[HypeMC]

Heap operations shared callback state, so using another heap during iteration or inside a comparator could cause incorrect ordering. Pass the owning heap into comparisons and keep callback invocation state local.

This bug predates #234 and already affected ordinary foreach. Returning InternalIterator added another way to encounter it through interleaved iterators.

For example:

$min = new Ds\Heap([1, 2, 3, 4, 5], fn($a, $b) => $b <=> $a);
$max = new Ds\Heap([1, 2, 3, 4, 5], fn($a, $b) => $a <=> $b);

$values = [];
foreach ($min as $value) {
    $values[] = $value;
    foreach ($max as $_) {}
}
echo json_encode($values);

Before: [1,2,5,4,3]
After: [1,2,3,4,5]