error[E0432]: unresolved import `issue_36881_aux`
  --> $DIR/issue-36881.rs:5:9
   |
LL |     use issue_36881_aux::Foo;
   |         ^^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `issue_36881_aux`
   |
help: you might be missing a crate named `issue_36881_aux`, add it to your project and import it in your code
   |
LL + extern crate issue_36881_aux;
   |

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0432`.