Add Clone trait to Unique

[gilhooleyd]

Using a Unique iterator requires the Clone trait, so require this trait when creating the Unique object.

See the discussion in #776

[Philippe-Cholet]

I was not gonna suggest to make a test for it but I see your point.
I would only suggest to keep things as simple as possible with just #[...] struct Item(u32);.
And format to pass CI.

[Philippe-Cholet]

Is the unique test not enough?! (in the same test file)

[jswrenn]

Yeah, there's no need to add an extra test here. Delete the test, run cargo fmt, and we can merge this.

[gilhooleyd]

Thanks for both of your help! I think I've removed the test with the new CL.

I added the test originally when I was trying to remove Clone, and the struct I created didn't implement Clone.
You're right that now that Clone is required, this does the exact same thing as the existing tests.

I wish this functionality didn't require Clone, but I see now that it's necessary to do the in-place iteration while removing dups. Thank you again for your time!

[jswrenn]

Ah, wait, could you also add it to the struct definition?

[jswrenn]

Like so:

#[derive(Clone)]
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
pub struct Unique<I>
where
    I: Iterator,
    I::Item: Eq + Hash + Clone,
{
    iter: UniqueBy<I, I::Item, ()>,
}

[gilhooleyd]

Done! Apologies for the churn

[Philippe-Cholet]

It's not a problem but could you squash these commits into one simple commit?

EDIT: Done, thanks!