fix: loosen restrictions on $state rune for return statements

.changeset/rotten-eggs-jog.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: loosen restrictions on $state rune for return statements

packages/svelte/src/compiler/errors.js

@@ -174,7 +174,9 @@ const runes = {
 	'invalid-derived-location': () =>
 		`$derived() can only be used as a variable declaration initializer or a class field`,
 	'invalid-state-location': () =>
-		`$state() can only be used as a variable declaration initializer or a class field`,
+		`$state() can only be used as a variable declaration initializer, a class field or a return statement if passed an object or array`,
+	'invalid-state-frozen-location': () =>
+		`$state.frozen() can only be used as a variable declaration initializer or a class field`,
 	'invalid-effect-location': () => `$effect() can only be used as an expression statement`,
 	/**
 	 * @param {boolean} is_binding

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

@@ -8,6 +8,7 @@ import {
 import { warn } from '../../warnings.js';
 import fuzzymatch from '../1-parse/utils/fuzzymatch.js';
 import { disallowed_parapgraph_contents, interactive_elements } from '../1-parse/utils/html.js';
+import { should_proxy_or_freeze } from '../3-transform/client/utils.js';
 import { binding_properties } from '../bindings.js';
 import { ContentEditableBindings, EventModifiers, SVGElements } from '../constants.js';
 import { is_custom_element_node } from '../nodes.js';
@@ -717,10 +718,23 @@ function validate_call_expression(node, scope, path) {
 
 	if (rune === '$state' || rune === '$derived') {
 		if (parent.type === 'VariableDeclarator') return;
+		if (
+			parent.type === 'ReturnStatement' &&
+			node.arguments.length === 1 &&
+			node.arguments[0].type !== 'SpreadElement' &&
+			should_proxy_or_freeze(node.arguments[0])
+		)
+			return;
 		if (parent.type === 'PropertyDefinition' && !parent.static && !parent.computed) return;
 		error(node, rune === '$derived' ? 'invalid-derived-location' : 'invalid-state-location');
 	}
 
+	if (rune === '$state.frozen') {
+		if (parent.type === 'VariableDeclarator') return;
+		if (parent.type === 'PropertyDefinition' && !parent.static && !parent.computed) return;
+		error(node, 'invalid-state-frozen-location');
+	}
+
 	if (rune === '$effect' || rune === '$effect.pre') {
 		if (parent.type !== 'ExpressionStatement') {
 			error(node, 'invalid-effect-location');

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

@@ -154,6 +154,17 @@ export const javascript_visitors_runes = {
 
 		return { ...node, body };
 	},
+	ReturnStatement(node, { state, visit, next }) {
+		const rune = get_rune(node.argument, state.scope);
+		if (rune === '$state' && node.argument?.type === 'CallExpression') {
+			const value = /** @type {import('estree').Expression} **/ (visit(node.argument.arguments[0]));
+			return {
+				...node,
+				argument: b.call('$.proxy', value)
+			};
+		}
+		next();
+	},
 	VariableDeclaration(node, { state, visit }) {
 		const declarations = [];