finalKeyword

Explanation

final has been reserved since the 2015 edition, part of the Rust Reference's original reserved-keyword list. It's grouped here with override and virtual because all three read like they'd belong to the same hypothetical future feature: something analogous to final in Java or C++, a marker that prevents further overriding or specialization of a trait implementation or method. No concrete RFC exists for this today — it's speculative, held in reserve in case Rust ever grows an inheritance-like or specialization mechanism where "no further overrides allowed" would be a meaningful thing to say.

Using final as an ordinary identifier is a compile error today. The raw-identifier form r#final is legal, the same escape hatch every reserved keyword offers.

Usage examples

Escaping the reservation with a raw identifier

let final = 5;     // error: expected identifier, found reserved keyword `final`
let r#final = 5;   // ok: the raw-identifier form escapes the reservation

Explanation

Embedded support: Full

Full support. Keyword reservation is a lexer-level fact, identical in #![no_std] and hosted Rust alike — final carries no defined meaning on any target, so there's no embedded-specific behavior to describe.

Usage examples

The `final` reservation, unaffected by target

let final = 5;     // error: expected identifier, found reserved keyword `final`, on every target
let r#final = 5;   // ok: the raw-identifier form escapes the reservation, on every target