Favour extends helper over objectWithoutProperties when whole object gets copied anyway (#7390)

packages/babel-plugin-transform-destructuring/README.md

@@ -51,3 +51,42 @@ require("@babel/core").transform("code", {
   plugins: ["@babel/plugin-transform-destructuring"]
 });
 ```
+
+## Options
+
+### `loose`
+
+`boolean`, defaults to `false`.
+
+Enabling this option will assume that what you want to destructure is an array and won't use `Array.from` on other iterables.
+
+### `useBuiltIns`
+
+`boolean`, defaults to `false`.
+
+Enabling this option will use `Object.assign` directly instead of the Babel's `extends` helper. 
+
+##### Example
+
+**.babelrc**
+
+```json
+{
+  "plugins": [
+    ["@babel/plugin-transform-destructuring", { "useBuiltIns": true }]
+  ]
+}
+```
+
+**In**
+
+```js
+var { ...x } = z;
+```
+
+**Out**
+
+```js
+var _z = z,
+    x = Object.assign({}, _z);
+```

packages/babel-plugin-transform-destructuring/src/index.js

@@ -4,13 +4,20 @@ import { types as t } from "@babel/core";
 export default declare((api, options) => {
   api.assertVersion(7);
 
-  const { loose = false } = options;
+  const { loose = false, useBuiltIns = false } = options;
+
   if (typeof loose !== "boolean") {
     throw new Error(`.loose must be a boolean or undefined`);
   }
 
   const arrayOnlySpread = loose;
 
+  function getExtendsHelper(file) {
+    return useBuiltIns
+      ? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
+      : file.addHelper("extends");
+  }
+
   /**
    * Test if a VariableDeclaration's declarations contains any Patterns.
    */
@@ -172,14 +179,21 @@ export default declare((api, options) => {
         keys.push(t.cloneNode(key));
       }
 
-      keys = t.arrayExpression(keys);
+      let value;
+      if (keys.length === 0) {
+        value = t.callExpression(getExtendsHelper(this), [
+          t.objectExpression([]),
+          t.cloneNode(objRef),
+        ]);
+      } else {
+        keys = t.arrayExpression(keys);
 
-      //
+        value = t.callExpression(this.addHelper("objectWithoutProperties"), [
+          t.cloneNode(objRef),
+          keys,
+        ]);
+      }
 
-      const value = t.callExpression(
-        this.addHelper("objectWithoutProperties"),
-        [t.cloneNode(objRef), keys],
-      );
       this.nodes.push(this.buildVariableAssignment(spreadProp.argument, value));
     }
 

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/es7-object-rest-builtins/input.js

@@ -0,0 +1,7 @@
+var z = {};
+var { ...x } = z;
+var { x, ...y } = z;
+var { [x]: x, ...y } = z;
+(function({ x, ...y }) { });
+
+({ x, y, ...z } = o);

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/es7-object-rest-builtins/options.json

@@ -0,0 +1,11 @@
+{
+  "plugins": [
+    "external-helpers",
+    ["transform-destructuring", { "useBuiltIns": true }],
+    "transform-spread",
+    "transform-parameters",
+    "transform-block-scoping",
+    "proposal-object-rest-spread",
+    "transform-regenerator"
+  ]
+}

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/es7-object-rest-builtins/output.js

@@ -0,0 +1,20 @@
+var z = {};
+var _z = z,
+    x = Object.assign({}, _z);
+var _z2 = z,
+    x = _z2.x,
+    y = babelHelpers.objectWithoutProperties(_z2, ["x"]);
+var _z3 = z,
+    x = _z3[x],
+    y = babelHelpers.objectWithoutProperties(_z3, [x]);
+
+(function (_ref) {
+  var x = _ref.x,
+      y = babelHelpers.objectWithoutProperties(_ref, ["x"]);
+});
+
+var _o = o;
+x = _o.x;
+y = _o.y;
+z = babelHelpers.objectWithoutProperties(_o, ["x", "y"]);
+_o;

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/es7-object-rest/output.js

@@ -1,6 +1,6 @@
 var z = {};
 var _z = z,
-    x = babelHelpers.objectWithoutProperties(_z, []);
+    x = babelHelpers.extends({}, _z);
 var _z2 = z,
     x = _z2.x,
     y = babelHelpers.objectWithoutProperties(_z2, ["x"]);