fix: always mark props as stateful (#16504)

Author: 7nik

.changeset/gorgeous-jeans-begin.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: always mark props as stateful

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

@@ -93,7 +93,10 @@ export function Identifier(node, context) {
 			context.state.expression.references.add(binding);
 			context.state.expression.has_state ||=
 				binding.kind !== 'static' &&
-				!binding.is_function() &&
+				(binding.kind === 'prop' ||
+					binding.kind === 'bindable_prop' ||
+					binding.kind === 'rest_prop' ||
+					!binding.is_function()) &&
 				!context.state.scope.evaluate(node).is_known;
 		}
 

packages/svelte/tests/runtime-runes/samples/props-default-value-function/_config.js

@@ -0,0 +1,15 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['client'],
+
+	test({ assert, target }) {
+		const btn = target.querySelector('button');
+
+		assert.htmlEqual(target.innerHTML, `<button>inc</button> Inner: 0 Inner: 0`);
+		btn?.click();
+		flushSync();
+		assert.htmlEqual(target.innerHTML, `<button>inc</button> Inner: 1 Inner: 1`);
+	}
+});

packages/svelte/tests/runtime-runes/samples/props-default-value-function/inner.svelte

@@ -0,0 +1,4 @@
+<script>
+	let { getter } = $props()
+</script>
+Inner: {getter()}

packages/svelte/tests/runtime-runes/samples/props-default-value-function/main.svelte

@@ -0,0 +1,14 @@
+<script>
+	import Wrapper1 from "./wrapper.svelte"
+	import Wrapper2 from "./wrapper2.svelte"
+	let count = $state(0);
+
+	let getter = $derived.by(() => {
+		const copy = count;
+		return () => copy;
+	});
+</script>
+
+<button onclick={() => count++}>inc</button>
+<Wrapper1 {getter}/>
+<Wrapper2 {getter}/>

packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper.svelte

@@ -0,0 +1,7 @@
+<script >
+  import Inner from "./inner.svelte";
+
+  const { getter = () => -1} = $props();
+</script>
+
+<Inner {getter} />

packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper2.svelte

@@ -0,0 +1,7 @@
+<script >
+  import Inner from "./inner.svelte";
+
+  const { getter = $bindable(() => -1)} = $props();
+</script>
+
+<Inner {getter} />