[babel 8] Remove core-js@2 & regenerator from transform-runtime (#16063)

packages/babel-plugin-transform-runtime/src/babel-7/index.cjs

@@ -0,0 +1,3 @@
+Object.defineProperty(exports, "createPolyfillPlugins", {
+  get: () => require("./polyfills.cjs"),
+});

packages/babel-plugin-transform-runtime/src/babel-7/index.d.cts

@@ -0,0 +1 @@
+export const createPolyfillPlugins: any;

packages/babel-plugin-transform-runtime/src/babel-7/polyfills.cjs

@@ -0,0 +1,80 @@
+// TODO(Babel 8) Remove this file
+if (process.env.BABEL_8_BREAKING) {
+  throw new Error(
+    "Internal Babel error: This file should only be loaded in Babel 7",
+  );
+}
+
+const pluginCorejs2 = require("babel-plugin-polyfill-corejs2").default;
+const pluginRegenerator = require("babel-plugin-polyfill-regenerator").default;
+
+const pluginsCompat = "#__secret_key__@babel/runtime__compatibility";
+
+function createCorejs2Plugin(options) {
+  return (api, _, filename) => pluginCorejs2(api, options, filename);
+}
+
+function createRegeneratorPlugin(options, useRuntimeRegenerator, corejsPlugin) {
+  if (!useRuntimeRegenerator) return corejsPlugin ?? undefined;
+  return (api, _, filename) => {
+    return {
+      ...pluginRegenerator(api, options, filename),
+      inherits: corejsPlugin ?? undefined,
+    };
+  };
+}
+
+module.exports = function createBasePolyfillsPlugin(
+  { corejs, regenerator = true },
+  runtimeVersion,
+  absoluteImports,
+  corejs3Plugin,
+) {
+  let proposals = false;
+  let rawVersion;
+
+  if (typeof corejs === "object" && corejs !== null) {
+    rawVersion = corejs.version;
+    proposals = Boolean(corejs.proposals);
+  } else {
+    rawVersion = corejs;
+  }
+
+  const corejsVersion = rawVersion ? Number(rawVersion) : false;
+
+  if (![false, 2, 3].includes(corejsVersion)) {
+    throw new Error(
+      `The \`core-js\` version must be false, 2 or 3, but got ${JSON.stringify(
+        rawVersion,
+      )}.`,
+    );
+  }
+
+  if (proposals && (!corejsVersion || corejsVersion < 3)) {
+    throw new Error(
+      "The 'proposals' option is only supported when using 'corejs: 3'",
+    );
+  }
+
+  if (typeof regenerator !== "boolean") {
+    throw new Error(
+      "The 'regenerator' option must be undefined, or a boolean.",
+    );
+  }
+
+  const polyfillOpts = {
+    method: "usage-pure",
+    absoluteImports,
+    [pluginsCompat]: { useBabelRuntime: true, runtimeVersion, ext: "" },
+  };
+
+  return createRegeneratorPlugin(
+    polyfillOpts,
+    regenerator,
+    corejsVersion === 2
+      ? createCorejs2Plugin(polyfillOpts)
+      : corejsVersion === 3
+      ? corejs3Plugin
+      : null,
+  );
+};

packages/babel-plugin-transform-runtime/src/core-js.ts

@@ -0,0 +1,52 @@
+// TODO: Consider removing babel-plugin-polyfill-corejs3 from here, and ask
+// users to explicitly enable it in their Babel configuration files.
+
+import type { PluginAPI } from "@babel/core";
+import _pluginCorejs3 from "babel-plugin-polyfill-corejs3";
+// eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
+const pluginCorejs3 = (_pluginCorejs3.default ||
+  _pluginCorejs3) as typeof _pluginCorejs3.default;
+
+import type { Options } from "./index.ts";
+
+const pluginsCompat = "#__secret_key__@babel/runtime__compatibility";
+
+export function createCorejs3Plugin(
+  corejs: Options["corejs"],
+  absoluteImports: boolean,
+) {
+  let proposals = false;
+  let rawVersion;
+
+  if (typeof corejs === "object" && corejs !== null) {
+    rawVersion = corejs.version;
+    proposals = Boolean(corejs.proposals);
+  } else {
+    rawVersion = corejs;
+  }
+
+  if (!rawVersion) return null;
+
+  const version = rawVersion ? Number(rawVersion) : false;
+
+  // TODO: Allow specifying minor versions
+  if (version !== 3) {
+    throw new Error(
+      `The \`core-js\` version must be 3, but got ${JSON.stringify(
+        rawVersion,
+      )}.`,
+    );
+  }
+
+  return (api: PluginAPI, _: {}, filename: string) =>
+    pluginCorejs3(
+      api,
+      {
+        method: "usage-pure",
+        proposals,
+        absoluteImports,
+        [pluginsCompat]: { useBabelRuntime: true, ext: "" },
+      },
+      filename,
+    );
+}

packages/babel-plugin-transform-runtime/src/index.ts

@@ -4,7 +4,10 @@ import { types as t, type CallerMetadata } from "@babel/core";
 
 import { hasMinVersion } from "./helpers.ts";
 import getRuntimePath, { resolveFSPath } from "./get-runtime-path/index.ts";
-import { createBasePolyfillsPlugin } from "./polyfills.ts";
+import { createCorejs3Plugin } from "./core-js.ts";
+
+// TODO(Babel 8): Remove this
+import babel7 from "./babel-7/index.cjs";
 
 function supportsStaticESM(caller: CallerMetadata | undefined) {
   // @ts-expect-error TS does not narrow down optional chaining
@@ -15,7 +18,6 @@ export interface Options {
   absoluteRuntime?: boolean;
   corejs?: string | number | { version: string | number; proposals?: boolean };
   helpers?: boolean;
-  regenerator?: boolean;
   useESModules?: boolean | "auto";
   version?: string;
 }
@@ -109,6 +111,17 @@ export default declare((api, options: Options, dirname) => {
     );
   }
 
+  if (process.env.BABEL_8_BREAKING) {
+    if (has(options, "regenerator")) {
+      throw new Error(
+        "The 'regenerator' option has been removed. The generators transform " +
+          "no longers relies on a 'regeneratorRuntime' global. " +
+          "If you still need to replace imports to the 'regeneratorRuntime' " +
+          "global, you can use babel-plugin-polyfill-regenerator.",
+      );
+    }
+  }
+
   const esModules =
     useESModules === "auto" ? api.caller(supportsStaticESM) : useESModules;
 
@@ -117,11 +130,19 @@ export default declare((api, options: Options, dirname) => {
   return {
     name: "transform-runtime",
 
-    inherits: createBasePolyfillsPlugin(
-      options,
-      runtimeVersion,
-      absoluteRuntime,
-    ),
+    inherits: process.env.BABEL_8_BREAKING
+      ? options.corejs
+        ? createCorejs3Plugin(options.corejs, absoluteRuntime)
+        : undefined
+      : babel7.createPolyfillPlugins(
+          options,
+          runtimeVersion,
+          absoluteRuntime,
+          options.corejs === 3 ||
+            (options.corejs as Options["corejs"] & object)?.version === 3
+            ? createCorejs3Plugin(options.corejs, absoluteRuntime)
+            : null,
+        ),
 
     pre(file) {
       if (!useRuntimeHelpers) return;

packages/babel-plugin-transform-runtime/test/fixtures/absoluteRuntime/complex-options/options.json

@@ -13,7 +13,6 @@
     [
       "transform-runtime",
       {
-        "regenerator": false,
         "corejs": false,
         "helpers": true,
         "useESModules": true,

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/options.json

@@ -1,3 +1,4 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
 }

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/options.json

@@ -1,3 +1,4 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
 }

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/options.json

@@ -1,4 +1,5 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [
     ["transform-runtime", { "corejs": 2, "version": "7.100.0" }],
     "transform-classes"

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/options.json

@@ -1,4 +1,5 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [
     "transform-for-of",
     ["transform-runtime", { "corejs": 2, "version": "7.100.0" }]

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/evaluated-static-methods/options.json

@@ -1,3 +1,4 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [["transform-runtime", { "corejs": 2 }]]
 }

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/options.json

@@ -1,3 +1,7 @@
 {
-  "plugins": [["transform-runtime", { "corejs": 2, "version": "7.100.0" }], "transform-regenerator"]
+  "BABEL_8_BREAKING": false,
+  "plugins": [
+    ["transform-runtime", { "corejs": 2, "version": "7.100.0" }],
+    "transform-regenerator"
+  ]
 }

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/instance-computed/options.json

@@ -1,3 +1,4 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
 }

packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/math-undefined-version/options.json

@@ -1,4 +1,5 @@
 {
+  "BABEL_8_BREAKING": false,
   "plugins": [
     [
       "transform-runtime",