message: Remove cache output and error handling
  Error handling is done by rustc and the stderr is simply printed. The
  `rustc --print <FOO>` command is always executed instead of using the
  cache.
diff: @@ -335,16 +335,7 @@ pub fn print<'a>(
  .arg("--print")
  .arg(print_opt_value)
  .env_remove("RUSTC_LOG");
  - let (output, error) = rustc
  - .cached_output(&process)
  - .chain_err(|| "failed to run `rustc --print=<INFO>`")?;
  - if output.is_empty() {
  - anyhow::bail!(
  - "output of --print={} missing from rustc\n{}",
  - print_opt_value,
  - output_err_info(&process, &output, &error)
  - );
  - }
  + let output = process.exec_with_output()?;
  let stdout = std::io::stdout();
  let mut lock = stdout.lock();
  if print_empty_line {
  @@ -352,7 +343,7 @@ pub fn print<'a>(
  } else {
  print_empty_line = true;
  }
  - lock.write_all(output.as_bytes())?;
  + lock.write_all(&output.stdout)?;
  drop(lock);
  }
  Ok(())
  