trait Marker {} impl Marker for u32 {} trait MyTrait { fn foo(&self) -> impl Marker where Self: Sized; } struct Outer; impl MyTrait for Outer { fn foo(&self) -> impl Marker { 42 } } impl dyn MyTrait { fn other(&self) -> impl Marker { MyTrait::foo(&self) //~^ ERROR the trait bound `&dyn MyTrait: MyTrait` is not satisfied //~| ERROR the trait bound `&dyn MyTrait: MyTrait` is not satisfied } } fn main() {}