error[E0277]: `&T` needs to have the same ABI as a pointer --> $DIR/check-size-at-cast-polymorphic-bad.rs:11:15 | LL | dyn_debug(t); | ^ `&T` needs to be a pointer-like type | = help: the trait `PointerLike` is not implemented for `&T` help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement | LL | fn polymorphic(t: &T) where &T: PointerLike { | +++++++++++++++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.