warning: extern crate `bar` is unused in crate `libfib`
  --> $DIR/libfib.rs:7:1
   |
LL | pub fn fib(n: u32) -> Vec<u32> {
   | ^
   |
   = help: remove the dependency or add `use bar as _;` to the crate root
   = note: requested on the command line with `-W unused-crate-dependencies`

warning: 1 warning emitted