rust/tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.rs

25 lines
565 B
Rust

//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
#![feature(trait_upcasting)]
trait Super {
type Assoc;
}
trait Sub: Super {}
impl<T: ?Sized> Super for T {
type Assoc = i32;
}
fn illegal(x: &dyn Sub<Assoc = ()>) -> &dyn Super<Assoc = i32> { x }
//~^ ERROR mismatched types
// Want to make sure that we can't "upcast" to a supertrait that has a different
// associated type that is instead provided by a blanket impl (and doesn't come
// from the object bounds).
fn main() {}