Replace require() with await import() in EXPORT_ES6 shell/runtime files

When EXPORT_ES6 is enabled, the generated JS used createRequire() to
polyfill require(), which breaks bundlers (webpack, Rollup, esbuild)
and Electron's renderer process. Since EXPORT_ES6 requires MODULARIZE,
the module body is wrapped in an async function where await is valid.

- shell.js: Remove createRequire block entirely. Use await import()
  for worker_threads, fs, path, url, util. Replace __dirname with
  import.meta.url for path resolution.
- shell_minimal.js: Same pattern for worker_threads and fs. Replace
  __dirname with new URL(..., import.meta.url) for wasm file loading.
- runtime_debug.js: Skip local require() for fs/util when EXPORT_ES6,
  reuse outer-scope variables from shell.js instead.
- runtime_common.js: Guard perf_hooks require() with EXPORT_ES6
  alternative.
- preamble.js: Hoist await import('node:v8') above instantiateSync()
  for NODE_CODE_CACHING since await can't be used inside sync functions.

Author: Bartek Wrona

src/lib/libcore.js

@@ -380,8 +380,7 @@ addToLibrary({
       var cmdstr = UTF8ToString(command);
       if (!cmdstr.length) return 0; // this is what glibc seems to do (shell works test?)
 
-      var cp = require('node:child_process');
-      var ret = cp.spawnSync(cmdstr, [], {shell:true, stdio:'inherit'});
+      var ret = nodeChildProcess.spawnSync(cmdstr, [], {shell:true, stdio:'inherit'});
 
       var _W_EXITCODE = (ret, sig) => ((ret) << 8 | (sig));
 

src/parseTools.mjs

@@ -954,6 +954,20 @@ function makeModuleReceiveWithVar(localName, moduleName, defaultValue) {
   return ret;
 }
 
+function makeNodeImport(module) {
+  if (EXPORT_ES6) {
+    return `await import('${module}')`;
+  }
+  return `require('${module}')`;
+}
+
+function makeNodeFilePath(filename) {
+  if (EXPORT_ES6) {
+    return `new URL('${filename}', import.meta.url)`;
+  }
+  return `__dirname + '/${filename}'`;
+}
+
 function makeRemovedFSAssert(fsName) {
   assert(ASSERTIONS);
   const lower = fsName.toLowerCase();
@@ -1241,6 +1255,8 @@ addToCompileTimeContext({
   makeModuleReceive,
   makeModuleReceiveExpr,
   makeModuleReceiveWithVar,
+  makeNodeFilePath,
+  makeNodeImport,
   makeRemovedFSAssert,
   makeRetainedCompilerSettings,
   makeReturn64,

src/preamble.js

@@ -549,7 +549,7 @@ function instantiateSync(file, info) {
   var binary = getBinarySync(file);
 #if NODE_CODE_CACHING
   if (ENVIRONMENT_IS_NODE) {
-    var v8 = require('node:v8');
+    var v8 = {{{ makeNodeImport('node:v8') }}};
     // Include the V8 version in the cache name, so that we don't try to
     // load cached code from another version, which fails silently (it seems
     // to load ok, but we do actually recompile the binary every time).

src/runtime_common.js

@@ -144,7 +144,7 @@ if (ENVIRONMENT_IS_NODE) {
   // depends on it for accurate timing.
   // Use `global` rather than `globalThis` here since older versions of node
   // don't have `globalThis`.
-  global.performance ??= require('perf_hooks').performance;
+  global.performance ??= ({{{ makeNodeImport('perf_hooks') }}}).performance;
 }
 #endif
 

src/runtime_debug.js

@@ -15,8 +15,8 @@ function dbg(...args) {
   // See https://github.com/emscripten-core/emscripten/issues/14804
   if (ENVIRONMENT_IS_NODE) {
     // TODO(sbc): Unify with err/out implementation in shell.sh.
-    var fs = require('node:fs');
-    var utils = require('node:util');
+    var fs = {{{ makeNodeImport('node:fs') }}};
+    var utils = {{{ makeNodeImport('node:util') }}};
     function stringify(a) {
       switch (typeof a) {
         case 'object': return utils.inspect(a);

src/shell.js

@@ -106,18 +106,9 @@ if (ENVIRONMENT_IS_PTHREAD) {
 #endif
 #endif
 
-#if ENVIRONMENT_MAY_BE_NODE && (EXPORT_ES6 || PTHREADS || WASM_WORKERS)
+#if ENVIRONMENT_MAY_BE_NODE && (PTHREADS || WASM_WORKERS)
 if (ENVIRONMENT_IS_NODE) {
-#if EXPORT_ES6
-  // When building an ES module `require` is not normally available.
-  // We need to use `createRequire()` to construct the require()` function.
-  const { createRequire } = await import('node:module');
-  /** @suppress{duplicate} */
-  var require = createRequire(import.meta.url);
-#endif
-
-#if PTHREADS || WASM_WORKERS
-  var worker_threads = require('node:worker_threads');
+  var worker_threads = {{{ makeNodeImport('node:worker_threads') }}};
   global.Worker = worker_threads.Worker;
   ENVIRONMENT_IS_WORKER = !worker_threads.isMainThread;
 #if PTHREADS
@@ -128,7 +119,6 @@ if (ENVIRONMENT_IS_NODE) {
 #if WASM_WORKERS
   ENVIRONMENT_IS_WASM_WORKER = ENVIRONMENT_IS_WORKER && worker_threads.workerData == 'em-ww'
 #endif
-#endif // PTHREADS || WASM_WORKERS
 }
 #endif // ENVIRONMENT_MAY_BE_NODE
 
@@ -199,11 +189,13 @@ if (ENVIRONMENT_IS_NODE) {
 
   // These modules will usually be used on Node.js. Load them eagerly to avoid
   // the complexity of lazy-loading.
-  var fs = require('node:fs');
+  var fs = {{{ makeNodeImport('node:fs') }}};
 
 #if EXPORT_ES6
   if (_scriptName.startsWith('file:')) {
-    scriptDirectory = require('node:path').dirname(require('node:url').fileURLToPath(_scriptName)) + '/';
+    var nodePath = {{{ makeNodeImport('node:path') }}};
+    var nodeUrl = {{{ makeNodeImport('node:url') }}};
+    scriptDirectory = nodePath.dirname(nodeUrl.fileURLToPath(_scriptName)) + '/';
   }
 #else
   scriptDirectory = __dirname + '/';
@@ -351,7 +343,7 @@ if (!ENVIRONMENT_IS_AUDIO_WORKLET)
 var defaultPrint = console.log.bind(console);
 var defaultPrintErr = console.error.bind(console);
 if (ENVIRONMENT_IS_NODE) {
-  var utils = require('node:util');
+  var utils = {{{ makeNodeImport('node:util') }}};
   var stringify = (a) => typeof a == 'object' ? utils.inspect(a) : a;
   defaultPrint = (...args) => fs.writeSync(1, args.map(stringify).join(' ') + '\n');
   defaultPrintErr = (...args) => fs.writeSync(2, args.map(stringify).join(' ') + '\n');

src/shell_minimal.js

@@ -55,7 +55,7 @@ var ENVIRONMENT_IS_WEB = !ENVIRONMENT_IS_NODE;
 
 #if ENVIRONMENT_MAY_BE_NODE && (PTHREADS || WASM_WORKERS)
 if (ENVIRONMENT_IS_NODE) {
-  var worker_threads = require('node:worker_threads');
+  var worker_threads = {{{ makeNodeImport('node:worker_threads') }}};
   global.Worker = worker_threads.Worker;
 }
 #endif
@@ -99,7 +99,7 @@ if (ENVIRONMENT_IS_NODE && ENVIRONMENT_IS_SHELL) {
 var defaultPrint = console.log.bind(console);
 var defaultPrintErr = console.error.bind(console);
 if (ENVIRONMENT_IS_NODE) {
-  var fs = require('node:fs');
+  var fs = {{{ makeNodeImport('node:fs') }}};
   defaultPrint = (...args) => fs.writeSync(1, args.join(' ') + '\n');
   defaultPrintErr = (...args) => fs.writeSync(2, args.join(' ') + '\n');
 }
@@ -181,13 +181,13 @@ if (!ENVIRONMENT_IS_PTHREAD) {
 // Wasm or Wasm2JS loading:
 
 if (ENVIRONMENT_IS_NODE) {
-  var fs = require('node:fs');
+  var fs = {{{ makeNodeImport('node:fs') }}};
 #if WASM == 2
-  if (globalThis.WebAssembly) Module['wasm'] = fs.readFileSync(__dirname + '/{{{ TARGET_BASENAME }}}.wasm');
-  else eval(fs.readFileSync(__dirname + '/{{{ TARGET_BASENAME }}}.wasm.js')+'');
+  if (globalThis.WebAssembly) Module['wasm'] = fs.readFileSync({{{ makeNodeFilePath(TARGET_BASENAME + '.wasm') }}});
+  else eval(fs.readFileSync({{{ makeNodeFilePath(TARGET_BASENAME + '.wasm.js') }}})+'');
 #else
 #if !WASM2JS
-  Module['wasm'] = fs.readFileSync(__dirname + '/{{{ TARGET_BASENAME }}}.wasm');
+  Module['wasm'] = fs.readFileSync({{{ makeNodeFilePath(TARGET_BASENAME + '.wasm') }}});
 #endif
 #endif
 }