impl Trait
types cannot appear nested in the generic arguments of other impl Trait
types.
Erroneous code example:
trait MyGenericTrait<T> {} trait MyInnerTrait {} fn foo( bar: impl MyGenericTrait<impl MyInnerTrait>, // error! ) {}
Type parameters for impl Trait
types must be explicitly defined as named generic parameters:
trait MyGenericTrait<T> {} trait MyInnerTrait {} fn foo<T: MyInnerTrait>( bar: impl MyGenericTrait<T>, // ok! ) {}