/**
 * When creating a standalone build, next.js outputs a server.js file that can be used as
 * an entry point into the server. However, because we want to customize some parts of the
 * http server (adding a socket.io server, serving the whole public directory), we
 * create the server ourselves, and just reproduce the setup that next.js would do.
 *
 * Because we need to directly import from node_modules files, this solution seems very hacky,
 * but it is arguably no more hacky than using the server.js that ships with the standalone
 * build.
 *
 * This function attempts to replicate the behavior of two next.js files:
 * - environment setup from server.js
 * - initialization of the request handler from start-server.ts
 *
 * Links:
 * - [standalone build](https://nextjs.org/docs/pages/api-reference/next-config-js/output#automatically-copying-traced-files)
 * - [server.js](https://github.com/vercel/next.js/blob/492156b4c5e2559b2a280f7d483cd85a8e8742a9/packages/next/src/build/utils.ts#L2108-L2113) (created programmatically)
 * - [start-server.ts](https://github.com/vercel/next.js/blob/492156b4c5e2559b2a280f7d483cd85a8e8742a9/packages/next/src/server/lib/start-server.ts#L296-L308)
 *
 * @returns the request handler provided by next.js
 */
export declare const setupNext: () => Promise<any>;