error: 'Dog' does not implement protocol 'Speaker': no `impl Speaker for Dog` provides method 'speak' (protocol erasure is impl-driven — a plain or `ufcs` free function with a matching receiver does not satisfy a protocol)
  --> examples/diagnostics/1197-diagnostics-protocol-erasure-no-impl.sx:18:16
   |
18 |   h : Holder = .{ s = d, b = 5 };   // <- 'Dog' does not implement 'Speaker'
   |                ^^^^^^^^^^^^^^^^^