Tracking Issue for `casefold`

[Jules-Bertholet]

Feature gate: #![feature(casefold)]

This is a tracking issue for Unicode-aware case folding APIs in the standard library. These APIs do not perform NFC/NFKC normalization.

Public API

// `core`

impl char {
    pub fn to_casefold_unnormalized(self) -> ToCasefold;
}

mod char {
    #[derive(Debug, Clone)]
    pub struct ToCasefold { … };
    impl Iterator for ToCasefold {
        type Item = char;
        …
    }
    impl DoubleEndedIterator for ToCasefold { … }
    impl FusedIterator for ToCasefold {}
    impl ExactSizeIterator for ToCasefold {}
    impl fmt::Display for ToCasefold { … }
}

impl str {
    pub fn eq_ignore_case_unnormalized(&self, other: &str) -> bool;
}

// `alloc`

impl str {
    pub fn to_casefold_unnormalized(&self) -> String;
}

Steps / History

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

• Implementation: Add APIs for case folding to the standard library #154742
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• Is the lack of normalization a deal-breaker? What is the best way to deal with that? Add APIs for case folding to the standard library #154742 (comment)

@rustbot label A-Unicode

Footnotes

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