[fix] Spread component props immutably during SSR (#8176)

By passing an empty object literal as first argument to Object.assign we can avoid having objects spread as props on a component being mutated during SSR. Fixes #8171
sveltejs · Jan 10, 2023 · b06e435 · b06e435
1 parent aa98397
commit b06e435
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Showing 4 changed files with 23 additions and 1 deletion.
diff --git 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/runtime/samples/spread-component-immutable/Widget.svelte b/test/runtime/samples/spread-component-immutable/Widget.svelte
diff --git a/test/runtime/samples/spread-component-immutable/_config.js b/test/runtime/samples/spread-component-immutable/_config.js
@@ -0,0 +1,15 @@
+const obj = {
+	x: 1,
+	y: 2,
+	z: 3
+};
+
+export default {
+	props: {
+		obj
+	},
+
+	test({ assert }) {
+		assert.deepEqual(obj, { x: 1, y: 2, z: 3 });
+	}
+};
diff --git a/test/runtime/samples/spread-component-immutable/main.svelte b/test/runtime/samples/spread-component-immutable/main.svelte
@@ -0,0 +1,7 @@
+<script>
+	import Widget from './Widget.svelte';
+
+	export let obj;
+</script>
+
+<Widget {...obj} x={2} />