tests/ui/type-alias-impl-trait/unnameable_type.rs


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#![feature(type_alias_impl_trait)]

// This test ensures that unnameable types stay unnameable
// https://github.com/rust-lang/rust/issues/63063#issuecomment-1360053614

// library
mod private {
    pub struct Private;
    pub trait Trait {
        fn dont_define_this(_private: Private) {}
    }
}

use private::Trait;

// downstream
type MyPrivate = impl Sized;
//~^ ERROR: unconstrained opaque type
impl Trait for u32 {
    fn dont_define_this(_private: MyPrivate) {}
    //~^ ERROR: incompatible type for trait
}

fn main() {}