From b9be4537c2459f8fc0312b796570003620bc8600 Mon Sep 17 00:00:00 2001 From: Josh Story Date: Tue, 5 Sep 2023 13:45:16 -0700 Subject: [PATCH] [Flight] provide property descriptors for client references (#27328) Client reference proxy should implement getOwnPropertyDescriptor. One practical place where this shows up is when consuming CJS module.exports in ESM modules. Node creates named exports it statically infers from the underlying source but it only sets the named export if the CJS exports hasOwnProperty. This trap will allow the proxy to respond affirmatively. I did not add unit tests because contriving the ESM <-> CJS scenario in Jest is challenging. I did add new components to the flight fixture which demonstrate that the named exports are properly constructed with the client reference whereas they were not before. --- fixtures/flight/src/App.js | 9 + fixtures/flight/src/Client.js | 21 ++ fixtures/flight/src/Dynamic.js | 12 ++ fixtures/flight/src/cjs/Note.js | 11 + fixtures/flight/yarn.lock | 83 ++++--- .../src/ReactFlightWebpackReferences.js | 204 ++++++++++-------- 6 files changed, 213 insertions(+), 127 deletions(-) create mode 100644 fixtures/flight/src/Client.js create mode 100644 fixtures/flight/src/Dynamic.js create mode 100644 fixtures/flight/src/cjs/Note.js diff --git a/fixtures/flight/src/App.js b/fixtures/flight/src/App.js index 201a55a43a208..71eb4fa5d97a0 100644 --- a/fixtures/flight/src/App.js +++ b/fixtures/flight/src/App.js @@ -10,6 +10,10 @@ const Counter3 = await(AsyncModule); import ShowMore from './ShowMore.js'; import Button from './Button.js'; import Form from './Form.js'; +import {Dynamic} from './Dynamic.js'; +import {Client} from './Client.js'; + +import {Note} from './cjs/Note.js'; import {like, greet} from './actions.js'; @@ -43,6 +47,11 @@ export default async function App() {
+
+ loaded statically: +
+ + diff --git a/fixtures/flight/src/Client.js b/fixtures/flight/src/Client.js new file mode 100644 index 0000000000000..dccd250e24c7f --- /dev/null +++ b/fixtures/flight/src/Client.js @@ -0,0 +1,21 @@ +'use client'; + +import * as React from 'react'; + +let LazyDynamic = React.lazy(() => + import('./Dynamic.js').then(exp => ({default: exp.Dynamic})) +); + +export function Client() { + const [loaded, load] = React.useReducer(() => true, false); + + return loaded ? ( +
+ loaded dynamically: +
+ ) : ( +
+ +
+ ); +} diff --git a/fixtures/flight/src/Dynamic.js b/fixtures/flight/src/Dynamic.js new file mode 100644 index 0000000000000..dac88887cfb53 --- /dev/null +++ b/fixtures/flight/src/Dynamic.js @@ -0,0 +1,12 @@ +'use client'; + +import * as React from 'react'; + +export function Dynamic() { + return ( +
+ This client component should be loaded in a single chunk even when it is + used as both a client reference and as a dynamic import. +
+ ); +} diff --git a/fixtures/flight/src/cjs/Note.js b/fixtures/flight/src/cjs/Note.js new file mode 100644 index 0000000000000..181b4b5dfb03e --- /dev/null +++ b/fixtures/flight/src/cjs/Note.js @@ -0,0 +1,11 @@ +'use client'; + +var React = require('react'); + +function Note() { + return 'This component was exported on a commonJS module and imported into ESM as a named import.'; +} + +module.exports = { + Note, +}; diff --git a/fixtures/flight/yarn.lock b/fixtures/flight/yarn.lock index 5fb49d7bf624d..89eeb091c7136 100644 --- a/fixtures/flight/yarn.lock +++ b/fixtures/flight/yarn.lock @@ -2690,17 +2690,17 @@ fastq "^1.6.0" "@pmmmwh/react-refresh-webpack-plugin@^0.5.3": - version "0.5.7" - resolved "https://registry.yarnpkg.com/@pmmmwh/react-refresh-webpack-plugin/-/react-refresh-webpack-plugin-0.5.7.tgz#58f8217ba70069cc6a73f5d7e05e85b458c150e2" - integrity sha512-bcKCAzF0DV2IIROp9ZHkRJa6O4jy7NlnHdWL3GmcUxYWNjLXkK5kfELELwEfSP5hXPfVL/qOGMAROuMQb9GG8Q== + version "0.5.11" + resolved "https://registry.yarnpkg.com/@pmmmwh/react-refresh-webpack-plugin/-/react-refresh-webpack-plugin-0.5.11.tgz#7c2268cedaa0644d677e8c4f377bc8fb304f714a" + integrity sha512-7j/6vdTym0+qZ6u4XbSAxrWBGYSdCfTzySkj7WAFgDLmSyWlOrWvpyzxlFh5jtw9dn0oL/jtW+06XfFiisN3JQ== dependencies: ansi-html-community "^0.0.8" common-path-prefix "^3.0.0" - core-js-pure "^3.8.1" + core-js-pure "^3.23.3" error-stack-parser "^2.0.6" find-up "^5.0.0" html-entities "^2.1.0" - loader-utils "^2.0.0" + loader-utils "^2.0.4" schema-utils "^3.0.0" source-map "^0.7.3" @@ -3002,7 +3002,7 @@ expect "^28.0.0" pretty-format "^28.0.0" -"@types/json-schema@*", "@types/json-schema@^7.0.5", "@types/json-schema@^7.0.6": +"@types/json-schema@*", "@types/json-schema@^7.0.5": version "7.0.6" resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.6.tgz#f4c7ec43e81b319a9815115031709f26987891f0" integrity sha512-3c+yGKvVP5Y9TYBEibGNR+kLtijnj7mYrXRg+WpFb2X9xm04g/DXYkfg4hmzJQosc9snFNUPkbYIhu+KAm6jJw== @@ -4050,10 +4050,10 @@ core-js-compat@^3.30.1, core-js-compat@^3.30.2: dependencies: browserslist "^4.21.5" -core-js-pure@^3.8.1: - version "3.24.1" - resolved "https://registry.yarnpkg.com/core-js-pure/-/core-js-pure-3.24.1.tgz#8839dde5da545521bf282feb7dc6d0b425f39fd3" - integrity sha512-r1nJk41QLLPyozHUUPmILCEMtMw24NG4oWK6RbsDdjzQgg9ZvrUsPBj1MnG0wXXp1DCDU6j+wUvEmBSrtRbLXg== +core-js-pure@^3.23.3: + version "3.32.1" + resolved "https://registry.yarnpkg.com/core-js-pure/-/core-js-pure-3.32.1.tgz#5775b88f9062885f67b6d7edce59984e89d276f3" + integrity sha512-f52QZwkFVDPf7UEQZGHKx6NYxsxmVGJe5DIvbzOdRMJlmT6yv0KDjR8rmy3ngr/t5wU54c7Sp/qIJH0ppbhVpQ== cosmiconfig@^6.0.0: version "6.0.0" @@ -4582,11 +4582,11 @@ error-ex@^1.3.1: is-arrayish "^0.2.1" error-stack-parser@^2.0.6: - version "2.0.6" - resolved "https://registry.yarnpkg.com/error-stack-parser/-/error-stack-parser-2.0.6.tgz#5a99a707bd7a4c58a797902d48d82803ede6aad8" - integrity sha512-d51brTeqC+BHlwF0BhPtcYgF5nlzf9ZZ0ZIUQNZpc9ZB9qw5IJ2diTrBY9jlCJkTLITYPjmiX6OWCwH+fuyNgQ== + version "2.1.4" + resolved "https://registry.yarnpkg.com/error-stack-parser/-/error-stack-parser-2.1.4.tgz#229cb01cdbfa84440bfa91876285b94680188286" + integrity sha512-Sk5V6wVazPhq5MhpO+AUxJn5x7XSXGl1R93Vn7i+zS15KDVxQijejNCrz8340/2bgLBjR9GtEG8ZVKONDjcqGQ== dependencies: - stackframe "^1.1.1" + stackframe "^1.3.4" es-abstract@^1.12.0: version "1.16.0" @@ -4751,8 +4751,9 @@ fast-glob@^3.2.11, fast-glob@^3.2.9: micromatch "^4.0.4" fast-json-stable-stringify@^2.0.0: - version "2.0.0" - resolved "https://registry.yarnpkg.com/fast-json-stable-stringify/-/fast-json-stable-stringify-2.0.0.tgz#d5142c0caee6b1189f87d3a76111064f86c8bbf2" + version "2.1.0" + resolved "https://registry.yarnpkg.com/fast-json-stable-stringify/-/fast-json-stable-stringify-2.1.0.tgz#874bf69c6f404c2b5d99c481341399fd55892633" + integrity sha512-lhd/wF+Lk98HZoTCtlVraHtfh5XYijIjalXck7saUtuanSDyLMxnHhSXEDJqHxD7msR8D0uCmqlkwjCV8xvwHw== fast-levenshtein@~2.0.4: version "2.0.6" @@ -5074,9 +5075,9 @@ html-encoding-sniffer@^2.0.1: whatwg-encoding "^1.0.5" html-entities@^2.1.0: - version "2.3.3" - resolved "https://registry.yarnpkg.com/html-entities/-/html-entities-2.3.3.tgz#117d7626bece327fc8baace8868fa6f5ef856e46" - integrity sha512-DV5Ln36z34NNTDgnz0EWGBLZENelNAtkiFA4kyNOG2tDI6Mz1uSWiq1wAKdyjnJwyDiDO7Fa2SO1CTxPXL8VxA== + version "2.4.0" + resolved "https://registry.yarnpkg.com/html-entities/-/html-entities-2.4.0.tgz#edd0cee70402584c8c76cc2c0556db09d1f45061" + integrity sha512-igBTJcNNNhvZFRtm8uA6xMY6xYleeDwn3PeBCkDz7tHttv4F2hsDI2aPgNERWzvRcNYHNT3ymRaQzllmXj4YsQ== html-escaper@^2.0.0: version "2.0.2" @@ -5958,17 +5959,23 @@ json-parse-even-better-errors@^2.3.0, json-parse-even-better-errors@^2.3.1: json-schema-traverse@^0.4.1: version "0.4.1" resolved "https://registry.yarnpkg.com/json-schema-traverse/-/json-schema-traverse-0.4.1.tgz#69f6a87d9513ab8bb8fe63bdb0979c448e684660" + integrity sha512-xbbCH5dCYU5T8LcEhhuh7HJ88HXuW3qsI3Y0zOZFKfZEHcpWiHU/Jxzk629Brsab/mMiHQti9wMP+845RPe3Vg== json-schema-traverse@^1.0.0: version "1.0.0" resolved "https://registry.yarnpkg.com/json-schema-traverse/-/json-schema-traverse-1.0.0.tgz#ae7bcb3656ab77a73ba5c49bf654f38e6b6860e2" integrity sha512-NM8/P9n3XjXhIZn1lLhkFaACTOURQXjWhV4BA/RnOv8xvgqtqpAX9IO4mRQxSx1Rlo4tqzeqb0sOlruaOy3dug== -json5@^2.1.0, json5@^2.1.2, json5@^2.2.1: +json5@^2.1.0, json5@^2.2.1: version "2.2.1" resolved "https://registry.yarnpkg.com/json5/-/json5-2.2.1.tgz#655d50ed1e6f95ad1a3caababd2b0efda10b395c" integrity sha512-1hqLFMSrGHRHxav9q9gNjJ5EXznIxGVO09xQRrwplcS8qs28pZ8s8hupZAmqDwZUmVZ2Qb2jnyPOWcDH8m8dlA== +json5@^2.1.2: + version "2.2.3" + resolved "https://registry.yarnpkg.com/json5/-/json5-2.2.3.tgz#78cd6f1a19bdc12b73db5ad0c61efd66c1e29283" + integrity sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg== + jsonfile@^6.0.1: version "6.1.0" resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-6.1.0.tgz#bc55b2634793c679ec6403094eb13698a6ec0aae" @@ -6017,7 +6024,7 @@ loader-runner@^4.2.0: resolved "https://registry.yarnpkg.com/loader-runner/-/loader-runner-4.3.0.tgz#c1b4a163b99f614830353b16755e7149ac2314e1" integrity sha512-3R/1M+yS3j5ou80Me59j7F9IMs4PXs3VqRrm0TU3AbKPxlmpoY1TNscJV/oGJXo8qCatFGTfDbY6W6ipGOYXfg== -loader-utils@^2.0.0: +loader-utils@^2.0.0, loader-utils@^2.0.4: version "2.0.4" resolved "https://registry.yarnpkg.com/loader-utils/-/loader-utils-2.0.4.tgz#8b5cb38b5c34a9a018ee1fc0e6a066d1dfcc528c" integrity sha512-xXqpXoINfFhgua9xiqD8fPFHgkoq1mmmpE92WlDbm9rNRd/EbRb+Gqf908T2DMfuHjjJlksiK2RbHVOdD/MqSw== @@ -7260,7 +7267,12 @@ pstree.remy@^1.1.8: resolved "https://registry.yarnpkg.com/pstree.remy/-/pstree.remy-1.1.8.tgz#c242224f4a67c21f686839bbdb4ac282b8373d3a" integrity sha512-77DZwxQmxKnu3aR542U+X8FypNzbfJ+C5XQDk3uWjWxn6151aIMGthWYRXTqT1E5oJvg+ljaa2OJi+VfvCOQ8w== -punycode@^2.1.0, punycode@^2.1.1: +punycode@^2.1.0: + version "2.3.0" + resolved "https://registry.yarnpkg.com/punycode/-/punycode-2.3.0.tgz#f67fa67c94da8f4d0cfff981aee4118064199b8f" + integrity sha512-rRV+zQD8tVFys26lAGR9WUuS4iUAngJScM+ZRSKtvl5tKeZ2t5bvdNFdNHBW9FWR4guGHlgmsZ1G7BSm2wTbuA== + +punycode@^2.1.1: version "2.1.1" resolved "https://registry.yarnpkg.com/punycode/-/punycode-2.1.1.tgz#b58b010ac40c22c5657616c8d2c2c02c7bf479ec" @@ -7688,11 +7700,11 @@ schema-utils@^2.6.5: ajv-keywords "^3.5.2" schema-utils@^3.0.0: - version "3.0.0" - resolved "https://registry.yarnpkg.com/schema-utils/-/schema-utils-3.0.0.tgz#67502f6aa2b66a2d4032b4279a2944978a0913ef" - integrity sha512-6D82/xSzO094ajanoOSbe4YvXWMfn2A//8Y1+MUqFAJul5Bs+yn36xbK9OtNDcRVSBJ9jjeoXftM6CfztsjOAA== + version "3.3.0" + resolved "https://registry.yarnpkg.com/schema-utils/-/schema-utils-3.3.0.tgz#f50a88877c3c01652a15b622ae9e9795df7a60fe" + integrity sha512-pN/yOAvcC+5rQ5nERGuwrjLlYvLTbCibnZ1I7B1LaiAz9BRBlE9GMgE/eqV30P7aJQUf7Ddimy/RsbYO/GrVGg== dependencies: - "@types/json-schema" "^7.0.6" + "@types/json-schema" "^7.0.8" ajv "^6.12.5" ajv-keywords "^3.5.2" @@ -7862,9 +7874,9 @@ source-map@^0.5.0: resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc" source-map@^0.7.3: - version "0.7.3" - resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.7.3.tgz#5302f8169031735226544092e64981f751750383" - integrity sha512-CkCj6giN3S+n9qrYiBTX5gystlENnRW5jZeNLHpe6aue+SrHcG5VYwujhW9s4dY31mEGsxBDrHR6oI69fTXsaQ== + version "0.7.4" + resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.7.4.tgz#a9bbe705c9d8846f4e08ff6765acf0f1b0898656" + integrity sha512-l3BikUxvPOcn5E74dZiq5BGsTb5yEwhaTSzccU6t4sDOH8NWJCstKO5QT2CvtFoK6F0saL7p9xHAqHOlCPJygA== spawn-command@^0.0.2-1: version "0.0.2-1" @@ -7886,10 +7898,10 @@ stack-utils@^2.0.3: dependencies: escape-string-regexp "^2.0.0" -stackframe@^1.1.1: - version "1.2.0" - resolved "https://registry.yarnpkg.com/stackframe/-/stackframe-1.2.0.tgz#52429492d63c62eb989804c11552e3d22e779303" - integrity sha512-GrdeshiRmS1YLMYgzF16olf2jJ/IzxXY9lhKOskuVziubpTYcYqyOwYeJKzQkwy7uN0fYSsbsC4RQaXf9LCrYA== +stackframe@^1.3.4: + version "1.3.4" + resolved "https://registry.yarnpkg.com/stackframe/-/stackframe-1.3.4.tgz#b881a004c8c149a5e8efef37d51b16e412943310" + integrity sha512-oeVtt7eWQS+Na6F//S4kJ2K2VbRlS9D43mAlMyVpVWovy9o+jfgH8O9agzANzaiLjclA0oYzUXEM4PurhSUChw== statuses@2.0.1: version "2.0.1" @@ -8379,8 +8391,9 @@ update-browserslist-db@^1.0.5: picocolors "^1.0.0" uri-js@^4.2.2: - version "4.2.2" - resolved "https://registry.yarnpkg.com/uri-js/-/uri-js-4.2.2.tgz#94c540e1ff772956e2299507c010aea6c8838eb0" + version "4.4.1" + resolved "https://registry.yarnpkg.com/uri-js/-/uri-js-4.4.1.tgz#9b1a52595225859e55f669d928f88c6c57f2a77e" + integrity sha512-7rKUyy33Q1yc98pQ1DAmLtwX109F7TIfWlW1Ydo8Wl1ii1SeHieeh0HHfPeL2fMXK6z0s8ecKs9frCuLJvndBg== dependencies: punycode "^2.1.0" diff --git a/packages/react-server-dom-webpack/src/ReactFlightWebpackReferences.js b/packages/react-server-dom-webpack/src/ReactFlightWebpackReferences.js index 9df0e43bd75e1..6952dad11134a 100644 --- a/packages/react-server-dom-webpack/src/ReactFlightWebpackReferences.js +++ b/packages/react-server-dom-webpack/src/ReactFlightWebpackReferences.js @@ -134,105 +134,125 @@ const deepProxyHandlers = { }, }; -const proxyHandlers = { - get: function ( - target: Function, - name: string, - receiver: Proxy, - ): $FlowFixMe { - switch (name) { - // These names are read by the Flight runtime if you end up using the exports object. - case '$$typeof': - return target.$$typeof; - case '$$id': - return target.$$id; - case '$$async': - return target.$$async; - case 'name': - return target.name; - // We need to special case this because createElement reads it if we pass this - // reference. - case 'defaultProps': - return undefined; - // Avoid this attempting to be serialized. - case 'toJSON': - return undefined; - case Symbol.toPrimitive: - // $FlowFixMe[prop-missing] - return Object.prototype[Symbol.toPrimitive]; - case '__esModule': - // Something is conditionally checking which export to use. We'll pretend to be - // an ESM compat module but then we'll check again on the client. - const moduleId = target.$$id; - target.default = registerClientReferenceImpl( - (function () { - throw new Error( - `Attempted to call the default export of ${moduleId} from the server ` + - `but it's on the client. It's not possible to invoke a client function from ` + - `the server, it can only be rendered as a Component or passed to props of a ` + - `Client Component.`, - ); - }: any), - target.$$id + '#', - target.$$async, - ); - return true; - case 'then': - if (target.then) { - // Use a cached value - return target.then; - } - if (!target.$$async) { - // If this module is expected to return a Promise (such as an AsyncModule) then - // we should resolve that with a client reference that unwraps the Promise on - // the client. - - const clientReference: ClientReference = - registerClientReferenceImpl(({}: any), target.$$id, true); - const proxy = new Proxy(clientReference, proxyHandlers); - - // Treat this as a resolved Promise for React's use() - target.status = 'fulfilled'; - target.value = proxy; - - const then = (target.then = registerClientReferenceImpl( - (function then(resolve, reject: any) { - // Expose to React. - return Promise.resolve(resolve(proxy)); - }: any), - // If this is not used as a Promise but is treated as a reference to a `.then` - // export then we should treat it as a reference to that name. - target.$$id + '#then', - false, - )); - return then; - } else { - // Since typeof .then === 'function' is a feature test we'd continue recursing - // indefinitely if we return a function. Instead, we return an object reference - // if we check further. - return undefined; - } - } - let cachedReference = target[name]; - if (!cachedReference) { - const reference: ClientReference = registerClientReferenceImpl( +function getReference(target: Function, name: string): $FlowFixMe { + switch (name) { + // These names are read by the Flight runtime if you end up using the exports object. + case '$$typeof': + return target.$$typeof; + case '$$id': + return target.$$id; + case '$$async': + return target.$$async; + case 'name': + return target.name; + // We need to special case this because createElement reads it if we pass this + // reference. + case 'defaultProps': + return undefined; + // Avoid this attempting to be serialized. + case 'toJSON': + return undefined; + case Symbol.toPrimitive: + // $FlowFixMe[prop-missing] + return Object.prototype[Symbol.toPrimitive]; + case '__esModule': + // Something is conditionally checking which export to use. We'll pretend to be + // an ESM compat module but then we'll check again on the client. + const moduleId = target.$$id; + target.default = registerClientReferenceImpl( (function () { throw new Error( - // eslint-disable-next-line react-internal/safe-string-coercion - `Attempted to call ${String(name)}() from the server but ${String( - name, - )} is on the client. ` + - `It's not possible to invoke a client function from the server, it can ` + - `only be rendered as a Component or passed to props of a Client Component.`, + `Attempted to call the default export of ${moduleId} from the server ` + + `but it's on the client. It's not possible to invoke a client function from ` + + `the server, it can only be rendered as a Component or passed to props of a ` + + `Client Component.`, ); }: any), - target.$$id + '#' + name, + target.$$id + '#', target.$$async, ); - Object.defineProperty((reference: any), 'name', {value: name}); - cachedReference = target[name] = new Proxy(reference, deepProxyHandlers); + return true; + case 'then': + if (target.then) { + // Use a cached value + return target.then; + } + if (!target.$$async) { + // If this module is expected to return a Promise (such as an AsyncModule) then + // we should resolve that with a client reference that unwraps the Promise on + // the client. + + const clientReference: ClientReference = + registerClientReferenceImpl(({}: any), target.$$id, true); + const proxy = new Proxy(clientReference, proxyHandlers); + + // Treat this as a resolved Promise for React's use() + target.status = 'fulfilled'; + target.value = proxy; + + const then = (target.then = registerClientReferenceImpl( + (function then(resolve, reject: any) { + // Expose to React. + return Promise.resolve(resolve(proxy)); + }: any), + // If this is not used as a Promise but is treated as a reference to a `.then` + // export then we should treat it as a reference to that name. + target.$$id + '#then', + false, + )); + return then; + } else { + // Since typeof .then === 'function' is a feature test we'd continue recursing + // indefinitely if we return a function. Instead, we return an object reference + // if we check further. + return undefined; + } + } + let cachedReference = target[name]; + if (!cachedReference) { + const reference: ClientReference = registerClientReferenceImpl( + (function () { + throw new Error( + // eslint-disable-next-line react-internal/safe-string-coercion + `Attempted to call ${String(name)}() from the server but ${String( + name, + )} is on the client. ` + + `It's not possible to invoke a client function from the server, it can ` + + `only be rendered as a Component or passed to props of a Client Component.`, + ); + }: any), + target.$$id + '#' + name, + target.$$async, + ); + Object.defineProperty((reference: any), 'name', {value: name}); + cachedReference = target[name] = new Proxy(reference, deepProxyHandlers); + } + return cachedReference; +} + +const proxyHandlers = { + get: function ( + target: Function, + name: string, + receiver: Proxy, + ): $FlowFixMe { + return getReference(target, name); + }, + getOwnPropertyDescriptor: function ( + target: Function, + name: string, + ): $FlowFixMe { + let descriptor = Object.getOwnPropertyDescriptor(target, name); + if (!descriptor) { + descriptor = { + value: getReference(target, name), + writable: false, + configurable: false, + enumerable: false, + }; + Object.defineProperty(target, name, descriptor); } - return cachedReference; + return descriptor; }, getPrototypeOf(target: Function): Object { // Pretend to be a Promise in case anyone asks.