repro.rs

enum Option<T> { Some(T), None }

fn try_reduce_with<PI, R, T>(pi: PI, reduce_op: R) -> Option<T>
where
    PI: ParallelIterator<Item = T>,
    R: Fn(T::Ok, T::Ok) -> T + Sync,
    T: Try + Send,
{
    let full = AtomicBool::new(false);
    let consumer = TryReduceWithConsumer {
        reduce_op: &reduce_op,
        full: &full,
    };
    pi.drive_unindexed(consumer)
}

struct TryReduceWithConsumer<'r, R: 'r> {
    reduce_op: &'r R,
    full: &'r AtomicBool,
}


pub trait ParallelIterator: Sized + Send {
    type Item: Send;

    fn drive_unindexed<C>(self, consumer: C) -> C::Result
    where
        C: UnindexedConsumer<Self::Item>;
}

pub trait Try {
    type Ok;
    type Error;
}