// `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;
}