message: some more debug output
diff: @@ -820,10 +820,10 @@ fn phase_rustc(mut args: env::Args, phase: RustcPhase) {
  if verbose > 0 {
  eprintln!(
  - "[cargo-miri rustc] captured input:\n{}",
  + "[cargo-miri rustc inside rustdoc] captured input:\n{}",
  std::str::from_utf8(&env.stdin).unwrap()
  );
  - eprintln!("[cargo-miri rustc] {:?}", cmd);
  + eprintln!("[cargo-miri rustc inside rustdoc] going to run:\n{:?}", cmd);
  }
  exec_with_pipe(cmd, &env.stdin);
  @@ -906,7 +906,10 @@ fn phase_rustc(mut args: env::Args, phase: RustcPhase) {
  // Run it.
  if verbose > 0 {
  - eprint!("[cargo-miri rustc] ");
  + eprintln!(
  + "[cargo-miri rustc] target_crate={target_crate} runnable_crate={runnable_crate} print={print}"
  + );
  + eprintln!("[cargo-miri rustc] going to run:");
  if verbose > 1 {
  for (key, value) in env_vars_from_cmd(&cmd) {
  eprintln!("{key}={value:?} \\");
  