From c1ecbd71cc7ba1923149cf9c00d270a1afe14557 Mon Sep 17 00:00:00 2001
From: Swashata Ghosh <swashata@wpquark.com>
Date: Sat, 4 May 2019 09:38:33 +0530
Subject: [PATCH] feat(babel): add performant destructuring

Per CRA, we add transform-destructuring with loose set to false.
However, for hooks, we turn selectiveLoose.
---
 .../__tests__/preset.spec.ts                  |  2 +-
 packages/babel-preset-base/package.json       |  1 +
 packages/babel-preset-base/src/preset.ts      | 24 +++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/packages/babel-preset-base/__tests__/preset.spec.ts b/packages/babel-preset-base/__tests__/preset.spec.ts
index 480b3681e..f949120fc 100644
--- a/packages/babel-preset-base/__tests__/preset.spec.ts
+++ b/packages/babel-preset-base/__tests__/preset.spec.ts
@@ -73,7 +73,7 @@ describe('preset in module', () => {
 			noJsonStrings: true,
 			noRuntime: true,
 		});
-		expect(plugins).toHaveLength(0);
+		expect(plugins).toHaveLength(1);
 	});
 
 	describe('for @babel/preset-env', () => {
diff --git a/packages/babel-preset-base/package.json b/packages/babel-preset-base/package.json
index 48ed499d9..3b14b670a 100644
--- a/packages/babel-preset-base/package.json
+++ b/packages/babel-preset-base/package.json
@@ -22,6 +22,7 @@
     "@babel/plugin-proposal-json-strings": "^7.2.0",
     "@babel/plugin-syntax-dynamic-import": "^7.2.0",
     "@babel/plugin-syntax-import-meta": "^7.2.0",
+    "@babel/plugin-transform-destructuring": "^7.4.4",
     "@babel/plugin-transform-runtime": "^7.4.4",
     "@babel/preset-env": "^7.4.4",
     "@babel/preset-react": "^7.0.0",
diff --git a/packages/babel-preset-base/src/preset.ts b/packages/babel-preset-base/src/preset.ts
index 0e85acdfb..c157407ee 100644
--- a/packages/babel-preset-base/src/preset.ts
+++ b/packages/babel-preset-base/src/preset.ts
@@ -101,6 +101,30 @@ export const preset = (opts: PresetOptions | null = {}) => {
 		}
 	});
 
+	// Necessary to include regardless of the environment because
+	// in practice some other transforms (such as object-rest-spread)
+	// don't work without it: https://github.com/babel/babel/issues/7215
+	plugins.push([
+		'@babel/plugin-transform-destructuring',
+		{
+			// Use loose mode for performance:
+			// https://github.com/facebook/create-react-app/issues/5602
+			loose: false,
+			selectiveLoose: [
+				'useState',
+				'useEffect',
+				'useContext',
+				'useReducer',
+				'useCallback',
+				'useMemo',
+				'useRef',
+				'useImperativeHandle',
+				'useLayoutEffect',
+				'useDebugValue',
+			],
+		},
+	]);
+
 	// Return the preset and some of stage-3 plugins
 	// We will remove them, once it becomes stage-4, i.e included in preset-env
 	return {