`adt_const_params` fun

main.rs

#![feature(adt_const_params)]
#![allow(incomplete_features, clippy::disallowed_names)]

#[derive(Debug)]
struct Foo {
    bar: i32,
    baz: String,
}

trait Field<T, const NAME: &'static str> {}
trait Get<T> {
    fn get<const NAME: &'static str>(&self) -> &T
    where
        Self: Field<T, NAME>;
}

impl Field<i32, "bar"> for Foo {}
impl Get<i32> for Foo {
    fn get<const NAME: &'static str>(&self) -> &i32 {
        &self.bar
    }
}

impl Field<String, "baz"> for Foo {}
impl Get<String> for Foo {
    fn get<const NAME: &'static str>(&self) -> &String {
        &self.baz
    }
}

fn main() {
    let foo = Foo {
        bar: 42,
        baz: "666".into(),
    };

    dbg!(foo.get::<"bar">());
    dbg!(foo.get::<"baz">());
    // dbg!(foo.get::<"quux">()); -- the trait `Field<_, "quux">` is not implemented for `Foo`
}