| error[E0038]: the trait `Expr` is not dyn compatible | 
 |   --> $DIR/mentions-Self-in-super-predicates.rs:12:27 | 
 |    | | 
 | LL |     elements: Vec<Box<dyn Expr + 'x>>, | 
 |    |                           ^^^^ `Expr` is not dyn compatible | 
 |    | | 
 | note: for a trait to be dyn compatible it needs to allow building a vtable | 
 |       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility> | 
 |   --> $DIR/mentions-Self-in-super-predicates.rs:5:21 | 
 |    | | 
 | LL | trait Expr: Debug + PartialEq { | 
 |    |       ----          ^^^^^^^^^ ...because it uses `Self` as a type parameter | 
 |    |       | | 
 |    |       this trait is not dyn compatible... | 
 |  | 
 | error[E0038]: the trait `Expr` is not dyn compatible | 
 |   --> $DIR/mentions-Self-in-super-predicates.rs:38:20 | 
 |    | | 
 | LL |     let a: Box<dyn Expr> = Box::new(SExpr::new()); | 
 |    |                    ^^^^ `Expr` is not dyn compatible | 
 |    | | 
 | note: for a trait to be dyn compatible it needs to allow building a vtable | 
 |       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility> | 
 |   --> $DIR/mentions-Self-in-super-predicates.rs:5:21 | 
 |    | | 
 | LL | trait Expr: Debug + PartialEq { | 
 |    |       ----          ^^^^^^^^^ ...because it uses `Self` as a type parameter | 
 |    |       | | 
 |    |       this trait is not dyn compatible... | 
 |  | 
 | error[E0038]: the trait `Expr` is not dyn compatible | 
 |   --> $DIR/mentions-Self-in-super-predicates.rs:40:20 | 
 |    | | 
 | LL |     let b: Box<dyn Expr> = Box::new(SExpr::new()); | 
 |    |                    ^^^^ `Expr` is not dyn compatible | 
 |    | | 
 | note: for a trait to be dyn compatible it needs to allow building a vtable | 
 |       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility> | 
 |   --> $DIR/mentions-Self-in-super-predicates.rs:5:21 | 
 |    | | 
 | LL | trait Expr: Debug + PartialEq { | 
 |    |       ----          ^^^^^^^^^ ...because it uses `Self` as a type parameter | 
 |    |       | | 
 |    |       this trait is not dyn compatible... | 
 |  | 
 | error: aborting due to 3 previous errors | 
 |  | 
 | For more information about this error, try `rustc --explain E0038`. |