error[E0308]: mismatched types --> $DIR/sugar.rs:12:7 | LL | a(x); | ^ expected trait `Foo + Send`, found trait `Foo + Sync` | = note: expected struct `Box<(dyn Foo + Send + 'static)>` found struct `Box<(dyn Foo + Sync + 'static)>` error: aborting due to previous error For more information about this error, try `rustc --explain E0308`.