[Fix] cache Object.prototype[__proto__] getter

.eslintrc

@@ -5,7 +5,7 @@
 
 	"rules": {
 		"id-length": 0,
-		"max-statements": [2, 20],
+		"max-statements": [2, 25],
 		"new-cap": [2, {
 			"capIsNewExceptions": [
 				"GetIntrinsic",

.github/workflows/node-twenties.yml

@@ -12,3 +12,34 @@ jobs:
       range: '>= 20'
       type: minors
       command: npm run tests-only
+
+  no-proto:
+    name: 'node, --disable-proto=delete'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@v2
+        with:
+          disable-sudo: true
+          egress-policy: audit
+          allowed-endpoints: >
+            github.com:443
+            raw.githubusercontent.com:443
+            nodejs.org:443
+            iojs.org:443
+            registry.npmjs.org:443
+            actions-results-receiver-production.githubapp.com:443
+
+      - uses: actions/checkout@v4
+        with:
+          show-progress: false
+      - uses: ljharb/actions/node/install@main
+      - run: NODE_OPTIONS=--disable-proto=delete npm run tests-only
+      - uses: codecov/[email protected]
+
+  finisher:
+    needs: [tests, no-proto]
+    name: 'node >= 20'
+    runs-on: ubuntu-latest
+    steps:
+      - run: true

implementation.js

@@ -5,12 +5,17 @@ var IsCallable = require('es-abstract/2024/IsCallable');
 var Type = require('es-abstract/2024/Type');
 var whichBuiltinType = require('which-builtin-type');
 var $TypeError = require('es-errors/type');
+var callBind = require('call-bind');
+var gOPD = require('gopd');
 
 var $gPO = GetIntrinsic('%Object.getPrototypeOf%', true);
 var $ObjectPrototype = GetIntrinsic('%Object.prototype%');
 
 var hasProto = [].__proto__ === Array.prototype; // eslint-disable-line no-proto
 
+var dunderGetter = !$gPO && hasProto && gOPD && gOPD(Object.prototype, '__proto__');
+var getDunder = dunderGetter && dunderGetter.get && callBind(dunderGetter.get);
+
 module.exports = function getPrototypeOf(O) {
 	if (Type(O) !== 'Object') {
 		throw new $TypeError('Reflect.getPrototypeOf called on non-object');
@@ -20,9 +25,8 @@ module.exports = function getPrototypeOf(O) {
 		return $gPO(O);
 	}
 
-	if (hasProto) {
-		// eslint-disable-next-line no-proto
-		var proto = O.__proto__;
+	if (getDunder) {
+		var proto = getDunder(O);
 		if (proto || proto === null) {
 			return proto;
 		}

package.json

@@ -61,6 +61,7 @@
 		"es-abstract": "^1.23.5",
 		"es-errors": "^1.3.0",
 		"get-intrinsic": "^1.2.4",
+		"gopd": "^1.0.1",
 		"which-builtin-type": "^1.1.4"
 	},
 	"devDependencies": {
@@ -89,5 +90,8 @@
 		"ignore": [
 			".github/workflows"
 		]
+	},
+	"testling": {
+		"files": "test/implementation.js"
 	}
 }

polyfill.js

@@ -4,15 +4,22 @@ var Type = require('es-abstract/2024/Type');
 
 var $TypeError = require('es-errors/type');
 
+var callBind = require('call-bind');
+var gOPD = require('gopd');
+
 var implementation = require('./implementation');
 
 var hasProto = [].__proto__ === Array.prototype; // eslint-disable-line no-proto
 
+var dunderGetter = hasProto && gOPD && gOPD(Object.prototype, '__proto__');
+var getDunder = dunderGetter && dunderGetter.get && callBind(dunderGetter.get);
+
 var getProto = function getPrototypeOf(value) {
 	if (Type(value) !== 'Object') {
 		throw new $TypeError('Reflect.getPrototypeOf called on non-object');
 	}
-	return value.__proto__; // eslint-disable-line no-proto
+	// eslint-disable-next-line no-proto
+	return getDunder ? getDunder(value) : value.__proto__;
 };
 
 module.exports = function getPolyfill() {

test/tests.js

@@ -22,4 +22,12 @@ module.exports = function (getPrototypeOf, t) {
 	t.equal(getPrototypeOf(function () {}), Function.prototype);
 	t.equal(getPrototypeOf([]), Array.prototype);
 	t.equal(getPrototypeOf({}), Object.prototype);
+
+	var obj = { __proto__: null };
+	if ('toString' in obj) {
+		t.comment('no null objects in this engine');
+		t.equal(getPrototypeOf(obj), Object.prototype, '"null" object has Object.prototype as [[Prototype]]');
+	} else {
+		t.equal(getPrototypeOf(obj), null, 'null object has null [[Prototype]]');
+	}
 };