From c79b909458b6265a18cc554dd2affd832b9797af Mon Sep 17 00:00:00 2001
From: Taku Fukada <naninunenor@gmail.com>
Date: Wed, 18 Dec 2024 18:15:49 +0900
Subject: [PATCH] fix: remove 'implements' from class declaration (#14749)

* fix: remove implements from class declaration

* add a smoke test
---
 .changeset/calm-maps-cover.md                                | 5 +++++
 .../src/compiler/phases/1-parse/remove_typescript_nodes.js   | 1 +
 .../samples/typescript-class-and-interface/_config.js        | 3 +++
 .../samples/typescript-class-and-interface/main.svelte       | 5 +++++
 4 files changed, 14 insertions(+)
 create mode 100644 .changeset/calm-maps-cover.md
 create mode 100644 packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/_config.js
 create mode 100644 packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/main.svelte

diff --git a/.changeset/calm-maps-cover.md b/.changeset/calm-maps-cover.md
new file mode 100644
index 0000000000..b7bd449c1a
--- /dev/null
+++ b/.changeset/calm-maps-cover.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: remove implements from class declarations
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 96639829bb..18c805128d 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
@@ -115,6 +115,7 @@ const visitors = {
 		if (node.declare) {
 			return b.empty;
 		}
+		delete node.implements;
 		return context.next();
 	},
 	VariableDeclaration(node, context) {
diff --git a/packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/_config.js b/packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/_config.js
new file mode 100644
index 0000000000..4e8f43d5db
--- /dev/null
+++ b/packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/_config.js
@@ -0,0 +1,3 @@
+import { test } from '../../assert';
+
+export default test({});
diff --git a/packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/main.svelte b/packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/main.svelte
new file mode 100644
index 0000000000..3d58f1072d
--- /dev/null
+++ b/packages/svelte/tests/runtime-browser/samples/typescript-class-and-interface/main.svelte
@@ -0,0 +1,5 @@
+<script lang="ts">
+  // TypeScript syntax should not cause compilation failure
+  interface MyInterface {}
+  class MyClass implements MyInterface {}
+</script>
\ No newline at end of file