esm: Add references to require() of ESM warning

lib/internal/modules/cjs/loader.js

@@ -259,7 +259,10 @@ function readPackageScope(checkPath) {
     if (checkPath.endsWith(path.sep + 'node_modules'))
       return false;
     const pjson = readPackage(checkPath);
-    if (pjson) return pjson;
+    if (pjson) return {
+      path: checkPath,
+      data: pjson
+    };
   }
   return false;
 }
@@ -964,13 +967,18 @@ let warnRequireESM = true;
 Module._extensions['.js'] = function(module, filename) {
   if (filename.endsWith('.js')) {
     const pkg = readPackageScope(filename);
-    if (pkg && pkg.type === 'module') {
+    if (pkg && pkg.data && pkg.data.type === 'module') {
       if (warnRequireESM) {
         process.emitWarning(
-          'require() of .js file ' + filename + ' is not supported as it is ' +
-          'an ES module due to having "type": "module" in its package.json ' +
-          'file.\nRather use import to load this module, or if you are the ' +
-          'author you may want to use the .cjs extension for this file.'
+          ((module.parent && module.parent.filename) ?
+            `${module.parent.filename} contains a ` : '') +
+          `require() of ${filename}, which is a .js file whose nearest ` +
+          'parent package.json contains "type": "module" which therefore ' +
+          'defines all .js files in that package scope as ES modules. ' +
+          'require() of ES modules is not allowed. Instead, rename ' +
+          `${filename} to end in .cjs, or change the requiring code to use ` +
+          'import(), or remove "type": "module" from ' +
+          `${path.resolve(pkg.path, 'package.json')}.`
         );
         warnRequireESM = false;
       }

test/es-module/test-cjs-esm-warn.js

@@ -6,9 +6,15 @@ const { spawn } = require('child_process');
 const assert = require('assert');
 const path = require('path');
 
-const entry = fixtures.path('/es-modules/cjs-esm.js');
+const requiring = path.resolve(fixtures.path('/es-modules/cjs-esm.js'));
+const required = path.resolve(
+  fixtures.path('/es-modules/package-type-module/cjs.js')
+);
+const pjson = path.resolve(
+  fixtures.path('/es-modules/package-type-module/package.json')
+);
 
-const child = spawn(process.execPath, [entry]);
+const child = spawn(process.execPath, [requiring]);
 let stderr = '';
 child.stderr.setEncoding('utf8');
 child.stderr.on('data', (data) => {
@@ -17,9 +23,11 @@ child.stderr.on('data', (data) => {
 child.on('close', common.mustCall((code, signal) => {
   assert.strictEqual(code, 0);
   assert.strictEqual(signal, null);
-  assert.strictEqual(stderr, `(node:${child.pid}) Warning: require() of .js ` +
-      `file ${path.resolve(entry, '../package-type-module/cjs.js')} is not ` +
-      'supported as it is an ES module due to having "type": "module" in its ' +
-      'package.json file.\nRather use import to load this module, or if you ' +
-      'are the author you may want to use the .cjs extension for this file.\n');
+  assert.strictEqual(stderr, `(node:${child.pid}) Warning: ${requiring} ` +
+    `contains a require() of ${required}, which is a .js file whose nearest ` +
+    'parent package.json contains "type": "module" which therefore defines ' +
+    'all .js files in that package scope as ES modules. require() of ES ' +
+    `modules is not allowed. Instead, rename ${required} to end in .cjs, or ` +
+    'change the requiring code to use import(), or remove "type": "module" ' +
+    `from ${pjson}.\n`);
 }));