| #![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(); |
| } |
