Fallow - Dead Code Analysis

Version updated for https://github.com/fallow-rs/fallow to version v1.1.0.

  • This action is used across all versions by 0 repositories.

Action Type

This is a Composite action.

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Action Summary

This GitHub Action, Fallow, is a Rust-based codebase analyzer for JavaScript and TypeScript that automates the detection of unused code, circular dependencies, code duplication, and complexity hotspots. It streamlines code maintenance by identifying dead files, exports, and dependencies, while also detecting issues like unresolved imports, unlisted dependencies, and duplicate or circular code structures. With significantly faster performance than comparable tools and no dependency on a Node.js runtime, it enables developers to quickly optimize and refactor their projects for better efficiency and maintainability.

Release notes

Features

  • Markdown output format — New --format markdown option for check and dupes commands, producing clean Markdown reports suitable for PR comments, CI summaries, and documentation
  • LSP issue type filtering — Filter which diagnostic types the LSP reports via initializationOptions.issueTypes, with corresponding VS Code fallow.issueTypes configuration
  • VS Code extension improvements — Added marketplace icon, issue type filter settings, and config-change-triggered re-analysis

Code Quality (Oxc-inspired)

Comprehensive code quality overhaul inspired by the Oxc ecosystem:

  • Expanded clippy lint coverage — Enabled all, pedantic, nursery, and cargo lint groups with a strategic allow-list for false positives, plus 13 restriction lints (undocumented_unsafe_blocks, unused_result_ok, clone_on_ref_ptr, infinite_loop, etc.)
  • #[expect] over #[allow] — All clippy suppressions now use #[expect(clippy::...)], which warns when a suppression becomes unnecessary — prevents dead annotations from accumulating
  • Rust compiler lints — Added unsafe_op_in_unsafe_fn, unused_unsafe, non_ascii_idents
  • Size assertions — ModuleNode (96B), ModuleInfo (256B) const assertions prevent accidental struct bloat
  • Dev profile optimizations — debug = false for faster builds, selective opt-level for proc-macro crates (serde_derive, clap_derive) and snapshot test deps (insta, similar)
  • Removed 5 unused dependencies — bincode and regex from core, indicatif and miette from CLI, tracing from LSP/MCP

CI Hardening

  • permissions: {} deny-all baseline — each job explicitly requests only contents: read
  • git diff --exit-code check catches uncommitted generated code
  • --document-private-items in doc check for comprehensive documentation validation

Refactors

  • Split graph.rs (2644 lines) into graph/{mod,types,build,reachability,re_exports,cycles}.rs
  • Split fix.rs (1561 lines) into fix/{mod,io,exports,enum_members,deps}.rs
  • Added comprehensive extract unit tests for JS/TS, Vue/Svelte SFC, Astro, MDX, and CSS Modules parsing

Infrastructure

  • Upgraded Cargo resolver from "2" to "3"
  • Bumped toml dependency to 1.0.7

Full Changelog: https://github.com/fallow-rs/fallow/compare/v1.0.4...v1.1.0