Modern Rust APIs (1.89 – 1.94)

This skill is a lookup table for stable Rust APIs added after 1.88. Use it when writing or reviewing Rust code — replace older verbose patterns with newer concise ones where the project's MSRV allows.

How to use this skill

1. Check the project's MSRV first. Look at Cargo.toml for rust-version = "X.Y". Only suggest APIs available at or below the MSRV. If MSRV is lower than an API's version, either skip the suggestion or note that "raising MSRV to X.Y unlocks this."

2. Scan the code for trigger patterns (see section below). Each trigger maps to a newer API. When you see one, suggest the replacement with a brief before/after.

3. For detailed API info, read the matching reference file in references/. Files are organized by domain, not by version.

4. Don't over-apply. Some patterns are fine as-is. Only suggest a change when the new API is clearly better (shorter, safer, or fixes a subtle bug).

Trigger patterns — fastest lookup

Scan for these code shapes first. Each points to a concrete API that replaces it.