message: use show_error to terminate
diff: @@ -366,7 +366,7 @@ fn main() {
  Err(ref e) => panic!("error during rustc call: {:?}", e),
  }
  } else {
  - eprintln!("Unexpected call: Must be called with either `miri` or `rustc` as first argument.")
  + show_error!("Must be called with either `miri` or `rustc` as first argument.")
  }
  }
  