Centralize Babel's own compilation config to make it easier to follow. (#7599)

.babelrc.js

@@ -1,48 +1,69 @@
 "use strict";
 
-const env = process.env.BABEL_ENV || process.env.NODE_ENV;
+module.exports = function(api) {
-const envOpts = {
+  const env = api.env();
-  loose: true,
+
+  const includeCoverage = process.env.BABEL_COVERAGE === "true";
+
+  const envOpts = {
+    loose: true,
+    modules: false,
+    exclude: ["transform-typeof-symbol"],
+  };
+
+  let convertESM = true;
+
+  switch (env) {
+    // Configs used during bundling builds.
+    case "babylon":
+    case "standalone":
+      convertESM = false;
+      break;
+    case "production":
+      // Config during builds before publish.
+      break;
+    case "development":
+      envOpts.debug = true;
+      envOpts.targets = {
+        node: "current",
+      };
+      break;
+    case "test":
+      envOpts.targets = {
+        node: "current",
+      };
+      break;
+  }
+
+  const config = {
+    comments: false,
+    presets: [["@babel/env", envOpts]],
+    plugins: [
+      // TODO: Use @babel/preset-flow when
+      // https://github.com/babel/babel/issues/7233 is fixed
+      "@babel/plugin-transform-flow-strip-types",
+      ["@babel/proposal-class-properties", { loose: true }],
+      "@babel/proposal-export-namespace-from",
+      "@babel/proposal-numeric-separator",
+      ["@babel/proposal-object-rest-spread", { useBuiltIns: true }],
+      convertESM ? "@babel/transform-modules-commonjs" : null,
+    ].filter(Boolean),
+    overrides: [
+      {
+        test: "packages/babylon",
+        plugins: [
+          "babel-plugin-transform-charcodes",
+          ["@babel/transform-for-of", { assumeArray: true }],
+        ],
+      },
+    ],
+  };
+
+  // we need to do this as long as we do not test everything from source
+  if (includeCoverage) {
+    config.auxiliaryCommentBefore = "istanbul ignore next";
+    config.plugins.push("babel-plugin-istanbul");
+  }
+
+  return config;
 };
-
-switch (env) {
-  case "development":
-    envOpts.debug = true;
-  // fall-through
-  case "test":
-  case "cov":
-    envOpts.targets = {
-      node: "current",
-    };
-}
-
-const config = {
-  comments: false,
-  presets: [["@babel/env", envOpts]],
-  plugins: [
-    // TODO: Use @babel/preset-flow when
-    // https://github.com/babel/babel/issues/7233 is fixed
-    "@babel/plugin-transform-flow-strip-types",
-    ["@babel/proposal-class-properties", { loose: true }],
-    "@babel/proposal-export-namespace-from",
-    "@babel/proposal-numeric-separator",
-    ["@babel/proposal-object-rest-spread", { useBuiltIns: true }],
-  ],
-  overrides: [
-    {
-      test: "packages/babylon",
-      plugins: [
-        "babel-plugin-transform-charcodes",
-        ["@babel/transform-for-of", { assumeArray: true }],
-      ],
-    },
-  ],
-};
-
-// we need to do this as long as we do not test everything from source
-if (env === "cov") {
-  config.auxiliaryCommentBefore = "istanbul ignore next";
-  config.plugins.push("babel-plugin-istanbul");
-}
-
-module.exports = config;

.babelrc.rollup.js

@@ -1,16 +0,0 @@
-"use strict";
-
-const cloneDeep = require("lodash/cloneDeep");
-const babelrc = require("./.babelrc.js");
-
-const config = cloneDeep(babelrc);
-
-const presetEnv = config.presets.find(preset => preset[0] === "@babel/env");
-
-if (!presetEnv) {
-  throw new Error("Error while extracting @preset/env from .babelrc.js");
-}
-
-presetEnv[1].modules = false;
-
-module.exports = config;

Gulpfile.js

@@ -98,8 +98,9 @@ function buildRollup(packages) {
         format: "cjs",
         plugins: [
           rollupBabel({
+            envName: "babylon",
             babelrc: false,
-            extends: "./.babelrc.rollup.js",
+            extends: "./.babelrc.js",
           }),
           rollupNodeResolve(),
         ],

Makefile

@@ -2,7 +2,7 @@ MAKEFLAGS = -j1
 FLOW_COMMIT = 622bbc4f07acb77eb1109830c70815f827401d90
 TEST262_COMMIT = 52f70e2f637731aae92a9c9a2d831310c3ab2e1e
 
-export NODE_ENV = test
+export BABEL_ENV = test
 
 # Fix color output until TravisCI fixes https://github.com/travis-ci/travis-ci/issues/7967
 export FORCE_COLOR = true
@@ -22,7 +22,7 @@ build: clean
 	node scripts/generators/typescript.js > ./packages/babel-types/lib/index.d.ts
 	# generate docs
 	node scripts/generators/docs.js > ./packages/babel-types/README.md
-ifneq ("$(BABEL_ENV)", "cov")
+ifneq ("$(BABEL_COVERAGE)", "true")
 	make build-standalone
 	make build-preset-env-standalone
 endif
@@ -82,7 +82,7 @@ test-ci:
 
 test-ci-coverage: SHELL:=/bin/bash
 test-ci-coverage:
-	BABEL_ENV=cov make bootstrap
+	BABEL_COVERAGE=true BABEL_ENV=test make bootstrap
 	TEST_TYPE=cov ./scripts/test-cov.sh
 	bash <(curl -s https://codecov.io/bash) -f coverage/coverage-final.json
 

package.json

@@ -12,6 +12,7 @@
   "devDependencies": {
     "@babel/cli": "7.0.0-beta.41",
     "@babel/core": "7.0.0-beta.41",
+    "@babel/plugin-transform-modules-commonjs": "7.0.0-beta.41",
     "@babel/preset-env": "7.0.0-beta.41",
     "@babel/preset-flow": "7.0.0-beta.41",
     "@babel/preset-stage-0": "7.0.0-beta.41",

scripts/gulp-tasks.js

@@ -39,25 +39,18 @@ function webpackBuild(opts) {
           test: /\.js$/,
           loader: "babel-loader",
           options: {
+            // Use the bundled config so that module syntax is passed through
+            // for Webpack.
+            envName: "standalone",
+
             // Some of the node_modules may have their own "babel" section in
             // their project.json (or a ".babelrc" file). We need to ignore
             // those as we're using our own Babel options.
             babelrc: false,
-            presets: [
+
-              [
+            // We explicitly load the `.babelrc.js` file since searching is
-                "@babel/env",
+            // turned off, but we still want to use the main config.
-                {
+            extends: "./.babelrc.js",
-                  loose: true,
-                  exclude: ["transform-typeof-symbol"],
-                },
-              ],
-            ],
-            overrides: [
-              {
-                exclude: /node_modules/,
-                presets: [["@babel/stage-0", { loose: true }]],
-              },
-            ],
           },
         },
       ],