module: error for CJS .js load within type: module

lib/internal/modules/cjs/loader.js

@@ -212,16 +212,17 @@ Module._debug = deprecate(debug, 'Module._debug is deprecated.', 'DEP0077');
 //   -> a.<ext>
 //   -> a/index.<ext>
 
-// Check if the directory is a package.json dir.
-const packageMainCache = Object.create(null);
-// Explicit exports from package.json files
-const packageExportsCache = new SafeMap();
+const packageJsonCache = new SafeMap();
 
-function readPackageRaw(requestPath) {
+function readPackage(requestPath) {
   const jsonPath = path.resolve(requestPath, 'package.json');
-  const json = internalModuleReadJSON(path.toNamespacedPath(jsonPath));
 
+  const existing = packageJsonCache.get(jsonPath);
+  if (existing !== undefined) return existing;
+
+  const json = internalModuleReadJSON(path.toNamespacedPath(jsonPath));
   if (json === undefined) {
+    packageJsonCache.set(jsonPath, false);
     return false;
   }
 
@@ -232,45 +233,47 @@ function readPackageRaw(requestPath) {
 
   try {
     const parsed = JSON.parse(json);
-    packageMainCache[requestPath] = parsed.main;
-    if (experimentalExports) {
-      packageExportsCache.set(requestPath, parsed.exports);
-    }
-    return parsed;
+    const filtered = {
+      main: parsed.main,
+      exports: parsed.exports,
+      type: parsed.type
+    };
+    packageJsonCache.set(jsonPath, filtered);
+    return filtered;
   } catch (e) {
     e.path = jsonPath;
     e.message = 'Error parsing ' + jsonPath + ': ' + e.message;
     throw e;
   }
 }
 
-function readPackage(requestPath) {
-  const entry = packageMainCache[requestPath];
-  if (entry)
-    return entry;
-
-  const pkg = readPackageRaw(requestPath);
-  if (pkg === false) return false;
-
-  return pkg.main;
-}
-
-function readExports(requestPath) {
-  if (packageExportsCache.has(requestPath)) {
-    return packageExportsCache.get(requestPath);
+function readPackageScope(checkPath) {
+  const rootSeparatorIndex = checkPath.indexOf(path.sep);
+  let separatorIndex;
+  while (
+    (separatorIndex = checkPath.lastIndexOf(path.sep)) > rootSeparatorIndex
+  ) {
+    checkPath = checkPath.slice(0, separatorIndex);
+    if (checkPath.endsWith(path.sep + 'node_modules'))
+      return false;
+    const pjson = readPackage(checkPath);
+    if (pjson) return pjson;
   }
+  return false;
+}
 
-  const pkg = readPackageRaw(requestPath);
-  if (!pkg) {
-    packageExportsCache.set(requestPath, null);
-    return null;
-  }
+function readPackageMain(requestPath) {
+  const pkg = readPackage(requestPath);
+  return pkg ? pkg.main : undefined;
+}
 
-  return pkg.exports;
+function readPackageExports(requestPath) {
+  const pkg = readPackage(requestPath);
+  return pkg ? pkg.exports : undefined;
 }
 
 function tryPackage(requestPath, exts, isMain, originalPath) {
-  const pkg = readPackage(requestPath);
+  const pkg = readPackageMain(requestPath);
 
   if (!pkg) {
     return tryExtensions(path.resolve(requestPath, 'index'), exts, isMain);
@@ -371,7 +374,7 @@ function resolveExports(nmPath, request, absoluteRequest) {
     }
 
     const basePath = path.resolve(nmPath, name);
-    const pkgExports = readExports(basePath);
+    const pkgExports = readPackageExports(basePath);
     const mappingKey = `.${expansion}`;
 
     if (typeof pkgExports === 'object' && pkgExports !== null) {
@@ -943,6 +946,12 @@ Module.prototype._compile = function(content, filename) {
 
 // Native extension for .js
 Module._extensions['.js'] = function(module, filename) {
+  if (filename.endsWith('.js')) {
+    const pkg = readPackageScope(filename);
+    if (pkg && pkg.type === 'module') {
+      throw new ERR_REQUIRE_ESM(filename);
+    }
+  }
   const content = fs.readFileSync(filename, 'utf8');
   module._compile(content, filename);
 };

src/node_file.cc

@@ -875,7 +875,8 @@ static void InternalModuleReadJSON(const FunctionCallbackInfo<Value>& args) {
   const size_t size = offset - start;
   if (size == 0 || (
     size == SearchString(&chars[start], size, "\"main\"") &&
-    size == SearchString(&chars[start], size, "\"exports\""))) {
+    size == SearchString(&chars[start], size, "\"exports\"") &&
+    size == SearchString(&chars[start], size, "\"type\""))) {
     return;
   } else {
     Local<String> chars_string =

test/es-module/test-esm-type-flag-errors.js

@@ -23,6 +23,13 @@ expect('', packageWithoutTypeMain, 'package-without-type');
 expect('--input-type=module', packageTypeModuleMain,
        'ERR_INPUT_TYPE_NOT_ALLOWED', true);
 
+try {
+  require('../fixtures/es-modules/package-type-module/index.js');
+  assert.fail('Expected CJS to fail loading from type: module package.');
+} catch (e) {
+  assert(e.toString().match(/Error \[ERR_REQUIRE_ESM\]: Must use import to load ES Module:/));
+}
+
 function expect(opt = '', inputFile, want, wantsError = false) {
   // TODO: Remove when --experimental-modules is unflagged
   opt = `--experimental-modules ${opt}`;

test/parallel/test-policy-integrity.js

@@ -212,6 +212,10 @@ test({
   shouldFail: false,
   entry: parentFilepath,
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [parentURL]: {
       body: parentBody,
       match: true,
@@ -227,6 +231,10 @@ test({
   preload: [depFilepath],
   entry: parentFilepath,
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [parentURL]: {
       body: parentBody,
       match: true,
@@ -279,6 +287,10 @@ test({
   shouldFail: false,
   entry: depFilepath,
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [depURL]: {
       body: depBody,
       match: true,
@@ -289,6 +301,10 @@ test({
   shouldFail: false,
   entry: depFilepath,
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [policyToDepRelativeURLString]: {
       body: depBody,
       match: true,
@@ -309,6 +325,10 @@ test({
   shouldFail: false,
   entry: depFilepath,
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [policyToDepRelativeURLString]: {
       body: depBody,
       match: true,
@@ -351,6 +371,10 @@ test({
   shouldFail: false,
   entry: workerSpawningFilepath,
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [workerSpawningURL]: {
       body: workerSpawningBody,
       match: true,
@@ -370,6 +394,10 @@ test({
   entry: workerSpawningFilepath,
   preload: [parentFilepath],
   resources: {
+    [packageURL]: {
+      body: packageBody,
+      match: true,
+    },
     [workerSpawningURL]: {
       body: workerSpawningBody,
       match: true,

test/parallel/test-policy-parse-integrity.js

@@ -36,8 +36,16 @@ if (!tmpdirURL.pathname.endsWith('/')) {
   tmpdirURL.pathname += '/';
 }
 
+const packageFilepath = path.join(tmpdir.path, 'package.json');
+const packageURL = pathToFileURL(packageFilepath);
+const packageBody = '{"main": "dep.js"}';
+
 function test({ shouldFail, integrity }) {
   const resources = {
+    [packageURL]: {
+      body: packageBody,
+      integrity: `sha256-${hash('sha256', packageBody)}`
+    },
     [depURL]: {
       body: depBody,
       integrity