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type Result<T, E = Error> = ::std::result::Result<T, E>;
struct Error;
trait ForEach {
type Input;
fn for_each<F, U>(self, f: F)
where
F: FnOnce(Self::Input) -> U;
}
impl<T> ForEach for A<T> {
type Input = T;
fn for_each<F, U>(self, f: F)
where
F: FnOnce(Self::Input) -> U,
{
todo!()
}
}
struct A<T>(T);
fn main() {
let a = A(Result::Ok(Result::Ok(()))); //~ ERROR type annotations needed
a.for_each(|a: Result<_>| {
let f = || match a {
Ok(Ok(a)) => {}
Ok(Err(a)) => {}
Err(a) => {}
};
});
}
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