Tracking issue for array::from_ref and array::from_mut

[lcnr]

Tracking issue for feature(array_from_ref) which adds the following methods

// std::array
pub fn from_ref<T>(s: &T) -> &[T; 1];
pub fn from_mut<T>(s: &mut T) -> &mut [T; 1];

Steps / History

• Implementation: add array::from_ref #77074
• FCP
• Stabilization PR

[WaffleLapkin]

Why is the mut version name differs from the slice variant? (from_ref_mut vs from_mut) Nvm, it's a typo in the issue description, the actual method is named from_mut.

What is blocking stabilization, it seems like there aren't any open questions/controversies. Shall I make a stabilization PR?

[m-ou-se]

@rfcbot merge

[rfcbot]

Team member @m-ou-se 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
• @sfackler

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.

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[rfcbot]

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

The RFC will be merged soon.

[oconnor663]

Has anyone proposed to stabilize these? Could I just open a PR to start that? :)

[WaffleLapkin]

@oconnor663 I've proposed. In fact, they were already stabilized :)

#84105

[mzji]

Since core::array::from_ref() and core::array::from_mut() has been stablized, could we now add impl<T> From<T> for [T; 1], impl<'a, T> From<&'a T> for &'a [T; 1] and impl<'a, T> From<&'a mut T> for &'a mut [T; 1] to libcore? These impls should be easy to implement (just one-liners) and ergonomic to use.

[jhpratt]

@mzji Feel free to create a pull request! I would imagine it would be accepted.

[zachs18]

[...] could we now add impl<T> From<T> for [T; 1], impl<'a, T> From<&'a T> for &'a [T; 1] and impl<'a, T> From<&'a mut T> for &'a mut [T; 1] to libcore? [...]

Adding From<T> for [T; 1] could conflict with downstream From<Local> for [Local; 1].
Similarly, since & and &mut are "fundamental" and behave like their pointee for coherence purposes, downstream impls of From<&'a Local> for &'a [Local; 1] etc are also currently allowed, such that adding impl<'a, T: 'a> From<&'a T> for &'a [T; 1] would also conflict.
Adding another x.into() candidate for x: &T also was pointed out as possibly being an issue for type inference
.