rust/tests/fail/dyn-upcast-trait-mismatch.rs

#![feature(trait_upcasting)]
#![allow(incomplete_features)]

trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
    fn a(&self) -> i32 {
        10
    }

    fn z(&self) -> i32 {
        11
    }

    fn y(&self) -> i32 {
        12
    }
}

trait Bar: Foo {
    fn b(&self) -> i32 {
        20
    }

    fn w(&self) -> i32 {
        21
    }
}

trait Baz: Bar {
    fn c(&self) -> i32 {
        30
    }
}

impl Foo for i32 {
    fn a(&self) -> i32 {
        100
    }
}

impl Bar for i32 {
    fn b(&self) -> i32 {
        200
    }
}

impl Baz for i32 {
    fn c(&self) -> i32 {
        300
    }
}

fn main() {
    let baz: &dyn Baz = &1;
    // We already fail on the implicit upcast inserted here.
    let baz_fake: &dyn Bar = unsafe { std::mem::transmute(baz) };
    //~^ERROR: upcast on a pointer whose vtable does not match its type
    let _err = baz_fake as &dyn Foo;
}