rust/compiler/rustc_resolve
Esteban Küber 8ba2950fb6 Detect case of missing lifetime in assoc type
When an associated type is missing a lifetime, point at its enclosing `impl`, whether it has or doesn't have lifetimes defined. If it does have a lifetime, suggest using it.

```
error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
  --> $DIR/missing-lifetime-in-assoc-type-1.rs:8:17
   |
LL | impl<'a> IntoIterator for &S {
   |     ---- there is a named lifetime specified on the impl block you could use
...
LL |     type Item = &T;
   |                 ^ this lifetime must come from the implemented type
   |
help: consider using the lifetime from the impl block
   |
LL |     type Item = &'a T;
   |                  ++
```

```
error: in the trait associated type is declared without lifetime parameters, so using a borrowed type for them requires that lifetime to come from the implemented type
  --> $DIR/missing-lifetime-in-assoc-type-2.rs:5:17
   |
LL | impl IntoIterator for &S {
   |     - you could add a lifetime on the impl block, if the trait or the self type can have one
LL |     type Item = &T;
   |                 ^ this lifetime must come from the implemented type
```
2025-10-31 20:45:33 +00:00
..
2025-10-04 18:18:58 +00:00