Svelte 5: "ownership_invalid_binding" with arrays

[dm-de]

Describe the bug

I'm unable to get rid of "ownership_invalid_binding" warning, which happens - for example - if I slice an array.

Look for Table.svelte in bottom example.
Table has a pagination inside - and it is required to slice the array.
So I use $effect to create new sliced array.

Reproduction

It shows warnng "ownership_invalid_binding" on start.
If you click pages 1 or 2. You will see more of them.

LINK

Logs

No response

System Info

svelte@5.0.0-next.243

Severity

annoyance

[paoloricciuti]

My immediate suspicion is that slice is updating the length source inside the array...since the length source has been created in App.svelte (at the moment of the array creation) and you are binding the array but not length this might cause some problem...will investigate this a bit later.

[trueadm]

So the issue here is these lines

$effect(() => {
  rows2 = rows.slice((page - 1) * limit, page * limit)
})

It messes with the ownership logic because rows2 might belong to Table.svelte, so it can be bound through as a prop, but all its contents are owned by App.svelte – so the ownership logic is muddled up. If you pass through bind:rows={rows}, things work fine again.

I'm honestly unsure how to approach this one and @Rich-Harris and @dummdidumm have more context here, so I'll defer to them.