feat(commonjs): set syntheticNamedExports for commonjs modules (#149)

BREAKING CHANGE:

The namedExports option has been removed, now requires rollup >= 2.3.4. Instead of manually defining named exports, rollup now handles this automatically for you.

* feat(commonjs): set syntheticNamedExports for commonjs modules

* feat(commonjs): remove namedExports option

* chore: merge with upstream

* chore(commonjs): restrict rollup version

* chore(commonjs): remove unused fixtures

Author: LarsDenBakker

packages/commonjs/README.md

@@ -106,47 +106,6 @@ Default: `true`
 
 If false, skips source map generation for CommonJS modules.
 
-### `namedExports`
-
-Type: `Object`<br>
-Default: `null`
-
-Explicitly specify unresolvable named exports.
-
-This plugin will attempt to create named exports, where appropriate, so you can do this...
-
-```js
-// importer.js
-import { named } from './exporter.js';
-
-// exporter.js
-module.exports = { named: 42 }; // or `exports.named = 42;`
-```
-
-...but that's not always possible:
-
-```js
-// importer.js
-import { named } from 'my-lib';
-
-// my-lib.js
-var myLib = exports;
-myLib.named = "you can't see me";
-```
-
-In those cases, you can specify custom named exports:
-
-```js
-commonjs({
-  namedExports: {
-    // left-hand side can be an absolute path, a path
-    // relative to the current directory, or the name
-    // of a module in node_modules
-    'my-lib': ['named']
-  }
-});
-```
-
 ### `ignore`
 
 Type: `Array[...String | (String) => Boolean]`<br>

packages/commonjs/package.json

@@ -46,7 +46,7 @@
     "require"
   ],
   "peerDependencies": {
-    "rollup": "^1.20.0||^2.0.0"
+    "rollup": "^2.3.4"
   },
   "dependencies": {
     "@rollup/pluginutils": "^3.0.8",
@@ -67,7 +67,7 @@
     "locate-character": "^2.0.5",
     "prettier": "^1.19.1",
     "require-relative": "^0.8.7",
-    "rollup": "^2.0.0",
+    "rollup": "^2.3.4",
     "rollup-plugin-babel": "^4.3.3",
     "shx": "^0.3.2",
     "source-map": "^0.6.1",

packages/commonjs/src/index.js

@@ -1,7 +1,6 @@
-import { realpathSync, existsSync, readFileSync } from 'fs';
-import { extname, resolve, normalize, join } from 'path';
+import { existsSync, readFileSync } from 'fs';
+import { extname, join } from 'path';
 
-import { sync as nodeResolveSync, isCore } from 'resolve';
 import { createFilter } from '@rollup/pluginutils';
 
 import getCommonDir from 'commondir';
@@ -48,40 +47,6 @@ export default function commonjs(options = {}) {
     ? getCommonDir(null, Array.from(dynamicRequireModuleSet).concat(process.cwd()))
     : null;
 
-  const customNamedExports = {};
-  if (options.namedExports) {
-    Object.keys(options.namedExports).forEach((id) => {
-      let resolveId = id;
-      let resolvedId;
-
-      if (isCore(id)) {
-        // resolve will not find npm modules with the same name as
-        // core modules without a trailing slash. Since core modules
-        // must be external, we can assume any core modules defined
-        // here are npm modules by that name.
-        resolveId += '/';
-      }
-
-      try {
-        resolvedId = nodeResolveSync(resolveId, { basedir: process.cwd() });
-      } catch (err) {
-        resolvedId = resolve(id);
-      }
-
-      // Note: customNamedExport's keys must be normalized file paths.
-      // resolve and nodeResolveSync both return normalized file paths
-      // so no additional normalization is necessary.
-      customNamedExports[resolvedId] = options.namedExports[id];
-
-      if (existsSync(resolvedId)) {
-        const realpath = realpathSync(resolvedId);
-        if (realpath !== resolvedId) {
-          customNamedExports[realpath] = options.namedExports[id];
-        }
-      }
-    });
-  }
-
   const esModulesWithoutDefaultExport = new Set();
   const esModulesWithDefaultExport = new Set();
 
@@ -111,8 +76,6 @@ export default function commonjs(options = {}) {
       return null;
     }
 
-    const normalizedId = normalize(id);
-
     const transformed = transformCommonjs(
       this.parse,
       code,
@@ -121,7 +84,6 @@ export default function commonjs(options = {}) {
       isEsModule,
       ignoreGlobal || isEsModule,
       ignoreRequire,
-      customNamedExports[normalizedId],
       sourceMap,
       isDynamicRequireModulesEnabled,
       dynamicRequireModuleSet,
@@ -143,6 +105,12 @@ export default function commonjs(options = {}) {
     name: 'commonjs',
 
     buildStart() {
+      if (options.namedExports != null) {
+        this.warn(
+          'The namedExports option from "@rollup/plugin-commonjs" is deprecated. Named exports are now handled automatically.'
+        );
+      }
+
       const [major, minor] = this.meta.rollupVersion.split('.').map(Number);
       const minVersion = peerDependencies.rollup.slice(2);
       const [minMajor, minMinor] = minVersion.split('.').map(Number);

packages/commonjs/src/transform.js

@@ -109,7 +109,6 @@ export function transformCommonjs(
   isEsModule,
   ignoreGlobal,
   ignoreRequire,
-  customNamedExports,
   sourceMap,
   isDynamicRequireModulesEnabled,
   dynamicRequireModuleSet,
@@ -562,8 +561,6 @@ export function transformCommonjs(
     });
   }
 
-  if (customNamedExports) customNamedExports.forEach(addExport);
-
   const defaultExportPropertyAssignments = [];
   let hasDefaultExport = false;
 
@@ -648,12 +645,13 @@ export function transformCommonjs(
     .trim()
     .append(wrapperEnd);
 
-  if (hasDefaultExport || named.length > 0 || shouldWrap || (!isEntry && !isEsModule)) {
+  const injectExportBlock = hasDefaultExport || named.length > 0 || shouldWrap || !isEntry;
+  if (injectExportBlock) {
     magicString.append(exportBlock);
   }
 
   code = magicString.toString();
   const map = sourceMap ? magicString.generateMap() : null;
 
-  return { code, map };
+  return { code, map, syntheticNamedExports: injectExportBlock };
 }

packages/commonjs/test/fixtures/.eslintrc

@@ -6,6 +6,7 @@
     "func-names": "off",
     "no-console": "off",
     "no-undefined": "off",
+    "no-undef": "off",
     "import/prefer-default-export": "off",
     "import/extensions": "off",
     "import/no-unresolved": "off",

packages/commonjs/test/fixtures/function/__esModule/main.js

@@ -2,4 +2,3 @@ import * as x from './answer';
 
 t.truthy('answer' in x);
 t.truthy('default' in x);
-t.truthy(!('__esModule' in x));

packages/commonjs/test/fixtures/function/named-exports-conditional/main.js

@@ -0,0 +1,3 @@
+import { named } from './x.js';
+
+t.is(named, 'foo');

packages/commonjs/test/fixtures/function/named-exports-conditional/x.js

@@ -0,0 +1,5 @@
+if (typeof someUnknownGlobal !== 'undefined') {
+  module.exports = { named: 'bar' };
+} else {
+  module.exports = { named: 'foo' };
+}

packages/commonjs/test/fixtures/function/named-exports-dynamic/_config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  context: {
+    window: {}
+  }
+};

packages/commonjs/test/fixtures/function/named-exports-dynamic/main.js

@@ -0,0 +1,7 @@
+import { named } from './x.js';
+
+t.is(named, undefined);
+
+window.addExport('named', 'foo');
+
+t.is(named, 'foo');