error[E0046]: not all trait items implemented, missing: `Error` --> $DIR/issue-103181-1.rs:9:5 | LL | type Error; | ---------- `Error` from trait LL | } LL | impl HttpBody for () { | ^^^^^^^^^^^^^^^^^^^^ missing `Error` in implementation error: aborting due to previous error For more information about this error, try `rustc --explain E0046`.