message: Set RUSTC and RUSTDOC env vars to invalid values to catch forgetting to set them
diff: @@ -134,6 +134,9 @@ pub fn main() {
  process::exit(0);
  }
  + env::set_var("RUSTC", "rustc_should_be_set_explicitly");
  + env::set_var("RUSTDOC", "rustdoc_should_be_set_explicitly");
  +
  let cg_clif_dylib =
  build_backend::build_backend(&dirs, channel, &host_compiler, use_unstable_features);
  match command {
  