🏗♻️ Consolidate all babel configs into babel.config.js (#27576)

.eslintrc

@@ -262,6 +262,9 @@
         "module": false,
         "process": false,
         "require": false
+      },
+      "rules": {
+        "local/no-module-exports": 0
       }
     },
     {

OWNERS

@@ -20,11 +20,11 @@
       owners: [{name: 'mrjoro'}, {name: 'ampproject/wg-outreach'}],
     },
     {
-      pattern: '{.*,babel.config.js,gulpfile.js}',
+      pattern: '{.*,gulpfile.js}',
       owners: [{name: 'ampproject/wg-infra'}],
     },
     {
-      pattern: '{package.json,yarn.lock}',
+      pattern: '{babel.config.js,package.json,yarn.lock}',
       owners: [
         {name: 'ampproject/wg-infra'},
         {name: 'ampproject/wg-runtime'},

babel.config.js

@@ -25,99 +25,42 @@
 
 'use strict';
 
-const minimist = require('minimist');
-const {isTravisBuild} = require('./build-system/common/travis');
-const argv = minimist(process.argv.slice(2));
+const {
+  getDepCheckConfig,
+  getPostClosureConfig,
+  getPreClosureConfig,
+  getSinglePassDepsConfig,
+  getSinglePassPostConfig,
+  getTestConfig,
+  getUnminifiedConfig,
+} = require('./build-system/babel-config');
 
-const isClosureCompiler =
-  argv._.includes('dist') ||
-  argv._.includes('check-types') ||
-  (argv._.length == 0 && argv.compiled);
-const {esm} = argv;
-
-const targets = (esm) => {
-  if (esm) {
-    return {'esmodules': true};
-  }
-
-  if (isTravisBuild()) {
-    return {'browsers': ['Last 2 versions', 'safari >= 9']};
-  }
-
-  return {'browsers': ['Last 2 versions']};
-};
-
-const plugins = (esm) => {
-  const leadingComments =
-    './build-system/babel-plugins/babel-plugin-transform-fix-leading-comments';
-  const reactConstantElements =
-    '@babel/plugin-transform-react-constant-elements';
-  const transformJSX = [
-    '@babel/plugin-transform-react-jsx',
-    {
-      pragma: 'Preact.createElement',
-      pragmaFrag: 'Preact.Fragment',
-      useSpread: true,
-    },
-  ];
-  const transformClasses = [
-    '@babel/plugin-transform-classes',
-    {
-      loose: false,
-    },
-  ];
-
-  if (esm) {
-    return [leadingComments, reactConstantElements, transformJSX];
-  }
-
-  return [
-    leadingComments,
-    reactConstantElements,
-    transformClasses,
-    transformJSX,
-  ];
-};
-
-const presets = (esm) => {
-  if (esm) {
-    return [
-      [
-        '@babel/preset-env',
-        {
-          'modules': false,
-          'targets': targets(esm),
-          'bugfixes': true,
-        },
-      ],
-    ];
-  }
-
-  return [
-    [
-      '@babel/preset-env',
-      {
-        'modules': isClosureCompiler ? false : 'commonjs',
-        'loose': true,
-        'targets': targets(esm),
-      },
-    ],
-  ];
-};
+/**
+ * Mapping of babel transform callers to their corresponding babel configs.
+ */
+const babelTransforms = new Map([
+  ['dep-check', getDepCheckConfig()],
+  ['post-closure', getPostClosureConfig()],
+  ['pre-closure', getPreClosureConfig()],
+  ['single-pass-deps', getSinglePassDepsConfig()],
+  ['single-pass-post', getSinglePassPostConfig()],
+  ['test', getTestConfig()],
+  ['unminified', getUnminifiedConfig()],
+]);
 
-// eslint-disable-next-line local/no-module-exports
+/**
+ * Main entry point. Returns babel config corresponding to the caller.
+ *
+ * @param {!Object} api
+ * @return {!Object}
+ */
 module.exports = function (api) {
-  api.cache(true);
-  // Closure Compiler builds do not use any of the default settings below until its
-  // an esm build. (Both Multipass and Singlepass)
-  if (isClosureCompiler && !esm) {
-    return {};
+  const caller = api.caller((caller) => caller.name);
+  if (babelTransforms.has(caller)) {
+    return babelTransforms.get(caller);
+  } else {
+    const err = new Error('Unrecognized Babel caller (see babel.config.js).');
+    err.showStack = false;
+    throw err;
   }
-
-  return {
-    'plugins': plugins(esm),
-    'presets': presets(esm),
-    'compact': false,
-    'sourceType': 'module',
-  };
 };

build-system/babel-config/.eslintrc

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "local/prefer-spread-props": 0
+  }
+}

build-system/babel-config/OWNERS

@@ -0,0 +1,14 @@
+// For an explanation of the OWNERS rules and syntax, see:
+// https://github.com/ampproject/amp-github-apps/blob/master/owners/OWNERS.example
+
+{
+  rules: [
+    {
+      owners: [
+        {name: 'ampproject/wg-infra'},
+        {name: 'ampproject/wg-runtime'},
+        {name: 'ampproject/wg-performance'},
+      ],
+    },
+  ],
+}

build-system/babel-config/dep-check-config.js

@@ -0,0 +1,61 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+const {getDevDependencies} = require('./dev-dependencies');
+
+/**
+ * Gets the config for babel transforms run during `gulp dep-check`.
+ *
+ * @return {!Object}
+ */
+function getDepCheckConfig() {
+  const reactJsxPlugin = [
+    '@babel/plugin-transform-react-jsx',
+    {
+      pragma: 'Preact.createElement',
+      pragmaFrag: 'Preact.Fragment',
+      useSpread: true,
+    },
+  ];
+  const presetEnv = [
+    '@babel/preset-env',
+    {
+      bugfixes: true,
+      modules: 'commonjs',
+      loose: true,
+      targets: {'browsers': ['Last 2 versions']},
+    },
+  ];
+  const depCheckPlugins = [
+    './build-system/babel-plugins/babel-plugin-transform-fix-leading-comments',
+    '@babel/plugin-transform-react-constant-elements',
+    '@babel/plugin-transform-classes',
+    reactJsxPlugin,
+  ];
+  const depCheckPresets = [presetEnv];
+  const devDependencies = getDevDependencies();
+  return {
+    compact: false,
+    ignore: devDependencies,
+    plugins: depCheckPlugins,
+    presets: depCheckPresets,
+  };
+}
+
+module.exports = {
+  getDepCheckConfig,
+};

build-system/babel-config/dev-dependencies.js

@@ -0,0 +1,33 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+const packageJson = require('../../package.json');
+
+/**
+ * Gets relative paths to all the devDependencies defined in package.json.
+ *
+ * @return {!Array<string>}
+ */
+function getDevDependencies() {
+  return Object.keys(packageJson.devDependencies).map(
+    (dependency) => `./node_modules/${dependency}`
+  );
+}
+
+module.exports = {
+  getDevDependencies,
+};

build-system/babel-config/index.js

@@ -0,0 +1,34 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+const fs = require('fs');
+
+/**
+ * Populates a single object with the babel configs from all the *-config.js
+ * files in this directory.
+ *
+ * @return {!Object}
+ */
+function getAllBabelConfigs() {
+  const babelConfigFiles = fs
+    .readdirSync(__dirname)
+    .filter((file) => file.includes('-config.js'));
+  const babelConfigs = babelConfigFiles.map((file) => require(`./${file}`));
+  return Object.assign({}, ...babelConfigs);
+}
+
+module.exports = getAllBabelConfigs();

build-system/babel-config/post-closure-config.js

@@ -0,0 +1,69 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+const argv = require('minimist')(process.argv.slice(2));
+
+/**
+ * Gets the config for post-closure babel transforms run during `gulp dist --esm`.
+ *
+ * @return {!Object}
+ */
+function getPostClosureConfig() {
+  if (!argv.esm) {
+    return {};
+  }
+
+  const reactJsxPlugin = [
+    '@babel/plugin-transform-react-jsx',
+    {
+      pragma: 'Preact.createElement',
+      pragmaFrag: 'Preact.Fragment',
+      useSpread: true,
+    },
+  ];
+  const postClosurePlugins = [
+    './build-system/babel-plugins/babel-plugin-transform-minified-comments',
+    './build-system/babel-plugins/babel-plugin-const-transformer',
+    './build-system/babel-plugins/babel-plugin-transform-remove-directives',
+    './build-system/babel-plugins/babel-plugin-transform-function-declarations',
+    './build-system/babel-plugins/babel-plugin-transform-stringish-literals',
+    './build-system/babel-plugins/babel-plugin-transform-fix-leading-comments',
+    '@babel/plugin-transform-react-constant-elements',
+    reactJsxPlugin,
+  ];
+  const presetEnv = [
+    '@babel/preset-env',
+    {
+      bugfixes: true,
+      modules: false,
+      targets: {'esmodules': true},
+    },
+  ];
+  const postClosurePresets = [presetEnv];
+  return {
+    compact: false,
+    inputSourceMap: false,
+    plugins: postClosurePlugins,
+    presets: postClosurePresets,
+    retainLines: false,
+    sourceMaps: true,
+  };
+}
+
+module.exports = {
+  getPostClosureConfig,
+};