error[E0308]: mismatched types
  --> $DIR/issue-13853.rs:14:9
   |
LL |     fn nodes<'a, I: Iterator<Item=&'a N>>(&self) -> I
   |                  - this type parameter              - expected `I` because of return type
...
LL |         self.iter()
   |         ^^^^^^^^^^^ expected type parameter `I`, found struct `std::slice::Iter`
   |
   = note: expected type parameter `I`
                      found struct `std::slice::Iter<'_, N>`
   = help: type parameters must be constrained to match other types
   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters

error[E0599]: no method named `iter` found for type `&G` in the current scope
  --> $DIR/issue-13853.rs:27:23
   |
LL |     for node in graph.iter() {
   |                       ^^^^ method not found in `&G`

error[E0308]: mismatched types
  --> $DIR/issue-13853.rs:37:13
   |
LL |     iterate(graph);
   |             ^^^^^
   |             |
   |             expected reference, found struct `std::vec::Vec`
   |             help: consider borrowing here: `&graph`
   |
   = note: expected reference `&_`
                 found struct `std::vec::Vec<Stuff>`

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0308, E0599.
For more information about an error, try `rustc --explain E0308`.