tools: add prefer-proto rule

fixup: add support for `Object.create(null)`

fixup: extend to any 1-argument Object.create call

fixup: add tests
PR-URL: nodejs#46083
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Geoffrey Booth <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>
Reviewed-By: Mohammed Keyvanzadeh <[email protected]>
Reviewed-By: Darshan Sen <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Jacob Smith <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>

Author: ljharb

.eslintrc.js

@@ -314,6 +314,7 @@ module.exports = {
     // Custom rules from eslint-plugin-node-core
     'node-core/no-unescaped-regexp-dot': 'error',
     'node-core/no-duplicate-requires': 'error',
+    'node-core/prefer-proto': 'error',
   },
   globals: {
     ByteLengthQueuingStrategy: 'readable',

benchmark/es/map-bench.js

@@ -25,7 +25,7 @@ function runObject(n) {
 }
 
 function runNullProtoObject(n) {
-  const m = Object.create(null);
+  const m = { __proto__: null };
   bench.start();
   for (let i = 0; i < n; i++) {
     m[`i${i}`] = i;
@@ -51,7 +51,7 @@ function runNullProtoLiteralObject(n) {
 }
 
 function StorageObject() {}
-StorageObject.prototype = Object.create(null);
+StorageObject.prototype = { __proto__: null };
 
 function runStorageObject(n) {
   const m = new StorageObject();

doc/api/assert.md

@@ -664,7 +664,7 @@ const obj3 = {
     b: 1,
   },
 };
-const obj4 = Object.create(obj1);
+const obj4 = { __proto__: obj1 };
 
 assert.deepEqual(obj1, obj1);
 // OK
@@ -699,7 +699,7 @@ const obj3 = {
     b: 1,
   },
 };
-const obj4 = Object.create(obj1);
+const obj4 = { __proto__: obj1 };
 
 assert.deepEqual(obj1, obj1);
 // OK
@@ -1623,7 +1623,7 @@ const obj3 = {
     b: 1,
   },
 };
-const obj4 = Object.create(obj1);
+const obj4 = { __proto__: obj1 };
 
 assert.notDeepEqual(obj1, obj1);
 // AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }
@@ -1656,7 +1656,7 @@ const obj3 = {
     b: 1,
   },
 };
-const obj4 = Object.create(obj1);
+const obj4 = { __proto__: obj1 };
 
 assert.notDeepEqual(obj1, obj1);
 // AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }

lib/_http_agent.js

@@ -32,7 +32,6 @@ const {
   FunctionPrototypeCall,
   NumberIsNaN,
   NumberParseInt,
-  ObjectCreate,
   ObjectKeys,
   ObjectSetPrototypeOf,
   ObjectValues,
@@ -111,9 +110,9 @@ function Agent(options) {
 
   // Don't confuse net and make it think that we're connecting to a pipe
   this.options.path = null;
-  this.requests = ObjectCreate(null);
-  this.sockets = ObjectCreate(null);
-  this.freeSockets = ObjectCreate(null);
+  this.requests = { __proto__: null };
+  this.sockets = { __proto__: null };
+  this.freeSockets = { __proto__: null };
   this.keepAliveMsecs = this.options.keepAliveMsecs || 1000;
   this.keepAlive = this.options.keepAlive || false;
   this.maxSockets = this.options.maxSockets || Agent.defaultMaxSockets;

lib/_http_outgoing.js

@@ -28,7 +28,6 @@ const {
   MathAbs,
   MathFloor,
   NumberPrototypeToString,
-  ObjectCreate,
   ObjectDefineProperty,
   ObjectKeys,
   ObjectValues,
@@ -217,7 +216,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headers', {
     if (val == null) {
       this[kOutHeaders] = null;
     } else if (typeof val === 'object') {
-      const headers = this[kOutHeaders] = ObjectCreate(null);
+      const headers = this[kOutHeaders] = { __proto__: null };
       const keys = ObjectKeys(val);
       // Retain for(;;) loop for performance reasons
       // Refs: https://github.com/nodejs/node/pull/30958
@@ -244,7 +243,7 @@ ObjectDefineProperty(OutgoingMessage.prototype, '_headerNames', {
   get: internalUtil.deprecate(function() {
     const headers = this[kOutHeaders];
     if (headers !== null) {
-      const out = ObjectCreate(null);
+      const out = { __proto__: null };
       const keys = ObjectKeys(headers);
       // Retain for(;;) loop for performance reasons
       // Refs: https://github.com/nodejs/node/pull/30958
@@ -667,7 +666,7 @@ OutgoingMessage.prototype.setHeader = function setHeader(name, value) {
 
   let headers = this[kOutHeaders];
   if (headers === null)
-    this[kOutHeaders] = headers = ObjectCreate(null);
+    this[kOutHeaders] = headers = { __proto__: null };
 
   headers[StringPrototypeToLowerCase(name)] = [name, value];
   return this;
@@ -742,7 +741,7 @@ OutgoingMessage.prototype.getRawHeaderNames = function getRawHeaderNames() {
 // Returns a shallow copy of the current outgoing headers.
 OutgoingMessage.prototype.getHeaders = function getHeaders() {
   const headers = this[kOutHeaders];
-  const ret = ObjectCreate(null);
+  const ret = { __proto__: null };
   if (headers) {
     const keys = ObjectKeys(headers);
     // Retain for(;;) loop for performance reasons

lib/_tls_common.js

@@ -26,7 +26,6 @@ const tls = require('tls');
 const {
   ArrayPrototypePush,
   JSONParse,
-  ObjectCreate,
   RegExpPrototypeSymbolReplace,
 } = primordials;
 
@@ -131,7 +130,7 @@ function translatePeerCertificate(c) {
   }
   if (c.infoAccess != null) {
     const info = c.infoAccess;
-    c.infoAccess = ObjectCreate(null);
+    c.infoAccess = { __proto__: null };
 
     // XXX: More key validation?
     RegExpPrototypeSymbolReplace(/([^\n:]*):([^\n]*)(?:\n|$)/g, info,

lib/buffer.js

@@ -33,7 +33,6 @@ const {
   NumberIsNaN,
   NumberMAX_SAFE_INTEGER,
   NumberMIN_SAFE_INTEGER,
-  ObjectCreate,
   ObjectDefineProperties,
   ObjectDefineProperty,
   ObjectSetPrototypeOf,
@@ -146,7 +145,7 @@ const constants = ObjectDefineProperties({}, {
 Buffer.poolSize = 8 * 1024;
 let poolSize, poolOffset, allocPool;
 
-const encodingsMap = ObjectCreate(null);
+const encodingsMap = { __proto__: null };
 for (let i = 0; i < encodings.length; ++i)
   encodingsMap[encodings[i]] = i;
 
@@ -845,7 +844,7 @@ Buffer.prototype[customInspectSymbol] = function inspect(recurseTimes, ctx) {
   if (ctx) {
     let extras = false;
     const filter = ctx.showHidden ? ALL_PROPERTIES : ONLY_ENUMERABLE;
-    const obj = ObjectCreate(null);
+    const obj = { __proto__: null };
     ArrayPrototypeForEach(getOwnNonIndexProperties(this, filter),
                           (key) => {
                             extras = true;

lib/diagnostics_channel.js

@@ -4,7 +4,6 @@ const {
   ArrayPrototypeIndexOf,
   ArrayPrototypePush,
   ArrayPrototypeSplice,
-  ObjectCreate,
   ObjectGetPrototypeOf,
   ObjectSetPrototypeOf,
   SymbolHasInstance,
@@ -92,7 +91,7 @@ class Channel {
   publish() {}
 }
 
-const channels = ObjectCreate(null);
+const channels = { __proto__: null };
 
 function channel(name) {
   let channel;

lib/events.js

@@ -33,7 +33,6 @@ const {
   FunctionPrototypeBind,
   FunctionPrototypeCall,
   NumberIsNaN,
-  ObjectCreate,
   ObjectDefineProperty,
   ObjectDefineProperties,
   ObjectGetPrototypeOf,
@@ -338,7 +337,7 @@ EventEmitter.init = function(opts) {
 
   if (this._events === undefined ||
       this._events === ObjectGetPrototypeOf(this)._events) {
-    this._events = ObjectCreate(null);
+    this._events = { __proto__: null };
     this._eventsCount = 0;
   }
 
@@ -547,7 +546,7 @@ function _addListener(target, type, listener, prepend) {
 
   events = target._events;
   if (events === undefined) {
-    events = target._events = ObjectCreate(null);
+    events = target._events = { __proto__: null };
     target._eventsCount = 0;
   } else {
     // To avoid recursion in the case that type === "newListener"! Before
@@ -685,7 +684,7 @@ EventEmitter.prototype.removeListener =
 
       if (list === listener || list.listener === listener) {
         if (--this._eventsCount === 0)
-          this._events = ObjectCreate(null);
+          this._events = { __proto__: null };
         else {
           delete events[type];
           if (events.removeListener)
@@ -740,11 +739,11 @@ EventEmitter.prototype.removeAllListeners =
       // Not listening for removeListener, no need to emit
       if (events.removeListener === undefined) {
         if (arguments.length === 0) {
-          this._events = ObjectCreate(null);
+          this._events = { __proto__: null };
           this._eventsCount = 0;
         } else if (events[type] !== undefined) {
           if (--this._eventsCount === 0)
-            this._events = ObjectCreate(null);
+            this._events = { __proto__: null };
           else
             delete events[type];
         }
@@ -758,7 +757,7 @@ EventEmitter.prototype.removeAllListeners =
           this.removeAllListeners(key);
         }
         this.removeAllListeners('removeListener');
-        this._events = ObjectCreate(null);
+        this._events = { __proto__: null };
         this._eventsCount = 0;
         return this;
       }

lib/internal/assert/assertion_error.js

@@ -6,7 +6,6 @@ const {
   Error,
   ErrorCaptureStackTrace,
   MathMax,
-  ObjectCreate,
   ObjectDefineProperty,
   ObjectGetPrototypeOf,
   ObjectKeys,
@@ -48,7 +47,7 @@ const kMaxShortLength = 12;
 
 function copyError(source) {
   const keys = ObjectKeys(source);
-  const target = ObjectCreate(ObjectGetPrototypeOf(source));
+  const target = { __proto__: ObjectGetPrototypeOf(source) };
   for (const key of keys) {
     target[key] = source[key];
   }