use std::default::Default;

fn main() {
    // this works
    let def = Defaultable::<usize>::default();
    // this does not
    let def = Defaultable::<MyDs>::default();
}

#[derive(Default)]
struct Defaultable<T> {
    inner: Option<T>,
    a_field: usize,
}

struct MyDs;

// #[derive(Default)]
// pub struct MyStruct<T> {
//     id: usize,
//     inner: Option<T>,
// }

// type MyAlias = MyStruct<MyDs>;