From 1c48d7cbdcbc78e397d5ace349198bbb87a9e6b6 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Mon, 20 Nov 2023 17:36:23 -0500
Subject: [PATCH] Typescript each indexed (#9567)

* failing test

* fix undefined index bug

* Update packages/svelte/src/compiler/phases/1-parse/read/context.js

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .../svelte/src/compiler/phases/1-parse/read/context.js   | 7 ++++++-
 .../samples/typescript-each-indexed/_config.js           | 9 +++++++++
 .../samples/typescript-each-indexed/main.svelte          | 7 +++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/main.svelte

diff --git a/packages/svelte/src/compiler/phases/1-parse/read/context.js b/packages/svelte/src/compiler/phases/1-parse/read/context.js
index 8bf1390969..2fc93c184e 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/context.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/context.js
@@ -106,7 +106,12 @@ function read_type_annotation(parser) {
 		const insert = '_ as ';
 		let a = parser.index - insert.length;
 		const template = ' '.repeat(a) + insert + parser.template.slice(parser.index);
-		const expression = parse_expression_at(template, parser.ts, a);
+		let expression = parse_expression_at(template, parser.ts, a);
+
+		// `array as item: string, index` becomes `string, index`, which is mistaken as a sequence expression - fix that
+		if (expression.type === 'SequenceExpression') {
+			expression = expression.expressions[0];
+		}
 
 		parser.index = /** @type {number} */ (expression.end);
 		return /** @type {any} */ (expression).typeAnnotation;
diff --git a/packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/_config.js b/packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/_config.js
new file mode 100644
index 0000000000..d8a932c1f0
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/_config.js
@@ -0,0 +1,9 @@
+import { test } from '../../test';
+
+export default test({
+	html: `
+		<span>0: a</span>
+		<span>1: b</span>
+		<span>2: c</span>
+	`
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/main.svelte b/packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/main.svelte
new file mode 100644
index 0000000000..2624f342a7
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/typescript-each-indexed/main.svelte
@@ -0,0 +1,7 @@
+<script lang="ts">
+	let letters = ['a', 'b', 'c'];
+</script>
+
+{#each letters as letter: string, i}
+	<span>{i}: {letter}</span>
+{/each}