Tracking Issue for `#![feature(const_slice_first_last)]`

[a1phyr]

This is a tracking issue for #![feature(const_slice_first_last)].

New const functions are:

• slice::first
• slice::split_first
• slice::last
• slice::split_last

Blocking on #![feature(const_mut_refs)]:

• slice::first_mut
• slice::split_first_mut
• slice::last_mut
• slice::split_last_mut

Steps

• Implementation: Constantify some slice methods #83571
• Stabilization PR (non-mut part): Partially stabilize const_slice_first_last #86593
• Stabilization PR (mut part)

[jhpratt]

Partial stabilization up as #86593.

[RalfJung]

@rust-lang/libs-api we're finally ready to const-stabilize the mut parts of this as well, I think. :)

[dtolnay]

@rfcbot fcp merge

const for these already-stable functions:

• https://doc.rust-lang.org/nightly/core/primitive.slice.html#method.first_mut
• https://doc.rust-lang.org/nightly/core/primitive.slice.html#method.split_first_mut
• https://doc.rust-lang.org/nightly/core/primitive.slice.html#method.last_mut
• https://doc.rust-lang.org/nightly/core/primitive.slice.html#method.split_last_mut

[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.