fix: take blockers of components into account (#17153)

Fixes #17122

Author: dummdidumm

.changeset/ready-flies-invite.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: take blockers of components into account

packages/svelte/src/compiler/phases/1-parse/state/element.js

@@ -242,6 +242,10 @@ export default function element(parser) {
 		parser.allow_whitespace();
 	}
 
+	if (element.type === 'Component') {
+		element.metadata.expression = new ExpressionMetadata();
+	}
+
 	if (element.type === 'SvelteComponent') {
 		const index = element.attributes.findIndex(
 			/** @param {any} attr */
@@ -257,6 +261,7 @@ export default function element(parser) {
 		}
 
 		element.expression = get_attribute_expression(definition);
+		element.metadata.expression = new ExpressionMetadata();
 	}
 
 	if (element.type === 'SvelteElement') {

packages/svelte/src/compiler/phases/2-analyze/visitors/Component.js

@@ -16,5 +16,11 @@ export function Component(node, context) {
 		binding !== null &&
 		(binding.kind !== 'normal' || node.name.includes('.'));
 
+	if (binding) {
+		node.metadata.expression.has_state = node.metadata.dynamic;
+		node.metadata.expression.dependencies.add(binding);
+		node.metadata.expression.references.add(binding);
+	}
+
 	visit_component(node, context);
 }

packages/svelte/src/compiler/phases/2-analyze/visitors/SvelteComponent.js

@@ -12,7 +12,7 @@ export function SvelteComponent(node, context) {
 		w.svelte_component_deprecated(node);
 	}
 
-	context.visit(node.expression);
+	context.visit(node.expression, { ...context.state, expression: node.metadata.expression });
 
 	visit_component(node, context);
 }

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

@@ -451,6 +451,11 @@ export function build_component(node, component_name, context) {
 		};
 	}
 
+	if (node.type !== 'SvelteSelf') {
+		// Component name itself could be blocked on async values
+		memoizer.check_blockers(node.metadata.expression);
+	}
+
 	const statements = [...snippet_declarations, ...memoizer.deriveds(context.state.analysis.runes)];
 
 	if (is_component_dynamic) {

packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js

@@ -325,17 +325,26 @@ export function build_inline_component(node, expression, context) {
 		);
 	}
 
+	if (node.type !== 'SvelteSelf') {
+		// Component name itself could be blocked on async values
+		optimiser.check_blockers(node.metadata.expression);
+	}
+
 	const is_async = optimiser.is_async();
 
 	if (is_async) {
 		statement = create_async_block(
-			b.block([optimiser.apply(), statement]),
+			b.block([
+				optimiser.apply(),
+				dynamic && custom_css_props.length === 0
+					? b.stmt(b.call('$$renderer.push', empty_comment))
+					: b.empty,
+				statement
+			]),
 			optimiser.blockers(),
 			optimiser.has_await
 		);
-	}
-
-	if (dynamic && custom_css_props.length === 0) {
+	} else if (dynamic && custom_css_props.length === 0) {
 		context.state.template.push(empty_comment);
 	}
 

packages/svelte/src/compiler/types/template.d.ts

@@ -308,6 +308,7 @@ export namespace AST {
 		type: 'Component';
 		/** @internal */
 		metadata: {
+			expression: ExpressionMetadata;
 			scopes: Record<string, Scope>;
 			dynamic: boolean;
 			/** The set of locally-defined snippets that this component tag could render,
@@ -355,6 +356,7 @@ export namespace AST {
 		expression: Expression;
 		/** @internal */
 		metadata: {
+			expression: ExpressionMetadata;
 			scopes: Record<string, Scope>;
 			/** The set of locally-defined snippets that this component tag could render,
 			 * used for CSS pruning purposes */

packages/svelte/tests/runtime-runes/samples/async-dynamic-component/Component.svelte

@@ -0,0 +1 @@
+Hi

packages/svelte/tests/runtime-runes/samples/async-dynamic-component/_config.js

@@ -0,0 +1,11 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['async-server', 'client', 'hydrate'],
+	ssrHtml: 'Hi Hi Hi Hi',
+	async test({ assert, target }) {
+		await tick();
+		assert.htmlEqual(target.innerHTML, 'Hi Hi Hi Hi');
+	}
+});

packages/svelte/tests/runtime-runes/samples/async-dynamic-component/main.svelte

@@ -0,0 +1,10 @@
+<script>
+	import Component from './Component.svelte'
+	const X = $derived(await Promise.resolve(Component))
+	const Y = await Promise.resolve(Component)
+</script>
+
+<X />
+<svelte:component this={X} />
+<Y />
+<svelte:component this={Y} />