Shared via Rust Playground

playground.rs

use std::any::Any;

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

impl<'a, 'b> PartialEq<Schema+'b> for Schema+'a {
    fn eq(&self, other: &(Schema+'b)) -> 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 = &Foo(1);
    let foo2: &Schema = &Foo(2);
    let bar: &Schema = &Bar;

    if foo1 == foo1 && foo1 != foo2 && foo1 != bar {
        println!("Hello, world!");
    }
}