Tracking Issue for `const` checked slice to `str` conversions

[WaffleLapkin]

Feature gate: #![feature(const_str_from_utf8)]

This is a tracking issue for str::{from_utf8, from_utf8_mut} and str::Utf8Error::{valid_up_to, error_len} as const fn

Public API

// core::str
pub const fn from_utf8_mut(v: &mut [u8]) -> Result<&mut str, Utf8Error>;

impl str {
    pub const fn from_utf8_mut(v: &mut [u8]) -> Result<&mut str, Utf8Error>;
}

Public API (stabilized in Rust 1.63)

// core::str

pub const fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error>;

impl Utf8Error {
    pub const fn valid_up_to(&self) -> usize;
    pub const fn error_len(&self) -> Option<usize>;
}

Steps / History

• Implementation: Make slice->str conversion and related functions const #90607
• Final comment period (FCP) (& functions)
• Stabilization PR (& functions)
• Final comment period (FCP) (&mut function)
• Stabilization PR (&mut function)

Unresolved Questions

• None yet.

[Amanieu]

@rfcbot merge

[rfcbot]

Team member @Amanieu 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
• @yaahc

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.

[WaffleLapkin]

Note that from_utf8_mut is not being stabilized as &mut is still unstable in const context.

cc @oli-obk

[Amanieu]

Tracking issue for &mut in const: #57349

[rfcbot]

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