Remove createRequire in favor of ES6 import (emscripten-core#23169)

Author: sbc100

src/closure-externs/closure-externs.js

@@ -15,9 +15,6 @@
 var EMSCRIPTEN$IMPORT$META;
 var EMSCRIPTEN$AWAIT$IMPORT;
 
-// Don't minify createRequire
-var createRequire;
-
 // Don't minify startWorker which we use to start workers once the runtime is ready.
 /**
  * @param {Object} Module

src/shell.js

@@ -103,22 +103,12 @@ if (ENVIRONMENT_IS_PTHREAD) {
 
 #if ENVIRONMENT_MAY_BE_NODE
 if (ENVIRONMENT_IS_NODE) {
-  // `require()` is no-op in an ESM module, use `createRequire()` to construct
-  // the require()` function.  This is only necessary for multi-environment
-  // builds, `-sENVIRONMENT=node` emits a static import declaration instead.
-  // TODO: Swap all `require()`'s with `import()`'s?
-#if EXPORT_ES6 && ENVIRONMENT_MAY_BE_WEB
-  const { createRequire } = await import('module');
-  let dirname = import.meta.url;
-  if (dirname.startsWith("data:")) {
-    dirname = '/';
-  }
-  /** @suppress{duplicate} */
-  var require = createRequire(dirname);
-#endif
-
 #if PTHREADS || WASM_WORKERS
+#if EXPORT_ES6
+  var worker_threads = await import('worker_threads');
+#else
   var worker_threads = require('worker_threads');
+#endif
   global.Worker = worker_threads.Worker;
   ENVIRONMENT_IS_WORKER = !worker_threads.isMainThread;
 #if PTHREADS
@@ -203,19 +193,21 @@ if (ENVIRONMENT_IS_NODE) {
   }
 #endif
 
-  // These modules will usually be used on Node.js. Load them eagerly to avoid
-  // the complexity of lazy-loading.
-  var fs = require('fs');
-  var nodePath = require('path');
-
 #if EXPORT_ES6
+  var fs = await import('fs');
+  var nodePath = await import('path');
+  var url = await import('url');
   // EXPORT_ES6 + ENVIRONMENT_IS_NODE always requires use of import.meta.url,
   // since there's no way getting the current absolute path of the module when
   // support for that is not available.
   if (!import.meta.url.startsWith('data:')) {
-    scriptDirectory = nodePath.dirname(require('url').fileURLToPath(import.meta.url)) + '/';
+    scriptDirectory = nodePath.dirname(url.fileURLToPath(import.meta.url)) + '/';
   }
 #else
+  // These modules will usually be used on Node.js. Load them eagerly to avoid
+  // the complexity of lazy-loading.
+  var fs = require('fs');
+  var nodePath = require('path');
   scriptDirectory = __dirname + '/';
 #endif
 

test/other/test_unoptimized_code_size.js.size

@@ -1 +1 @@
-54298
+54011

test/other/test_unoptimized_code_size_no_asserts.js.size

@@ -1 +1 @@
-29718
+29431

test/other/test_unoptimized_code_size_strict.js.size

@@ -1 +1 @@
-53094
+52807

third_party/closure-compiler/node-externs/url.js

@@ -30,6 +30,7 @@
 
 /**
  * @type {Object.<string,*>}
+ * @suppress {duplicate}
  */
 var url = {};
 

tools/link.py

@@ -2365,21 +2365,6 @@ def phase_binaryen(target, options, wasm_target):
     write_file(final_js, js)
 
 
-def node_es6_imports():
-  if not settings.EXPORT_ES6 or not settings.ENVIRONMENT_MAY_BE_NODE:
-    return ''
-
-  # Multi-environment builds uses `await import` in `shell.js`
-  if settings.ENVIRONMENT_MAY_BE_WEB:
-    return ''
-
-  # Use static import declaration if we only target Node.js
-  return '''
-import { createRequire } from 'module';
-const require = createRequire(import.meta.url);
-'''
-
-
 def node_pthread_detection():
   # Under node we detect that we are running in a pthread by checking the
   # workerData property.
@@ -2394,11 +2379,10 @@ def modularize():
   logger.debug(f'Modularizing, assigning to var {settings.EXPORT_NAME}')
   src = read_file(final_js)
 
-  # Multi-environment ES6 builds require an async function
+  # When targetting node and ES6 we use `await import ..` in the generated code
+  # so the outer function needs to be marked as async.
   async_emit = ''
-  if settings.EXPORT_ES6 and \
-     settings.ENVIRONMENT_MAY_BE_NODE and \
-     settings.ENVIRONMENT_MAY_BE_WEB:
+  if settings.EXPORT_ES6 and settings.ENVIRONMENT_MAY_BE_NODE:
     async_emit = 'async '
 
   # TODO: Remove when https://bugs.webkit.org/show_bug.cgi?id=223533 is resolved.
@@ -2449,25 +2433,23 @@ def modularize():
       if settings.ENVIRONMENT_MAY_BE_NODE:
         script_url_node = "if (typeof __filename != 'undefined') _scriptName = _scriptName || __filename;"
     if settings.MODULARIZE == 'instance':
-      src = '''%(node_imports)s
+      src = '''\
   var _scriptName = %(script_url)s;
   %(script_url_node)s
   %(src)s
 ''' % {
-        'node_imports': node_es6_imports(),
         'script_url': script_url,
         'script_url_node': script_url_node,
         'src': src,
       }
     else:
-      src = '''%(node_imports)s
+      src = '''\
 var %(EXPORT_NAME)s = (() => {
   var _scriptName = %(script_url)s;
   %(script_url_node)s
   return (%(src)s);
 })();
 ''' % {
-        'node_imports': node_es6_imports(),
         'EXPORT_NAME': settings.EXPORT_NAME,
         'script_url': script_url,
         'script_url_node': script_url_node,