module: reduce circular dependency of internal/modules/cjs/loader

Previously `internal/bootstrap/pre_execution.js` requires
`internal/modules/cjs/loader.js` which in turn requires
`internal/bootstrap/pre_execution.js`. This patch moves the
entry point execution logic out of `pre_execution.js` and
puts it into `internal/modules/run_main.js`. It also tests
that `Module.runMain` can be monkey-patched before further
deprecation/refactoring can be done.

Also added an internal assertion `hasLoadedAnyUserCJSModule`
for documentation purposes.

PR-URL: https://github.com/nodejs/node/pull/30349
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 9 insertions, 58 deletions

diff --git a/lib/internal/bootstrap/pre_execution.js b/lib/internal/bootstrap/pre_execution.js
index 793ee18142..8edec86a3e 100644
--- a/lib/internal/bootstrap/pre_execution.js
+++ b/lib/internal/bootstrap/pre_execution.js
@@ -5,7 +5,7 @@ const { Object, SafeWeakMap } = primordials;
 const { getOptionValue } = require('internal/options');
 const { Buffer } = require('buffer');
 const { ERR_MANIFEST_ASSERT_INTEGRITY } = require('internal/errors').codes;
-const path = require('path');
+const assert = require('internal/assert');
 
 function prepareMainThreadExecution(expandArgv1 = false) {
   // Patch the process object with legacy properties and normalizations
@@ -60,6 +60,9 @@ function prepareMainThreadExecution(expandArgv1 = false) {
   initializeDeprecations();
   initializeCJSLoader();
   initializeESMLoader();
+
+  const CJSLoader = require('internal/modules/cjs/loader');
+  assert(!CJSLoader.hasLoadedAnyUserCJSModule);
   loadPreloadModules();
   initializeFrozenIntrinsics();
 }
@@ -394,7 +397,11 @@ function initializePolicy() {
 }
 
 function initializeCJSLoader() {
-  require('internal/modules/cjs/loader').Module._initPaths();
+  const CJSLoader = require('internal/modules/cjs/loader');
+  CJSLoader.Module._initPaths();
+  // TODO(joyeecheung): deprecate this in favor of a proper hook?
+  CJSLoader.Module.runMain =
+    require('internal/modules/run_main').executeUserEntryPoint;
 }
 
 function initializeESMLoader() {
@@ -433,67 +440,11 @@ function loadPreloadModules() {
   }
 }
 
-function resolveMainPath(main) {
-  const { toRealPath, Module: CJSModule } =
-      require('internal/modules/cjs/loader');
-
-  // Note extension resolution for the main entry point can be deprecated in a
-  // future major.
-  let mainPath = CJSModule._findPath(path.resolve(main), null, true);
-  if (!mainPath)
-    return;
-
-  const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
-  if (!preserveSymlinksMain)
-    mainPath = toRealPath(mainPath);
-
-  return mainPath;
-}
-
-function shouldUseESMLoader(mainPath) {
-  const userLoader = getOptionValue('--experimental-loader');
-  if (userLoader)
-    return true;
-  // Determine the module format of the main
-  if (mainPath && mainPath.endsWith('.mjs'))
-    return true;
-  if (!mainPath || mainPath.endsWith('.cjs'))
-    return false;
-  const { readPackageScope } = require('internal/modules/cjs/loader');
-  const pkg = readPackageScope(mainPath);
-  return pkg && pkg.data.type === 'module';
-}
-
-function runMainESM(mainPath) {
-  const esmLoader = require('internal/process/esm_loader');
-  const { pathToFileURL } = require('internal/url');
-  const { hasUncaughtExceptionCaptureCallback } =
-      require('internal/process/execution');
-  return esmLoader.initializeLoader().then(() => {
-    const main = path.isAbsolute(mainPath) ?
-      pathToFileURL(mainPath).href : mainPath;
-    return esmLoader.ESMLoader.import(main);
-  }).catch((e) => {
-    if (hasUncaughtExceptionCaptureCallback()) {
-      process._fatalException(e);
-      return;
-    }
-    internalBinding('errors').triggerUncaughtException(
-      e,
-      true /* fromPromise */
-    );
-  });
-}
-
-
 module.exports = {
   patchProcessObject,
-  resolveMainPath,
-  runMainESM,
   setupCoverageHooks,
   setupWarningHandler,
   setupDebugEnv,
-  shouldUseESMLoader,
   prepareMainThreadExecution,
   initializeDeprecations,
   initializeESMLoader,