From bec570891a3bf640ddf7a5d1cb349ff7b5bf6565 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 14 Jan 2025 17:19:04 -0500
Subject: [PATCH] fix spreading of symbol properties onto component

---
 packages/svelte/src/internal/client/reactivity/props.js  | 5 +++++
 .../samples/attachment-component-spread/Child.svelte     | 5 +++++
 .../samples/attachment-component-spread/_config.js       | 6 ++++++
 .../samples/attachment-component-spread/main.svelte      | 9 +++++++++
 4 files changed, 25 insertions(+)
 create mode 100644 packages/svelte/tests/runtime-runes/samples/attachment-component-spread/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/attachment-component-spread/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/attachment-component-spread/main.svelte

diff --git a/packages/svelte/src/internal/client/reactivity/props.js b/packages/svelte/src/internal/client/reactivity/props.js
index 3e5a0258c7..4017be56ab 100644
--- a/packages/svelte/src/internal/client/reactivity/props.js
+++ b/packages/svelte/src/internal/client/reactivity/props.js
@@ -231,9 +231,14 @@ const spread_props_handler = {
 
 		for (let p of target.props) {
 			if (is_function(p)) p = p();
+
 			for (const key in p) {
 				if (!keys.includes(key)) keys.push(key);
 			}
+
+			for (const key of Object.getOwnPropertySymbols(p)) {
+				if (!keys.includes(key)) keys.push(key);
+			}
 		}
 
 		return keys;
diff --git a/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/Child.svelte b/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/Child.svelte
new file mode 100644
index 0000000000..6760da61fa
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/Child.svelte
@@ -0,0 +1,5 @@
+<script>
+	let props = $props();
+</script>
+
+<div {...props}></div>
diff --git a/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/_config.js b/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/_config.js
new file mode 100644
index 0000000000..fa1c9b0599
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/_config.js
@@ -0,0 +1,6 @@
+import { test } from '../../test';
+
+export default test({
+	ssrHtml: `<div></div>`,
+	html: `<div>set from component</div>`
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/main.svelte b/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/main.svelte
new file mode 100644
index 0000000000..cf2551a8cf
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/attachment-component-spread/main.svelte
@@ -0,0 +1,9 @@
+<script>
+	import Child from './Child.svelte';
+
+	let stuff = $state({
+		[Symbol()]: (node) => node.textContent = 'set from component'
+	});
+</script>
+
+<Child {...stuff} />