[pull] main from react:main

packages/react-client/src/ReactFlightClient.js

@@ -256,7 +256,7 @@ function ReactPromise(status: any, value: any, reason: any) {
 // We subclass Promise.prototype so that we get other methods like .catch
 ReactPromise.prototype = Object.create(Promise.prototype) as any;
 // TODO: This doesn't return a new Promise chain unlike the real .then
-ReactPromise.prototype.then = function <T>(
+function reactPromiseThen<T>(
   this: SomeChunk<T>,
   resolve: (value: T) => mixed,
   reject?: (reason: mixed) => mixed,
@@ -326,7 +326,17 @@ ReactPromise.prototype.then = function <T>(
       }
       break;
   }
-};
+}
+// The shadowing `then` must be defined with `Object.defineProperty` instead of
+// assignment. Assignment would throw when `Promise.prototype` is frozen (e.g.
+// by SES lockdown) because assigning over an inherited non-writable property
+// is rejected.
+Object.defineProperty(ReactPromise.prototype, 'then', {
+  writable: true,
+  enumerable: true,
+  configurable: true,
+  value: reactPromiseThen,
+});
 
 export type FindSourceMapURLCallback = (
   fileName: string,

packages/react-server-dom-webpack/src/__tests__/ReactFlightNonWritablePromiseThen-test.js

@@ -0,0 +1,56 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+import {patchMessageChannel} from '../../../../scripts/jest/patchMessageChannel';
+
+// Polyfills for test environment
+global.ReadableStream =
+  require('web-streams-polyfill/ponyfill/es6').ReadableStream;
+global.TextEncoder = require('util').TextEncoder;
+global.TextDecoder = require('util').TextDecoder;
+
+describe('ReactFlight with a non-writable Promise.prototype.then', () => {
+  let originalThen;
+
+  beforeEach(() => {
+    jest.resetModules();
+    originalThen = Object.getOwnPropertyDescriptor(Promise.prototype, 'then');
+    // eslint-disable-next-line no-extend-native
+    Object.defineProperty(Promise.prototype, 'then', {
+      ...originalThen,
+      writable: false,
+    });
+  });
+
+  afterEach(() => {
+    // eslint-disable-next-line no-extend-native
+    Object.defineProperty(Promise.prototype, 'then', originalThen);
+  });
+
+  it('can require Server and Client entrypoints', () => {
+    patchMessageChannel(require('scheduler'));
+    // Simulate the condition resolution
+    jest.mock('react', () => require('react/react.react-server'));
+    jest.mock('react-server-dom-webpack/server', () =>
+      require('react-server-dom-webpack/server.browser'),
+    );
+    require('./utils/WebpackMock');
+    const ReactServerDOMServer = require('react-server-dom-webpack/server');
+    expect(typeof ReactServerDOMServer.decodeReply).toBe('function');
+
+    __unmockReact();
+    jest.resetModules();
+    const ReactServerDOMClient = require('react-server-dom-webpack/client');
+    expect(typeof ReactServerDOMClient.createFromReadableStream).toBe(
+      'function',
+    );
+  });
+});

packages/react-server/src/ReactFlightReplyServer.js

@@ -126,7 +126,7 @@ function ReactPromise(status: any, value: any, reason: any) {
 // We subclass Promise.prototype so that we get other methods like .catch
 ReactPromise.prototype = Object.create(Promise.prototype) as any;
 // TODO: This doesn't return a new Promise chain unlike the real .then
-ReactPromise.prototype.then = function <T>(
+function reactPromiseThen<T>(
   this: SomeChunk<T>,
   resolve: (value: T) => mixed,
   reject: ?(reason: mixed) => mixed,
@@ -197,7 +197,17 @@ ReactPromise.prototype.then = function <T>(
       }
       break;
   }
-};
+}
+// The shadowing `then` must be defined with `Object.defineProperty` instead of
+// assignment. Assignment would throw when `Promise.prototype` is frozen (e.g.
+// by SES lockdown) because assigning over an inherited non-writable property
+// is rejected.
+Object.defineProperty(ReactPromise.prototype, 'then', {
+  writable: true,
+  enumerable: true,
+  configurable: true,
+  value: reactPromiseThen,
+});
 
 const ObjectPrototype = Object.prototype;
 const ArrayPrototype = Array.prototype;