From cb14c6dbd8e2e62bd68a85e4ecbdd049e22cbc00 Mon Sep 17 00:00:00 2001
From: Emil Tholin <emtholin@gmail.com>
Date: Mon, 9 Jan 2023 02:01:00 +0100
Subject: [PATCH] Spread component props immutably during SSR

---
 .../compile/render_ssr/handlers/InlineComponent.ts    |  2 +-
 .../Component.svelte                                  |  0
 .../ssr-spread-component-props-immutably/_config.js   |  5 +++++
 .../ssr-spread-component-props-immutably/expected.js  | 11 +++++++++++
 .../ssr-spread-component-props-immutably/input.svelte | 11 +++++++++++
 5 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 test/js/samples/ssr-spread-component-props-immutably/Component.svelte
 create mode 100644 test/js/samples/ssr-spread-component-props-immutably/_config.js
 create mode 100644 test/js/samples/ssr-spread-component-props-immutably/expected.js
 create mode 100644 test/js/samples/ssr-spread-component-props-immutably/input.svelte

diff --git a/src/compiler/compile/render_ssr/handlers/InlineComponent.ts b/src/compiler/compile/render_ssr/handlers/InlineComponent.ts
index 8287b46268..73d31940e2 100644
--- a/src/compiler/compile/render_ssr/handlers/InlineComponent.ts
+++ b/src/compiler/compile/render_ssr/handlers/InlineComponent.ts
@@ -36,7 +36,7 @@ export default function(node: InlineComponent, renderer: Renderer, options: Rend
 	let props;
 
 	if (uses_spread) {
-		props = x`@_Object.assign(${
+		props = x`@_Object.assign({}, ${
 			node.attributes
 				.map(attribute => {
 					if (attribute.is_spread) {
diff --git a/test/js/samples/ssr-spread-component-props-immutably/Component.svelte b/test/js/samples/ssr-spread-component-props-immutably/Component.svelte
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/js/samples/ssr-spread-component-props-immutably/_config.js b/test/js/samples/ssr-spread-component-props-immutably/_config.js
new file mode 100644
index 0000000000..bee4ab630c
--- /dev/null
+++ b/test/js/samples/ssr-spread-component-props-immutably/_config.js
@@ -0,0 +1,5 @@
+export default {
+	options: {
+		generate: 'ssr'
+	}
+};
diff --git a/test/js/samples/ssr-spread-component-props-immutably/expected.js b/test/js/samples/ssr-spread-component-props-immutably/expected.js
new file mode 100644
index 0000000000..34780d2af8
--- /dev/null
+++ b/test/js/samples/ssr-spread-component-props-immutably/expected.js
@@ -0,0 +1,11 @@
+/* generated by Svelte vX.Y.Z */
+import { create_ssr_component, validate_component } from "svelte/internal";
+
+import Component from './Component.svelte';
+
+const Component_1 = create_ssr_component(($$result, $$props, $$bindings, slots) => {
+	let props = { x: 1, y: 2, z: 3 };
+	return `${validate_component(Component, "Component").$$render($$result, Object.assign({}, props, { x: 2 }), {}, {})}`;
+});
+
+export default Component_1;
\ No newline at end of file
diff --git a/test/js/samples/ssr-spread-component-props-immutably/input.svelte b/test/js/samples/ssr-spread-component-props-immutably/input.svelte
new file mode 100644
index 0000000000..352cb915e6
--- /dev/null
+++ b/test/js/samples/ssr-spread-component-props-immutably/input.svelte
@@ -0,0 +1,11 @@
+<script>
+	import Component from './Component.svelte';
+
+	let props = {
+		x: 1,
+		y: 2,
+		z: 3,
+	};
+</script>
+
+<Component {...props} x={2} />