binding wrongly invalidates value that doesn't depend on it

[pushkine]

Consider the following :

<script>
	const object = { property : 'string' }
	$: value = object.property
</script>

<input bind:value />

svelte rightly compiles it down to :

function input_input_handler() {
	value = this.value;
	$$invalidate(0, value);
}

now add a button that mutates object.property on click

<button on:click={() => (object.property = 'string')}>

and svelte will wrongly also invalidate object at input

function input_input_handler() {
	value = this.value;
	($$invalidate(1, value), $$invalidate(0, object));
}

which will in turn trigger the reactive statement $: value = object.property altough only value changed

this compiles into the same code with immutables, it just doesn't run reactive statements because of equality checks

https://svelte.dev/repl/21f9a5430bf34348b471417a30fb0af9?version=3.18.2

related : #4426

[Conduitry]

This seems to be related to the fix for #2444, and I'm not sure what the correct behavior is here.

[tanhauhau]

hmm.. you are binding with a reactive declared variable, value, the value of value is always derived from object.property, so are you expecting when changing value of value via <input bind:value /> gets propagated back to object.property ? 🤔

[tanhauhau]

relevant:

<script>
  import Component from './Component.svelte';
	
	export let emails = ['[email protected]', '[email protected]'];
	$: set = new Set(emails)
</script>

{#each emails as email}
	<Component email={email} bind:set />
{/each}

https://svelte.dev/repl/3a8736942c8149fea7e88b864fa7d9e1?version=3.23.0

updating set, invalidates both set and email, causing it to always reset

[ribizli]

Similar situation here with store and array: https://svelte.dev/repl/9bc03311dae044e8b9de7776735a8e09?version=3.24.1
Checkbox cannot be checked, because it will be reset. (this is a reproduction REPL only)

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[stale]

This issue has been closed as it was previously marked as stale and saw no subsequent activity.