File: type-alias-impl-trait-in-fn-body.rs

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rustc 1.87.0%2Bdfsg1-1
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//! Test that it is basically not possible to declare *and opaquely use* opaque types
//! in function bodies. This will work again once we have a `#[defines]` attribute

#![feature(type_alias_impl_trait)]

use std::fmt::Debug;

fn main() {
    //~^ ERROR: item does not constrain
    type Existential = impl Debug;

    #[define_opaque(Existential)]
    fn f() -> Existential {}
    println!("{:?}", f());
}