Feature gate: #![feature(str_first_last_char)]

This is a tracking issue for methods for extracting the first or last character of a str as a char. PR #89603 was submitted in 2021 (predating ACPs) but was closed after a few months due to author inactivity. ACP rust-lang/libs-team#764 proposes trying again to add these methods, this time constified.

Public API

// core::str

impl str {
    pub const fn first_char(&self) -> Option<char>
    pub const fn last_char(&self) -> Option<char>
    pub const fn split_first_char(&self) -> Option<(char, &str)>
    pub const fn split_last_char(&self) -> Option<(char, &str)>
}

Steps / History

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

• ACP: Add str::split_first and others libs-team#764
• Implementation: libcore: add str::first, str::split_first, str::last and str::split_last methods #89603 (abandoned, not const)
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• _char suffix or not?