Feature gate: #![feature(freeze)]

This is a tracking issue for the core::marker::Freeze trait

This trait allows generic code to restrict generic parameters to types without interior mutability.

Public API

use std::marker::Freeze;

trait Trait<T: Freeze + 'static> {
    const VALUE: T;
    const VALUE_REF: &'static T = &Self::VALUE;
}

Steps / History

• Implementation: Expose the Freeze trait again (unstably) and forbid implementing it manually #121840
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• naming the trait differently (see #121501 (comment))