src/test/ui/unknown-language-item.stderr

error[E0522]: definition of an unknown language item: `foo`
  --> $DIR/unknown-language-item.rs:14:1
   |
LL | #[lang = "foo"]
   | ^^^^^^^^^^^^^^^ definition of unknown language item `foo`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0522`.