ast-grep

name	ast-grep
description	Guides ccusage structural code searches with ast-grep. Use when finding Rust or TypeScript syntax patterns, validating migrations, or writing AST-based search commands.

ast-grep

Reach for ast-grep when a search depends on syntax structure — a macro call with particular arguments, a match arm shape, an attribute on an item. rg is faster for plain text, and reduce-similarities owns duplicate-code detection.

ast-grep comes from the Nix dev shell, so prefix with direnv exec . when the shell is not already active. There is no sgconfig.yml here: relational rules go through scan --inline-rules or a throwaway --rule file rather than a project rule set. Scoping to rust, apps, docs, or nix keeps large searches quick, though a bare root search already skips gitignored trees.

Start with run --pattern and widen only if it under-matches. Give relational rules stopBy: end, or they stop at the first node in that direction. When a pattern does not match the shape you expected, dump the parse with --debug-query.

https://ast-grep.github.io/guide/pattern-syntax.html

https://ast-grep.github.io/reference/rule.html