Kmerge fails

[rust-itertools]

Kmerge fails

[tailhook]

Ah, okay, it's not a crash it actually is wrong result :)

[tailhook]

Here is a test with more clear output:

#[test]
fn kmerge_reverse() {
    let its = vec![3, 2, 1, 0].into_iter().map(|s| (s..10).step(4));
    assert_eq!(
        its.kmerge().collect::<Vec<_>>(),
        (0..10).collect::<Vec<_>>());
}

Output:

   thread 'kmerge_reverse' panicked at 'assertion failed: `(left == right)`
   (left: `[1, 0, 2, 3, 4, 5, 6, 7, 8, 9]`, right: `[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]`)', tests/tests.rs:416

[bluss]

Thanks for the bug report!

[tailhook]

This produces a bug in my application. So if you're not looking at it, can you give me some pointers where the error might be?

[bluss]

src/kmerge.rs has the heap logic. Prime suspicion would be that the bespoke heap logic is to blame. I'm a bit curious why the quickcheck doesn't catch it though. Probably because it's always testing exactly three input iterators.

[tailhook]

Looks good. Thanks!

[bluss]

0.4.17 released with the fix. In hindsight, it's obvious that the existing quickcheck for kmerge didn't exercise it fully (always used a heap of size 3 or smaller).