From 9d29625c8ea7b3270fce0cd0eeb2c2dd0b5dfdc0 Mon Sep 17 00:00:00 2001
From: Austin Bonander <austin.bonander@gmail.com>
Date: Wed, 25 Sep 2019 12:58:19 -0700
Subject: [PATCH] google-protobuf: adjust Message.clone[Message]() (#38476)

Returning [the polymorphic `this` type](https://www.typescriptlang.org/docs/handbook/advanced-types.html#polymorphic-this-types) ensures calling `.clone()` or `.cloneMessage()` on a subclass instance doesn't require a redundant cast.
---
 types/google-protobuf/google-protobuf-tests.ts | 5 +++++
 types/google-protobuf/index.d.ts               | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/types/google-protobuf/google-protobuf-tests.ts b/types/google-protobuf/google-protobuf-tests.ts
index 8104ba4680..1f1c69cc6c 100644
--- a/types/google-protobuf/google-protobuf-tests.ts
+++ b/types/google-protobuf/google-protobuf-tests.ts
@@ -534,3 +534,8 @@ class MySimple extends jspb.Message {
     return jspb.Message.getField(this, 15) != null;
   }
 };
+
+// ensures messages are cloneable without a redundant cast
+const myMessage: MySimple = new MySimple();
+const myClonedMessage: MySimple = myMessage.clone();
+const myClonedMessage2: MySimple = myMessage.cloneMessage()
diff --git a/types/google-protobuf/index.d.ts b/types/google-protobuf/index.d.ts
index cc6de4f146..ee70b7618c 100644
--- a/types/google-protobuf/index.d.ts
+++ b/types/google-protobuf/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/google/google-protobuf
 // Definitions by: Marcus Longmuir <https://github.com/marcuslongmuir>
 //                 Chaitanya Kamatham <https://github.com/kamthamc>
+//                 Austin Bonander <https://github.com/abonander>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 type ByteSource = ArrayBuffer | Uint8Array | number[] | string;
@@ -110,8 +111,8 @@ export abstract class Message {
   static equals(m1: Message, m2: Message): boolean;
   static compareExtensions(extension1: {}, extension2: {}): boolean;
   static compareFields(field1: any, field2: any): boolean;
-  cloneMessage(): Message;
-  clone(): Message;
+  cloneMessage(): this;
+  clone(): this;
   static clone<T extends Message>(msg: T): T;
   static cloneMessage<T extends Message>(msg: T): T;
   static copyInto(fromMessage: Message, toMessage: Message): void;