Update webpack to v4 (#6366)

* Update webpack to v4

* add todo

* add link

package.json

@@ -114,7 +114,7 @@
     "snapshot-diff": "0.4.0",
     "strip-ansi": "4.0.0",
     "tempy": "0.2.1",
-    "webpack": "3.12.0"
+    "webpack": "4.39.1"
   },
   "scripts": {
     "prepublishOnly": "echo \"Error: must publish from dist/\" && exit 1",

scripts/build/build.js

@@ -99,7 +99,7 @@ async function run(params) {
     await execa("rm", ["-rf", ".cache"]);
   }
 
-  const bundleCache = new Cache(".cache/", "v13");
+  const bundleCache = new Cache(".cache/", "v14");
   await bundleCache.load();
 
   console.log(chalk.inverse(" Building packages "));

scripts/build/bundler.js

@@ -176,13 +176,16 @@ function getWebpackConfig(bundle) {
       path: path.resolve(root, "dist"),
       filename: bundle.output,
       library: ["prettierPlugins", bundle.name],
-      libraryTarget: "umd"
+      libraryTarget: "umd",
+      // https://github.com/webpack/webpack/issues/6642
+      globalObject: 'new Function("return this")()'
     },
-    plugins: [
-      new webpack.DefinePlugin({
-        "process.env.NODE_ENV": JSON.stringify("production")
-      })
-    ]
+    optimization: {
+      // TODO: enable this
+      // `parser-postcss.js` can't work with terser
+      // https://github.com/prettier/prettier/pull/6200#issuecomment-500018106
+      minimize: false
+    }
   };
 }