ast-grep

CodeRabbit’s guide to ast-grep.

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 0.44.0.

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 repository root)
• util_dirs: List of directories containing utility configs to support rule management (relative to repository root)
• essential_rules: Enable the ast-grep essentials package (default: true)
• packages: List of GitHub packages to use (format: owner/repo)

Example Configuration

reviews:
  tools:
    ast-grep:
      rule_dirs:
        - "rules/javascript"
        - "rules/python"
      util_dirs:
        - "utils"
      essential_rules: true
      packages:
        - "owner/custom-rules"

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.

Links

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

Files

ast-grep will run on the following file types:

• Bash (.bash, .bats, .command, .env, .ksh, .sh, .sh.in, .tmux, .tool, .zsh)
• Bicep (.bicep)
• C (.c, .h)
• C++ (.c++, .cc, .cpp, .cu, .cxx, .hh, .hpp, .ino)
• C# (.cs)
• CSS (.css)
• Dart (.dart)
• Elixir (.ex, .exs)
• Glimmer JavaScript (.gjs)
• Glimmer TypeScript (.gts)
• Go (.go)
• Haskell (.hs)
• HTML (.htm, .html, .xhtml)
• Java (.java)
• JavaScript (.cjs, .js, .jsx, .mjs)
• JSON (.json)
• Kotlin (.kt, .ktm, .kts)
• Lua (.lua)
• Markdown (.md)
• PHP (.php)
• Python (.py, .py3, .pyi)
• Ruby (.gemspec, .rb, .rbw)
• Rust (.rs)
• Scala (.sc, .scala)
• SQL (.sql)
• Swift (.swift)
• TOML (.toml)
• TSX (.tsx)
• TypeScript (.cts, .mts, .ts)
• YAML (.yaml, .yml)