Tracking Issue for core::clone::CloneToUninit trait · Issue #126799 · rust-lang/rust (original) (raw)

Feature gate: #![feature(clone_to_uninit)]

This is a tracking issue for CloneToUninit and its impls. This trait backs the behavior of Rc::make_mut and Arc::make_mut, and likely in the future also Box::clone.

Public API

// core::clone

pub unsafe trait CloneToUninit { unsafe fn clone_to_uninit(&self, dst: *mut Self); }

unsafe impl<T: Clone> CloneToUninit for T; unsafe impl<T: Clone> CloneToUninit for [T];

// TODO: // unsafe impl CloneToUninit for str; // unsafe impl CloneToUninit for CStr; // unsafe impl CloneToUninit for OsStr; // unsafe impl CloneToUninit for Path;

Steps / History

• Implementation: Generalize {Rc,Arc}::make_mut() to unsized types. #116113
• CloneToUninit impls #126877
• Convert Box::clone to be based on CloneToUninit
• Final comment period (FCP)1
• Stabilization PR

Unresolved Questions

• Consider using *mut () in the signature instead of *mut Self. This makes CloneToUninit dyn-safe. Generalize {Rc,Arc}::make_mut() to unsized types. #116113 (comment)

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩