error[E0597]: borrowed value does not live long enough
  --> $DIR/issue-30438-a.rs:12:17
   |
LL |         return &Test { s: &self.s};
   |                 ^^^^^^^^^^^^^^^^^^- temporary value only lives until here
   |                 |
   |                 temporary value does not live long enough
   |
note: borrowed value must be valid for the anonymous lifetime #1 defined on the method body at 11:5...
  --> $DIR/issue-30438-a.rs:11:5
   |
LL | /     fn index(&self, _: usize) -> &Self::Output {
LL | |         return &Test { s: &self.s};
LL | |         //~^ ERROR: borrowed value does not live long enough
LL | |     }
   | |_____^
   = note: consider using a `let` binding to increase its lifetime

error: aborting due to previous error

For more information about this error, try `rustc --explain E0597`.