Use conditional exports in @babel/runtime for CJS/ESM

.gitignore

@@ -26,18 +26,22 @@ package-lock.json
 /packages/babel-compat-data/build
 
 /packages/babel-runtime/helpers/*.js
-!/packages/babel-runtime/helpers/toArray.js
-!/packages/babel-runtime/helpers/iterableToArray.js
-!/packages/babel-runtime/helpers/temporalRef.js
+/packages/babel-runtime/helpers/*/*.js
+/packages/babel-runtime/helpers/*/*.mjs
+!/packages/babel-runtime/helpers/toArray/*
+!/packages/babel-runtime/helpers/iterableToArray/*
+!/packages/babel-runtime/helpers/temporalRef/*
 /packages/babel-runtime/helpers/esm/*.js
 !/packages/babel-runtime/helpers/esm/toArray.js
 !/packages/babel-runtime/helpers/esm/iterableToArray.js
 !/packages/babel-runtime/helpers/esm/temporalRef.js
 
 /packages/babel-runtime-corejs2/helpers/*.js
-!/packages/babel-runtime-corejs2/helpers/toArray.js
-!/packages/babel-runtime-corejs2/helpers/iterableToArray.js
-!/packages/babel-runtime-corejs2/helpers/temporalRef.js
+/packages/babel-runtime-corejs2/helpers/*/*.js
+/packages/babel-runtime-corejs2/helpers/*/*.mjs
+!/packages/babel-runtime-corejs2/helpers/toArray/*
+!/packages/babel-runtime-corejs2/helpers/iterableToArray/*
+!/packages/babel-runtime-corejs2/helpers/temporalRef/*
 /packages/babel-runtime-corejs2/helpers/esm/*.js
 !/packages/babel-runtime-corejs2/helpers/esm/toArray.js
 !/packages/babel-runtime-corejs2/helpers/esm/iterableToArray.js
@@ -46,6 +50,8 @@ package-lock.json
 !/packages/babel-runtime-corejs2/core-js/map.js
 
 /packages/babel-runtime-corejs3/helpers/*.js
+/packages/babel-runtime-corejs3/helpers/*/*.js
+/packages/babel-runtime-corejs3/helpers/*/*.mjs
 /packages/babel-runtime-corejs3/helpers/esm/*.js
 /packages/babel-runtime-corejs3/core-js/**/*.js
 /packages/babel-runtime-corejs3/core-js-stable/**/*.js

Gulpfile.mjs

@@ -298,10 +298,10 @@ function buildRollup(packages, targetBrowsers) {
             babelrc: false,
             babelHelpers: "bundled",
             extends: "./babel.config.js",
-            extensions: [".mjs", ".cjs", ".ts", ".js"],
+            extensions: [".ts", ".js", ".mjs", ".cjs"],
           }),
           rollupNodeResolve({
-            extensions: [".mjs", ".cjs", ".ts", ".js", ".json"],
+            extensions: [".ts", ".js", ".mjs", ".cjs", ".json"],
             browser: nodeResolveBrowser,
             preferBuiltins: true,
           }),

Makefile

@@ -196,6 +196,14 @@ prepublish:
 	IS_PUBLISH=true $(MAKE) test
 
 new-version:
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!!!!!!                                                   !!!!!!"
+	@echo "!!!!!!   Update DUAL_MODE_RUNTIME in transform-runtime   !!!!!!"
+	@echo "!!!!!!                                                   !!!!!!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
+	@exit 1
 	git pull --rebase
 	$(YARN) release-tool version -f @babel/standalone
 

packages/babel-plugin-transform-runtime/scripts/build-dist.js

@@ -112,51 +112,74 @@ function writeCorejsExports(pkgDirname, runtimeRoot, paths) {
   outputFile(pkgJsonPath, JSON.stringify(pkgJson, undefined, 2) + "\n");
 }
 
-function writeHelpers(runtimeName, { corejs } = {}) {
-  const helperPaths = writeHelperFiles(runtimeName, { corejs, esm: false });
-  const helperESMPaths = writeHelperFiles(runtimeName, { corejs, esm: true });
-  writeHelperExports(runtimeName, helperPaths.concat(helperESMPaths));
+function writeHelperFile(
+  runtimeName,
+  pkgDirname,
+  helperPath,
+  helperName,
+  { esm, corejs }
+) {
+  const filePath = path.join(helperPath, esm ? "index.mjs" : "index.js");
+  const fullPath = path.join(pkgDirname, filePath);
+
+  outputFile(
+    fullPath,
+    buildHelper(runtimeName, pkgDirname, fullPath, helperName, { esm, corejs })
+  );
+
+  return `./${filePath}`;
 }
 
-function writeHelperExports(runtimeName, helperPaths) {
+function writeHelperLegacyESMFile(pkgDirname, helperName) {
+  const fullPath = path.join(pkgDirname, "helpers", "esm", `${helperName}.js`);
+
+  outputFile(fullPath, `export { default } from "../${helperName}/index.mjs"`);
+}
+
+function writeHelpers(runtimeName, { corejs } = {}) {
+  const pkgDirname = getRuntimeRoot(runtimeName);
   const helperSubExports = {};
-  for (const helperPath of helperPaths) {
-    helperSubExports[helperPath.replace(".js", "")] = helperPath;
+  for (const helperName of helpers.list) {
+    const helperPath = path.join("helpers", helperName);
+    helperSubExports[`./${helperPath}`] = {
+      module: writeHelperFile(runtimeName, pkgDirname, helperPath, helperName, {
+        esm: true,
+        corejs,
+      }),
+      node: writeHelperFile(runtimeName, pkgDirname, helperPath, helperName, {
+        esm: false,
+        corejs,
+      }),
+      get default() {
+        return this.module;
+      },
+    };
+    writeHelperLegacyESMFile(pkgDirname, helperName);
   }
+
+  writeHelperExports(runtimeName, helperSubExports);
+}
+
+function writeHelperExports(runtimeName, helperSubExports) {
   const exports = {
-    "./helpers/": "./helpers/",
     ...helperSubExports,
     "./package": "./package.json",
     "./package.json": "./package.json",
     "./regenerator": "./regenerator/index.js",
+    "./regenerator/*.js": "./regenerator/*.js",
+    "./helpers/esm/*": "./helpers/esm/*.js",
+    // These patterns are deprecated, but since patterns
+    // containing * are not supported in every Node.js
+    // version we keep them for better compatibility.
     "./regenerator/": "./regenerator/",
+    "./helpers/esm/": "./helpers/esm/",
   };
   const pkgDirname = getRuntimeRoot(runtimeName);
   const pkgJsonPath = require.resolve(`${pkgDirname}/package.json`);
   const pkgJson = require(pkgJsonPath);
   pkgJson.exports = exports;
   outputFile(pkgJsonPath, JSON.stringify(pkgJson, undefined, 2) + "\n");
 }
-function writeHelperFiles(runtimeName, { esm, corejs }) {
-  const pkgDirname = getRuntimeRoot(runtimeName);
-  const helperPaths = [];
-  for (const helperName of helpers.list) {
-    const helperPath =
-      "./" + path.join("helpers", esm ? "esm" : "", `${helperName}.js`);
-    const helperFilename = path.join(pkgDirname, helperPath);
-    outputFile(
-      helperFilename,
-      buildHelper(runtimeName, pkgDirname, helperFilename, helperName, {
-        esm,
-        corejs,
-      })
-    );
-
-    helperPaths.push(helperPath);
-  }
-
-  return helperPaths;
-}
 
 function getRuntimeRoot(runtimeName) {
   return path.resolve(
@@ -184,7 +207,7 @@ function buildHelper(
     for (const dep of helpers.getDependencies(helperName)) {
       const id = (dependencies[dep] = t.identifier(t.toIdentifier(dep)));
       tree.body.push(template.statement.ast`
-        var ${id} = require("${`./${dep}`}");
+        var ${id} = require("${dep}");
       `);
       bindings.push(id.name);
     }
@@ -211,8 +234,9 @@ function buildHelper(
         transformRuntime,
         { corejs, useESModules: esm, version: runtimeVersion },
       ],
-      buildRuntimeRewritePlugin(runtimeName, helperName, esm),
-    ],
+      buildRuntimeRewritePlugin(runtimeName, helperName),
+      esm ? null : addDefaultCJSExport,
+    ].filter(Boolean),
     overrides: [
       {
         exclude: /typeof/,
@@ -222,8 +246,7 @@ function buildHelper(
   }).code;
 }
 
-function buildRuntimeRewritePlugin(runtimeName, helperName, esm) {
-  const helperPath = esm ? "helpers/esm" : "helpers";
+function buildRuntimeRewritePlugin(runtimeName, helperName) {
   /**
    * rewrite helpers imports to runtime imports
    * @example
@@ -233,7 +256,7 @@ function buildRuntimeRewritePlugin(runtimeName, helperName, esm) {
    */
   function adjustImportPath(node) {
     if (helpers.list.includes(node.value)) {
-      node.value = `${runtimeName}/${helperPath}/${node.value}`;
+      node.value = `${runtimeName}/helpers/${node.value}`;
     }
   }
 
@@ -266,3 +289,21 @@ function buildRuntimeRewritePlugin(runtimeName, helperName, esm) {
     },
   };
 }
+
+function addDefaultCJSExport({ template }) {
+  return {
+    visitor: {
+      Program: {
+        exit(path) {
+          path.pushContainer(
+            "body",
+            template.statements.ast`
+              module.exports.default = module.exports;
+              module.exports.__esModule = true;
+            `
+          );
+        },
+      },
+    },
+  };
+}

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

@@ -4,7 +4,7 @@ import { types as t } from "@babel/core";
 
 import getCoreJS2Definitions from "./runtime-corejs2-definitions";
 import getCoreJS3Definitions from "./runtime-corejs3-definitions";
-import { typeAnnotationToString } from "./helpers";
+import { typeAnnotationToString, hasMinVersion } from "./helpers";
 import getRuntimePath from "./get-runtime-path";
 
 function supportsStaticESM(caller) {
@@ -78,6 +78,20 @@ export default declare((api, options, dirname) => {
     throw new Error(`The 'version' option must be a version string.`);
   }
 
+  // In recent @babel/runtime versions, we can use require("helper").default
+  // instead of require("helper") so that it has the same interface as the
+  // ESM helper, and bundlers can better exchange one format for the other.
+  // TODO(Babel 8): Remove this check, it's always true
+  const DUAL_MODE_RUNTIME = "7.12.12";
+  const supportsCJSDefault = hasMinVersion(DUAL_MODE_RUNTIME, runtimeVersion);
+  if (supportsCJSDefault && useESModules && !absoluteRuntime) {
+    console.warn(
+      `[@babel/plugin-transform-runtime] The 'useESModules' option is not necessary when using` +
+        ` a @babel/runtime version >= ${DUAL_MODE_RUNTIME} and not using the 'absoluteRuntime'` +
+        ` option, because it automatically detects the necessary module format.`,
+    );
+  }
+
   function has(obj, key) {
     return Object.prototype.hasOwnProperty.call(obj, key);
   }
@@ -211,13 +225,19 @@ export default declare((api, options, dirname) => {
             `${modulePath}/${helpersDir}/${name}`,
             name,
             blockHoist,
+            true,
           );
         });
       }
 
       const cache = new Map();
 
-      this.addDefaultImport = (source, nameHint, blockHoist) => {
+      this.addDefaultImport = (
+        source,
+        nameHint,
+        blockHoist,
+        isHelper = false,
+      ) => {
         // If something on the page adds a helper when the file is an ES6
         // file, we can't reused the cached helper name after things have been
         // transformed because it has almost certainly been renamed.
@@ -229,7 +249,8 @@ export default declare((api, options, dirname) => {
           cached = t.cloneNode(cached);
         } else {
           cached = addDefault(file.path, source, {
-            importedInterop: "uncompiled",
+            importedInterop:
+              isHelper && supportsCJSDefault ? "compiled" : "uncompiled",
             nameHint,
             blockHoist,
           });

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-compiled-modern-runtime/input.mjs

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-compiled-modern-runtime/options.json

@@ -0,0 +1,7 @@
+{
+  "plugins": [
+    ["transform-runtime", { "version": "7.100.0" }],
+    "transform-classes",
+    "transform-modules-commonjs"
+  ]
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-compiled-modern-runtime/output.js

@@ -0,0 +1,9 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault").default;
+
+var _classCallCheck2 = _interopRequireDefault(require("@babel/runtime/helpers/classCallCheck"));
+
+let A = function A() {
+  (0, _classCallCheck2.default)(this, A);
+};

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-compiled-old-runtime/input.mjs

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-compiled-old-runtime/options.json

@@ -0,0 +1,7 @@
+{
+  "plugins": [
+    "transform-runtime",
+    "transform-classes",
+    "transform-modules-commonjs"
+  ]
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-compiled-old-runtime/output.js

@@ -0,0 +1,9 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
+
+var _classCallCheck2 = _interopRequireDefault(require("@babel/runtime/helpers/classCallCheck"));
+
+let A = function A() {
+  (0, _classCallCheck2.default)(this, A);
+};

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-modern-runtime/input.mjs

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-modern-runtime/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["transform-runtime", { "version": "7.100.0" }],
+    "transform-classes"
+  ]
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-modern-runtime/output.mjs

@@ -0,0 +1,5 @@
+import _classCallCheck from "@babel/runtime/helpers/classCallCheck";
+
+let A = function A() {
+  _classCallCheck(this, A);
+};

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-old-runtime/input.mjs

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-old-runtime/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-runtime", "transform-classes"]
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/import-old-runtime/output.mjs

@@ -0,0 +1,5 @@
+import _classCallCheck from "@babel/runtime/helpers/classCallCheck";
+
+let A = function A() {
+  _classCallCheck(this, A);
+};

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

@@ -0,0 +1,3 @@
+{
+  "validateLogs": true
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/require-modern-runtime/input.js

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/require-modern-runtime/options.json

@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["transform-runtime", { "version": "7.100.0" }],
+    "transform-classes"
+  ]
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/require-modern-runtime/output.js

@@ -0,0 +1,7 @@
+var _classCallCheck = require("@babel/runtime/helpers/classCallCheck").default;
+
+let A = function A() {
+  "use strict";
+
+  _classCallCheck(this, A);
+};

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/require-old-runtime/input.js

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/require-old-runtime/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-runtime", "transform-classes"]
+}

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/require-old-runtime/output.js

@@ -0,0 +1,7 @@
+var _classCallCheck = require("@babel/runtime/helpers/classCallCheck");
+
+let A = function A() {
+  "use strict";
+
+  _classCallCheck(this, A);
+};

packages/babel-plugin-transform-runtime/test/fixtures/dual-babel-runtime/useESModules-modern-runtime/input.mjs

@@ -0,0 +1 @@
+class A {}