  ipcp_value()
    : sources (0), next (0), scc_next (0), topo_next (0),
      spec_node (0), dfs (0), low_link (0), on_stack (false) {}
  ipcp_value()
    : sources (0), next (0), scc_next (0), topo_next (0),
      spec_node (0), dfs (0), low_link (0), on_stack (false) {}