
+            r#"
+class A(Bar):
+    ...
+"#
+            .trim(),
+        );
+        assert_eq!(fixed, 1);
+    }
+
+    #[test]
+    fn apply_single_removal() {
+        let fixes = vec![Fix {
             content: String::new(),
-            location: start,
-            end_location: end,
-        }
+            location: Location::new(1, 7),
+            end_location: Location::new(1, 15),
+        }];
+        let locator = Locator::new(
+            r#"
+class A(object):
+    ...
+"#
+            .trim(),
+        );
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(
+            contents,
+            r#"
+class A:
+    ...
+"#
+            .trim()
+        );
+        assert_eq!(fixed, 1);
     }
 
-    pub fn replacement(content: String, start: Location, end: Location) -> Self {
-        Self {
-            content,
-            location: start,
-            end_location: end,
-        }
+    #[test]
+    fn apply_double_removal() {
+        let fixes = vec![
+            Fix {
+                content: String::new(),
+                location: Location::new(1, 7),
+                end_location: Location::new(1, 16),
+            },
+            Fix {
+                content: String::new(),
+                location: Location::new(1, 16),
+                end_location: Location::new(1, 23),
+            },
+        ];
+        let locator = Locator::new(
+            r#"
+class A(object, object):
+    ...
+"#
+            .trim(),
+        );
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+
+        assert_eq!(
+            contents,
+            r#"
+class A:
+    ...
+"#
+            .trim()
+        );
+        assert_eq!(fixed, 2);
     }
 
-    pub fn insertion(content: String, at: Location) -> Self {
-        Self {
-            content,
-            location: at,
-            end_location: at,
-        }
+    #[test]
+    fn ignore_overlapping_fixes() {
+        let fixes = vec![
+            Fix {
+                content: String::new(),
+                location: Location::new(1, 7),
+                end_location: Location::new(1, 15),
+            },
+            Fix {
+                content: "ignored".to_string(),
+                location: Location::new(1, 9),
+                end_location: Location::new(1, 11),
+            },
+        ];
+        let locator = Locator::new(
+            r#"
+class A(object):
+    ...
+"#
+            .trim(),
+        );
+        let (contents, fixed) = apply_fixes(fixes.iter(), &locator);
+        assert_eq!(
+            contents,
+            r#"
+class A:
+    ...
+"#
+            .trim(),
+        );
+        assert_eq!(fixed, 1);
     }
 }

src/cache.rs

@@ -1,6 +1,6 @@
+#![cfg_attr(target_family = "wasm", allow(dead_code))]
 use std::collections::hash_map::DefaultHasher;
 use std::fs;
-use std::fs::{create_dir_all, File, Metadata};
 use std::hash::{Hash, Hasher};
 use std::io::Write;
 use std::path::{Path, PathBuf};
@@ -8,16 +8,15 @@ use std::path::{Path, PathBuf};
 use anyhow::Result;
 use filetime::FileTime;
 use log::error;
-use once_cell::sync::Lazy;
 use path_absolutize::Absolutize;
 use serde::{Deserialize, Serialize};
 
 use crate::message::Message;
 use crate::settings::{flags, Settings};
 
+pub const CACHE_DIR_NAME: &str = ".ruff_cache";
+
 const CARGO_PKG_VERSION: &str = env!("CARGO_PKG_VERSION");
-static CACHE_DIR: Lazy<Option<String>> = Lazy::new(|| std::env::var("RUFF_CACHE_DIR").ok());
-pub const DEFAULT_CACHE_DIR_NAME: &str = ".ruff_cache";
 
 #[derive(Serialize, Deserialize)]
 struct CacheMetadata {
@@ -39,9 +38,7 @@ struct CheckResult {
 /// Return the cache directory for a given project root. Defers to the
 /// `RUFF_CACHE_DIR` environment variable, if set.
 pub fn cache_dir(project_root: &Path) -> PathBuf {
-    CACHE_DIR
-        .as_ref()
-        .map_or_else(|| project_root.join(DEFAULT_CACHE_DIR_NAME), PathBuf::from)
+    project_root.join(CACHE_DIR_NAME)
 }
 
 fn content_dir() -> &'static Path {
@@ -57,10 +54,11 @@ fn cache_key<P: AsRef<Path>>(path: P, settings: &Settings, autofix: flags::Autof
     hasher.finish()
 }
 
+#[allow(dead_code)]
 /// Initialize the cache at the specified `Path`.
 pub fn init(path: &Path) -> Result<()> {
     // Create the cache directories.
-    create_dir_all(path.join(content_dir()))?;
+    fs::create_dir_all(path.join(content_dir()))?;
 
     // Add the CACHEDIR.TAG.
     if !cachedir::is_tagged(path)? {
@@ -70,7 +68,7 @@ pub fn init(path: &Path) -> Result<()> {
     // Add the .gitignore.
     let gitignore_path = path.join(".gitignore");
     if !gitignore_path.exists() {
-        let mut file = File::create(gitignore_path)?;
+        let mut file = fs::File::create(gitignore_path)?;
         file.write_all(b"*")?;
     }
 
@@ -91,7 +89,7 @@ fn read_sync(cache_dir: &Path, key: u64) -> Result<Vec<u8>, std::io::Error> {
 /// Get a value from the cache.
 pub fn get<P: AsRef<Path>>(
     path: P,
-    metadata: &Metadata,
+    metadata: &fs::Metadata,
     settings: &Settings,
     autofix: flags::Autofix,
 ) -> Option<Vec<Message>> {
@@ -115,7 +113,7 @@ pub fn get<P: AsRef<Path>>(
 /// Set a value in the cache.
 pub fn set<P: AsRef<Path>>(
     path: P,
-    metadata: &Metadata,
+    metadata: &fs::Metadata,
     settings: &Settings,
     autofix: flags::Autofix,
     messages: &[Message],

src/checkers/imports.rs

@@ -7,47 +7,49 @@ use rustpython_parser::ast::Suite;
 use crate::ast::visitor::Visitor;
 use crate::directives::IsortDirectives;
 use crate::isort;
-use crate::isort::track::ImportTracker;
-use crate::registry::Check;
+use crate::isort::track::{Block, ImportTracker};
+use crate::registry::{Diagnostic, RuleCode};
 use crate::settings::{flags, Settings};
-use crate::source_code_locator::SourceCodeLocator;
-use crate::source_code_style::SourceCodeStyleDetector;
-
-fn check_import_blocks(
-    tracker: ImportTracker,
-    locator: &SourceCodeLocator,
-    settings: &Settings,
-    stylist: &SourceCodeStyleDetector,
-    autofix: flags::Autofix,
-    package: Option<&Path>,
-) -> Vec<Check> {
-    let mut checks = vec![];
-    for block in tracker.into_iter() {
-        if !block.imports.is_empty() {
-            if let Some(check) =
-                isort::plugins::check_imports(&block, locator, settings, stylist, autofix, package)
-            {
-                checks.push(check);
-            }
-        }
-    }
-    checks
-}
+use crate::source_code::{Locator, Stylist};
 
 #[allow(clippy::too_many_arguments)]
 pub fn check_imports(
     python_ast: &Suite,
-    locator: &SourceCodeLocator,
+    locator: &Locator,
     directives: &IsortDirectives,
     settings: &Settings,
-    stylist: &SourceCodeStyleDetector,
+    stylist: &Stylist,
     autofix: flags::Autofix,
     path: &Path,
     package: Option<&Path>,
-) -> Vec<Check> {
-    let mut tracker = ImportTracker::new(locator, directives, path);
-    for stmt in python_ast {
-        tracker.visit_stmt(stmt);
+) -> Vec<Diagnostic> {
+    // Extract all imports from the AST.
+    let tracker = {
+        let mut tracker = ImportTracker::new(locator, directives, path);
+        for stmt in python_ast {
+            tracker.visit_stmt(stmt);
+        }
+        tracker
+    };
+    let blocks: Vec<&Block> = tracker.iter().collect();
+
+    // Enforce import rules.
+    let mut diagnostics = vec![];
+    if settings.enabled.contains(&RuleCode::I001) {
+        for block in &blocks {
+            if !block.imports.is_empty() {
+                if let Some(diagnostic) = isort::rules::organize_imports(
+                    block, locator, settings, stylist, autofix, package,
+                ) {
+                    diagnostics.push(diagnostic);
+                }
+            }
+        }
     }
-    check_import_blocks(tracker, locator, settings, stylist, autofix, package)
+    if settings.enabled.contains(&RuleCode::I002) {
+        diagnostics.extend(isort::rules::add_required_imports(
+            &blocks, python_ast, locator, settings, autofix,
+        ));
+    }
+    diagnostics
 }

src/checkers/lines.rs

@@ -1,26 +1,29 @@
 //! Lint rules based on checking raw physical lines.
 
-use crate::pycodestyle::checks::{line_too_long, no_newline_at_end_of_file};
-use crate::pygrep_hooks::plugins::{blanket_noqa, blanket_type_ignore};
-use crate::pyupgrade::checks::unnecessary_coding_comment;
-use crate::registry::{Check, CheckCode};
+use crate::pycodestyle::rules::{doc_line_too_long, line_too_long, no_newline_at_end_of_file};
+use crate::pygrep_hooks::rules::{blanket_noqa, blanket_type_ignore};
+use crate::pyupgrade::rules::unnecessary_coding_comment;
+use crate::registry::{Diagnostic, RuleCode};
 use crate::settings::{flags, Settings};
 
 pub fn check_lines(
     contents: &str,
     commented_lines: &[usize],
+    doc_lines: &[usize],
     settings: &Settings,
     autofix: flags::Autofix,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
+) -> Vec<Diagnostic> {
+    let mut diagnostics: Vec<Diagnostic> = vec![];
 
-    let enforce_unnecessary_coding_comment = settings.enabled.contains(&CheckCode::UP009);
-    let enforce_line_too_long = settings.enabled.contains(&CheckCode::E501);
-    let enforce_no_newline_at_end_of_file = settings.enabled.contains(&CheckCode::W292);
-    let enforce_blanket_type_ignore = settings.enabled.contains(&CheckCode::PGH003);
-    let enforce_blanket_noqa = settings.enabled.contains(&CheckCode::PGH004);
+    let enforce_blanket_noqa = settings.enabled.contains(&RuleCode::PGH004);
+    let enforce_blanket_type_ignore = settings.enabled.contains(&RuleCode::PGH003);
+    let enforce_doc_line_too_long = settings.enabled.contains(&RuleCode::W505);
+    let enforce_line_too_long = settings.enabled.contains(&RuleCode::E501);
+    let enforce_no_newline_at_end_of_file = settings.enabled.contains(&RuleCode::W292);
+    let enforce_unnecessary_coding_comment = settings.enabled.contains(&RuleCode::UP009);
 
     let mut commented_lines_iter = commented_lines.iter().peekable();
+    let mut doc_lines_iter = doc_lines.iter().peekable();
     for (index, line) in contents.lines().enumerate() {
         while commented_lines_iter
             .next_if(|lineno| &(index + 1) == *lineno)
@@ -28,59 +31,66 @@ pub fn check_lines(
         {
             if enforce_unnecessary_coding_comment {
                 if index < 2 {
-                    if let Some(check) = unnecessary_coding_comment(
+                    if let Some(diagnostic) = unnecessary_coding_comment(
                         index,
                         line,
                         matches!(autofix, flags::Autofix::Enabled)
-                            && settings.fixable.contains(&CheckCode::UP009),
+                            && settings.fixable.contains(&RuleCode::UP009),
                     ) {
-                        checks.push(check);
+                        diagnostics.push(diagnostic);
                     }
                 }
             }
 
             if enforce_blanket_type_ignore {
-                if commented_lines.contains(&(index + 1)) {
-                    if let Some(check) = blanket_type_ignore(index, line) {
-                        checks.push(check);
-                    }
+                if let Some(diagnostic) = blanket_type_ignore(index, line) {
+                    diagnostics.push(diagnostic);
                 }
             }
 
             if enforce_blanket_noqa {
-                if commented_lines.contains(&(index + 1)) {
-                    if let Some(check) = blanket_noqa(index, line) {
-                        checks.push(check);
-                    }
+                if let Some(diagnostic) = blanket_noqa(index, line) {
+                    diagnostics.push(diagnostic);
+                }
+            }
+        }
+
+        while doc_lines_iter
+            .next_if(|lineno| &(index + 1) == *lineno)
+            .is_some()
+        {
+            if enforce_doc_line_too_long {
+                if let Some(diagnostic) = doc_line_too_long(index, line, settings) {
+                    diagnostics.push(diagnostic);
                 }
             }
         }
 
         if enforce_line_too_long {
-            if let Some(check) = line_too_long(index, line, settings) {
-                checks.push(check);
+            if let Some(diagnostic) = line_too_long(index, line, settings) {
+                diagnostics.push(diagnostic);
             }
         }
     }
 
     if enforce_no_newline_at_end_of_file {
-        if let Some(check) = no_newline_at_end_of_file(
+        if let Some(diagnostic) = no_newline_at_end_of_file(
             contents,
             matches!(autofix, flags::Autofix::Enabled)
-                && settings.fixable.contains(&CheckCode::W292),
+                && settings.fixable.contains(&RuleCode::W292),
         ) {
-            checks.push(check);
+            diagnostics.push(diagnostic);
         }
     }
 
-    checks
+    diagnostics
 }
 
 #[cfg(test)]
 mod tests {
 
     use super::check_lines;
-    use crate::registry::CheckCode;
+    use crate::registry::RuleCode;
     use crate::settings::{flags, Settings};
 
     #[test]
@@ -90,9 +100,10 @@ mod tests {
             check_lines(
                 line,
                 &[],
+                &[],
                 &Settings {
                     line_length,
-                    ..Settings::for_rule(CheckCode::E501)
+                    ..Settings::for_rule(RuleCode::E501)
                 },
                 flags::Autofix::Enabled,
             )

src/checkers/noqa.rs

@@ -6,14 +6,15 @@ use nohash_hasher::IntMap;
 use rustpython_parser::ast::Location;
 
 use crate::ast::types::Range;
-use crate::autofix::Fix;
+use crate::fix::Fix;
 use crate::noqa::{is_file_exempt, Directive};
-use crate::registry::{Check, CheckCode, CheckKind, UnusedCodes, CODE_REDIRECTS};
+use crate::registry::{Diagnostic, DiagnosticKind, RuleCode, CODE_REDIRECTS};
 use crate::settings::{flags, Settings};
+use crate::violations::UnusedCodes;
 use crate::{noqa, violations};
 
 pub fn check_noqa(
-    checks: &mut Vec<Check>,
+    diagnostics: &mut Vec<Diagnostic>,
     contents: &str,
     commented_lines: &[usize],
     noqa_line_for: &IntMap<usize, usize>,
@@ -23,13 +24,13 @@ pub fn check_noqa(
     let mut noqa_directives: IntMap<usize, (Directive, Vec<&str>)> = IntMap::default();
     let mut ignored = vec![];
 
-    let enforce_noqa = settings.enabled.contains(&CheckCode::RUF100);
+    let enforce_noqa = settings.enabled.contains(&RuleCode::RUF100);
 
     let lines: Vec<&str> = contents.lines().collect();
     for lineno in commented_lines {
         // If we hit an exemption for the entire file, bail.
         if is_file_exempt(lines[lineno - 1]) {
-            checks.drain(..);
+            diagnostics.drain(..);
             return;
         }
 
@@ -40,14 +41,14 @@ pub fn check_noqa(
         }
     }
 
-    // Remove any ignored checks.
-    for (index, check) in checks.iter().enumerate() {
-        if matches!(check.kind, CheckKind::BlanketNOQA(..)) {
+    // Remove any ignored diagnostics.
+    for (index, diagnostic) in diagnostics.iter().enumerate() {
+        if matches!(diagnostic.kind, DiagnosticKind::BlanketNOQA(..)) {
             continue;
         }
 
-        // Is the check ignored by a `noqa` directive on the parent line?
-        if let Some(parent_lineno) = check.parent.map(|location| location.row()) {
+        // Is the violation ignored by a `noqa` directive on the parent line?
+        if let Some(parent_lineno) = diagnostic.parent.map(|location| location.row()) {
             let noqa_lineno = noqa_line_for.get(&parent_lineno).unwrap_or(&parent_lineno);
             if commented_lines.contains(noqa_lineno) {
                 let noqa = noqa_directives.entry(noqa_lineno - 1).or_insert_with(|| {
@@ -55,13 +56,13 @@ pub fn check_noqa(
                 });
                 match noqa {
                     (Directive::All(..), matches) => {
-                        matches.push(check.kind.code().as_ref());
+                        matches.push(diagnostic.kind.code().as_ref());
                         ignored.push(index);
                         continue;
                     }
                     (Directive::Codes(.., codes), matches) => {
-                        if noqa::includes(check.kind.code(), codes) {
-                            matches.push(check.kind.code().as_ref());
+                        if noqa::includes(diagnostic.kind.code(), codes) {
+                            matches.push(diagnostic.kind.code().as_ref());
                             ignored.push(index);
                             continue;
                         }
@@ -71,21 +72,23 @@ pub fn check_noqa(
             }
         }
 
-        // Is the check ignored by a `noqa` directive on the same line?
-        let check_lineno = check.location.row();
-        let noqa_lineno = noqa_line_for.get(&check_lineno).unwrap_or(&check_lineno);
+        // Is the diagnostic ignored by a `noqa` directive on the same line?
+        let diagnostic_lineno = diagnostic.location.row();
+        let noqa_lineno = noqa_line_for
+            .get(&diagnostic_lineno)
+            .unwrap_or(&diagnostic_lineno);
         if commented_lines.contains(noqa_lineno) {
             let noqa = noqa_directives
                 .entry(noqa_lineno - 1)
                 .or_insert_with(|| (noqa::extract_noqa_directive(lines[noqa_lineno - 1]), vec![]));
             match noqa {
                 (Directive::All(..), matches) => {
-                    matches.push(check.kind.code().as_ref());
+                    matches.push(diagnostic.kind.code().as_ref());
                     ignored.push(index);
                 }
                 (Directive::Codes(.., codes), matches) => {
-                    if noqa::includes(check.kind.code(), codes) {
-                        matches.push(check.kind.code().as_ref());
+                    if noqa::includes(diagnostic.kind.code(), codes) {
+                        matches.push(diagnostic.kind.code().as_ref());
                         ignored.push(index);
                     }
                 }
@@ -100,19 +103,19 @@ pub fn check_noqa(
             match directive {
                 Directive::All(spaces, start, end) => {
                     if matches.is_empty() {
-                        let mut check = Check::new(
+                        let mut diagnostic = Diagnostic::new(
                             violations::UnusedNOQA(None),
                             Range::new(Location::new(row + 1, start), Location::new(row + 1, end)),
                         );
                         if matches!(autofix, flags::Autofix::Enabled)
-                            && settings.fixable.contains(check.kind.code())
+                            && settings.fixable.contains(diagnostic.kind.code())
                         {
-                            check.amend(Fix::deletion(
+                            diagnostic.amend(Fix::deletion(
                                 Location::new(row + 1, start - spaces),
                                 Location::new(row + 1, lines[row].chars().count()),
                             ));
                         }
-                        checks.push(check);
+                        diagnostics.push(diagnostic);
                     }
                 }
                 Directive::Codes(spaces, start, end, codes) => {
@@ -123,7 +126,7 @@ pub fn check_noqa(
                     let mut self_ignore = false;
                     for code in codes {
                         let code = CODE_REDIRECTS.get(code).map_or(code, AsRef::as_ref);
-                        if code == CheckCode::RUF100.as_ref() {
+                        if code == RuleCode::RUF100.as_ref() {
                             self_ignore = true;
                             break;
                         }
@@ -131,8 +134,8 @@ pub fn check_noqa(
                         if matches.contains(&code) || settings.external.contains(code) {
                             valid_codes.push(code);
                         } else {
-                            if let Ok(check_code) = CheckCode::from_str(code) {
-                                if settings.enabled.contains(&check_code) {
+                            if let Ok(rule_code) = RuleCode::from_str(code) {
+                                if settings.enabled.contains(&rule_code) {
                                     unmatched_codes.push(code);
                                 } else {
                                     disabled_codes.push(code);
@@ -151,7 +154,7 @@ pub fn check_noqa(
                         && unknown_codes.is_empty()
                         && unmatched_codes.is_empty())
                     {
-                        let mut check = Check::new(
+                        let mut diagnostic = Diagnostic::new(
                             violations::UnusedNOQA(Some(UnusedCodes {
                                 disabled: disabled_codes
                                     .iter()
@@ -169,22 +172,22 @@ pub fn check_noqa(
                             Range::new(Location::new(row + 1, start), Location::new(row + 1, end)),
                         );
                         if matches!(autofix, flags::Autofix::Enabled)
-                            && settings.fixable.contains(check.kind.code())
+                            && settings.fixable.contains(diagnostic.kind.code())
                         {
                             if valid_codes.is_empty() {
-                                check.amend(Fix::deletion(
+                                diagnostic.amend(Fix::deletion(
                                     Location::new(row + 1, start - spaces),
                                     Location::new(row + 1, lines[row].chars().count()),
                                 ));
                             } else {
-                                check.amend(Fix::replacement(
+                                diagnostic.amend(Fix::replacement(
                                     format!("# noqa: {}", valid_codes.join(", ")),
                                     Location::new(row + 1, start),
                                     Location::new(row + 1, lines[row].chars().count()),
                                 ));
                             }
                         }
-                        checks.push(check);
+                        diagnostics.push(diagnostic);
                     }
                 }
                 Directive::None => {}
@@ -194,6 +197,6 @@ pub fn check_noqa(
 
     ignored.sort_unstable();
     for index in ignored.iter().rev() {
-        checks.swap_remove(*index);
+        diagnostics.swap_remove(*index);
     }
 }

src/checkers/tokens.rs

@@ -3,31 +3,31 @@
 use rustpython_parser::lexer::{LexResult, Tok};
 
 use crate::lex::docstring_detection::StateMachine;
-use crate::registry::{Check, CheckCode};
-use crate::ruff::checks::Context;
-use crate::settings::flags;
-use crate::source_code_locator::SourceCodeLocator;
-use crate::{eradicate, flake8_implicit_str_concat, flake8_quotes, pycodestyle, ruff, Settings};
+use crate::registry::{Diagnostic, RuleCode};
+use crate::ruff::rules::Context;
+use crate::settings::{flags, Settings};
+use crate::source_code::Locator;
+use crate::{eradicate, flake8_implicit_str_concat, flake8_quotes, pycodestyle, ruff};
 
 pub fn check_tokens(
-    locator: &SourceCodeLocator,
+    locator: &Locator,
     tokens: &[LexResult],
     settings: &Settings,
     autofix: flags::Autofix,
-) -> Vec<Check> {
-    let mut checks: Vec<Check> = vec![];
+) -> Vec<Diagnostic> {
+    let mut diagnostics: Vec<Diagnostic> = vec![];
 
-    let enforce_ambiguous_unicode_character = settings.enabled.contains(&CheckCode::RUF001)
-        || settings.enabled.contains(&CheckCode::RUF002)
-        || settings.enabled.contains(&CheckCode::RUF003);
-    let enforce_quotes = settings.enabled.contains(&CheckCode::Q000)
-        || settings.enabled.contains(&CheckCode::Q001)
-        || settings.enabled.contains(&CheckCode::Q002)
-        || settings.enabled.contains(&CheckCode::Q003);
-    let enforce_commented_out_code = settings.enabled.contains(&CheckCode::ERA001);
-    let enforce_invalid_escape_sequence = settings.enabled.contains(&CheckCode::W605);
-    let enforce_implicit_string_concatenation = settings.enabled.contains(&CheckCode::ISC001)
-        || settings.enabled.contains(&CheckCode::ISC002);
+    let enforce_ambiguous_unicode_character = settings.enabled.contains(&RuleCode::RUF001)
+        || settings.enabled.contains(&RuleCode::RUF002)
+        || settings.enabled.contains(&RuleCode::RUF003);
+    let enforce_quotes = settings.enabled.contains(&RuleCode::Q000)
+        || settings.enabled.contains(&RuleCode::Q001)
+        || settings.enabled.contains(&RuleCode::Q002)
+        || settings.enabled.contains(&RuleCode::Q003);
+    let enforce_commented_out_code = settings.enabled.contains(&RuleCode::ERA001);
+    let enforce_invalid_escape_sequence = settings.enabled.contains(&RuleCode::W605);
+    let enforce_implicit_string_concatenation = settings.enabled.contains(&RuleCode::ISC001)
+        || settings.enabled.contains(&RuleCode::ISC002);
 
     let mut state_machine = StateMachine::default();
     for &(start, ref tok, end) in tokens.iter().flatten() {
@@ -40,7 +40,7 @@ pub fn check_tokens(
         // RUF001, RUF002, RUF003
         if enforce_ambiguous_unicode_character {
             if matches!(tok, Tok::String { .. } | Tok::Comment(_)) {
-                checks.extend(ruff::checks::ambiguous_unicode_character(
+                diagnostics.extend(ruff::rules::ambiguous_unicode_character(
                     locator,
                     start,
                     end,
@@ -62,15 +62,16 @@ pub fn check_tokens(
         // flake8-quotes
         if enforce_quotes {
             if matches!(tok, Tok::String { .. }) {
-                if let Some(check) = flake8_quotes::checks::quotes(
+                if let Some(diagnostic) = flake8_quotes::rules::quotes(
                     locator,
                     start,
                     end,
                     is_docstring,
-                    &settings.flake8_quotes,
+                    settings,
+                    autofix,
                 ) {
-                    if settings.enabled.contains(check.kind.code()) {
-                        checks.push(check);
+                    if settings.enabled.contains(diagnostic.kind.code()) {
+                        diagnostics.push(diagnostic);
                     }
                 }
             }
@@ -79,10 +80,10 @@ pub fn check_tokens(
         // eradicate
         if enforce_commented_out_code {
             if matches!(tok, Tok::Comment(_)) {
-                if let Some(check) =
-                    eradicate::checks::commented_out_code(locator, start, end, settings, autofix)
+                if let Some(diagnostic) =
+                    eradicate::rules::commented_out_code(locator, start, end, settings, autofix)
                 {
-                    checks.push(check);
+                    diagnostics.push(diagnostic);
                 }
             }
         }
@@ -90,12 +91,12 @@ pub fn check_tokens(
         // W605
         if enforce_invalid_escape_sequence {
             if matches!(tok, Tok::String { .. }) {
-                checks.extend(pycodestyle::checks::invalid_escape_sequence(
+                diagnostics.extend(pycodestyle::rules::invalid_escape_sequence(
                     locator,
                     start,
                     end,
                     matches!(autofix, flags::Autofix::Enabled)
-                        && settings.fixable.contains(&CheckCode::W605),
+                        && settings.fixable.contains(&RuleCode::W605),
                 ));
             }
         }
@@ -103,12 +104,12 @@ pub fn check_tokens(
 
     // ISC001, ISC002
     if enforce_implicit_string_concatenation {
-        checks.extend(
-            flake8_implicit_str_concat::checks::implicit(tokens, locator)
+        diagnostics.extend(
+            flake8_implicit_str_concat::rules::implicit(tokens, locator)
                 .into_iter()
-                .filter(|check| settings.enabled.contains(check.kind.code())),
+                .filter(|diagnostic| settings.enabled.contains(diagnostic.kind.code())),
         );
     }
 
-    checks
+    diagnostics
 }

src/cli.rs

@@ -4,12 +4,13 @@ use clap::{command, Parser};
 use regex::Regex;
 use rustc_hash::FxHashMap;
 
-use crate::fs;
 use crate::logging::LogLevel;
-use crate::registry::{CheckCode, CheckCodePrefix};
+use crate::registry::{RuleCode, RuleCodePrefix};
+use crate::resolver::ConfigProcessor;
 use crate::settings::types::{
     FilePattern, PatternPrefixPair, PerFileIgnore, PythonVersion, SerializationFormat,
 };
+use crate::{fs, mccabe};
 
 #[derive(Debug, Parser)]
 #[command(author, about = "Ruff: An extremely fast Python linter.")]
@@ -20,31 +21,31 @@ pub struct Cli {
     pub files: Vec<PathBuf>,
     /// Path to the `pyproject.toml` or `ruff.toml` file to use for
     /// configuration.
-    #[arg(long)]
+    #[arg(long, conflicts_with = "isolated")]
     pub config: Option<PathBuf>,
     /// Enable verbose logging.
     #[arg(short, long, group = "verbosity")]
     pub verbose: bool,
-    /// Only log errors.
+    /// Print lint violations, but nothing else.
     #[arg(short, long, group = "verbosity")]
     pub quiet: bool,
     /// Disable all logging (but still exit with status code "1" upon detecting
-    /// errors).
+    /// lint violations).
     #[arg(short, long, group = "verbosity")]
     pub silent: bool,
-    /// Exit with status code "0", even upon detecting errors.
+    /// Exit with status code "0", even upon detecting lint violations.
     #[arg(short, long)]
     pub exit_zero: bool,
     /// Run in watch mode by re-running whenever files change.
     #[arg(short, long)]
     pub watch: bool,
-    /// Attempt to automatically fix lint errors.
+    /// Attempt to automatically fix lint violations.
     #[arg(long, overrides_with("no_fix"))]
     fix: bool,
     #[clap(long, overrides_with("fix"), hide = true)]
     no_fix: bool,
-    /// Fix any fixable lint errors, but don't report on leftover violations.
-    /// Implies `--fix`.
+    /// Fix any fixable lint violations, but don't report on leftover
+    /// violations. Implies `--fix`.
     #[arg(long, overrides_with("no_fix_only"))]
     fix_only: bool,
     #[clap(long, overrides_with("fix_only"), hide = true)]
@@ -56,47 +57,50 @@ pub struct Cli {
     /// Disable cache reads.
     #[arg(short, long)]
     pub no_cache: bool,
-    /// Comma-separated list of error codes to enable (or ALL, to enable all
-    /// checks).
-    #[arg(long, value_delimiter = ',')]
-    pub select: Option<Vec<CheckCodePrefix>>,
-    /// Like --select, but adds additional error codes on top of the selected
+    /// Ignore all configuration files.
+    #[arg(long, conflicts_with = "config")]
+    pub isolated: bool,
+    /// Comma-separated list of rule codes to enable (or ALL, to enable all
+    /// rules).
+    #[arg(long, value_delimiter = ',', value_name = "RULE_CODE")]
+    pub select: Option<Vec<RuleCodePrefix>>,
+    /// Like --select, but adds additional rule codes on top of the selected
     /// ones.
-    #[arg(long, value_delimiter = ',')]
-    pub extend_select: Option<Vec<CheckCodePrefix>>,
-    /// Comma-separated list of error codes to disable.
-    #[arg(long, value_delimiter = ',')]
-    pub ignore: Option<Vec<CheckCodePrefix>>,
-    /// Like --ignore, but adds additional error codes on top of the ignored
+    #[arg(long, value_delimiter = ',', value_name = "RULE_CODE")]
+    pub extend_select: Option<Vec<RuleCodePrefix>>,
+    /// Comma-separated list of rule codes to disable.
+    #[arg(long, value_delimiter = ',', value_name = "RULE_CODE")]
+    pub ignore: Option<Vec<RuleCodePrefix>>,
+    /// Like --ignore, but adds additional rule codes on top of the ignored
     /// ones.
-    #[arg(long, value_delimiter = ',')]
-    pub extend_ignore: Option<Vec<CheckCodePrefix>>,
-    /// List of paths, used to exclude files and/or directories from checks.
-    #[arg(long, value_delimiter = ',')]
+    #[arg(long, value_delimiter = ',', value_name = "RULE_CODE")]
+    pub extend_ignore: Option<Vec<RuleCodePrefix>>,
+    /// List of paths, used to omit files and/or directories from analysis.
+    #[arg(long, value_delimiter = ',', value_name = "FILE_PATTERN")]
     pub exclude: Option<Vec<FilePattern>>,
-    /// Like --exclude, but adds additional files and directories on top of the
-    /// excluded ones.
-    #[arg(long, value_delimiter = ',')]
+    /// Like --exclude, but adds additional files and directories on top of
+    /// those already excluded.
+    #[arg(long, value_delimiter = ',', value_name = "FILE_PATTERN")]
     pub extend_exclude: Option<Vec<FilePattern>>,
-    /// List of error codes to treat as eligible for autofix. Only applicable
+    /// List of rule codes to treat as eligible for autofix. Only applicable
     /// when autofix itself is enabled (e.g., via `--fix`).
-    #[arg(long, value_delimiter = ',')]
-    pub fixable: Option<Vec<CheckCodePrefix>>,
-    /// List of error codes to treat as ineligible for autofix. Only applicable
+    #[arg(long, value_delimiter = ',', value_name = "RULE_CODE")]
+    pub fixable: Option<Vec<RuleCodePrefix>>,
+    /// List of rule codes to treat as ineligible for autofix. Only applicable
     /// when autofix itself is enabled (e.g., via `--fix`).
-    #[arg(long, value_delimiter = ',')]
-    pub unfixable: Option<Vec<CheckCodePrefix>>,
+    #[arg(long, value_delimiter = ',', value_name = "RULE_CODE")]
+    pub unfixable: Option<Vec<RuleCodePrefix>>,
     /// List of mappings from file pattern to code to exclude
     #[arg(long, value_delimiter = ',')]
     pub per_file_ignores: Option<Vec<PatternPrefixPair>>,
-    /// Output serialization format for error messages.
-    #[arg(long, value_enum)]
+    /// Output serialization format for violations.
+    #[arg(long, value_enum, env = "RUFF_FORMAT")]
     pub format: Option<SerializationFormat>,
     /// The name of the file when passing it through stdin.
     #[arg(long)]
     pub stdin_filename: Option<PathBuf>,
     /// Path to the cache directory.
-    #[arg(long)]
+    #[arg(long, env = "RUFF_CACHE_DIR")]
     pub cache_dir: Option<PathBuf>,
     /// Show violations with source code.
     #[arg(long, overrides_with("no_show_source"))]
@@ -126,7 +130,7 @@ pub struct Cli {
     /// The minimum Python version that should be supported.
     #[arg(long)]
     pub target_version: Option<PythonVersion>,
-    /// Set the line-length for length-associated checks and automatic
+    /// Set the line-length for length-associated rules and automatic
     /// formatting.
     #[arg(long)]
     pub line_length: Option<usize>,
@@ -176,7 +180,7 @@ pub struct Cli {
         conflicts_with = "stdin_filename",
         conflicts_with = "watch",
     )]
-    pub explain: Option<CheckCode>,
+    pub explain: Option<RuleCode>,
     /// Generate shell completion
     #[arg(
         long,
@@ -209,7 +213,7 @@ pub struct Cli {
         conflicts_with = "watch",
     )]
     pub show_files: bool,
-    /// See the settings Ruff will use to check a given Python file.
+    /// See the settings Ruff will use to lint a given Python file.
     #[arg(
         long,
         // Fake subcommands.
@@ -240,6 +244,7 @@ impl Cli {
                 explain: self.explain,
                 files: self.files,
                 generate_shell_completion: self.generate_shell_completion,
+                isolated: self.isolated,
                 no_cache: self.no_cache,
                 quiet: self.quiet,
                 show_files: self.show_files,
@@ -298,9 +303,10 @@ pub struct Arguments {
     pub config: Option<PathBuf>,
     pub diff: bool,
     pub exit_zero: bool,
-    pub explain: Option<CheckCode>,
+    pub explain: Option<RuleCode>,
     pub files: Vec<PathBuf>,
     pub generate_shell_completion: Option<clap_complete_command::Shell>,
+    pub isolated: bool,
     pub no_cache: bool,
     pub quiet: bool,
     pub show_files: bool,
@@ -318,18 +324,18 @@ pub struct Overrides {
     pub dummy_variable_rgx: Option<Regex>,
     pub exclude: Option<Vec<FilePattern>>,
     pub extend_exclude: Option<Vec<FilePattern>>,
-    pub extend_ignore: Option<Vec<CheckCodePrefix>>,
-    pub extend_select: Option<Vec<CheckCodePrefix>>,
-    pub fixable: Option<Vec<CheckCodePrefix>>,
-    pub ignore: Option<Vec<CheckCodePrefix>>,
+    pub extend_ignore: Option<Vec<RuleCodePrefix>>,
+    pub extend_select: Option<Vec<RuleCodePrefix>>,
+    pub fixable: Option<Vec<RuleCodePrefix>>,
+    pub ignore: Option<Vec<RuleCodePrefix>>,
     pub line_length: Option<usize>,
     pub max_complexity: Option<usize>,
     pub per_file_ignores: Option<Vec<PatternPrefixPair>>,
     pub respect_gitignore: Option<bool>,
-    pub select: Option<Vec<CheckCodePrefix>>,
+    pub select: Option<Vec<RuleCodePrefix>>,
     pub show_source: Option<bool>,
     pub target_version: Option<PythonVersion>,
-    pub unfixable: Option<Vec<CheckCodePrefix>>,
+    pub unfixable: Option<Vec<RuleCodePrefix>>,
     // TODO(charlie): Captured in pyproject.toml as a default, but not part of `Settings`.
     pub cache_dir: Option<PathBuf>,
     pub fix: Option<bool>,
@@ -339,6 +345,87 @@ pub struct Overrides {
     pub update_check: Option<bool>,
 }
 
+impl ConfigProcessor for &Overrides {
+    fn process_config(&self, config: &mut crate::settings::configuration::Configuration) {
+        if let Some(cache_dir) = &self.cache_dir {
+            config.cache_dir = Some(cache_dir.clone());
+        }
+        if let Some(dummy_variable_rgx) = &self.dummy_variable_rgx {
+            config.dummy_variable_rgx = Some(dummy_variable_rgx.clone());
+        }
+        if let Some(exclude) = &self.exclude {
+            config.exclude = Some(exclude.clone());
+        }
+        if let Some(extend_exclude) = &self.extend_exclude {
+            config.extend_exclude.extend(extend_exclude.clone());
+        }
+        if let Some(fix) = &self.fix {
+            config.fix = Some(*fix);
+        }
+        if let Some(fix_only) = &self.fix_only {
+            config.fix_only = Some(*fix_only);
+        }
+        if let Some(fixable) = &self.fixable {
+            config.fixable = Some(fixable.clone());
+        }
+        if let Some(format) = &self.format {
+            config.format = Some(*format);
+        }
+        if let Some(force_exclude) = &self.force_exclude {
+            config.force_exclude = Some(*force_exclude);
+        }
+        if let Some(ignore) = &self.ignore {
+            config.ignore = Some(ignore.clone());
+        }
+        if let Some(line_length) = &self.line_length {
+            config.line_length = Some(*line_length);
+        }
+        if let Some(max_complexity) = &self.max_complexity {
+            config.mccabe = Some(mccabe::settings::Options {
+                max_complexity: Some(*max_complexity),
+            });
+        }
+        if let Some(per_file_ignores) = &self.per_file_ignores {
+            config.per_file_ignores = Some(collect_per_file_ignores(per_file_ignores.clone()));
+        }
+        if let Some(respect_gitignore) = &self.respect_gitignore {
+            config.respect_gitignore = Some(*respect_gitignore);
+        }
+        if let Some(select) = &self.select {
+            config.select = Some(select.clone());
+        }
+        if let Some(show_source) = &self.show_source {
+            config.show_source = Some(*show_source);
+        }
+        if let Some(target_version) = &self.target_version {
+            config.target_version = Some(*target_version);
+        }
+        if let Some(unfixable) = &self.unfixable {
+            config.unfixable = Some(unfixable.clone());
+        }
+        if let Some(update_check) = &self.update_check {
+            config.update_check = Some(*update_check);
+        }
+        // Special-case: `extend_ignore` and `extend_select` are parallel arrays, so
+        // push an empty array if only one of the two is provided.
+        match (&self.extend_ignore, &self.extend_select) {
+            (Some(extend_ignore), Some(extend_select)) => {
+                config.extend_ignore.push(extend_ignore.clone());
+                config.extend_select.push(extend_select.clone());
+            }
+            (Some(extend_ignore), None) => {
+                config.extend_ignore.push(extend_ignore.clone());
+                config.extend_select.push(Vec::new());
+            }
+            (None, Some(extend_select)) => {
+                config.extend_ignore.push(Vec::new());
+                config.extend_select.push(extend_select.clone());
+            }
+            (None, None) => {}
+        }
+    }
+}
+
 /// Map the CLI settings to a `LogLevel`.
 pub fn extract_log_level(cli: &Arguments) -> LogLevel {
     if cli.silent {
@@ -354,7 +441,7 @@ pub fn extract_log_level(cli: &Arguments) -> LogLevel {
 
 /// Convert a list of `PatternPrefixPair` structs to `PerFileIgnore`.
 pub fn collect_per_file_ignores(pairs: Vec<PatternPrefixPair>) -> Vec<PerFileIgnore> {
-    let mut per_file_ignores: FxHashMap<String, Vec<CheckCodePrefix>> = FxHashMap::default();
+    let mut per_file_ignores: FxHashMap<String, Vec<RuleCodePrefix>> = FxHashMap::default();
     for pair in pairs {
         per_file_ignores
             .entry(pair.pattern)

src/commands.rs

@@ -15,18 +15,18 @@ use rustpython_ast::Location;
 use serde::Serialize;
 use walkdir::WalkDir;
 
-use crate::autofix::fixer;
-use crate::cache::DEFAULT_CACHE_DIR_NAME;
+use crate::cache::CACHE_DIR_NAME;
 use crate::cli::Overrides;
+use crate::diagnostics::{lint_path, lint_stdin, Diagnostics};
 use crate::iterators::par_iter;
-use crate::linter::{add_noqa_to_path, lint_path, lint_stdin, Diagnostics};
+use crate::linter::add_noqa_to_path;
 use crate::logging::LogLevel;
 use crate::message::Message;
-use crate::registry::CheckCode;
+use crate::registry::RuleCode;
 use crate::resolver::{FileDiscovery, PyprojectDiscovery};
 use crate::settings::flags;
 use crate::settings::types::SerializationFormat;
-use crate::{cache, fs, one_time_warning, packages, resolver, violations};
+use crate::{cache, fix, fs, packaging, resolver, violations, warn_user_once};
 
 /// Run the linter over a collection of files.
 pub fn run(
@@ -35,7 +35,7 @@ pub fn run(
     file_strategy: &FileDiscovery,
     overrides: &Overrides,
     cache: flags::Cache,
-    autofix: fixer::Mode,
+    autofix: fix::FixMode,
 ) -> Result<Diagnostics> {
     // Collect all the Python files to check.
     let start = Instant::now();
@@ -45,12 +45,7 @@ pub fn run(
     debug!("Identified files to lint in: {:?}", duration);
 
     if paths.is_empty() {
-        one_time_warning!(
-            "{}{} {}",
-            "warning".yellow().bold(),
-            ":".bold(),
-            "No Python files found under the given path(s)".bold()
-        );
+        warn_user_once!("No Python files found under the given path(s)");
         return Ok(Diagnostics::default());
     }
 
@@ -82,7 +77,7 @@ pub fn run(
     };
 
     // Discover the package root for each Python file.
-    let package_roots = packages::detect_package_roots(
+    let package_roots = packaging::detect_package_roots(
         &paths
             .iter()
             .flatten()
@@ -117,7 +112,7 @@ pub fn run(
             .unwrap_or_else(|(path, message)| {
                 if let Some(path) = &path {
                     let settings = resolver.resolve(path, pyproject_strategy);
-                    if settings.enabled.contains(&CheckCode::E902) {
+                    if settings.enabled.contains(&RuleCode::E902) {
                         Diagnostics::new(vec![Message {
                             kind: violations::IOError(message).into(),
                             location: Location::default(),
@@ -161,7 +156,7 @@ pub fn run_stdin(
     pyproject_strategy: &PyprojectDiscovery,
     file_strategy: &FileDiscovery,
     overrides: &Overrides,
-    autofix: fixer::Mode,
+    autofix: fix::FixMode,
 ) -> Result<Diagnostics> {
     if let Some(filename) = filename {
         if !resolver::python_file_at_path(filename, pyproject_strategy, file_strategy, overrides)? {
@@ -174,7 +169,7 @@ pub fn run_stdin(
     };
     let package_root = filename
         .and_then(Path::parent)
-        .and_then(packages::detect_package_root);
+        .and_then(packaging::detect_package_root);
     let stdin = read_from_stdin()?;
     let mut diagnostics = lint_stdin(filename, package_root, &stdin, settings, autofix)?;
     diagnostics.messages.sort_unstable();
@@ -196,12 +191,7 @@ pub fn add_noqa(
     debug!("Identified files to lint in: {:?}", duration);
 
     if paths.is_empty() {
-        one_time_warning!(
-            "{}{} {}",
-            "warning".yellow().bold(),
-            ":".bold(),
-            "No Python files found under the given path(s)".bold()
-        );
+        warn_user_once!("No Python files found under the given path(s)");
         return Ok(0);
     }
 
@@ -271,12 +261,7 @@ pub fn show_files(
         resolver::python_files_in_path(files, pyproject_strategy, file_strategy, overrides)?;
 
     if paths.is_empty() {
-        one_time_warning!(
-            "{}{} {}",
-            "warning".yellow().bold(),
-            ":".bold(),
-            "No Python files found under the given path(s)".bold()
-        );
+        warn_user_once!("No Python files found under the given path(s)");
         return Ok(());
     }
 
@@ -298,18 +283,18 @@ pub fn show_files(
 #[derive(Serialize)]
 struct Explanation<'a> {
     code: &'a str,
-    category: &'a str,
+    origin: &'a str,
     summary: &'a str,
 }
 
-/// Explain a `CheckCode` to the user.
-pub fn explain(code: &CheckCode, format: &SerializationFormat) -> Result<()> {
+/// Explain a `RuleCode` to the user.
+pub fn explain(code: &RuleCode, format: &SerializationFormat) -> Result<()> {
     match format {
         SerializationFormat::Text | SerializationFormat::Grouped => {
             println!(
                 "{} ({}): {}",
                 code.as_ref(),
-                code.category().title(),
+                code.origin().title(),
                 code.kind().summary()
             );
         }
@@ -318,7 +303,7 @@ pub fn explain(code: &CheckCode, format: &SerializationFormat) -> Result<()> {
                 "{}",
                 serde_json::to_string_pretty(&Explanation {
                     code: code.as_ref(),
-                    category: code.category().title(),
+                    origin: code.origin().title(),
                     summary: &code.kind().summary(),
                 })?
             );
@@ -340,10 +325,10 @@ pub fn explain(code: &CheckCode, format: &SerializationFormat) -> Result<()> {
 pub fn clean(level: &LogLevel) -> Result<()> {
     for entry in WalkDir::new(&*path_dedot::CWD)
         .into_iter()
-        .filter_map(std::result::Result::ok)
+        .filter_map(Result::ok)
         .filter(|entry| entry.file_type().is_dir())
     {
-        let cache = entry.path().join(DEFAULT_CACHE_DIR_NAME);
+        let cache = entry.path().join(CACHE_DIR_NAME);
         if cache.is_dir() {
             if level >= &LogLevel::Default {
                 eprintln!("Removing cache at: {}", fs::relativize_path(&cache).bold());

src/cst/matchers.rs

@@ -1,5 +1,7 @@
 use anyhow::{bail, Result};
-use libcst_native::{Expr, Import, ImportFrom, Module, SmallStatement, Statement};
+use libcst_native::{
+    Call, Expr, Expression, Import, ImportFrom, Module, SmallStatement, Statement,
+};
 
 pub fn match_module(module_text: &str) -> Result<Module> {
     match libcst_native::parse_module(module_text, None) {
@@ -8,6 +10,13 @@ pub fn match_module(module_text: &str) -> Result<Module> {
     }
 }
 
+pub fn match_expression(expression_text: &str) -> Result<Expression> {
+    match libcst_native::parse_expression(expression_text) {
+        Ok(expression) => Ok(expression),
+        Err(_) => bail!("Failed to extract CST from source"),
+    }
+}
+
 pub fn match_expr<'a, 'b>(module: &'a mut Module<'b>) -> Result<&'a mut Expr<'b>> {
     if let Some(Statement::Simple(expr)) = module.body.first_mut() {
         if let Some(SmallStatement::Expr(expr)) = expr.body.first_mut() {
@@ -43,3 +52,11 @@ pub fn match_import_from<'a, 'b>(module: &'a mut Module<'b>) -> Result<&'a mut I
         bail!("Expected Statement::Simple")
     }
 }
+
+pub fn match_call<'a, 'b>(expression: &'a mut Expression<'b>) -> Result<&'a mut Call<'b>> {
+    if let Expression::Call(call) = expression {
+        Ok(call)
+    } else {
+        bail!("Expected SmallStatement::Expr")
+    }
+}

src/diagnostics.rs

@@ -0,0 +1,154 @@
+#![cfg_attr(target_family = "wasm", allow(dead_code))]
+use std::fs::write;
+use std::io;
+use std::io::Write;
+use std::ops::AddAssign;
+use std::path::Path;
+
+use anyhow::Result;
+use log::debug;
+use similar::TextDiff;
+
+use crate::linter::{lint_fix, lint_only};
+use crate::message::Message;
+use crate::settings::{flags, Settings};
+use crate::{cache, fix, fs};
+
+#[derive(Debug, Default)]
+pub struct Diagnostics {
+    pub messages: Vec<Message>,
+    pub fixed: usize,
+}
+
+impl Diagnostics {
+    pub fn new(messages: Vec<Message>) -> Self {
+        Self { messages, fixed: 0 }
+    }
+}
+
+impl AddAssign for Diagnostics {
+    fn add_assign(&mut self, other: Self) {
+        self.messages.extend(other.messages);
+        self.fixed += other.fixed;
+    }
+}
+
+/// Lint the source code at the given `Path`.
+pub fn lint_path(
+    path: &Path,
+    package: Option<&Path>,
+    settings: &Settings,
+    cache: flags::Cache,
+    autofix: fix::FixMode,
+) -> Result<Diagnostics> {
+    // Validate the `Settings` and return any errors.
+    settings.validate()?;
+
+    // Check the cache.
+    // TODO(charlie): `fixer::Mode::Apply` and `fixer::Mode::Diff` both have
+    // side-effects that aren't captured in the cache. (In practice, it's fine
+    // to cache `fixer::Mode::Apply`, since a file either has no fixes, or we'll
+    // write the fixes to disk, thus invalidating the cache. But it's a bit hard
+    // to reason about. We need to come up with a better solution here.)
+    let metadata = if matches!(cache, flags::Cache::Enabled)
+        && matches!(autofix, fix::FixMode::None | fix::FixMode::Generate)
+    {
+        let metadata = path.metadata()?;
+        if let Some(messages) = cache::get(path, &metadata, settings, autofix.into()) {
+            debug!("Cache hit for: {}", path.to_string_lossy());
+            return Ok(Diagnostics::new(messages));
+        }
+        Some(metadata)
+    } else {
+        None
+    };
+
+    // Read the file from disk.
+    let contents = fs::read_file(path)?;
+
+    // Lint the file.
+    let (messages, fixed) = if matches!(autofix, fix::FixMode::Apply | fix::FixMode::Diff) {
+        let (transformed, fixed, messages) = lint_fix(&contents, path, package, settings)?;
+        if fixed > 0 {
+            if matches!(autofix, fix::FixMode::Apply) {
+                write(path, transformed)?;
+            } else if matches!(autofix, fix::FixMode::Diff) {
+                let mut stdout = io::stdout().lock();
+                TextDiff::from_lines(&contents, &transformed)
+                    .unified_diff()
+                    .header(&fs::relativize_path(path), &fs::relativize_path(path))
+                    .to_writer(&mut stdout)?;
+                stdout.write_all(b"\n")?;
+                stdout.flush()?;
+            }
+        }
+        (messages, fixed)
+    } else {
+        let messages = lint_only(&contents, path, package, settings, autofix.into())?;
+        let fixed = 0;
+        (messages, fixed)
+    };
+
+    // Re-populate the cache.
+    if let Some(metadata) = metadata {
+        cache::set(path, &metadata, settings, autofix.into(), &messages);
+    }
+
+    Ok(Diagnostics { messages, fixed })
+}
+
+/// Generate `Diagnostic`s from source code content derived from
+/// stdin.
+pub fn lint_stdin(
+    path: Option<&Path>,
+    package: Option<&Path>,
+    contents: &str,
+    settings: &Settings,
+    autofix: fix::FixMode,
+) -> Result<Diagnostics> {
+    // Validate the `Settings` and return any errors.
+    settings.validate()?;
+
+    // Lint the inputs.
+    let (messages, fixed) = if matches!(autofix, fix::FixMode::Apply | fix::FixMode::Diff) {
+        let (transformed, fixed, messages) = lint_fix(
+            contents,
+            path.unwrap_or_else(|| Path::new("-")),
+            package,
+            settings,
+        )?;
+
+        if matches!(autofix, fix::FixMode::Apply) {
+            // Write the contents to stdout, regardless of whether any errors were fixed.
+            io::stdout().write_all(transformed.as_bytes())?;
+        } else if matches!(autofix, fix::FixMode::Diff) {
+            // But only write a diff if it's non-empty.
+            if fixed > 0 {
+                let text_diff = TextDiff::from_lines(contents, &transformed);
+                let mut unified_diff = text_diff.unified_diff();
+                if let Some(path) = path {
+                    unified_diff.header(&fs::relativize_path(path), &fs::relativize_path(path));
+                }
+
+                let mut stdout = io::stdout().lock();
+                unified_diff.to_writer(&mut stdout)?;
+                stdout.write_all(b"\n")?;
+                stdout.flush()?;
+            }
+        }
+
+        (messages, fixed)
+    } else {
+        let messages = lint_only(
+            contents,
+            path.unwrap_or_else(|| Path::new("-")),
+            package,
+            settings,
+            autofix.into(),
+        )?;
+        let fixed = 0;
+        (messages, fixed)
+    };
+
+    Ok(Diagnostics { messages, fixed })
+}

src/directives.rs

@@ -6,7 +6,7 @@ use rustpython_ast::Location;
 use rustpython_parser::lexer::{LexResult, Tok};
 
 use crate::registry::LintSource;
-use crate::Settings;
+use crate::settings::Settings;
 
 bitflags! {
     pub struct Flags: u32 {
@@ -20,7 +20,7 @@ impl Flags {
         if settings
             .enabled
             .iter()
-            .any(|check_code| matches!(check_code.lint_source(), LintSource::Imports))
+            .any(|rule_code| matches!(rule_code.lint_source(), LintSource::Imports))
         {
             Flags::NOQA | Flags::ISORT
         } else {
@@ -33,6 +33,7 @@ impl Flags {
 pub struct IsortDirectives {
     pub exclusions: IntSet<usize>,
     pub splits: Vec<usize>,
+    pub skip_file: bool,
 }
 
 pub struct Directives {
@@ -89,26 +90,26 @@ pub fn extract_noqa_line_for(lxr: &[LexResult]) -> IntMap<usize, usize> {
 pub fn extract_isort_directives(lxr: &[LexResult]) -> IsortDirectives {
     let mut exclusions: IntSet<usize> = IntSet::default();
     let mut splits: Vec<usize> = Vec::default();
-    let mut skip_file: bool = false;
     let mut off: Option<Location> = None;
     let mut last: Option<Location> = None;
     for &(start, ref tok, end) in lxr.iter().flatten() {
         last = Some(end);
 
-        // No need to keep processing, but we do need to determine the last token.
-        if skip_file {
-            continue;
-        }
-
         let Tok::Comment(comment_text) = tok else {
             continue;
         };
 
+        // `isort` allows for `# isort: skip` and `# isort: skip_file` to include or
+        // omit a space after the colon. The remaining action comments are
+        // required to include the space, and must appear on their own lines.
         let comment_text = comment_text.trim_end();
         if comment_text == "# isort: split" {
             splits.push(start.row());
-        } else if comment_text == "# isort: skip_file" {
-            skip_file = true;
+        } else if comment_text == "# isort: skip_file" || comment_text == "# isort:skip_file" {
+            return IsortDirectives {
+                skip_file: true,
+                ..IsortDirectives::default()
+            };
         } else if off.is_some() {
             if comment_text == "# isort: on" {
                 if let Some(start) = off {
@@ -119,7 +120,7 @@ pub fn extract_isort_directives(lxr: &[LexResult]) -> IsortDirectives {
                 off = None;
             }
         } else {
-            if comment_text.contains("isort: skip") {
+            if comment_text.contains("isort: skip") || comment_text.contains("isort:skip") {
                 exclusions.insert(start.row());
             } else if comment_text == "# isort: off" {
                 off = Some(start);
@@ -127,14 +128,7 @@ pub fn extract_isort_directives(lxr: &[LexResult]) -> IsortDirectives {
         }
     }
 
-    if skip_file {
-        // Enforce `isort: skip_file`.
-        if let Some(end) = last {
-            for row in 1..=end.row() {
-                exclusions.insert(row);
-            }
-        }
-    } else if let Some(start) = off {
+    if let Some(start) = off {
         // Enforce unterminated `isort: off`.
         if let Some(end) = last {
             for row in start.row() + 1..=end.row() {
@@ -142,7 +136,11 @@ pub fn extract_isort_directives(lxr: &[LexResult]) -> IsortDirectives {
             }
         }
     }
-    IsortDirectives { exclusions, splits }
+    IsortDirectives {
+        exclusions,
+        splits,
+        ..IsortDirectives::default()
+    }
 }
 
 #[cfg(test)]
@@ -280,10 +278,7 @@ x = 1
 y = 2
 z = x + 1";
         let lxr: Vec<LexResult> = lexer::make_tokenizer(contents).collect();
-        assert_eq!(
-            extract_isort_directives(&lxr).exclusions,
-            IntSet::from_iter([1, 2, 3, 4])
-        );
+        assert_eq!(extract_isort_directives(&lxr).exclusions, IntSet::default());
 
         let contents = "# isort: off
 x = 1
@@ -292,10 +287,7 @@ y = 2
 # isort: skip_file
 z = x + 1";
         let lxr: Vec<LexResult> = lexer::make_tokenizer(contents).collect();
-        assert_eq!(
-            extract_isort_directives(&lxr).exclusions,
-            IntSet::from_iter([1, 2, 3, 4, 5, 6])
-        );
+        assert_eq!(extract_isort_directives(&lxr).exclusions, IntSet::default());
     }
 
     #[test]

src/doc_lines.rs

@@ -0,0 +1,58 @@
+//! Doc line extraction. In this context, a doc line is a line consisting of a
+//! standalone comment or a constant string statement.
+
+use rustpython_ast::{Constant, ExprKind, Stmt, StmtKind, Suite};
+use rustpython_parser::lexer::{LexResult, Tok};
+
+use crate::ast::visitor;
+use crate::ast::visitor::Visitor;
+
+/// Extract doc lines (standalone comments) from a token sequence.
+pub fn doc_lines_from_tokens(lxr: &[LexResult]) -> Vec<usize> {
+    let mut doc_lines: Vec<usize> = Vec::default();
+    let mut prev: Option<usize> = None;
+    for (start, tok, end) in lxr.iter().flatten() {
+        if matches!(tok, Tok::Indent | Tok::Dedent | Tok::Newline) {
+            continue;
+        }
+        if matches!(tok, Tok::Comment(..)) {
+            if let Some(prev) = prev {
+                if start.row() > prev {
+                    doc_lines.push(start.row());
+                }
+            } else {
+                doc_lines.push(start.row());
+            }
+        }
+        prev = Some(end.row());
+    }
+    doc_lines
+}
+
+#[derive(Default)]
+struct StringLinesVisitor {
+    string_lines: Vec<usize>,
+}
+
+impl Visitor<'_> for StringLinesVisitor {
+    fn visit_stmt(&mut self, stmt: &Stmt) {
+        if let StmtKind::Expr { value } = &stmt.node {
+            if let ExprKind::Constant {
+                value: Constant::Str(..),
+                ..
+            } = &value.node
+            {
+                self.string_lines
+                    .extend(value.location.row()..=value.end_location.unwrap().row());
+            }
+        }
+        visitor::walk_stmt(self, stmt);
+    }
+}
+
+/// Extract doc lines (standalone strings) from an AST.
+pub fn doc_lines_from_ast(python_ast: &Suite) -> Vec<usize> {
+    let mut visitor = StringLinesVisitor::default();
+    visitor.visit_body(python_ast);
+    visitor.string_lines
+}

src/eradicate/mod.rs

@@ -1,5 +1,5 @@
-pub mod checks;
-pub mod detection;
+pub(crate) mod detection;
+pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
@@ -10,19 +10,19 @@ mod tests {
     use test_case::test_case;
 
     use crate::linter::test_path;
-    use crate::registry::CheckCode;
+    use crate::registry::RuleCode;
     use crate::settings;
 
-    #[test_case(CheckCode::ERA001, Path::new("ERA001.py"); "ERA001")]
-    fn checks(check_code: CheckCode, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", check_code.as_ref(), path.to_string_lossy());
-        let checks = test_path(
+    #[test_case(RuleCode::ERA001, Path::new("ERA001.py"); "ERA001")]
+    fn rules(rule_code: RuleCode, path: &Path) -> Result<()> {
+        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/eradicate")
                 .join(path)
                 .as_path(),
-            &settings::Settings::for_rule(check_code),
+            &settings::Settings::for_rule(rule_code),
         )?;
-        insta::assert_yaml_snapshot!(snapshot, checks);
+        insta::assert_yaml_snapshot!(snapshot, diagnostics);
         Ok(())
     }
 }

src/eradicate/rules.rs

@@ -1,11 +1,12 @@
 use rustpython_ast::Location;
 
 use crate::ast::types::Range;
-use crate::autofix::Fix;
 use crate::eradicate::detection::comment_contains_code;
-use crate::registry::CheckCode;
-use crate::settings::flags;
-use crate::{violations, Check, Settings, SourceCodeLocator};
+use crate::fix::Fix;
+use crate::registry::{Diagnostic, RuleCode};
+use crate::settings::{flags, Settings};
+use crate::source_code::Locator;
+use crate::violations;
 
 fn is_standalone_comment(line: &str) -> bool {
     for char in line.chars() {
@@ -20,25 +21,25 @@ fn is_standalone_comment(line: &str) -> bool {
 
 /// ERA001
 pub fn commented_out_code(
-    locator: &SourceCodeLocator,
+    locator: &Locator,
     start: Location,
     end: Location,
     settings: &Settings,
     autofix: flags::Autofix,
-) -> Option<Check> {
+) -> Option<Diagnostic> {
     let location = Location::new(start.row(), 0);
     let end_location = Location::new(end.row() + 1, 0);
     let line = locator.slice_source_code_range(&Range::new(location, end_location));
 
     // Verify that the comment is on its own line, and that it contains code.
     if is_standalone_comment(&line) && comment_contains_code(&line, &settings.task_tags[..]) {
-        let mut check = Check::new(violations::CommentedOutCode, Range::new(start, end));
+        let mut diagnostic = Diagnostic::new(violations::CommentedOutCode, Range::new(start, end));
         if matches!(autofix, flags::Autofix::Enabled)
-            && settings.fixable.contains(&CheckCode::ERA001)
+            && settings.fixable.contains(&RuleCode::ERA001)
         {
-            check.amend(Fix::deletion(location, end_location));
+            diagnostic.amend(Fix::deletion(location, end_location));
         }
-        Some(check)
+        Some(diagnostic)
     } else {
         None
     }

src/fix.rs

@@ -0,0 +1,53 @@
+use rustpython_ast::Location;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Copy, Clone, Hash)]
+pub enum FixMode {
+    Generate,
+    Apply,
+    Diff,
+    None,
+}
+
+impl From<bool> for FixMode {
+    fn from(value: bool) -> Self {
+        if value {
+            FixMode::Apply
+        } else {
+            FixMode::None
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Fix {
+    pub content: String,
+    pub location: Location,
+    pub end_location: Location,
+}
+
+impl Fix {
+    pub fn deletion(start: Location, end: Location) -> Self {
+        Self {
+            content: String::new(),
+            location: start,
+            end_location: end,
+        }
+    }
+
+    pub fn replacement(content: String, start: Location, end: Location) -> Self {
+        Self {
+            content,
+            location: start,
+            end_location: end,
+        }
+    }
+
+    pub fn insertion(content: String, at: Location) -> Self {
+        Self {
+            content,
+            location: at,
+            end_location: at,
+        }
+    }
+}

src/flake8_2020/mod.rs

@@ -1,4 +1,4 @@
-pub mod plugins;
+pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
@@ -9,28 +9,28 @@ mod tests {
     use test_case::test_case;
 
     use crate::linter::test_path;
-    use crate::registry::CheckCode;
+    use crate::registry::RuleCode;
     use crate::settings;
 
-    #[test_case(CheckCode::YTT101, Path::new("YTT101.py"); "YTT101")]
-    #[test_case(CheckCode::YTT102, Path::new("YTT102.py"); "YTT102")]
-    #[test_case(CheckCode::YTT103, Path::new("YTT103.py"); "YTT103")]
-    #[test_case(CheckCode::YTT201, Path::new("YTT201.py"); "YTT201")]
-    #[test_case(CheckCode::YTT202, Path::new("YTT202.py"); "YTT202")]
-    #[test_case(CheckCode::YTT203, Path::new("YTT203.py"); "YTT203")]
-    #[test_case(CheckCode::YTT204, Path::new("YTT204.py"); "YTT204")]
-    #[test_case(CheckCode::YTT301, Path::new("YTT301.py"); "YTT301")]
-    #[test_case(CheckCode::YTT302, Path::new("YTT302.py"); "YTT302")]
-    #[test_case(CheckCode::YTT303, Path::new("YTT303.py"); "YTT303")]
-    fn checks(check_code: CheckCode, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", check_code.as_ref(), path.to_string_lossy());
-        let checks = test_path(
+    #[test_case(RuleCode::YTT101, Path::new("YTT101.py"); "YTT101")]
+    #[test_case(RuleCode::YTT102, Path::new("YTT102.py"); "YTT102")]
+    #[test_case(RuleCode::YTT103, Path::new("YTT103.py"); "YTT103")]
+    #[test_case(RuleCode::YTT201, Path::new("YTT201.py"); "YTT201")]
+    #[test_case(RuleCode::YTT202, Path::new("YTT202.py"); "YTT202")]
+    #[test_case(RuleCode::YTT203, Path::new("YTT203.py"); "YTT203")]
+    #[test_case(RuleCode::YTT204, Path::new("YTT204.py"); "YTT204")]
+    #[test_case(RuleCode::YTT301, Path::new("YTT301.py"); "YTT301")]
+    #[test_case(RuleCode::YTT302, Path::new("YTT302.py"); "YTT302")]
+    #[test_case(RuleCode::YTT303, Path::new("YTT303.py"); "YTT303")]
+    fn rules(rule_code: RuleCode, path: &Path) -> Result<()> {
+        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_2020")
                 .join(path)
                 .as_path(),
-            &settings::Settings::for_rule(check_code),
+            &settings::Settings::for_rule(rule_code),
         )?;
-        insta::assert_yaml_snapshot!(snapshot, checks);
+        insta::assert_yaml_snapshot!(snapshot, diagnostics);
         Ok(())
     }
 }

src/flake8_2020/rules.rs

@@ -4,7 +4,7 @@ use rustpython_ast::{Cmpop, Constant, Expr, ExprKind, Located};
 use crate::ast::helpers::match_module_member;
 use crate::ast::types::Range;
 use crate::checkers::ast::Checker;
-use crate::registry::{Check, CheckCode};
+use crate::registry::{Diagnostic, RuleCode};
 use crate::violations;
 
 fn is_sys(checker: &Checker, expr: &Expr, target: &str) -> bool {
@@ -32,17 +32,16 @@ pub fn subscript(checker: &mut Checker, value: &Expr, slice: &Expr) {
                     ..
                 } = &upper.node
                 {
-                    if *i == BigInt::from(1)
-                        && checker.settings.enabled.contains(&CheckCode::YTT303)
+                    if *i == BigInt::from(1) && checker.settings.enabled.contains(&RuleCode::YTT303)
                     {
-                        checker.checks.push(Check::new(
+                        checker.diagnostics.push(Diagnostic::new(
                             violations::SysVersionSlice1Referenced,
                             Range::from_located(value),
                         ));
                     } else if *i == BigInt::from(3)
-                        && checker.settings.enabled.contains(&CheckCode::YTT101)
+                        && checker.settings.enabled.contains(&RuleCode::YTT101)
                     {
-                        checker.checks.push(Check::new(
+                        checker.diagnostics.push(Diagnostic::new(
                             violations::SysVersionSlice3Referenced,
                             Range::from_located(value),
                         ));
@@ -54,15 +53,15 @@ pub fn subscript(checker: &mut Checker, value: &Expr, slice: &Expr) {
                 value: Constant::Int(i),
                 ..
             } => {
-                if *i == BigInt::from(2) && checker.settings.enabled.contains(&CheckCode::YTT102) {
-                    checker.checks.push(Check::new(
+                if *i == BigInt::from(2) && checker.settings.enabled.contains(&RuleCode::YTT102) {
+                    checker.diagnostics.push(Diagnostic::new(
                         violations::SysVersion2Referenced,
                         Range::from_located(value),
                     ));
                 } else if *i == BigInt::from(0)
-                    && checker.settings.enabled.contains(&CheckCode::YTT301)
+                    && checker.settings.enabled.contains(&RuleCode::YTT301)
                 {
-                    checker.checks.push(Check::new(
+                    checker.diagnostics.push(Diagnostic::new(
                         violations::SysVersion0Referenced,
                         Range::from_located(value),
                     ));
@@ -97,9 +96,9 @@ pub fn compare(checker: &mut Checker, left: &Expr, ops: &[Cmpop], comparators: &
                     ) = (ops, comparators)
                     {
                         if *n == BigInt::from(3)
-                            && checker.settings.enabled.contains(&CheckCode::YTT201)
+                            && checker.settings.enabled.contains(&RuleCode::YTT201)
                         {
-                            checker.checks.push(Check::new(
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::SysVersionInfo0Eq3Referenced,
                                 Range::from_located(left),
                             ));
@@ -118,8 +117,8 @@ pub fn compare(checker: &mut Checker, left: &Expr, ops: &[Cmpop], comparators: &
                         }],
                     ) = (ops, comparators)
                     {
-                        if checker.settings.enabled.contains(&CheckCode::YTT203) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::YTT203) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::SysVersionInfo1CmpInt,
                                 Range::from_located(left),
                             ));
@@ -144,8 +143,8 @@ pub fn compare(checker: &mut Checker, left: &Expr, ops: &[Cmpop], comparators: &
                 }],
             ) = (ops, comparators)
             {
-                if checker.settings.enabled.contains(&CheckCode::YTT204) {
-                    checker.checks.push(Check::new(
+                if checker.settings.enabled.contains(&RuleCode::YTT204) {
+                    checker.diagnostics.push(Diagnostic::new(
                         violations::SysVersionInfoMinorCmpInt,
                         Range::from_located(left),
                     ));
@@ -170,14 +169,14 @@ pub fn compare(checker: &mut Checker, left: &Expr, ops: &[Cmpop], comparators: &
         ) = (ops, comparators)
         {
             if s.len() == 1 {
-                if checker.settings.enabled.contains(&CheckCode::YTT302) {
-                    checker.checks.push(Check::new(
+                if checker.settings.enabled.contains(&RuleCode::YTT302) {
+                    checker.diagnostics.push(Diagnostic::new(
                         violations::SysVersionCmpStr10,
                         Range::from_located(left),
                     ));
                 }
-            } else if checker.settings.enabled.contains(&CheckCode::YTT103) {
-                checker.checks.push(Check::new(
+            } else if checker.settings.enabled.contains(&RuleCode::YTT103) {
+                checker.diagnostics.push(Diagnostic::new(
                     violations::SysVersionCmpStr3,
                     Range::from_located(left),
                 ));
@@ -195,7 +194,7 @@ pub fn name_or_attribute(checker: &mut Checker, expr: &Expr) {
         &checker.from_imports,
         &checker.import_aliases,
     ) {
-        checker.checks.push(Check::new(
+        checker.diagnostics.push(Diagnostic::new(
             violations::SixPY3Referenced,
             Range::from_located(expr),
         ));

src/flake8_annotations/fixes.rs

@@ -4,11 +4,11 @@ use rustpython_parser::lexer;
 use rustpython_parser::lexer::Tok;
 
 use crate::ast::types::Range;
-use crate::autofix::Fix;
-use crate::source_code_locator::SourceCodeLocator;
+use crate::fix::Fix;
+use crate::source_code::Locator;
 
 /// ANN204
-pub fn add_return_none_annotation(locator: &SourceCodeLocator, stmt: &Stmt) -> Result<Fix> {
+pub fn add_return_none_annotation(locator: &Locator, stmt: &Stmt) -> Result<Fix> {
     let range = Range::from_located(stmt);
     let contents = locator.slice_source_code_range(&range);
 

src/flake8_annotations/mod.rs

@@ -1,6 +1,6 @@
 mod fixes;
-pub mod helpers;
-pub mod plugins;
+pub(crate) mod helpers;
+pub(crate) mod rules;
 pub mod settings;
 
 #[cfg(test)]
@@ -9,37 +9,38 @@ mod tests {
 
     use anyhow::Result;
 
+    use crate::flake8_annotations;
     use crate::linter::test_path;
-    use crate::registry::CheckCode;
-    use crate::{flake8_annotations, Settings};
+    use crate::registry::RuleCode;
+    use crate::settings::Settings;
 
     #[test]
     fn defaults() -> Result<()> {
-        let checks = test_path(
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_annotations/annotation_presence.py"),
             &Settings {
                 ..Settings::for_rules(vec![
-                    CheckCode::ANN001,
-                    CheckCode::ANN002,
-                    CheckCode::ANN003,
-                    CheckCode::ANN101,
-                    CheckCode::ANN102,
-                    CheckCode::ANN201,
-                    CheckCode::ANN202,
-                    CheckCode::ANN204,
-                    CheckCode::ANN205,
-                    CheckCode::ANN206,
-                    CheckCode::ANN401,
+                    RuleCode::ANN001,
+                    RuleCode::ANN002,
+                    RuleCode::ANN003,
+                    RuleCode::ANN101,
+                    RuleCode::ANN102,
+                    RuleCode::ANN201,
+                    RuleCode::ANN202,
+                    RuleCode::ANN204,
+                    RuleCode::ANN205,
+                    RuleCode::ANN206,
+                    RuleCode::ANN401,
                 ])
             },
         )?;
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(diagnostics);
         Ok(())
     }
 
     #[test]
     fn suppress_dummy_args() -> Result<()> {
-        let checks = test_path(
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_annotations/suppress_dummy_args.py"),
             &Settings {
                 flake8_annotations: flake8_annotations::settings::Settings {
@@ -49,21 +50,21 @@ mod tests {
                     allow_star_arg_any: false,
                 },
                 ..Settings::for_rules(vec![
-                    CheckCode::ANN001,
-                    CheckCode::ANN002,
-                    CheckCode::ANN003,
-                    CheckCode::ANN101,
-                    CheckCode::ANN102,
+                    RuleCode::ANN001,
+                    RuleCode::ANN002,
+                    RuleCode::ANN003,
+                    RuleCode::ANN101,
+                    RuleCode::ANN102,
                 ])
             },
         )?;
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(diagnostics);
         Ok(())
     }
 
     #[test]
     fn mypy_init_return() -> Result<()> {
-        let checks = test_path(
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_annotations/mypy_init_return.py"),
             &Settings {
                 flake8_annotations: flake8_annotations::settings::Settings {
@@ -73,21 +74,21 @@ mod tests {
                     allow_star_arg_any: false,
                 },
                 ..Settings::for_rules(vec![
-                    CheckCode::ANN201,
-                    CheckCode::ANN202,
-                    CheckCode::ANN204,
-                    CheckCode::ANN205,
-                    CheckCode::ANN206,
+                    RuleCode::ANN201,
+                    RuleCode::ANN202,
+                    RuleCode::ANN204,
+                    RuleCode::ANN205,
+                    RuleCode::ANN206,
                 ])
             },
         )?;
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(diagnostics);
         Ok(())
     }
 
     #[test]
     fn suppress_none_returning() -> Result<()> {
-        let checks = test_path(
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_annotations/suppress_none_returning.py"),
             &Settings {
                 flake8_annotations: flake8_annotations::settings::Settings {
@@ -97,21 +98,21 @@ mod tests {
                     allow_star_arg_any: false,
                 },
                 ..Settings::for_rules(vec![
-                    CheckCode::ANN201,
-                    CheckCode::ANN202,
-                    CheckCode::ANN204,
-                    CheckCode::ANN205,
-                    CheckCode::ANN206,
+                    RuleCode::ANN201,
+                    RuleCode::ANN202,
+                    RuleCode::ANN204,
+                    RuleCode::ANN205,
+                    RuleCode::ANN206,
                 ])
             },
         )?;
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(diagnostics);
         Ok(())
     }
 
     #[test]
     fn allow_star_arg_any() -> Result<()> {
-        let checks = test_path(
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_annotations/allow_star_arg_any.py"),
             &Settings {
                 flake8_annotations: flake8_annotations::settings::Settings {
@@ -120,28 +121,28 @@ mod tests {
                     suppress_none_returning: false,
                     allow_star_arg_any: true,
                 },
-                ..Settings::for_rules(vec![CheckCode::ANN401])
+                ..Settings::for_rules(vec![RuleCode::ANN401])
             },
         )?;
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(diagnostics);
         Ok(())
     }
 
     #[test]
     fn allow_overload() -> Result<()> {
-        let checks = test_path(
+        let diagnostics = test_path(
             Path::new("./resources/test/fixtures/flake8_annotations/allow_overload.py"),
             &Settings {
                 ..Settings::for_rules(vec![
-                    CheckCode::ANN201,
-                    CheckCode::ANN202,
-                    CheckCode::ANN204,
-                    CheckCode::ANN205,
-                    CheckCode::ANN206,
+                    RuleCode::ANN201,
+                    RuleCode::ANN202,
+                    RuleCode::ANN204,
+                    RuleCode::ANN205,
+                    RuleCode::ANN206,
                 ])
             },
         )?;
-        insta::assert_yaml_snapshot!(checks);
+        insta::assert_yaml_snapshot!(diagnostics);
         Ok(())
     }
 }

src/flake8_annotations/rules.rs

@@ -8,9 +8,9 @@ use crate::checkers::ast::Checker;
 use crate::docstrings::definition::{Definition, DefinitionKind};
 use crate::flake8_annotations::fixes;
 use crate::flake8_annotations::helpers::match_function_def;
-use crate::registry::CheckCode;
+use crate::registry::{Diagnostic, RuleCode};
 use crate::visibility::Visibility;
-use crate::{violations, visibility, Check};
+use crate::{violations, visibility};
 
 #[derive(Default)]
 struct ReturnStatementVisitor<'a> {
@@ -57,7 +57,7 @@ where
     F: FnOnce() -> String,
 {
     if checker.match_typing_expr(annotation, "Any") {
-        checker.checks.push(Check::new(
+        checker.diagnostics.push(Diagnostic::new(
             violations::DynamicallyTypedExpression(func()),
             Range::from_located(annotation),
         ));
@@ -85,15 +85,15 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 .chain(args.kwonlyargs.iter())
             {
                 if let Some(expr) = &arg.node.annotation {
-                    if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                    if checker.settings.enabled.contains(&RuleCode::ANN401) {
                         check_dynamically_typed(checker, expr, || arg.node.arg.to_string());
                     };
                 } else {
                     if !(checker.settings.flake8_annotations.suppress_dummy_args
                         && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
                     {
-                        if checker.settings.enabled.contains(&CheckCode::ANN001) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN001) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingTypeFunctionArgument(arg.node.arg.to_string()),
                                 Range::from_located(arg),
                             ));
@@ -106,7 +106,7 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
             if let Some(arg) = &args.vararg {
                 if let Some(expr) = &arg.node.annotation {
                     if !checker.settings.flake8_annotations.allow_star_arg_any {
-                        if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                        if checker.settings.enabled.contains(&RuleCode::ANN401) {
                             let name = arg.node.arg.to_string();
                             check_dynamically_typed(checker, expr, || format!("*{name}"));
                         }
@@ -115,8 +115,8 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                     if !(checker.settings.flake8_annotations.suppress_dummy_args
                         && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
                     {
-                        if checker.settings.enabled.contains(&CheckCode::ANN002) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN002) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingTypeArgs(arg.node.arg.to_string()),
                                 Range::from_located(arg),
                             ));
@@ -129,7 +129,7 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
             if let Some(arg) = &args.kwarg {
                 if let Some(expr) = &arg.node.annotation {
                     if !checker.settings.flake8_annotations.allow_star_arg_any {
-                        if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                        if checker.settings.enabled.contains(&RuleCode::ANN401) {
                             let name = arg.node.arg.to_string();
                             check_dynamically_typed(checker, expr, || format!("**{name}"));
                         }
@@ -138,8 +138,8 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                     if !(checker.settings.flake8_annotations.suppress_dummy_args
                         && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
                     {
-                        if checker.settings.enabled.contains(&CheckCode::ANN003) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN003) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingTypeKwargs(arg.node.arg.to_string()),
                                 Range::from_located(arg),
                             ));
@@ -150,7 +150,7 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
 
             // ANN201, ANN202, ANN401
             if let Some(expr) = &returns {
-                if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                if checker.settings.enabled.contains(&RuleCode::ANN401) {
                     check_dynamically_typed(checker, expr, || name.to_string());
                 };
             } else {
@@ -164,16 +164,16 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
 
                 match visibility {
                     Visibility::Public => {
-                        if checker.settings.enabled.contains(&CheckCode::ANN201) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN201) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingReturnTypePublicFunction(name.to_string()),
                                 helpers::identifier_range(stmt, checker.locator),
                             ));
                         }
                     }
                     Visibility::Private => {
-                        if checker.settings.enabled.contains(&CheckCode::ANN202) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN202) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingReturnTypePrivateFunction(name.to_string()),
                                 helpers::identifier_range(stmt, checker.locator),
                             ));
@@ -203,15 +203,15 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 // ANN401 for dynamically typed arguments
                 if let Some(annotation) = &arg.node.annotation {
                     has_any_typed_arg = true;
-                    if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                    if checker.settings.enabled.contains(&RuleCode::ANN401) {
                         check_dynamically_typed(checker, annotation, || arg.node.arg.to_string());
                     }
                 } else {
                     if !(checker.settings.flake8_annotations.suppress_dummy_args
                         && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
                     {
-                        if checker.settings.enabled.contains(&CheckCode::ANN001) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN001) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingTypeFunctionArgument(arg.node.arg.to_string()),
                                 Range::from_located(arg),
                             ));
@@ -225,7 +225,7 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 has_any_typed_arg = true;
                 if let Some(expr) = &arg.node.annotation {
                     if !checker.settings.flake8_annotations.allow_star_arg_any {
-                        if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                        if checker.settings.enabled.contains(&RuleCode::ANN401) {
                             let name = arg.node.arg.to_string();
                             check_dynamically_typed(checker, expr, || format!("*{name}"));
                         }
@@ -234,8 +234,8 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                     if !(checker.settings.flake8_annotations.suppress_dummy_args
                         && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
                     {
-                        if checker.settings.enabled.contains(&CheckCode::ANN002) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN002) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingTypeArgs(arg.node.arg.to_string()),
                                 Range::from_located(arg),
                             ));
@@ -249,7 +249,7 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 has_any_typed_arg = true;
                 if let Some(expr) = &arg.node.annotation {
                     if !checker.settings.flake8_annotations.allow_star_arg_any {
-                        if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                        if checker.settings.enabled.contains(&RuleCode::ANN401) {
                             let name = arg.node.arg.to_string();
                             check_dynamically_typed(checker, expr, || format!("**{name}"));
                         }
@@ -258,8 +258,8 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                     if !(checker.settings.flake8_annotations.suppress_dummy_args
                         && checker.settings.dummy_variable_rgx.is_match(&arg.node.arg))
                     {
-                        if checker.settings.enabled.contains(&CheckCode::ANN003) {
-                            checker.checks.push(Check::new(
+                        if checker.settings.enabled.contains(&RuleCode::ANN003) {
+                            checker.diagnostics.push(Diagnostic::new(
                                 violations::MissingTypeKwargs(arg.node.arg.to_string()),
                                 Range::from_located(arg),
                             ));
@@ -273,15 +273,15 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 if let Some(arg) = args.args.first() {
                     if arg.node.annotation.is_none() {
                         if visibility::is_classmethod(checker, cast::decorator_list(stmt)) {
-                            if checker.settings.enabled.contains(&CheckCode::ANN102) {
-                                checker.checks.push(Check::new(
+                            if checker.settings.enabled.contains(&RuleCode::ANN102) {
+                                checker.diagnostics.push(Diagnostic::new(
                                     violations::MissingTypeCls(arg.node.arg.to_string()),
                                     Range::from_located(arg),
                                 ));
                             }
                         } else {
-                            if checker.settings.enabled.contains(&CheckCode::ANN101) {
-                                checker.checks.push(Check::new(
+                            if checker.settings.enabled.contains(&RuleCode::ANN101) {
+                                checker.diagnostics.push(Diagnostic::new(
                                     violations::MissingTypeSelf(arg.node.arg.to_string()),
                                     Range::from_located(arg),
                                 ));
@@ -293,7 +293,7 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
 
             // ANN201, ANN202
             if let Some(expr) = &returns {
-                if checker.settings.enabled.contains(&CheckCode::ANN401) {
+                if checker.settings.enabled.contains(&RuleCode::ANN401) {
                     check_dynamically_typed(checker, expr, || name.to_string());
                 }
             } else {
@@ -306,44 +306,44 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 }
 
                 if visibility::is_classmethod(checker, cast::decorator_list(stmt)) {
-                    if checker.settings.enabled.contains(&CheckCode::ANN206) {
-                        checker.checks.push(Check::new(
+                    if checker.settings.enabled.contains(&RuleCode::ANN206) {
+                        checker.diagnostics.push(Diagnostic::new(
                             violations::MissingReturnTypeClassMethod(name.to_string()),
                             helpers::identifier_range(stmt, checker.locator),
                         ));
                     }
                 } else if visibility::is_staticmethod(checker, cast::decorator_list(stmt)) {
-                    if checker.settings.enabled.contains(&CheckCode::ANN205) {
-                        checker.checks.push(Check::new(
+                    if checker.settings.enabled.contains(&RuleCode::ANN205) {
+                        checker.diagnostics.push(Diagnostic::new(
                             violations::MissingReturnTypeStaticMethod(name.to_string()),
                             helpers::identifier_range(stmt, checker.locator),
                         ));
                     }
-                } else if visibility::is_init(stmt) {
+                } else if visibility::is_init(cast::name(stmt)) {
                     // Allow omission of return annotation in `__init__` functions, as long as at
                     // least one argument is typed.
-                    if checker.settings.enabled.contains(&CheckCode::ANN204) {
+                    if checker.settings.enabled.contains(&RuleCode::ANN204) {
                         if !(checker.settings.flake8_annotations.mypy_init_return
                             && has_any_typed_arg)
                         {
-                            let mut check = Check::new(
+                            let mut diagnostic = Diagnostic::new(
                                 violations::MissingReturnTypeSpecialMethod(name.to_string()),
                                 helpers::identifier_range(stmt, checker.locator),
                             );
-                            if checker.patch(check.kind.code()) {
+                            if checker.patch(diagnostic.kind.code()) {
                                 match fixes::add_return_none_annotation(checker.locator, stmt) {
                                     Ok(fix) => {
-                                        check.amend(fix);
+                                        diagnostic.amend(fix);
                                     }
                                     Err(e) => error!("Failed to generate fix: {e}"),
                                 }
                             }
-                            checker.checks.push(check);
+                            checker.diagnostics.push(diagnostic);
                         }
                     }
-                } else if visibility::is_magic(stmt) {
-                    if checker.settings.enabled.contains(&CheckCode::ANN204) {
-                        checker.checks.push(Check::new(
+                } else if visibility::is_magic(cast::name(stmt)) {
+                    if checker.settings.enabled.contains(&RuleCode::ANN204) {
+                        checker.diagnostics.push(Diagnostic::new(
                             violations::MissingReturnTypeSpecialMethod(name.to_string()),
                             helpers::identifier_range(stmt, checker.locator),
                         ));
@@ -351,16 +351,16 @@ pub fn definition(checker: &mut Checker, definition: &Definition, visibility: &V
                 } else {
                     match visibility {
                         Visibility::Public => {
-                            if checker.settings.enabled.contains(&CheckCode::ANN201) {
-                                checker.checks.push(Check::new(
+                            if checker.settings.enabled.contains(&RuleCode::ANN201) {
+                                checker.diagnostics.push(Diagnostic::new(
                                     violations::MissingReturnTypePublicFunction(name.to_string()),
                                     helpers::identifier_range(stmt, checker.locator),
                                 ));
                             }
                         }
                         Visibility::Private => {
-                            if checker.settings.enabled.contains(&CheckCode::ANN202) {
-                                checker.checks.push(Check::new(
+                            if checker.settings.enabled.contains(&RuleCode::ANN202) {
+                                checker.diagnostics.push(Diagnostic::new(
                                     violations::MissingReturnTypePrivateFunction(name.to_string()),
                                     helpers::identifier_range(stmt, checker.locator),
                                 ));

src/flake8_annotations/settings.rs

@@ -26,7 +26,7 @@ pub struct Options {
         value_type = "bool",
         example = "suppress-dummy-args = true"
     )]
-    /// Whether to suppress `ANN000`-level errors for arguments matching the
+    /// Whether to suppress `ANN000`-level violations for arguments matching the
     /// "dummy" variable regex (like `_`).
     pub suppress_dummy_args: Option<bool>,
     #[option(
@@ -34,8 +34,8 @@ pub struct Options {
         value_type = "bool",
         example = "suppress-none-returning = true"
     )]
-    /// Whether to suppress `ANN200`-level errors for functions that meet either
-    /// of the following criteria:
+    /// Whether to suppress `ANN200`-level violations for functions that meet
+    /// either of the following criteria:
     ///
     /// - Contain no `return` statement.
     /// - Explicit `return` statement(s) all return `None` (explicitly or

src/flake8_bandit/checks/assert_used.rs

@@ -1,10 +0,0 @@
-use rustpython_ast::{Located, StmtKind};
-
-use crate::ast::types::Range;
-use crate::registry::Check;
-use crate::violations;
-
-/// S101
-pub fn assert_used(stmt: &Located<StmtKind>) -> Check {
-    Check::new(violations::AssertUsed, Range::from_located(stmt))
-}