[node] fix TypeScript + ESM in Windows (#9487)

ESM on Windows versions of Node.js require `--loader PATH` to be a `file://` protocol.
This PR allows `vc dev` to be used with both TypeScript and ESM

packages/node/src/fork-dev-server.ts

@@ -0,0 +1,102 @@
+import once from '@tootallnate/once';
+import { cloneEnv, Config, Meta } from '@vercel/build-utils';
+import { ChildProcess, fork, ForkOptions } from 'child_process';
+import { pathToFileURL } from 'url';
+import { join } from 'path';
+
+export function forkDevServer(options: {
+  tsConfig: any;
+  config: Config;
+  maybeTranspile: boolean;
+  workPath: string | undefined;
+  isTypeScript: boolean;
+  isEsm: boolean;
+  require_: NodeRequire;
+  entrypoint: string;
+  meta: Meta;
+
+  /**
+   * A path to the dev-server path. This is used in tests.
+   */
+  devServerPath?: string;
+}) {
+  let nodeOptions = process.env.NODE_OPTIONS;
+  const tsNodePath = options.require_.resolve('ts-node');
+  const esmLoader = pathToFileURL(join(tsNodePath, '..', '..', 'esm.mjs'));
+  const cjsLoader = join(tsNodePath, '..', '..', 'register', 'index.js');
+  const devServerPath =
+    options.devServerPath || join(__dirname, 'dev-server.js');
+
+  if (options.maybeTranspile) {
+    if (options.isTypeScript) {
+      if (options.isEsm) {
+        nodeOptions = `--loader ${esmLoader} ${nodeOptions || ''}`;
+      } else {
+        nodeOptions = `--require ${cjsLoader} ${nodeOptions || ''}`;
+      }
+    } else {
+      if (options.isEsm) {
+        // no transform needed because Node.js supports ESM natively
+      } else {
+        nodeOptions = `--require ${cjsLoader} ${nodeOptions || ''}`;
+      }
+    }
+  }
+
+  const forkOptions: ForkOptions = {
+    cwd: options.workPath,
+    execArgv: [],
+    env: cloneEnv(process.env, options.meta.env, {
+      VERCEL_DEV_ENTRYPOINT: options.entrypoint,
+      VERCEL_DEV_IS_ESM: options.isEsm ? '1' : undefined,
+      VERCEL_DEV_CONFIG: JSON.stringify(options.config),
+      VERCEL_DEV_BUILD_ENV: JSON.stringify(options.meta.buildEnv || {}),
+      TS_NODE_TRANSPILE_ONLY: '1',
+      TS_NODE_COMPILER_OPTIONS: options.tsConfig?.compilerOptions
+        ? JSON.stringify(options.tsConfig.compilerOptions)
+        : undefined,
+      NODE_OPTIONS: nodeOptions,
+    }),
+  };
+  const child = fork(devServerPath, [], forkOptions);
+
+  checkForPid(devServerPath, child);
+
+  return child;
+}
+
+function checkForPid(
+  path: string,
+  process: ChildProcess
+): asserts process is ChildProcess & { pid: number } {
+  if (!process.pid) {
+    throw new Error(`Child Process has no "pid" when forking: "${path}"`);
+  }
+}
+
+/**
+ * When launching a dev-server, we want to know its state.
+ * This function will be used to know whether it was exited (due to some error),
+ * or it is listening to new requests, and we can start proxying requests.
+ */
+export async function readMessage(
+  child: ChildProcess
+): Promise<
+  | { state: 'message'; value: { port: number } }
+  | { state: 'exit'; value: [number, string | null] }
+> {
+  const onMessage = once<{ port: number }>(child, 'message');
+  const onExit = once.spread<[number, string | null]>(child, 'close');
+  const result = await Promise.race([
+    onMessage.then(x => {
+      return { state: 'message' as const, value: x };
+    }),
+    onExit.then(v => {
+      return { state: 'exit' as const, value: v };
+    }),
+  ]);
+  onExit.cancel();
+  onMessage.cancel();
+
+  return result;
+}