error: `impl` item signature doesn't match `trait` item signature
  --> $DIR/lifetime-mismatch-between-trait-and-impl.rs:6:5
   |
LL |     fn foo<'a>(x: &i32, y: &'a i32) -> &'a i32;
   |     ------------------------------------------- expected `fn(&'1 i32, &'a i32) -> &'a i32`
...
LL |     fn foo<'a>(x: &'a i32, y: &'a i32) -> &'a i32 {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 i32, &'1 i32) -> &'1 i32`
   |
   = note: expected `fn(&'1 i32, &'a i32) -> &'a i32`
              found `fn(&'1 i32, &'1 i32) -> &'1 i32`
   = help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
   = help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output

error: aborting due to previous error