feat: add support for Babel v8

index.js

@@ -7,6 +7,7 @@ const {
   _getExtensions,
   _parentName,
   _shouldHighlightCode,
+  isBabel8,
 } = require("./lib/babel-options-util");
 
 const VersionChecker = require('ember-cli-version-checker');
@@ -139,8 +140,12 @@ module.exports = {
     };
 
     if (shouldCompileModules) {
-      options.moduleIds = true;
-      options.getModuleId = require("./lib/relative-module-paths").getRelativeModulePath;
+      // In Babel 8, the root-level `moduleIds` and `getModuleId` options have
+      // been moved to plugin options (handled in _getModulesPlugin).
+      if (!isBabel8()) {
+        options.moduleIds = true;
+        options.getModuleId = require("./lib/relative-module-paths").getRelativeModulePath;
+      }
     }
 
     options.highlightCode = _shouldHighlightCode(this.parent);
@@ -230,14 +235,20 @@ module.exports = {
   },
 
   _getHelpersPlugin() {
+    const runtimeOptions = {
+      version: this._getHelperVersion(),
+      regenerator: false,
+    };
+
+    // In Babel 8, the `useESModules` option has been removed.
+    if (!isBabel8()) {
+      runtimeOptions.useESModules = true;
+    }
+
     return [
       [
         require.resolve('@babel/plugin-transform-runtime'),
-        {
-          version: this._getHelperVersion(),
-          regenerator: false,
-          useESModules: true
-        }
+        runtimeOptions,
       ]
     ]
   },

lib/babel-options-util.js

@@ -2,6 +2,7 @@ const VersionChecker = require("ember-cli-version-checker");
 const resolvePackagePath = require("resolve-package-path");
 const clone = require("clone");
 const semver = require("semver");
+const { isBabel8 } = require("./babel-version");
 
 const APP_BABEL_RUNTIME_VERSION = new WeakMap();
 
@@ -27,18 +28,34 @@ function _getPresetEnv(config, project) {
   delete presetOptions.plugins;
   delete presetOptions.postTransformPlugins;
 
+  // In Babel 8, the `loose` and `spec` options have been removed from
+  // @babel/preset-env in favor of top-level `assumptions`.
+  if (isBabel8()) {
+    delete presetOptions.loose;
+    delete presetOptions.spec;
+  }
+
   return [require.resolve("@babel/preset-env"), presetOptions];
 }
 
 function _getModulesPlugin() {
   const resolvePath = require("./relative-module-paths")
     .resolveRelativeModulePath;
 
+  const amdOptions = { noInterop: true };
+
+  // In Babel 8, the root-level `moduleIds` and `getModuleId` options have
+  // been moved to plugin options.
+  if (isBabel8()) {
+    amdOptions.moduleIds = true;
+    amdOptions.getModuleId = require("./relative-module-paths").getRelativeModulePath;
+  }
+
   return [
     [require.resolve("babel-plugin-module-resolver"), { resolvePath }],
     [
       require.resolve("@babel/plugin-transform-modules-amd"),
-      { noInterop: true },
+      amdOptions,
     ],
   ];
 }
@@ -274,14 +291,22 @@ function _getEmberDataPackagesPolyfill(config, parent) {
   }
 }
 function _getHelpersPlugin(project) {
+  const runtimeOptions = {
+    version: _getHelperVersion(project),
+    regenerator: false,
+  };
+
+  // In Babel 8, the `useESModules` option has been removed from
+  // @babel/plugin-transform-runtime. ESM is now auto-detected via
+  // package.json#exports.
+  if (!isBabel8()) {
+    runtimeOptions.useESModules = true;
+  }
+
   return [
     [
       require.resolve("@babel/plugin-transform-runtime"),
-      {
-        version: _getHelperVersion(project),
-        regenerator: false,
-        useESModules: true,
-      },
+      runtimeOptions,
     ],
   ];
 }
@@ -320,9 +345,12 @@ function _addDecoratorPlugins(plugins, options, config, parent, project) {
       );
     }
   } else {
+    // In Babel 8, unknown options cause errors, so we omit the `legacy`
+    // option that was passed in Babel 7.
+    const staticBlockOptions = isBabel8() ? {} : { legacy: true };
     addPlugin(
       plugins,
-      [require.resolve("@babel/plugin-transform-class-static-block"), { legacy: true }],
+      [require.resolve("@babel/plugin-transform-class-static-block"), staticBlockOptions],
       _buildClassFeaturePluginConstraints(
         {
           before: ["@babel/plugin-proposal-decorators"],
@@ -343,9 +371,13 @@ function _addDecoratorPlugins(plugins, options, config, parent, project) {
       );
     }
   } else {
+    // In Babel 8, the `legacy: true` option is replaced by `version: "legacy"`.
+    const decoratorOptions = isBabel8()
+      ? { version: "legacy" }
+      : { legacy: true };
     addPlugin(
       plugins,
-      [require.resolve("@babel/plugin-proposal-decorators"), { legacy: true }],
+      [require.resolve("@babel/plugin-proposal-decorators"), decoratorOptions],
       _buildClassFeaturePluginConstraints(
         {
           before: ["@babel/plugin-transform-class-properties"],
@@ -449,11 +481,14 @@ function _addTypeScriptPlugin(plugins, parent, project) {
       );
     }
   } else {
+    // In Babel 8, `allowDeclareFields` is always enabled and the option has
+    // been removed. Passing it would cause a validation error.
+    const tsOptions = isBabel8() ? {} : { allowDeclareFields: true };
     addPlugin(
       plugins,
       [
         require.resolve("@babel/plugin-transform-typescript"),
-        { allowDeclareFields: true },
+        tsOptions,
       ],
       {
         before: [
@@ -641,4 +676,5 @@ module.exports = {
   _getModulesPlugin,
   _getPresetEnv,
   _shouldHighlightCode,
+  isBabel8,
 };

lib/babel-version.js

@@ -0,0 +1,53 @@
+'use strict';
+
+const semver = require("semver");
+const resolvePackagePath = require("resolve-package-path");
+
+let _babelMajorVersion;
+
+/**
+ * Returns the major version of the installed @babel/core package.
+ * The result is cached for the lifetime of the process.
+ *
+ * @returns {number} The major version (e.g. 7 or 8)
+ */
+function getBabelMajorVersion() {
+  if (_babelMajorVersion !== undefined) return _babelMajorVersion;
+
+  const pkgPath = resolvePackagePath("@babel/core", __dirname);
+  if (pkgPath) {
+    const pkg = require(pkgPath);
+    _babelMajorVersion = semver.major(pkg.version);
+  } else {
+    _babelMajorVersion = 7;
+  }
+  return _babelMajorVersion;
+}
+
+/**
+ * Returns true if @babel/core v8 or higher is installed.
+ *
+ * @returns {boolean}
+ */
+function isBabel8() {
+  return getBabelMajorVersion() >= 8;
+}
+
+/**
+ * Reset the cached version (used in tests).
+ */
+function _resetBabelMajorVersion() {
+  _babelMajorVersion = undefined;
+}
+
+/**
+ * Override the cached Babel major version (used in tests).
+ * Pass `undefined` to reset to auto-detection.
+ *
+ * @param {number|undefined} version
+ */
+function _overrideBabelMajorVersion(version) {
+  _babelMajorVersion = version;
+}
+
+module.exports = { getBabelMajorVersion, isBabel8, _resetBabelMajorVersion, _overrideBabelMajorVersion };

lib/ember-plugins.js

@@ -1,5 +1,6 @@
 const semver = require("semver");
 const resolvePackagePath = require("resolve-package-path");
+const { isBabel8 } = require("./babel-version");
 
 function _getDebugMacroPlugins(appRoot) {
   const isProduction = process.env.EMBER_ENV === "production";
@@ -161,6 +162,11 @@ function _getModuleResolutionPlugins(config) {
 
 function _getProposalDecoratorsAndClassPlugins(config) {
   if (!config.shouldIgnoreDecoratorAndClassPlugins) {
+    // In Babel 8, `legacy: true` is replaced by `version: "legacy"`.
+    const decoratorOptions = isBabel8()
+      ? { version: "legacy" }
+      : { legacy: true };
+
     return [
     /**
       * Required for apps to use `@ember/template-compliation`
@@ -173,7 +179,7 @@ function _getProposalDecoratorsAndClassPlugins(config) {
       * we need to compile it away.
       */
       ["@babel/plugin-transform-class-static-block"],
-      ["@babel/plugin-proposal-decorators", { legacy: true }],
+      ["@babel/plugin-proposal-decorators", decoratorOptions],
       ["@babel/plugin-transform-class-properties"],
     ];
   }