fix: extend derived/state validation error to indirect exports

.changeset/perfect-queens-reflect.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: extend derived/state validation error to indirect exports

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

@@ -57,5 +57,21 @@ export function ExportNamedDeclaration(node, context) {
 				}
 			}
 		}
+
+		if (!context.state.ast_type /* .svelte.js module */ || context.state.ast_type === 'module') {
+			for (const specified of node.specifiers) {
+				const binding = context.state.scope.get(specified.local.name);
+
+				if (!binding) continue;
+
+				if (binding.kind === 'derived') {
+					e.derived_invalid_export(node);
+				}
+
+				if ((binding.kind === 'state' || binding.kind === 'raw_state') && binding.reassigned) {
+					e.state_invalid_export(node);
+				}
+			}
+		}
 	}
 }

packages/svelte/tests/compiler-errors/samples/export-derived-state-indirect/_config.js

@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+	error: {
+		code: 'derived_invalid_export',
+		message:
+			'Cannot export derived state from a module. To expose the current derived value, export a function returning its value',
+		position: [70, 76]
+	}
+});

packages/svelte/tests/compiler-errors/samples/export-derived-state-indirect/main.svelte.js

@@ -0,0 +1,5 @@
+let count = $state(0);
+
+const double = $derived(count * 2);
+
+export { double };

packages/svelte/tests/compiler-errors/samples/export-state-indirect/_config.js

@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+	error: {
+		code: 'state_invalid_export',
+		message:
+			"Cannot export state from a module if it is reassigned. Either export a function returning the state value or only mutate the state value's properties",
+		position: [211, 220]
+	}
+});

packages/svelte/tests/compiler-errors/samples/export-state-indirect/main.svelte.js

@@ -0,0 +1,15 @@
+const object = $state({
+	ok: true
+});
+
+let primitive = $state('nope');
+
+export function update_object() {
+	object.ok = !object.ok;
+}
+
+export function update_primitive() {
+	primitive = 'yep';
+}
+
+export { object, primitive };