warning: method `foo` is never used
  --> $DIR/issue-22536-copy-mustnt-zero.rs:8:8
   |
LL | trait Resources {
   |       --------- method in this trait
LL |     type Buffer: Copy;
LL |     fn foo(&self) {}
   |        ^^^
   |
   = note: `#[warn(dead_code)]` on by default

warning: 1 warning emitted