From 53af138d588f77bb8f4f10f9ad15fd4f798b50ef Mon Sep 17 00:00:00 2001
From: Paolo Ricciuti <ricciutipaolo@gmail.com>
Date: Thu, 7 Nov 2024 21:18:45 +0100
Subject: [PATCH] fix: read index as a source in legacy keyed each block
 (#14208)

Fixes #14203
---
 .changeset/late-dodos-film.md                          |  5 +++++
 .../phases/3-transform/client/visitors/EachBlock.js    |  4 ++--
 .../keyed-each-bind-read-index/Component.svelte        |  5 +++++
 .../samples/keyed-each-bind-read-index/_config.js      |  9 +++++++++
 .../samples/keyed-each-bind-read-index/main.svelte     | 10 ++++++++++
 5 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/late-dodos-film.md
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/Component.svelte
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/_config.js
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/main.svelte

diff --git a/.changeset/late-dodos-film.md b/.changeset/late-dodos-film.md
new file mode 100644
index 0000000000..c3636019da
--- /dev/null
+++ b/.changeset/late-dodos-film.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: read index as a source in legacy keyed each block
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index fb6338cae3..55d7ded247 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -196,7 +196,7 @@ export function EachBlock(node, context) {
 					// forbidden in runes mode
 					return b.member(
 						each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,
-						index,
+						(flags & EACH_INDEX_REACTIVE) !== 0 ? get_value(index) : index,
 						true
 					);
 				}
@@ -208,7 +208,7 @@ export function EachBlock(node, context) {
 
 				const left = b.member(
 					each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,
-					index,
+					(flags & EACH_INDEX_REACTIVE) !== 0 ? get_value(index) : index,
 					true
 				);
 
diff --git a/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/Component.svelte b/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/Component.svelte
new file mode 100644
index 0000000000..988c2b6457
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/Component.svelte
@@ -0,0 +1,5 @@
+<script>
+	export let item;
+	console.log(item);
+	item = 1;
+</script>
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/_config.js b/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/_config.js
new file mode 100644
index 0000000000..8b5db4df40
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/_config.js
@@ -0,0 +1,9 @@
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, logs }) {
+		const p = target.querySelector('p');
+		assert.equal(p?.innerHTML, '1');
+		assert.deepEqual(logs, [0]);
+	}
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/main.svelte b/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/main.svelte
new file mode 100644
index 0000000000..384722f5aa
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/keyed-each-bind-read-index/main.svelte
@@ -0,0 +1,10 @@
+<script>
+	import Component from './Component.svelte';
+	const items = [0];
+</script>
+
+{#each items as item, idx(item)}
+	<Component bind:item />
+{/each}
+
+<p>{items}</p>
\ No newline at end of file