diff --git a/src/cargo/lib.rs b/src/cargo/lib.rs
index 435d582a3782..6379abe27841 100644
--- a/src/cargo/lib.rs
+++ b/src/cargo/lib.rs
@@ -166,3 +166,5 @@ fn _display_error(err: &Error, shell: &mut Shell, as_err: bool) -> bool {
     }
     false
 }
+
+fn unused() {}