Second-level function not doing reactive update

[hykilpikonna]

Describe the bug

Second-level function updates are not triggering reactive update, as it's not wrapped with $.mutate by the compiler. Is there a way to manually do $.mutate?

<script lang="ts">
  let obj = {count: 0}	
  const increment = () => obj.count++
	const helper = (o) => o.count++
</script>

<div>count is {obj.count}</div>

<button onclick={increment}>+1</button>
<button onclick={() => helper(obj)}>+1</button>

Reproduction

https://svelte.dev/playground/19fcb36153b84f83b83fb9ba92b38463?version=5.14.4

Logs

No response

System Info

System:
    OS: Windows 11 10.0.22631
    CPU: (16) x64 AMD Ryzen 7 7840HS with Radeon 780M Graphics
    Memory: 3.75 GB / 27.69 GB
  Binaries:
    Node: 22.5.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
    bun: 1.1.38 - ~\.bun\bin\bun.EXE
  Browsers:
    Edge: Chromium (127.0.2651.74)
    Internet Explorer: 11.0.22621.3527

Severity

annoyance

[webJose]

Are you intentionally staying in Svelte v4?

[hykilpikonna]

Are you intentionally staying in Svelte v4?

Yes, see this issue for my issue with Svelte 5 Runes: #14754

[webJose]

I see. Ok, in this case, what you present here is Svelte v4's inability to refactor things in a nice way, and one of the main drivers for signals (runes). Generally speaking, what you want is not possible.

Maybe some son of a gun like a core team member could help you further here, so I'll just shut up now since I have no solutions for you.

[paoloricciuti]

Yup this is just how svelte 4 works and one of the main reasons why svelte 5 is a rewrite. Thanks for reporting but I'm gonna close this

[webJose]

BTW, if PR #14639 is released, you could pair it with alien-signals or similar. Maybe that way you could achieve your goal.

[hykilpikonna]

Yup this is just how svelte 4 works and one of the main reasons why svelte 5 is a rewrite. Thanks for reporting but I'm gonna close this

It would be nice to have a way to manually trigger or wrap $.mutate in a function...