feat(commonjs): support all styles of transpiled ES modules

BREAKING CHANGES: CJS entry points will always have a default export

packages/commonjs/src/helpers.js

@@ -20,9 +20,21 @@ export const HELPERS_ID = '\0commonjsHelpers.js';
 
 // `x['default']` is used instead of `x.default` for backward compatibility with ES3 browsers.
 // Minifiers like uglify will usually transpile it back if compatibility with ES3 is not enabled.
+// This will no longer be necessary once Rollup switches to ES6 output, likely
+// in Rollup 3
+
+// The "hasOwnProperty" call in "getDefaultExportFromCjs" is technically not
+// needed, but for consumers that use Rollup's old interop pattern, it will fix
+// rollup/rollup-plugin-commonjs#224
+// We should remove it once Rollup core and this plugin are updated to not use
+// this pattern any more
 export const HELPERS = `
 export var commonjsGlobal = typeof globalThis !== 'undefined' ? globalThis : typeof window !== 'undefined' ? window : typeof global !== 'undefined' ? global : typeof self !== 'undefined' ? self : {};
 
+export function getDefaultExportFromCjs (x) {
+	return x && x.__esModule && Object.prototype.hasOwnProperty.call(x, 'default') ? x['default'] : x;
+}
+
 export function createCommonjsModule(fn, basedir, module) {
 	return module = {
 	  path: basedir,

packages/commonjs/src/index.js

@@ -80,14 +80,10 @@ export default function commonjs(options = {}) {
       return null;
     }
 
-    const moduleInfo = this.getModuleInfo(id);
-
     const transformed = transformCommonjs(
       this.parse,
       code,
       id,
-      moduleInfo.isEntry,
-      moduleInfo.importers && moduleInfo.importers.length > 0,
       isEsModule,
       ignoreGlobal || isEsModule,
       ignoreRequire,

packages/commonjs/src/transform.js

@@ -105,8 +105,6 @@ export function transformCommonjs(
   parse,
   code,
   id,
-  isEntry,
-  hasImporters,
   isEsModule,
   ignoreGlobal,
   ignoreRequire,
@@ -577,7 +575,7 @@ export function transformCommonjs(
   let wrapperEnd = '';
 
   const moduleName = deconflict(scope, globals, getName(id));
-  if ((!isEntry || hasImporters) && !isEsModule) {
+  if (!isEsModule) {
     const exportModuleExports = {
       str: `export { ${moduleName} as __moduleExports };`,
       name: '__moduleExports'
@@ -647,38 +645,37 @@ export function transformCommonjs(
       }
     }
 
-    if (!hasDefaultExport && (names.length || ((!isEntry || hasImporters) && !isEsModule))) {
+    if (!(isEsModule || hasDefaultExport)) {
       wrapperEnd = `\n\nvar ${moduleName} = {\n${names
         .map(({ name, deconflicted }) => `\t${name}: ${deconflicted}`)
         .join(',\n')}\n};`;
     }
   }
 
-  const defaultExport = `export default ${moduleName};`;
-
-  const named = namedExportDeclarations
-    .filter((x) => x.name !== 'default' || !hasDefaultExport)
-    .map((x) => x.str);
-
-  const exportBlock = `\n\n${(isEsModule ? [] : [defaultExport])
-    .concat(named)
-    .concat(hasDefaultExport ? defaultExportPropertyAssignments : [])
-    .join('\n')}`;
-
   magicString
     .trim()
     .prepend(importBlock + wrapperStart)
     .trim()
     .append(wrapperEnd);
 
-  const injectExportBlock =
-    hasDefaultExport || named.length > 0 || shouldWrap || !isEntry || hasImporters;
-  if (injectExportBlock) {
-    magicString.append(exportBlock);
-  }
+  const defaultExport =
+    code.indexOf('__esModule') >= 0
+      ? `export default /*@__PURE__*/${HELPERS_NAME}.getDefaultExportFromCjs(${moduleName});`
+      : `export default ${moduleName};`;
+
+  const named = namedExportDeclarations
+    .filter((x) => x.name !== 'default' || !hasDefaultExport)
+    .map((x) => x.str);
+
+  magicString.append(
+    `\n\n${(isEsModule ? [] : [defaultExport])
+      .concat(named)
+      .concat(hasDefaultExport ? defaultExportPropertyAssignments : [])
+      .join('\n')}`
+  );
 
   code = magicString.toString();
   const map = sourceMap ? magicString.generateMap() : null;
 
-  return { code, map, syntheticNamedExports: injectExportBlock };
+  return { code, map, syntheticNamedExports: '__moduleExports' };
 }

packages/commonjs/test/fixtures/form/no-exports-entry/output.js

@@ -6,3 +6,10 @@ var foo = function () {
 };
 
 var input = 42;
+
+var input_1 = {
+
+};
+
+export default input_1;
+export { input_1 as __moduleExports };

packages/commonjs/test/fixtures/function/late-entry-dependency/_config.js

@@ -0,0 +1,23 @@
+const path = require('path');
+const fs = require('fs');
+
+const ID_MAIN = path.join(__dirname, 'main.js');
+const ID_OTHER = path.join(__dirname, 'other.js');
+
+module.exports = {
+  options: {
+    input: [ID_MAIN, ID_OTHER],
+    plugins: [
+      {
+        load(id) {
+          if (id === ID_MAIN) {
+            return new Promise((resolve) =>
+              setTimeout(() => resolve(fs.readFileSync(ID_MAIN, 'utf8')), 100)
+            );
+          }
+          return null;
+        }
+      }
+    ]
+  }
+};

packages/commonjs/test/fixtures/function/late-entry-dependency/main.js

@@ -0,0 +1,3 @@
+const foo = require('./other.js');
+
+t.is(foo, 'foo');

packages/commonjs/test/fixtures/function/late-entry-dependency/other.js

@@ -0,0 +1 @@
+module.exports = 'foo';

packages/commonjs/test/fixtures/function/no-exports-entry/dep.js

@@ -0,0 +1 @@
+module.exports = 42;

packages/commonjs/test/fixtures/function/no-exports-entry/main.js

@@ -0,0 +1,3 @@
+const dep = require('./dep.js');
+
+t.is(dep, 42);

packages/commonjs/test/fixtures/function/transpiled-esm-default/dep.js

@@ -0,0 +1,2 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.default = 'default';

packages/commonjs/test/fixtures/function/transpiled-esm-default/main.js

@@ -0,0 +1,3 @@
+import dep from './dep';
+
+t.is(dep, 'default');

packages/commonjs/test/fixtures/function/transpiled-esm-entry-default/_config.js

@@ -0,0 +1,9 @@
+const path = require('path');
+
+module.exports = {
+  description:
+    'Creates correct exports if an ES module that was transpiled to CJS is used as entry point',
+  options: {
+    input: [path.join(__dirname, 'main.js'), path.join(__dirname, 'entry.js')]
+  }
+};

packages/commonjs/test/fixtures/function/transpiled-esm-entry-default/entry.js

@@ -0,0 +1,2 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.default = 'default';

packages/commonjs/test/fixtures/function/transpiled-esm-entry-default/main.js

@@ -0,0 +1,3 @@
+import * as entry from './entry.js';
+
+t.deepEqual(entry, { default: 'default' });

packages/commonjs/test/fixtures/function/transpiled-esm-entry-mixed/_config.js

@@ -0,0 +1,9 @@
+const path = require('path');
+
+module.exports = {
+  description:
+    'Creates correct exports if an ES module that was transpiled to CJS is used as entry point',
+  options: {
+    input: [path.join(__dirname, 'main.js'), path.join(__dirname, 'entry.js')]
+  }
+};

packages/commonjs/test/fixtures/function/transpiled-esm-entry-mixed/entry.js

@@ -0,0 +1,3 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.default = 'default';
+exports.named = 'named';

packages/commonjs/test/fixtures/function/transpiled-esm-entry-mixed/main.js

@@ -0,0 +1,3 @@
+import * as entry from './entry.js';
+
+t.deepEqual(entry, { default: 'default', named: 'named' });

packages/commonjs/test/fixtures/function/transpiled-esm-entry-named/_config.js

@@ -0,0 +1,9 @@
+const path = require('path');
+
+module.exports = {
+  description:
+    'Creates correct exports if an ES module that was transpiled to CJS is used as entry point',
+  options: {
+    input: [path.join(__dirname, 'main.js'), path.join(__dirname, 'entry.js')]
+  }
+};

packages/commonjs/test/fixtures/samples/use-own-output/from-rollup.js → packages/commonjs/test/fixtures/function/transpiled-esm-entry-named/entry.js

@@ -1,2 +1,2 @@
 Object.defineProperty(exports, '__esModule', { value: true });
-exports.x = 10;
+exports.named = 'named';

packages/commonjs/test/fixtures/function/transpiled-esm-entry-named/main.js

@@ -0,0 +1,11 @@
+import * as entry from './entry.js';
+
+t.deepEqual(entry, {
+  // Technically, this should ideally not exist, or if we cannot avoid it due
+  // to runtime default export detection, it should probably be undefined. We
+  // return the namespace instead as this will fix
+  // rollup/rollup-plugin-commonjs#224 until the remaining Rollup interop has
+  // been updated
+  default: { named: 'named' },
+  named: 'named'
+});

packages/commonjs/test/fixtures/function/transpiled-esm-mixed/dep.js

@@ -0,0 +1,3 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.named = 'named';
+exports.default = 'default';

packages/commonjs/test/fixtures/function/transpiled-esm-mixed/main.js

@@ -0,0 +1,4 @@
+import dep, { named } from './dep';
+
+t.is(dep, 'default');
+t.is(named, 'named');

packages/commonjs/test/fixtures/function/transpiled-esm-named/dep.js

@@ -0,0 +1,2 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.named = 'named';

packages/commonjs/test/fixtures/function/transpiled-esm-named/main.js

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

packages/commonjs/test/fixtures/function/transpiled-esm-namespace-default/dep.js

@@ -0,0 +1,2 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.default = 'default';

packages/commonjs/test/fixtures/function/transpiled-esm-namespace-default/main.js

@@ -0,0 +1,5 @@
+import * as x from './dep';
+
+t.deepEqual(x, {
+  default: 'default'
+});

packages/commonjs/test/fixtures/function/transpiled-esm-namespace-mixed/dep.js

@@ -0,0 +1,3 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.named = 'named';
+exports.default = 'default';

packages/commonjs/test/fixtures/function/transpiled-esm-namespace-mixed/main.js

@@ -0,0 +1,6 @@
+import * as x from './dep';
+
+t.deepEqual(x, {
+  default: 'default',
+  named: 'named'
+});

packages/commonjs/test/fixtures/function/transpiled-esm-namespace-named/dep.js

@@ -0,0 +1,2 @@
+Object.defineProperty(exports, '__esModule', { value: true });
+exports.named = 'named';

packages/commonjs/test/fixtures/function/transpiled-esm-namespace-named/main.js

@@ -0,0 +1,11 @@
+import * as x from './dep';
+
+t.deepEqual(x, {
+  named: 'named',
+  // Technically, this should ideally not exist, or if we cannot avoid it due
+  // to runtime default export detection, it should probably be undefined. We
+  // return the namespace instead as this will fix
+  // rollup/rollup-plugin-commonjs#224 until the remaining Rollup interop has
+  // been updated
+  default: { named: 'named' }
+});