types: don't allow any object in the first parameter if second parameter is not given in TextBasedChannel#send (#4736)

typings/index.ts

@@ -1,6 +1,6 @@
 /// <reference path="index.d.ts" />
 
-import { Client } from 'discord.js';
+import { Client, Message, MessageAttachment, MessageEmbed } from 'discord.js';
 
 const client: Client = new Client();
 
@@ -25,4 +25,29 @@ client.on('messageReactionRemoveAll', async message => {
   console.log(`messageReactionRemoveAll - content: ${message.content}`);
 });
 
+// These are to check that stuff is the right type
+declare const assertIsMessage: (m: Promise<Message>) => void;
+declare const assertIsMessageArray: (m: Promise<Message[]>) => void;
+
+client.on('message', ({ channel }) => {
+  assertIsMessage(channel.send('string'));
+  assertIsMessage(channel.send({}));
+  assertIsMessage(channel.send({ embed: {} }));
+  assertIsMessage(channel.send({ another: 'property' }, {}));
+
+  const attachment = new MessageAttachment('file.png');
+  const embed = new MessageEmbed();
+  assertIsMessage(channel.send(attachment));
+  assertIsMessage(channel.send(embed));
+  assertIsMessage(channel.send([attachment, embed]));
+
+  assertIsMessageArray(channel.send(Symbol('another primitive'), { split: true }));
+  assertIsMessageArray(channel.send({ split: true }));
+
+  // @ts-expect-error
+  channel.send();
+  // @ts-expect-error
+  channel.send({ another: 'property' });
+});
+
 client.login('absolutely-valid-token');