From 6550013b73f52dfc5dec980d4f483cc3d07d5eac Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Mon, 7 May 2018 00:03:12 +0200
Subject: [PATCH] lib: lazy load necessary loaders

PR-URL: https://github.com/nodejs/node/pull/20567
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
---
 lib/internal/modules/cjs/loader.js | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 022f58d27e2..e471cc013a6 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -23,8 +23,6 @@
 
 const { NativeModule } = require('internal/bootstrap/loaders');
 const util = require('util');
-const { decorateErrorStack } = require('internal/util');
-const { getURLFromFilePath } = require('internal/url');
 const vm = require('vm');
 const assert = require('assert').ok;
 const fs = require('fs');
@@ -53,11 +51,21 @@ const {
 
 module.exports = Module;
 
-// these are below module.exports for the circular reference
-const asyncESM = require('internal/process/esm_loader');
-const ModuleJob = require('internal/modules/esm/module_job');
-const createDynamicModule = require(
-  'internal/modules/esm/create_dynamic_module');
+let asyncESM;
+let ModuleJob;
+let createDynamicModule;
+let getURLFromFilePath;
+let decorateErrorStack;
+
+function lazyLoadESM() {
+  asyncESM = require('internal/process/esm_loader');
+  ModuleJob = require('internal/modules/esm/module_job');
+  createDynamicModule = require(
+    'internal/modules/esm/create_dynamic_module');
+  decorateErrorStack = require('internal/util').decorateErrorStack;
+  getURLFromFilePath = require('internal/url').getURLFromFilePath;
+}
+
 const {
   CHAR_UPPERCASE_A,
   CHAR_LOWERCASE_A,
@@ -497,6 +505,7 @@ Module._load = function(request, parent, isMain) {
   }
 
   if (experimentalModules && isMain) {
+    if (asyncESM === undefined) lazyLoadESM();
     asyncESM.loaderPromise.then((loader) => {
       return loader.import(getURLFromFilePath(request).pathname);
     })
@@ -604,6 +613,7 @@ Module.prototype.load = function(filename) {
   this.loaded = true;
 
   if (experimentalModules) {
+    if (asyncESM === undefined) lazyLoadESM();
     const ESMLoader = asyncESM.ESMLoader;
     const url = getURLFromFilePath(filename);
     const urlString = `${url}`;
@@ -722,6 +732,7 @@ Module._extensions['.node'] = function(module, filename) {
 };
 
 if (experimentalModules) {
+  if (asyncESM === undefined) lazyLoadESM();
   Module._extensions['.mjs'] = function(module, filename) {
     throw new ERR_REQUIRE_ESM(filename);
   };
@@ -797,5 +808,5 @@ Module._preloadModules = function(requests) {
 
 Module._initPaths();
 
-// backwards compatibility
+// Backwards compatibility
 Module.Module = Module;