Expose opt-in useESModules:"auto" from transform-runtime to toggle based on 'supportsStaticESM'

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

@@ -25,6 +25,10 @@ function resolveAbsoluteRuntime(moduleName: string, dirname: string) {
   }
 }
 
+function supportsStaticESM(caller) {
+  return !!(caller && caller.supportsStaticESM);
+}
+
 export default declare((api, options, dirname) => {
   api.assertVersion(7);
 
@@ -45,9 +49,9 @@ export default declare((api, options, dirname) => {
   if (typeof useRuntimeHelpers !== "boolean") {
     throw new Error("The 'helpers' option must be undefined, or a boolean.");
   }
-  if (typeof useESModules !== "boolean") {
+  if (typeof useESModules !== "boolean" && useESModules !== "auto") {
     throw new Error(
-      "The 'useESModules' option must be undefined, or a boolean.",
+      "The 'useESModules' option must be undefined, or a boolean, or 'auto'.",
     );
   }
   if (
@@ -107,6 +111,9 @@ export default declare((api, options, dirname) => {
     );
   }
 
+  const esModules =
+    useESModules === "auto" ? api.caller(supportsStaticESM) : useESModules;
+
   const injectCoreJS2 = `${corejsVersion}` === "2";
   const moduleName = injectCoreJS2
     ? "@babel/runtime-corejs2"
@@ -145,7 +152,7 @@ export default declare((api, options, dirname) => {
             isInteropHelper && !isModule(file.path) ? 4 : undefined;
 
           const helpersDir =
-            useESModules && file.path.node.sourceType === "module"
+            esModules && file.path.node.sourceType === "module"
               ? "helpers/esm"
               : "helpers";
 

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-cjs-auto/input.js

@@ -0,0 +1 @@
+class Foo extends Bar {}

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-cjs-auto/options.json

@@ -0,0 +1,7 @@
+{
+  "caller": {
+    "name": "babel-test",
+    "supportsStaticESM": true
+  },
+  "plugins": [["transform-runtime", { "useESModules": "auto" }], "transform-classes"]
+}

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-cjs-auto/output.js

@@ -0,0 +1,23 @@
+var _classCallCheck = require("@babel/runtime/helpers/classCallCheck");
+
+var _possibleConstructorReturn = require("@babel/runtime/helpers/possibleConstructorReturn");
+
+var _getPrototypeOf = require("@babel/runtime/helpers/getPrototypeOf");
+
+var _inherits = require("@babel/runtime/helpers/inherits");
+
+let Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  _inherits(Foo, _Bar);
+
+  function Foo() {
+    _classCallCheck(this, Foo);
+
+    return _possibleConstructorReturn(this, _getPrototypeOf(Foo).apply(this, arguments));
+  }
+
+  return Foo;
+}(Bar);

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-cjs/options.json

@@ -1,3 +1,7 @@
 {
+  "caller": {
+    "name": "babel-test",
+    "supportsStaticESM": true
+  },
   "plugins": [["transform-runtime", { "useESModules": true }], "transform-classes"]
 }

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-mjs-auto/input.mjs

@@ -0,0 +1 @@
+class Foo extends Bar {}

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-mjs-auto/options.json

@@ -0,0 +1,7 @@
+{
+  "caller": {
+    "name": "babel-test",
+    "supportsStaticESM": true
+  },
+  "plugins": [["transform-runtime", { "useESModules": "auto" }], "transform-classes"]
+}

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-mjs-auto/output.mjs

@@ -0,0 +1,18 @@
+import _classCallCheck from "@babel/runtime/helpers/esm/classCallCheck";
+import _possibleConstructorReturn from "@babel/runtime/helpers/esm/possibleConstructorReturn";
+import _getPrototypeOf from "@babel/runtime/helpers/esm/getPrototypeOf";
+import _inherits from "@babel/runtime/helpers/esm/inherits";
+
+let Foo =
+/*#__PURE__*/
+function (_Bar) {
+  _inherits(Foo, _Bar);
+
+  function Foo() {
+    _classCallCheck(this, Foo);
+
+    return _possibleConstructorReturn(this, _getPrototypeOf(Foo).apply(this, arguments));
+  }
+
+  return Foo;
+}(Bar);

packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules-mjs/options.json

@@ -1,3 +1,7 @@
 {
+  "caller": {
+    "name": "babel-test",
+    "supportsStaticESM": true
+  },
   "plugins": [["transform-runtime", { "useESModules": true }], "transform-classes"]
 }