fix: preserve component function context (#12089)

We need to pass the SFC component function to the snippet dev time function or else nested snippets result in the wrong context being set

fixes #12040

Author: dummdidumm

.changeset/wet-bats-exercise.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: preserve component function context for nested components

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

@@ -886,7 +886,12 @@ function serialize_inline_component(node, component_name, context) {
 
 		if (slot_name === 'default' && !has_children_prop) {
 			push_prop(
-				b.init('children', context.state.options.dev ? b.call('$.wrap_snippet', slot_fn) : slot_fn)
+				b.init(
+					'children',
+					context.state.options.dev
+						? b.call('$.wrap_snippet', slot_fn, b.id(context.state.analysis.name))
+						: slot_fn
+				)
 			);
 			// We additionally add the default slot as a boolean, so that the slot render function on the other
 			// side knows it should get the content to render from $$props.children
@@ -2699,7 +2704,7 @@ export const template_visitors = {
 		let snippet = b.arrow(args, body);
 
 		if (context.state.options.dev) {
-			snippet = b.call('$.wrap_snippet', snippet);
+			snippet = b.call('$.wrap_snippet', snippet, b.id(context.state.analysis.name));
 		}
 
 		const declaration = b.var(node.expression, snippet);

packages/svelte/src/internal/client/dom/blocks/snippet.js

@@ -39,15 +39,13 @@ export function snippet(get_snippet, node, ...args) {
  * In development, wrap the snippet function so that it passes validation, and so that the
  * correct component context is set for ownership checks
  * @param {(node: import('#client').TemplateNode, ...args: any[]) => import('#client').Dom} fn
- * @returns
+ * @param {any} component
  */
-export function wrap_snippet(fn) {
-	let component = /** @type {import('#client').ComponentContext} */ (current_component_context);
-
+export function wrap_snippet(fn, component) {
 	return add_snippet_symbol(
 		(/** @type {import('#client').TemplateNode} */ node, /** @type {any[]} */ ...args) => {
 			var previous_component_function = dev_current_component_function;
-			set_dev_current_component_function(component.function);
+			set_dev_current_component_function(component);
 
 			try {
 				return fn(node, ...args);

packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-6/Component1.svelte

@@ -0,0 +1,5 @@
+<script>
+	let { children } = $props();
+</script>
+
+{@render children()}

packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-6/Component2.svelte

@@ -0,0 +1,5 @@
+<script>
+	let { children } = $props();
+</script>
+
+{@render children()}

packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-6/Component3.svelte

@@ -0,0 +1,5 @@
+<script lang="ts">
+	let { count = $bindable() } = $props();
+</script>
+
+<button onclick={() => count.value++}>{count.value}</button>

packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-6/_config.js

@@ -0,0 +1,23 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+// Tests that nested snippets preserve correct component function context so we don't get false positive warnings
+export default test({
+	html: `<button>0</button>`,
+
+	compileOptions: {
+		dev: true
+	},
+
+	test({ assert, target, warnings }) {
+		const button = target.querySelector('button');
+
+		button?.click();
+		flushSync();
+
+		assert.htmlEqual(target.innerHTML, `<button>1</button>`);
+		assert.deepEqual(warnings, []);
+	},
+
+	warnings: []
+});

packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-6/main.svelte

@@ -0,0 +1,13 @@
+<script>
+	import Component1 from './Component1.svelte';
+	import Component2 from './Component2.svelte';
+	import Component3 from './Component3.svelte';
+
+	let count = $state({ value: 0 });
+</script>
+
+<Component1>
+	<Component2>
+		<Component3 bind:count></Component3>
+	</Component2>
+</Component1>