Tracking Issue for UnsafeCell::from_mut

[JoJoJet]

Feature gate: #![feature(unsafe_cell_from_mut)]

This is a tracking issue for UnsafeCell::from_mut, which makes it possible to convert &mut T to &mut UnsafeCell<T> in safe code.

Public API

// core::cell

impl<T: ?Sized> UnsafeCell<T> {
    pub fn from_mut(&mut T) -> &mut Self;
}

Steps / History

• ACP: Add a conversion from &mut T to &mut UnsafeCell<T> libs-team#198
• Implementation: Add a conversion from &mut T to &mut UnsafeCell<T> #111654
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• None yet.

Footnotes

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

[JoJoJet]

For a straightforward addition like this, what's an appropriate amount of time to wait before pushing for stabilization?

[QuineDot]

This should also be added to SyncUnsafeCell to keep their APIs the same.

[clarfonthey]

Since Cell::from_mut is stabilised, it feels weird that this isn't.

[dtolnay]

@rust-lang/libs-api:
@rfcbot fcp merge

[rfcbot]

Team member @dtolnay has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.