error: methods with the following characteristics: (`to_*` and `self` type is not `Copy`) usually take `self` by reference
  --> $DIR/wrong_self_convention2.rs:28:19
   |
LL |         fn to_u64(self) -> u64 {
   |                   ^^^^
   |
   = note: `-D clippy::wrong-self-convention` implied by `-D warnings`
   = help: consider choosing a less ambiguous name

error: aborting due to previous error