warning: external crate `bar` unused in `warn_attr`: remove the dependency or add `use bar as _;`
  --> $DIR/warn-attr.rs:7:1
   |
LL | #![warn(unused_crate_dependencies)]
   | ^
   |
note: the lint level is defined here
  --> $DIR/warn-attr.rs:7:9
   |
LL | #![warn(unused_crate_dependencies)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
   = help: remove unnecessary dependency `bar`

warning: 1 warning emitted

