From 4fbd2a6f104e5f458264a129c39dac469717da2a Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Thu, 24 Oct 2024 13:20:04 +0100
Subject: [PATCH] fix: ensure props internally untracks current_value on sets
 (#13859)

* fix: ensure props internally untracks current_value on sets

* Update packages/svelte/src/internal/client/reactivity/props.js

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/short-jokes-speak.md                  |  5 +++++
 .../src/internal/client/reactivity/props.js      |  7 ++-----
 .../samples/props-assignment-tracking/_config.js | 16 ++++++++++++++++
 .../props-assignment-tracking/main.svelte        | 10 ++++++++++
 4 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/short-jokes-speak.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/main.svelte

diff --git a/.changeset/short-jokes-speak.md b/.changeset/short-jokes-speak.md
new file mode 100644
index 0000000000..0b2552e29b
--- /dev/null
+++ b/.changeset/short-jokes-speak.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure props internally untracks current_value on sets
diff --git a/packages/svelte/src/internal/client/reactivity/props.js b/packages/svelte/src/internal/client/reactivity/props.js
index 32969139bf..1d0f7b239f 100644
--- a/packages/svelte/src/internal/client/reactivity/props.js
+++ b/packages/svelte/src/internal/client/reactivity/props.js
@@ -373,8 +373,6 @@ export function prop(props, key, flags, fallback) {
 	if (!immutable) current_value.equals = safe_equals;
 
 	return function (/** @type {any} */ value, /** @type {boolean} */ mutation) {
-		var current = get(current_value);
-
 		// legacy nonsense — need to ensure the source is invalidated when necessary
 		// also needed for when handling inspect logic so we can inspect the correct source signal
 		if (is_signals_recorded) {
@@ -398,12 +396,11 @@ export function prop(props, key, flags, fallback) {
 				if (fallback_used && fallback_value !== undefined) {
 					fallback_value = new_value;
 				}
-				get(current_value); // force a synchronisation immediately
+				untrack(() => get(current_value)); // force a synchronisation immediately
 			}
 
 			return value;
 		}
-
-		return current;
+		return get(current_value);
 	};
 }
diff --git a/packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/_config.js b/packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/_config.js
new file mode 100644
index 0000000000..f08a40706f
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/_config.js
@@ -0,0 +1,16 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	test({ assert, logs, target }) {
+		const btn = target.querySelector('button');
+
+		flushSync(() => {
+			btn?.click();
+			btn?.click();
+			btn?.click();
+		});
+
+		assert.deepEqual(logs, ['effect']);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/main.svelte b/packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/main.svelte
new file mode 100644
index 0000000000..4a21fa6801
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-assignment-tracking/main.svelte
@@ -0,0 +1,10 @@
+<script>
+	let {display = true} = $props();
+
+	$effect(()=>{
+		display = true;
+		console.log("effect")
+	});
+</script>
+
+<button onclick={() => display = !display} >display</button>