src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.rs

// Validation stops this too early.
//@compile-flags: -Zmiri-disable-validation

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

    #[allow(dead_code)]
    fn z(&self) -> i32 {
        11
    }

    #[allow(dead_code)]
    fn y(&self) -> i32 {
        12
    }
}

trait Bar: Foo {
    #[allow(dead_code)]
    fn b(&self) -> i32 {
        20
    }

    #[allow(dead_code)]
    fn w(&self) -> i32 {
        21
    }
}

trait Baz: Bar {
    #[allow(dead_code)]
    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() {
    unsafe {
        let baz: &dyn Baz = &1;
        let baz_fake: *const dyn Bar = std::mem::transmute(baz);
        let _err = baz_fake as *const dyn Foo;
        //~^ERROR: using vtable for `Baz` but `Bar` was expected
    }
}