esm: fallback to readFileSync when source is nullish

lib/internal/modules/esm/load.js

@@ -261,5 +261,6 @@ function throwUnknownModuleFormat(url, format) {
 module.exports = {
  defaultLoad,
  defaultLoadSync,
+ getSourceSync,
  throwUnknownModuleFormat,
 };

lib/internal/modules/esm/translators.js

@@ -31,6 +31,7 @@ function lazyTypes() {
 }
 
 const { containsModuleSyntax } = internalBinding('contextify');
+const { BuiltinModule } = require('internal/bootstrap/realm');
 const assert = require('internal/assert');
 const { readFileSync } = require('fs');
 const { dirname, extname, isAbsolute } = require('path');
@@ -58,6 +59,17 @@ const asyncESM = require('internal/process/esm_loader');
 const { emitWarningSync } = require('internal/process/warning');
 const { internalCompileFunction } = require('internal/vm');
 
+// Lazy-loading to avoid circular dependencies.
+let getSourceSync;
+/**
+ * @param {Parameters<typeof import('./load').getSourceSync>[0]} url
+ * @returns {ReturnType<typeof import('./load').getSourceSync>}
+ */
+function getSource(url) {
+ getSourceSync ??= require('internal/modules/esm/load').getSourceSync;
+ return getSourceSync(url);
+}
+
 /** @type {import('deps/cjs-module-lexer/lexer.js').parse} */
 let cjsParse;
 /**
@@ -225,21 +237,19 @@ function loadCJSModule(module, source, url, filename) {
  // eslint-disable-next-line func-name-matching,func-style
  const requireFn = function require(specifier) {
  let importAttributes = kEmptyObject;
- if (!StringPrototypeStartsWith(specifier, 'node:')) {
+ if (!StringPrototypeStartsWith(specifier, 'node:') && !BuiltinModule.normalizeRequirableId(specifier)) {
  // TODO: do not depend on the monkey-patchable CJS loader here.
  const path = CJSModule._resolveFilename(specifier, module);
- if (specifier !== path) {
- switch (extname(path)) {
- case '.json':
- importAttributes = { __proto__: null, type: 'json' };
- break;
- case '.node':
- return CJSModule._load(specifier, module);
- default:
+ switch (extname(path)) {
+ case '.json':
+ importAttributes = { __proto__: null, type: 'json' };
+ break;
+ case '.node':
+ return CJSModule._load(specifier, module);
+ default:
  // fall through
- }
- specifier = `${pathToFileURL(path)}`;
  }
+ specifier = `${pathToFileURL(path)}`;
  }
  const job = asyncESM.esmLoader.getModuleJobSync(specifier, url, importAttributes);
  job.runSync();
@@ -276,7 +286,8 @@ function createCJSModuleWrap(url, source, isMain, loadCJS = loadCJSModule) {
  debug(`Translating CJSModule ${url}`);
 
  const filename = StringPrototypeStartsWith(url, 'file://') ? fileURLToPath(url) : url;
- source = stringify(source);
+ // In case the source was not provided by the `load` step, we need fetch it now.
+ source = stringify(source ?? getSource(new URL(url)).source);
 
  const { exportNames, module } = cjsPreparseModuleExports(filename, source);
  cjsCache.set(url, module);

test/es-module/test-esm-loader-hooks.mjs

@@ -746,4 +746,39 @@ describe('Loader hooks', { concurrency: true }, () => {
  assert.strictEqual(code, 0);
  assert.strictEqual(signal, null);
  });
+
+ it('should handle mixed of opt-in modules and non-opt-in ones', async () => {
+ const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+ '--no-warnings',
+ '--experimental-loader',
+ `data:text/javascript,const fixtures=${JSON.stringify(fixtures.path('empty.js'))};export ${
+ encodeURIComponent(function resolve(s, c, n) {
+ if (s.endsWith('entry-point')) {
+ return {
+ shortCircuit: true,
+ url: 'file:///c:/virtual-entry-point',
+ format: 'commonjs',
+ };
+ }
+ return n(s, c);
+ })
+ }export ${
+ encodeURIComponent(async function load(u, c, n) {
+ if (u === 'file:///c:/virtual-entry-point') {
+ return {
+ shortCircuit: true,
+ source: `"use strict";require(${JSON.stringify(fixtures)});console.log("Hello");`,
+ format: 'commonjs',
+ };
+ }
+ return n(u, c);
+ })}`,
+ 'entry-point',
+ ]);
+
+ assert.strictEqual(stderr, '');
+ assert.strictEqual(stdout, 'Hello\n');
+ assert.strictEqual(code, 0);
+ assert.strictEqual(signal, null);
+ });
 });