From e695d3dcf48ea5ea4d38c7cf25e3d436ec967871 Mon Sep 17 00:00:00 2001
From: Simon Holthausen <simon.holthausen@vercel.com>
Date: Tue, 3 Sep 2024 10:34:52 +0200
Subject: [PATCH] declare keyword

---
 .../phases/1-parse/remove_typescript_nodes.js | 19 +++++++++++++++++--
 .../samples/typescript/main.svelte            | 13 ++++++++++++-
 2 files changed, 29 insertions(+), 3 deletions(-)

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 a614590230..872b71a4df 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
@@ -105,12 +105,27 @@ const visitors = {
 	},
 	FunctionExpression: remove_this_param,
 	FunctionDeclaration: remove_this_param,
+	TSDeclareFunction() {
+		return b.empty;
+	},
+	ClassDeclaration(node, context) {
+		if (node.declare) {
+			return b.empty;
+		}
+		return context.next();
+	},
+	VariableDeclaration(node, context) {
+		if (node.declare) {
+			return b.empty;
+		}
+		return context.next();
+	},
 	TSModuleDeclaration(node, context) {
 		if (!node.body) return b.empty;
 
 		// namespaces can contain non-type nodes
-		const cleaned = context.visit(node.body.body);
-		if (cleaned.length !== 0) {
+		const cleaned = /** @type {any[]} */ (node.body.body).map((entry) => context.visit(entry));
+		if (cleaned.some((entry) => entry !== b.empty)) {
 			e.typescript_invalid_feature(node, 'namespaces with non-type nodes');
 		}
 
diff --git a/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte b/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte
index 549e0f91e5..d1c4f361ba 100644
--- a/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/typescript/main.svelte
@@ -9,7 +9,18 @@
 	}
 
 	class Foo {
-		constructor(public readonly name: string) {}
+		constructor(readonly name: string) {}
+	}
+
+	declare const declared_const: number;
+	declare function declared_fn(): void;
+	declare class declared_class {
+		foo: number;
+	}
+
+	declare module 'foobar' {}
+	namespace SomeNamespace {
+		export type Foo = true
 	}
 
 	export type { Hello };