error[E0599]: no variant named `Triangle` found for enum `Shape`
  --> tests/compile-fail/surface_demuxenum_port_extramissing.rs:20:18
   |
6  |     enum Shape {
   |     ---------- variant `Triangle` not found here
...
20 |         my_demux[Triangle] -> for_each(std::mem::drop);
   |                  ^^^^^^^^ variant not found in `Shape`