From b2809f5d69d5738f310760a6a155977c497eb71d Mon Sep 17 00:00:00 2001
From: Lyrkan <850046+Lyrkan@users.noreply.github.com>
Date: Mon, 15 Jul 2019 22:44:06 +0200
Subject: [PATCH] Don't make @babel/preset-env force all transforms in prod

---
 fixtures/js/async_function.js |  7 +++++++
 lib/loaders/babel.js          |  1 -
 test/functional.js            | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 fixtures/js/async_function.js

diff --git a/fixtures/js/async_function.js b/fixtures/js/async_function.js
new file mode 100644
index 00000000..f684caef
--- /dev/null
+++ b/fixtures/js/async_function.js
@@ -0,0 +1,7 @@
+async function foo() {
+    console.log('foo');
+}
+
+foo().then(() => {
+    console.log('bar');
+});
diff --git a/lib/loaders/babel.js b/lib/loaders/babel.js
index 6ed2e30b..0580d53c 100644
--- a/lib/loaders/babel.js
+++ b/lib/loaders/babel.js
@@ -42,7 +42,6 @@ module.exports = {
                 // https://babeljs.io/docs/en/babel-preset-env#modules
                 modules: false,
                 targets: {},
-                forceAllTransforms: webpackConfig.isProduction(),
                 useBuiltIns: webpackConfig.babelOptions.useBuiltIns,
                 corejs: webpackConfig.babelOptions.corejs,
             };
diff --git a/test/functional.js b/test/functional.js
index b213da46..69fe15bd 100644
--- a/test/functional.js
+++ b/test/functional.js
@@ -1148,6 +1148,41 @@ module.exports = {
             });
         });
 
+        it('Babel does not force transforms if they are not needed', (done) => {
+            const cwd = process.cwd();
+            after(() => {
+                process.chdir(cwd);
+            });
+
+            const appDir = testSetup.createTestAppDir();
+            process.chdir(appDir);
+
+            fs.writeFileSync(
+                path.join(appDir, 'package.json'),
+
+                // Chrome 55 supports async and arrow functions
+                '{"browserslist": "Chrome 55"}'
+            );
+
+            const config = createWebpackConfig('www/build', 'prod');
+            config.setPublicPath('/build');
+            config.addEntry('async', './js/async_function.js');
+            config.configureBabel(null, {
+                useBuiltIns: 'usage',
+                corejs: 3,
+            });
+
+            testSetup.runWebpack(config, async(webpackAssert) => {
+                webpackAssert.assertOutputFileContains(
+                    'async.js',
+                    'async function(){console.log("foo")}().then(()=>{console.log("bar")})'
+                );
+
+                done();
+            });
+        });
+
+
         it('When enabled, react JSX is transformed!', (done) => {
             const config = createWebpackConfig('www/build', 'dev');
             config.setPublicPath('/build');