src/test/ui/impl-trait/issues/issue-70877.rs

   1 // revisions: min_tait full_tait
   2 #![feature(min_type_alias_impl_trait)]
   3 #![cfg_attr(full_tait, feature(type_alias_impl_trait))]
   4 #![feature(impl_trait_in_bindings)]
   5 #![allow(incomplete_features)]
   6
   7 type FooArg<'a> = &'a dyn ToString;
   8 type FooRet = impl std::fmt::Debug;
   9
  10 type FooItem = Box<dyn Fn(FooArg) -> FooRet>;
  11 type Foo = impl Iterator<Item = FooItem>; //~ ERROR: type mismatch
  12
  13 #[repr(C)]
  14 struct Bar(u8);
  15
  16 impl Iterator for Bar {
  17     type Item = FooItem;
  18
  19     fn next(&mut self) -> Option<Self::Item> {
  20         Some(Box::new(quux))
  21     }
  22 }
  23
  24 fn quux(st: FooArg) -> FooRet {
  25     Some(st.to_string())
  26 }
  27
  28 fn ham() -> Foo {
  29     Bar(1)
  30 }
  31
  32 fn oof() -> impl std::fmt::Debug {
  33     let mut bar = ham();
  34     let func = bar.next().unwrap();
  35     return func(&"oof");
  36 }
  37
  38 fn main() {
  39     let _ = oof();
  40 }