Invalidating functions cannot be declared as @const

[brunnerh]

Describe the bug

If a function is defined via @const that causes invalidation of state, this will throw an error because $$invalidate will not be in scope.

Possibly a known/intended limitation.

Reproduction

<script>
	let items = [
		{ name: 'A', selected: true },
		{ name: 'B', selected: false },
		{ name: 'C', selected: false },
	]
</script>

{#each items as item}
	{@const toggle = () => item.selected = !item.selected}
	<div>
		{item.selected ? '☑' : '☐'}
		{item.name}
		<button on:click={toggle}>Toggle</button>
	</div>
{/each}

REPL

Logs

Uncaught ReferenceError: $$invalidate is not defined
    at HTMLButtonElement.constants_0 (eval at handle_message (about:srcdoc:14:8), <anonymous>:389:32)
    at HTMLButtonElement.eval (eval at handle_message (about:srcdoc:14:8), <anonymous>:435:65)

System Info

REPL / Chrome & Firefox

Severity

annoyance

[Conduitry]

This should be fixed in 3.54.0 - https://svelte.dev/repl/fc201eac554e4ef89256a46e49efdee2?version=3.54.0