error[E0277]: the trait bound `S: Hidden` is not satisfied
  --> $DIR/sealed-trait-local.rs:17:20
   |
LL | impl a::Sealed for S {}
   |                    ^ the trait `Hidden` is not implemented for `S`
   |
note: required by a bound in `Sealed`
  --> $DIR/sealed-trait-local.rs:3:23
   |
LL |     pub trait Sealed: self::b::Hidden {
   |                       ^^^^^^^^^^^^^^^ required by this bound in `Sealed`
   = note: `Sealed` is a "sealed trait", because to implement it you also need to implement `a::b::Hidden`, which is not accessible; this is usually done to force you to use one of the provided types that already implement it

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.