  --> [ local path prefix ]/top_ports/implements_missing_port_beyond_four.fpp:19:23
   |
19 | topology A implements I {
   |                       ^ port interface not implemented
   |
  ::: [ local path prefix ]/top_ports/implements_missing_port_beyond_four.fpp:4:5
   |
 4 |     output port p5: [5] P
   |     --------------------- port instance missing

