error: struct must have at least one generic parameter.
 --> $DIR/err-01-no-generic.rs:6:8
  |
6 | struct AllSubsystems {
  |        ^^^^^^^^^^^^^

error[E0599]: no method named `replace_a` found for struct `AllSubsystems` in the current scope
  --> $DIR/err-01-no-generic.rs:16:17
   |
6  | struct AllSubsystems {
   | -------------------- method `replace_a` not found for this
...
16 |     let _all = all.replace_a(77u8);
   |                    ^^^^^^^^^ method not found in `AllSubsystems`