Versions and Testing

[lints.rust]
rust_2018_idioms = { level = "warn", priority = -1 }
unused_lifetimes = "warn"

[lints.clippy]
needless_lifetimes = "warn"
extra_unused_lifetimes = "warn"

pub struct Parser<'a> { src: &'a str, pos: usize }

impl<'a> Parser<'a> {
    pub fn new(src: &'a str) -> Self { Parser { src, pos: 0 } }
    pub fn next_token(&mut self) -> Option<&'a str> {
        let rest = self.src.get(self.pos..)?.trim_start();
        if rest.is_empty() { return None; }
        let start = self.src.len() - rest.len();
        let end = rest.find(' ').unwrap_or(rest.len());
        self.pos = start + end;
        Some(&rest[..end])
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn tokens_outlive_the_parser_borrow() {
        let text = String::from("a b");
        let mut p = Parser::new(&text);
        let a = p.next_token();
        let b = p.next_token();     // compiles only if next_token takes a short &mut self
        drop(p);                    // tokens borrow `text`, not `p`
        assert_eq!((a, b), (Some("a"), Some("b")));
    }

    fn is_static<T: 'static>(_: &T) {}

    #[test]
    fn config_is_owned() {
        let cfg = String::from("x");     // stand-in for an owned config type
        is_static(&cfg);                 // fails to compile if the type gains a borrowed field
    }
}

/// A token cannot outlive the source text:
///
/// ```compile_fail
/// let tok;
/// {
///     let text = String::from("a b");
///     let mut p = mycrate::Parser::new(&text);
///     tok = p.next_token();
/// }
/// println!("{tok:?}");
/// ```
pub fn _doc_anchor() {}

SKILL=path/to/rust-lifetime-annotation-advisor
for t in elision_check missing_lifetime static_bounds lifetime_smells; do
  rustc -O --edition 2021 "$SKILL/scripts/$t.rs" -o "/tmp/$t"
done
/tmp/missing_lifetime src/ --strict          # high-severity: would not compile
/tmp/elision_check src/ --strict             # noise: elidable and unused lifetimes
/tmp/static_bounds src/ --json > static.json # advisory: review, do not gate
/tmp/lifetime_smells src/ --max-lifetimes 2