error[E0621]: explicit lifetime required in the type of `y`
  --> $DIR/ex1-return-one-existing-name-if-else.rs:2:27
   |
LL | fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32 {
   |                           ---- help: add explicit lifetime `'a` to the type of `y`: `&'a i32`
LL |     if x > y { x } else { y }
   |                           ^ lifetime `'a` required

error: aborting due to previous error

For more information about this error, try `rustc --explain E0621`.