error[E0515]: cannot return value referencing local variable `z`
  --> $DIR/issue-48697.rs:9:5
   |
LL |     let k = f(&z);
   |               -- `z` is borrowed here
LL |     f(x)
   |     ^^^^ returns a value referencing data owned by the current function

error: aborting due to previous error

For more information about this error, try `rustc --explain E0515`.