error[E0375]: implementing the trait `CoerceUnsized` requires multiple coercions --> $DIR/E0375.rs:10:12 | LL | impl CoerceUnsized> for Foo {} | ^^^^^^^^^^^^^^^^^^^^^^^^ requires multiple coercions | = note: `CoerceUnsized` may only be implemented for a coercion between structures with one field being coerced = note: currently, 2 fields need coercions: `b` (`T` to `U`), `c` (`U` to `T`) error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0375`.