ast-grep

How CodeRabbit runs ast-grep to find code patterns and report rule matches in pull requests.

ast-grep is an open-source static analysis tool that uses abstract syntax trees (AST) to find patterns in your codebase, helping identify security vulnerabilities and enforce code quality standards. CodeRabbit runs ast-grep version 0.45.2 on supported changed files using the essentials package and any custom rules you configure.

Configuration Options

You can configure ast-grep in your .coderabbit.yaml file or through CodeRabbit’s settings page under “Reviews → Tools → ast-grep”. The following options are available:

• rule_dirs: List of directories containing your custom ast-grep rules, relative to the repository root (default: [])
• util_dirs: List of directories containing utility configs to support rule management, relative to the repository root (default: [])
• essential_rules: Enable the ast-grep essentials package (default: true)
• packages: List of GitHub packages to use in owner/repository format (default: [])

Example Configuration

reviews:
  tools:
    ast-grep:
      rule_dirs: []
      util_dirs: []
      essential_rules: true
      packages: []

CodeRabbit will only run ast-grep if you have configured at least one of the following:

• Custom rule directories (rule_dirs)
• Essential rules enabled (essential_rules: true)
• Custom packages (packages)

util_dirs can be used to support shared utility configs, but by itself it does not cause ast-grep to run.

CodeRabbit also skips ast-grep when the pull request contains no changed files with a supported extension. Individual files that are 8 MiB or larger are skipped.

Links

• ast-grep Documentation
• Writing ast-grep Rules
• ast-grep Rule Object Properties
• ast-grep Essentials Package

Files

ast-grep runs on changed files with the following extensions:

• .bash
• .c
• .cpp
• .cs
• .css
• .erb (parsed as HTML)
• .ex
• .exs
• .go
• .h
• .hpp
• .hs
• .html
• .java
• .js
• .json
• .jsx
• .kt
• .lua
• .php
• .py
• .rb
• .rs
• .scala
• .sh
• .sql
• .swift
• .ts
• .tsx
• .yaml
• .yml