vector<Target *> group = extract_group(pending, *tool);
FileTarget &tgt = dynamic_cast<FileTarget &>(*tool->create_target(group));
pending.push_back(&tgt);
vector<Target *> group = extract_group(pending, *tool);
FileTarget &tgt = dynamic_cast<FileTarget &>(*tool->create_target(group));
pending.push_back(&tgt);