Tracking Issue for `case_ignorable`

Feature gate: #![feature(case_ignorable)]

This is a tracking issue for a method to query the Unicode Case_Ignorable property on char. This narrow-use property is used to implement lowercasing behavior for word-final Greek sigma (e.g. in str::to_lowercase()).

Public API

// core

impl char {
    pub fn is_case_ignorable(self) -> bool;
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• Implementation: https://github.com/rust-lang/rust/pull/146173 https://github.com/rust-lang/rust/pull/154849
• Final comment period (FCP)^1
• Stabilization PR

Unresolved Questions

• None yet.

@rustbot label -S-tracking-unimplemented S-tracking-needs-to-bake

Start with the public API and the linked implementation PRs (#146173 and #154849), then read the stabilization process described in the linked Rust dev guide. The remaining checklist items are the final comment period and stabilization PR; done means the feature has completed that process and is stabilized.