fix(typings): allow to bind to a non-secure Http2Server (#4853)

lib/index.ts

@@ -1,6 +1,6 @@
 import http = require("http");
 import type { Server as HTTPSServer } from "https";
-import type { Http2SecureServer } from "http2";
+import type { Http2SecureServer, Http2Server } from "http2";
 import { createReadStream } from "fs";
 import { createDeflate, createGzip, createBrotliCompress } from "zlib";
 import accepts = require("accepts");
@@ -56,6 +56,12 @@ type ParentNspNameMatchFn = (
 
 type AdapterConstructor = typeof Adapter | ((nsp: Namespace) => Adapter);
 
+type TServerInstance =
+  | http.Server
+  | HTTPSServer
+  | Http2SecureServer
+  | Http2Server;
+
 interface ServerOptions extends EngineOptions, AttachOptions {
   /**
    * name of the path to capture
@@ -203,7 +209,7 @@ export class Server<
    * @private
    */
   _connectTimeout: number;
-  private httpServer: http.Server | HTTPSServer | Http2SecureServer;
+  private httpServer: TServerInstance;
   private _corsMiddleware: (
     req: http.IncomingMessage,
     res: http.ServerResponse,
@@ -217,28 +223,13 @@ export class Server<
    * @param [opts]
    */
   constructor(opts?: Partial<ServerOptions>);
+  constructor(srv?: TServerInstance | number, opts?: Partial<ServerOptions>);
   constructor(
-    srv?: http.Server | HTTPSServer | Http2SecureServer | number,
+    srv: undefined | Partial<ServerOptions> | TServerInstance | number,
     opts?: Partial<ServerOptions>
   );
   constructor(
-    srv:
-      | undefined
-      | Partial<ServerOptions>
-      | http.Server
-      | HTTPSServer
-      | Http2SecureServer
-      | number,
-    opts?: Partial<ServerOptions>
-  );
-  constructor(
-    srv:
-      | undefined
-      | Partial<ServerOptions>
-      | http.Server
-      | HTTPSServer
-      | Http2SecureServer
-      | number,
+    srv: undefined | Partial<ServerOptions> | TServerInstance | number,
     opts: Partial<ServerOptions> = {}
   ) {
     super();
@@ -271,9 +262,7 @@ export class Server<
     opts.cleanupEmptyChildNamespaces = !!opts.cleanupEmptyChildNamespaces;
     this.sockets = this.of("/");
     if (srv || typeof srv == "number")
-      this.attach(
-        srv as http.Server | HTTPSServer | Http2SecureServer | number
-      );
+      this.attach(srv as TServerInstance | number);
 
     if (this.opts.cors) {
       this._corsMiddleware = corsMiddleware(this.opts.cors);
@@ -407,7 +396,7 @@ export class Server<
    * @return self
    */
   public listen(
-    srv: http.Server | HTTPSServer | Http2SecureServer | number,
+    srv: TServerInstance | number,
     opts: Partial<ServerOptions> = {}
   ): this {
     return this.attach(srv, opts);
@@ -421,7 +410,7 @@ export class Server<
    * @return self
    */
   public attach(
-    srv: http.Server | HTTPSServer | Http2SecureServer | number,
+    srv: TServerInstance | number,
     opts: Partial<ServerOptions> = {}
   ): this {
     if ("function" == typeof srv) {
@@ -527,7 +516,7 @@ export class Server<
    * @private
    */
   private initEngine(
-    srv: http.Server | HTTPSServer | Http2SecureServer,
+    srv: TServerInstance,
     opts: EngineOptions & AttachOptions
   ): void {
     // initialize engine
@@ -550,9 +539,7 @@ export class Server<
    * @param srv http server
    * @private
    */
-  private attachServe(
-    srv: http.Server | HTTPSServer | Http2SecureServer
-  ): void {
+  private attachServe(srv: TServerInstance): void {
     debug("attaching client serving req handler");
 
     const evs = srv.listeners("request").slice(0);