Shared via Rust Playground

playground.rs

use std::any::Any;

trait Schema {
    fn eq(&self, other: &Schema) -> bool;
    fn as_any(&self) -> &Any;
}

impl PartialEq<Schema> for Schema {
    fn eq(&self, other: &Schema) -> bool {
        Schema::eq(self, other)
    }
}

#[derive(PartialEq)]
struct Foo(i32);

impl Schema for Foo {
    fn eq(&self, other: &Schema) -> bool {
         other.as_any().downcast_ref::<Self>().map_or(false, |x| x == self)
    }

    fn as_any(&self) -> &Any { self }
}

#[derive(PartialEq)]
struct Bar;

impl Schema for Bar {
    fn eq(&self, other: &Schema) -> bool {
         other.as_any().downcast_ref::<Self>().map_or(false, |x| x == self)
    }

    fn as_any(&self) -> &Any { self }
}

fn main() {
    let foo1: &(Schema+'static) = &Foo(1);

    if PartialEq::eq(foo1, foo1) {
        println!("Hello, world!");
    }
}