fix: correctly reference destructured derived binding in event handler (#10333)

.changeset/strong-pans-doubt.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: correctly reference destructured derived binding in event handler

packages/svelte/src/compiler/phases/3-transform/client/utils.js

@@ -523,6 +523,16 @@ function get_hoistable_params(node, context) {
 				// We need both the subscription for getting the value and the store for updating
 				params.push(b.id(binding.node.name.slice(1)));
 				params.push(b.id(binding.node.name));
+			} else if (
+				// If it's a destructured derived binding, then we can extract the derived signal reference and use that.
+				binding.expression !== null &&
+				binding.expression.type === 'MemberExpression' &&
+				binding.expression.object.type === 'CallExpression' &&
+				binding.expression.object.callee.type === 'Identifier' &&
+				binding.expression.object.callee.name === '$.get' &&
+				binding.expression.object.arguments[0].type === 'Identifier'
+			) {
+				params.push(b.id(binding.expression.object.arguments[0].name));
 			} else if (
 				// If we are referencing a simple $$props value, then we need to reference the object property instead
 				binding.kind === 'prop' &&

packages/svelte/tests/runtime-runes/samples/destructure-derived-event/_config.js

@@ -0,0 +1,15 @@
+import { test } from '../../test';
+import { log } from './log.js';
+
+export default test({
+	before_test() {
+		log.length = 0;
+	},
+
+	async test({ assert, target, window }) {
+		const btn = target.querySelector('button');
+		await btn?.click();
+
+		assert.deepEqual(log, ['works!']);
+	}
+});

packages/svelte/tests/runtime-runes/samples/destructure-derived-event/log.js

@@ -0,0 +1,2 @@
+/** @type {any[]} */
+export const log = [];

packages/svelte/tests/runtime-runes/samples/destructure-derived-event/main.svelte

@@ -0,0 +1,15 @@
+<script>
+	import { log } from './log.js';
+
+	let structured = $state({
+		handler() {
+			log.push('works!')
+		}
+	});
+</script>
+
+{#if structured}
+  {@const { handler } = structured}
+
+  <button onclick={() => handler()}>click me</button>
+{/if}