feat(pluginutils): add native node es modules support (rollup#419)

* feat(pluginutils): add native node es modules support

Ref rollup#412 rollup#413

Enable native node es modules via "exports" field in package.json.
Added custom plugin to generate nested package.json with `{"type": "module"}`
to prevent mjs extension usage.

* Export emitModulePackageFile from shared config

* Bundle estree-walker

* Swap options

packages/pluginutils/package.json

@@ -12,7 +12,7 @@
   "bugs": {
     "url": "https://github.com/rollup/plugins/issues"
   },
-  "main": "dist/index.js",
+  "main": "./dist/cjs/index.js",
   "engines": {
     "node": ">= 8.0.0"
   },
@@ -75,12 +75,17 @@
       "!**/types.ts"
     ]
   },
-  "module": "dist/index.es.js",
+  "exports": {
+    "require": "./dist/cjs/index.js",
+    "import": "./dist/es/index.js"
+  },
+  "module": "./dist/es/index.js",
   "nyc": {
     "extension": [
       ".js",
       ".ts"
     ]
   },
+  "type": "commonjs",
   "types": "types/index.d.ts"
 }

packages/pluginutils/rollup.config.js

@@ -1,7 +1,11 @@
+import { builtinModules } from 'module';
+
 import commonjs from '@rollup/plugin-commonjs';
 import resolve from '@rollup/plugin-node-resolve';
 import typescript from '@rollup/plugin-typescript';
 
+import { emitModulePackageFile } from '../../shared/rollup.config';
+
 import pkg from './package.json';
 
 export default {
@@ -11,16 +15,9 @@ export default {
     commonjs({ include: '../../node_modules/.pnpm/registry.npmjs.org/**' }),
     typescript({ include: '**/*.{ts,js}', module: 'esnext' })
   ],
-  external: Object.keys(pkg.dependencies).concat('path', 'util'),
+  external: [...builtinModules, 'picomatch'],
   output: [
-    {
-      format: 'cjs',
-      file: pkg.main,
-      exports: 'named'
-    },
-    {
-      format: 'es',
-      file: pkg.module
-    }
+    { file: pkg.main, format: 'cjs', exports: 'named' },
+    { file: pkg.module, format: 'es', plugins: [emitModulePackageFile()] }
   ]
 };

shared/rollup.config.js

@@ -23,3 +23,16 @@ export function createConfig(pkg) {
     ]
   };
 }
+
+export function emitModulePackageFile() {
+  return {
+    name: 'emit-module-package-file',
+    generateBundle() {
+      this.emitFile({
+        type: 'asset',
+        fileName: 'package.json',
+        source: `{"type":"module"}`
+      });
+    }
+  };
+}