fix: put expressions in effects unless known to be static

Author: Rich-Harris

.changeset/tender-apples-repair.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: put expressions in effects unless known to be static

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

@@ -90,7 +90,8 @@ export function Identifier(node, context) {
 	if (binding) {
 		if (context.state.expression) {
 			context.state.expression.dependencies.add(binding);
-			context.state.expression.has_state ||= binding.kind !== 'normal';
+			context.state.expression.has_state ||=
+				!binding.is_function() && !context.state.scope.evaluate(node).is_known;
 		}
 
 		if (

packages/svelte/tests/runtime-runes/samples/reactive-identifier/_config.js

@@ -0,0 +1,13 @@
+import { flushSync } from '../../../../src/index-client';
+import { test } from '../../test';
+
+export default test({
+	html: `<button>0</button>`,
+
+	test({ assert, target }) {
+		const btn = target.querySelector('button');
+
+		flushSync(() => btn?.click());
+		assert.htmlEqual(target.innerHTML, `<button>1</button>`);
+	}
+});

packages/svelte/tests/runtime-runes/samples/reactive-identifier/main.svelte

@@ -0,0 +1,13 @@
+<script>
+	let count = $state(0);
+
+	let object = {
+		toString() {
+			return count;
+		}
+	};
+</script>
+
+<button onclick={() => count += 1}>
+	{object}
+</button>