error: unit struct has nothing to dissolve
 --> tests/allref/10-dissolve-unit-struct.rs:3:30
  |
3 | #[derive(Debug, Copy, Clone, Dissolve)]
  |                              ^^^^^^^^
  |
  = note: this error originates in the derive macro `Dissolve` (in Nightly builds, run with -Z macro-backtrace for more info)