fix

Author: Rich-Harris

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -371,6 +371,7 @@ export function analyze_component(root, source, options) {
 		uses_component_bindings: false,
 		uses_render_tags: false,
 		needs_context: false,
+		needs_props: false,
 		custom_element: options.customElementOptions ?? options.customElement,
 		inject_styles: options.css === 'injected' || options.customElement,
 		accessors: options.customElement
@@ -818,6 +819,8 @@ const legacy_scope_tweaker = {
 			return next();
 		}
 
+		state.analysis.needs_props = true;
+
 		if (!node.declaration) {
 			for (const specifier of node.specifiers) {
 				const binding = /** @type {import('#compiler').Binding} */ (
@@ -946,6 +949,8 @@ const runes_scope_tweaker = {
 		}
 
 		if (rune === '$props') {
+			state.analysis.needs_props = true;
+
 			for (const property of /** @type {import('estree').ObjectPattern} */ (node.id).properties) {
 				if (property.type !== 'Property') continue;
 

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

@@ -442,28 +442,12 @@ export function client_component(source, analysis, options) {
 
 	let should_inject_props =
 		should_inject_context ||
+		analysis.needs_props ||
 		analysis.uses_props ||
 		analysis.uses_rest_props ||
 		analysis.uses_slots ||
 		analysis.slot_names.size > 0;
 
-	if (!should_inject_props) {
-		for (const declaration of analysis.instance.scope.declarations.values()) {
-			if (declaration.declaration_kind === 'synthetic') {
-				continue;
-			}
-
-			if (
-				declaration.kind === 'prop' ||
-				declaration.kind === 'bindable_prop' ||
-				declaration.kind === 'rest_prop'
-			) {
-				should_inject_props = true;
-				break;
-			}
-		}
-	}
-
 	const body = [
 		...state.hoisted,
 		...module.body,

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

@@ -1228,6 +1228,8 @@ function serialize_event_handler(node, { state, visit }) {
 
 		return handler;
 	} else {
+		state.analysis.needs_props = true;
+
 		// Function + .call to preserve "this" context as much as possible
 		return b.function(
 			null,

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

@@ -58,6 +58,7 @@ export interface ComponentAnalysis extends Analysis {
 	uses_component_bindings: boolean;
 	uses_render_tags: boolean;
 	needs_context: boolean;
+	needs_props: boolean;
 	custom_element: boolean | SvelteOptions['customElement'];
 	/** If `true`, should append styles through JavaScript */
 	inject_styles: boolean;