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#![feature(type_alias_impl_trait)]
type FooArg<'a> = &'a dyn ToString;
type FooItem = Box<dyn Fn(FooArg) -> FooRet>;
#[repr(C)]
struct Bar(u8);
impl Iterator for Bar {
type Item = FooItem;
fn next(&mut self) -> Option<Self::Item> {
Some(Box::new(quux))
}
}
pub type FooRet = impl std::fmt::Debug;
#[define_opaque(FooRet)]
pub fn quux(st: FooArg) -> FooRet {
Some(st.to_string())
}
pub type Foo = impl Iterator<Item = FooItem>;
#[define_opaque(Foo)]
pub fn ham() -> Foo {
//~^ ERROR: item does not constrain `FooRet::{opaque#0}`
Bar(1)
}
#[define_opaque(Foo)]
pub fn oof() -> impl std::fmt::Debug {
//~^ ERROR: item does not constrain `FooRet::{opaque#0}`
//~| ERROR: item does not constrain `Foo::{opaque#0}`
let mut bar = ham();
let func = bar.next().unwrap();
return func(&"oof");
//~^ ERROR: opaque type's hidden type cannot be another opaque type
}
fn main() {
let _ = oof();
}
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