mirror of https://github.com/rust-lang/rust
37 lines
687 B
Rust
37 lines
687 B
Rust
#![feature(type_alias_impl_trait)]
|
|
|
|
type FooArg<'a> = &'a dyn ToString;
|
|
type FooRet = impl std::fmt::Debug;
|
|
|
|
type FooItem = Box<dyn Fn(FooArg) -> FooRet>;
|
|
type Foo = impl Iterator<Item = FooItem>;
|
|
|
|
#[repr(C)]
|
|
struct Bar(u8);
|
|
|
|
impl Iterator for Bar {
|
|
type Item = FooItem;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
Some(Box::new(quux))
|
|
}
|
|
}
|
|
|
|
fn quux(st: FooArg) -> FooRet {
|
|
Some(st.to_string())
|
|
}
|
|
|
|
fn ham() -> Foo {
|
|
Bar(1)
|
|
}
|
|
|
|
fn oof(_: Foo) -> impl std::fmt::Debug {
|
|
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(ham());
|
|
}
|