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The Rust Reference & the Ferrocene FLS

# The two documents defining Rust — the project's non-normative Reference and the certification-grade Ferrocene Language Specification, now adopted as the seed of the official spec.

Referencesaved 2026-08-09source #rust#specification#language#reference#ferrocene

Why kept

The language-definition paper trail behind Rust compilers & the language definition — what "the spec" currently means in Rust and where the official one is coming from.

Notes

  • The Rust Reference — the project's own description of syntax and semantics; explicitly non-normative ("does not have the authority of the compiler"), but the right daily answer to "what are the rules?".
  • Ferrocene Language Specification — written by Ferrous Systems for compiler qualification (ISO 26262); structured like a true standard, pinned to specific rustc versions; donated to the Rust Project in 2025 and adopted by the t-spec team (chartered by RFC 3355) as the basis of the official specification.
  • The operational rules the Reference leaves open (aliasing models for unsafe code) live in miri's Tree Borrows / Stacked Borrows work and the Unsafe Code Guidelines — the parts of "the spec" still being decided.
  • Contrast anchors: the JVMS (contractual, TCK-enforced) and the Go spec (short, readable, authoritative).