with_lifetime.rs

// An iterator over the File descriptors contained in an FD ring buffer
pub struct RingIter<'a> {
    ring: &'a Ring,
    offset: u64,
}

impl Iterator for RingIter<'a> {
    type Item = RawFd;

    fn next(&'a mut self) -> Option<RawFd> {
      // ...
    }
}

//////
// Result:
// src/ring.rs:152:28: 152:30 error: use of undeclared lifetime name `'a` [E0261]
// src/ring.rs:152 impl Iterator for RingIter<'a> {
//                                            ^~
// src/ring.rs:152:28: 152:30 help: run `rustc --explain E0261` to see a detailed explanation
// src/ring.rs:155:14: 155:16 error: use of undeclared lifetime name `'a` [E0261]
// src/ring.rs:155     fn next(&'a mut self) -> Option<RawFd> {
//                              ^~
// 

without_lifetime.rs

// An iterator over the File descriptors contained in an FD ring buffer
pub struct RingIter<'a> {
    ring: &'a Ring,
    offset: u64,
}

impl Iterator for RingIter {
    type Item = RawFd;

    fn next(&mut self) -> Option<RawFd> {
      // ...
    }
}
/////
// Result:
// src/ring.rs:152:19: 152:27 error: wrong number of lifetime parameters: expected 1, found 0 [E0107]
// src/ring.rs:152 impl Iterator for RingIter {
//                                    ^~~~~~~~