module: do not check circular dependencies for exported proxies

lib/internal/modules/cjs/loader.js

@@ -107,6 +107,11 @@ const {
   CHAR_COLON
 } = require('internal/constants');
 
+
+const {
+  isProxy
+} = require('internal/util/types');
+
 const isWindows = process.platform === 'win32';
 
 const relativeResolveCache = ObjectCreate(null);
@@ -821,7 +826,7 @@ function emitCircularRequireWarning(prop) {
 }
 
 // A Proxy that can be used as the prototype of a module.exports object and
-// warns when non-existend properties are accessed.
+// warns when non-existent properties are accessed.
 const CircularRequirePrototypeWarningProxy = new Proxy({}, {
   get(target, prop) {
     // Allow __esModule access in any case because it is used in the output
@@ -840,20 +845,22 @@ const CircularRequirePrototypeWarningProxy = new Proxy({}, {
   }
 });
 
-// Object.prototype and ObjectProtoype refer to our 'primordials' versions
+// Object.prototype and ObjectPrototype refer to our 'primordials' versions
 // and are not identical to the versions on the global object.
 const PublicObjectPrototype = global.Object.prototype;
 
 function getExportsForCircularRequire(module) {
   if (module.exports &&
+      !isProxy(module.exports) &&
       ObjectGetPrototypeOf(module.exports) === PublicObjectPrototype &&
       // Exclude transpiled ES6 modules / TypeScript code because those may
-      // employ unusual patterns for accessing 'module.exports'. That should be
-      // okay because ES6 modules have a different approach to circular
+      // employ unusual patterns for accessing 'module.exports'. That should
+      // be okay because ES6 modules have a different approach to circular
       // dependencies anyway.
       !module.exports.__esModule) {
     // This is later unset once the module is done loading.
-    ObjectSetPrototypeOf(module.exports, CircularRequirePrototypeWarningProxy);
+    ObjectSetPrototypeOf(
+      module.exports, CircularRequirePrototypeWarningProxy);
   }
 
   return module.exports;
@@ -943,6 +950,7 @@ Module._load = function(request, parent, isMain) {
         }
       }
     } else if (module.exports &&
+               !isProxy(module.exports) &&
                ObjectGetPrototypeOf(module.exports) ===
                  CircularRequirePrototypeWarningProxy) {
       ObjectSetPrototypeOf(module.exports, PublicObjectPrototype);

test/fixtures/cycles/warning-skip-proxy-traps-a.js

@@ -0,0 +1,17 @@
+module.exports = new Proxy({}, {
+  get(_target, prop) { throw new Error(`get: ${String(prop)}`); },
+  getPrototypeOf() { throw new Error('getPrototypeOf'); },
+  setPrototypeOf() { throw new Error('setPrototypeOf'); },
+  isExtensible() { throw new Error('isExtensible'); },
+  preventExtensions() { throw new Error('preventExtensions'); },
+  getOwnPropertyDescriptor() { throw new Error('getOwnPropertyDescriptor'); },
+  defineProperty() { throw new Error('defineProperty'); },
+  has() { throw new Error('has'); },
+  set() { throw new Error('set'); },
+  deleteProperty() { throw new Error('deleteProperty'); },
+  ownKeys() { throw new Error('ownKeys'); },
+  apply() { throw new Error('apply'); },
+  construct() { throw new Error('construct'); }
+});
+
+require('./warning-skip-proxy-traps-b.js');

test/fixtures/cycles/warning-skip-proxy-traps-b.js

@@ -0,0 +1,10 @@
+const assert = require('assert');
+
+const object = require('./warning-skip-proxy-traps-a.js');
+
+assert.throws(() => {
+  object.missingPropProxyTrap;
+}, {
+  message: 'get: missingPropProxyTrap',
+  name: 'Error',
+});

test/parallel/test-module-circular-dependency-warning.js

@@ -38,3 +38,8 @@ assert.strictEqual(esmTranspiledExport.__esModule, true);
 const halfTranspiledExport =
   require(fixtures.path('cycles', 'warning-esm-half-transpiled-a.js'));
 assert.strictEqual(halfTranspiledExport.__esModule, undefined);
+
+// No circular check is done to prevent triggering proxy traps, if
+// module.exports is set to a proxy that contains a `getPrototypeOf` or
+// `setPrototypeOf` trap.
+require(fixtures.path('cycles', 'warning-skip-proxy-traps-a.js'));