Crate

proc-macro2

Stable TokenStream for use outside proc-macro context.

What it is

proc-macro2 provides a usable-outside-proc-macros version of Rust's proc_macro::TokenStream. It allows proc-macro helper libraries like syn and quote to be compiled, tested, and used in regular code rather than only inside procedural macros.

Why it is commonly used

An implementation detail of the syn/quote proc-macro ecosystem. Application code rarely depends on it directly — its high repo count comes from crates that ship proc-macros.

979

Repositories

89%

Actively maintained

864

Updated ≤ 30 days

3.6M

Total stars

819

Owners

Counted from the Cargo.toml manifests of the 979 indexed repositories that declare proc-macro2 as a dependency — not download counts. Dependency data last verified 2026-08-13.

Browse 979 repositories using proc-macro2 in Repos →

Often used with

Crates that show up unusually often in proc-macro2 projects. The most distinctive pairings rank first — crates these projects use far more than the average indexed Rust project does, not just crates that are popular everywhere. Each percentage is the share of proc-macro2 projects that also use it.

darling10.6%quote97.3%syn96.7%prettyplease11.8%convert_case11.1%inventory10.1%heck14.7%cargo_metadata11%pin-project11.3%either12.5%pretty_assertions13%num-bigint11.6%derive_more16.8%paste18%hashbrown14.8%rstest10%proptest13.6%insta11.5%pin-project-lite11%cfg-if15.1%strum_macros12.6%num-traits21.9%smallvec24.7%tracing-opentelemetry11.8%

Used by these organizations

Cloudflare Mozilla AWS Microsoft Google Oxide Computer Parity Technologies Deno Zed Industries Turso SurrealDB Embark Studios The Rust Project Fuel Labs Astral Tauri Bun OpenAI Union Warp Alacritty Meilisearch Rerun Tokio Bevy Engine Bytecode Alliance Linebender Nushell Qdrant Polars Quickwit Datadog Hyperium Embassy Actix probe-rs PyO3 Yew Leptos Wasmer Typst Tracel AI Serde Diesel Rayon Clap RustCrypto Servo esp-rs Paradigm Matrix.org

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