1 An `impl Trait` type expands to a recursive type.
3 Erroneous code example:
6 fn make_recursive_type() -> impl Sized {
7 [make_recursive_type(), make_recursive_type()]
11 An `impl Trait` type must be expandable to a concrete type that contains no
12 `impl Trait` types. For example the previous example tries to create an
13 `impl Trait` type `T` that is equal to `[T, T]`.