error[E0377]: the trait `CoerceUnsized` may only be implemented for a coercion between structures --> $DIR/E0377.rs:12:1 | LL | impl CoerceUnsized> for Foo where T: CoerceUnsized {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: expected coercion between the same definition; expected `Foo`, found `Bar` error: aborting due to previous error For more information about this error, try `rustc --explain E0377`.