Function clean_during_match

libbuild2/algorithm.cxx:3325–3365

  }

  bool
  clean_during_match (tracer& trace, action a, const target& t)
  {
    // Let's keep this as close to update_during_match() semantically as
    // possible until we see a clear reason to deviate.

    // We have a problem with fsdir{}: if the directory is not empty because
    // there are other targets that depend on it and we execute it here and
    // now, it will not remove the directory (because it's not yet empty) but
    // will cause the target to be in the executed state, which means that
    // when other targets try to execute it, it will be a noop and the
    // directory will be left behind.

    assert (a == perform_clean_id && !t.is_a<fsdir> ());

    target_state os (t.matched_state (a));

    if (os == target_state::unchanged)
      return false;
    else
    {
      target_state ns;
      if (os != target_state::changed)
      {
        phase_switch ps (t.ctx, run_phase::execute);
        ns = execute_direct_sync (a, t);
      }
      else
        ns = os;

      if (ns != os && ns != target_state::unchanged)
      {
        l6 ([&]{trace << "cleaned " << t
                      << "; old state " << os
                      << "; new state " << ns;});
        return true;
      }
      else
        return false;
    }
  }

  bool
  clean_during_match_prerequisites (tracer& trace,