From 9b2a8f15fbf9c96b3cdb7af54eb72f557730a177 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Wed, 6 Nov 2024 16:48:27 +0100
Subject: [PATCH] fix: ignore `as` type expressions on property definitions
 (#14181)

fixes #14179
---
 .changeset/dull-laws-end.md                                  | 5 +++++
 .../src/compiler/phases/1-parse/remove_typescript_nodes.js   | 5 +++--
 .../svelte/tests/runtime-runes/samples/typescript/_config.js | 1 +
 .../tests/runtime-runes/samples/typescript/main.svelte       | 1 +
 4 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/dull-laws-end.md

diff --git a/.changeset/dull-laws-end.md b/.changeset/dull-laws-end.md
new file mode 100644
index 0000000000..595424826e
--- /dev/null
+++ b/.changeset/dull-laws-end.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ignore `as` type expressions on property definitions
diff --git a/packages/svelte/src/compiler/phases/1-parse/remove_typescript_nodes.js b/packages/svelte/src/compiler/phases/1-parse/remove_typescript_nodes.js
index 5febef420d..36a25f5124 100644
--- a/packages/svelte/src/compiler/phases/1-parse/remove_typescript_nodes.js
+++ b/packages/svelte/src/compiler/phases/1-parse/remove_typescript_nodes.js
@@ -56,13 +56,14 @@ const visitors = {
 		if (node.exportKind === 'type') return b.empty;
 		return node;
 	},
-	PropertyDefinition(node) {
+	PropertyDefinition(node, { next }) {
 		if (node.accessor) {
 			e.typescript_invalid_feature(
 				node,
 				'accessor fields (related TSC proposal is not stage 4 yet)'
 			);
 		}
+		return next();
 	},
 	TSAsExpression(node, context) {
 		return context.visit(node.expression);
@@ -97,7 +98,7 @@ const visitors = {
 		if ((node.readonly || node.accessibility) && context.path.at(-2)?.kind === 'constructor') {
 			e.typescript_invalid_feature(node, 'accessibility modifiers on constructor parameters');
 		}
-		return node.parameter;
+		return context.visit(node.parameter);
 	},
 	FunctionExpression: remove_this_param,
 	FunctionDeclaration: remove_this_param,
diff --git a/packages/svelte/tests/runtime-runes/samples/typescript/_config.js b/packages/svelte/tests/runtime-runes/samples/typescript/_config.js
index 7c9552b7b2..c15cd18225 100644
--- a/packages/svelte/tests/runtime-runes/samples/typescript/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/typescript/_config.js
@@ -1,6 +1,7 @@
 import { flushSync } from 'svelte';
 import { test } from '../../test';
 
+// This test mainly checks that all types are properly ignored by the compiler
 export default test({
 	html: '<button>clicks: 0</button>',
 
diff --git a/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte b/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte
index 6c9cacdeff..71638688f2 100644
--- a/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte
@@ -10,6 +10,7 @@
 
 	class Foo {
 		public name: string;
+		x = 'x' as const;
 		constructor(name: string) {
 			this.name = name;
 		}