From d776e522d2b960195d35b5ff0cbaf9ec60915702 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Sun, 1 Sep 2024 20:57:17 +0200
Subject: [PATCH] fix: ensure reactive graph is fully traversed in the marking
 phase for non-runes mode (#13059)

* fix: ensure signal status is set in legacy mode

fixes #13051

* add (failing) test

* alternative fix

* add changeset

* alternative fix

* add comment

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
Co-authored-by: Dominic Gannaway <dg@domgan.com>
---
 .changeset/angry-weeks-design.md               |  5 +++++
 .../src/internal/client/reactivity/effects.js  |  9 ++++++++-
 .../Child.svelte                               | 15 +++++++++++++++
 .../_config.js                                 | 18 ++++++++++++++++++
 .../main.svelte                                |  8 ++++++++
 .../state.js                                   |  3 +++
 6 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/angry-weeks-design.md
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/_config.js
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/main.svelte
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/state.js

diff --git a/.changeset/angry-weeks-design.md b/.changeset/angry-weeks-design.md
new file mode 100644
index 000000000000..897f2e2192e0
--- /dev/null
+++ b/.changeset/angry-weeks-design.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure reactive graph is fully traversed in the marking phase for non-runes mode
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index e0d97beaf244..585800d148de 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -33,7 +33,8 @@ import {
 	UNOWNED,
 	CLEAN,
 	INSPECT_EFFECT,
-	HEAD_EFFECT
+	HEAD_EFFECT,
+	MAYBE_DIRTY
 } from '../constants.js';
 import { set } from './sources.js';
 import * as e from '../errors.js';
@@ -281,6 +282,12 @@ export function legacy_pre_effect_reset() {
 		for (var token of context.l.r1) {
 			var effect = token.effect;
 
+			// If the effect is CLEAN, then make it MAYBE_DIRTY. This ensures we traverse through
+			// the effects dependencies and correctly ensure each dependency is up-to-date.
+			if ((effect.f & CLEAN) !== 0) {
+				set_signal_status(effect, MAYBE_DIRTY);
+			}
+
 			if (check_dirtiness(effect)) {
 				update_effect(effect);
 			}
diff --git a/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/Child.svelte b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/Child.svelte
new file mode 100644
index 000000000000..58ec0f651639
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/Child.svelte
@@ -0,0 +1,15 @@
+<script>
+	import { writable } from 'svelte/store';
+	import { store } from './state.js';
+
+	export let value;
+
+	const copy = writable(value);
+
+	$: {
+		copy.set(value);
+		store.set({ value });
+	}
+</script>
+
+<p>{$copy}</p>
diff --git a/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/_config.js b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/_config.js
new file mode 100644
index 000000000000..7db95248aaa6
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/_config.js
@@ -0,0 +1,18 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+import { store } from './state.js';
+
+export default test({
+	html: '<p>0</p><button>1</button>',
+
+	before_test() {
+		store.set({ value: 0 });
+	},
+
+	async test({ assert, target }) {
+		const button = target.querySelector('button');
+		flushSync(() => button?.click());
+
+		assert.htmlEqual(target.innerHTML, '<p>1</p><button>1</button>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/main.svelte b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/main.svelte
new file mode 100644
index 000000000000..1d7a9d6e8f60
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/main.svelte
@@ -0,0 +1,8 @@
+<script>
+	import { store } from './state.js';
+	import Child from './Child.svelte';
+</script>
+
+<Child value={$store.value} />
+
+<button on:click={() => store.set({ value: 1 })}>1</button>
diff --git a/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/state.js b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/state.js
new file mode 100644
index 000000000000..030378b5e7d0
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/store-updated-in-reactive-statement/state.js
@@ -0,0 +1,3 @@
+import { writable } from 'svelte/store';
+
+export const store = writable({ value: 0 });