error: Input port index is unused. (Is the port on the correct side?)
 --> tests/compile-fail/surface_port_unused_both.rs:7:10
  |
7 |         [0]src -> dst[0];
  |          ^

error: Output port index is unused. (Is the port on the correct side?)
 --> tests/compile-fail/surface_port_unused_both.rs:7:23
  |
7 |         [0]src -> dst[0];
  |                       ^