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

packages/babel-plugin-proposal-object-rest-spread/README.md

@@ -71,8 +71,7 @@ For detailed information please check out [Spread VS. Object.assign](http://2ali
 
 `boolean`, defaults to `false`.
 
-Enabling this option will use `Object.assign` directly instead of the Babel's `extends` helper. Keep in mind that this flag only applies when `loose: true`.
+Enabling this option will use `Object.assign` directly instead of the Babel's `extends` helper. 
-
 
 ##### Example
 

packages/babel-plugin-proposal-object-rest-spread/src/index.js

@@ -11,6 +11,12 @@ export default declare((api, opts) => {
     throw new Error(".loose must be a boolean, or undefined");
   }
 
+  function getExtendsHelper(file) {
+    return useBuiltIns
+      ? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
+      : file.addHelper("extends");
+  }
+
   function hasRestElement(path) {
     let foundRestElement = false;
     visitRestElements(path, () => {
@@ -97,6 +103,17 @@ export default declare((api, opts) => {
     const impureComputedPropertyDeclarators = replaceImpureComputedKeys(path);
     const { keys, allLiteral } = extractNormalizedKeys(path);
 
+    if (keys.length === 0) {
+      return [
+        impureComputedPropertyDeclarators,
+        restElement.argument,
+        t.callExpression(getExtendsHelper(file), [
+          t.objectExpression([]),
+          t.cloneNode(objRef),
+        ]),
+      ];
+    }
+
     let keyExpression;
     if (!allLiteral) {
       // map to toPropertyKey to handle the possible non-string values
@@ -396,9 +413,7 @@ export default declare((api, opts) => {
 
         let helper;
         if (loose) {
-          helper = useBuiltIns
+          helper = getExtendsHelper(file);
-            ? t.memberExpression(t.identifier("Object"), t.identifier("assign"))
-            : file.addHelper("extends");
         } else {
           helper = file.addHelper("objectSpread");
         }

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/catch-clause/output.js

@@ -1,5 +1,5 @@
 try {} catch (_ref) {
-  let a34 = babelHelpers.objectWithoutProperties(_ref, []);
+  let a34 = babelHelpers.extends({}, _ref);
 }
 
 try {} catch (_ref2) {

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/duplicate-decl-bug/output.js

@@ -3,5 +3,5 @@ it("es7.objectRestSpread", () => {
     a: 1,
     b: 2
   };
-  let copy = babelHelpers.objectWithoutProperties(original, []);
+  let copy = babelHelpers.extends({}, original);
 });

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/nested-computed-key/output.js

@@ -2,8 +2,8 @@ var _ref2;
 
 const {
   [(_ref) => {
-    let rest = babelHelpers.objectWithoutProperties(_ref, []);
+    let rest = babelHelpers.extends({}, _ref);
-    let b = babelHelpers.objectWithoutProperties({}, []);
+    let b = babelHelpers.extends({}, {});
   }]: a,
-  [(_ref2 = {}, ({} = _ref2), d = babelHelpers.objectWithoutProperties(_ref2, []), _ref2)]: c
+  [(_ref2 = {}, ({} = _ref2), d = babelHelpers.extends({}, _ref2), _ref2)]: c
 } = {};

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/nested-default-value/output.js

@@ -2,8 +2,8 @@ var _ref2;
 
 const {
   a = (_ref) => {
-    let rest = babelHelpers.objectWithoutProperties(_ref, []);
+    let rest = babelHelpers.extends({}, _ref);
-    let b = babelHelpers.objectWithoutProperties({}, []);
+    let b = babelHelpers.extends({}, {});
   },
-  c = (_ref2 = {}, ({} = _ref2), d = babelHelpers.objectWithoutProperties(_ref2, []), _ref2)
+  c = (_ref2 = {}, ({} = _ref2), d = babelHelpers.extends({}, _ref2), _ref2)
 } = {};

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/nested-order/output.js

@@ -1,3 +1,3 @@
-const bar = babelHelpers.objectWithoutProperties(obj.a, []),
+const bar = babelHelpers.extends({}, obj.a),
-      baz = babelHelpers.objectWithoutProperties(obj.b, []),
+      baz = babelHelpers.extends({}, obj.b),
-      foo = babelHelpers.objectWithoutProperties(obj, []);
+      foo = babelHelpers.extends({}, obj);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/parameters/output.js

@@ -1,5 +1,5 @@
 function a(_ref) {
-  let a34 = babelHelpers.objectWithoutProperties(_ref, []);
+  let a34 = babelHelpers.extends({}, _ref);
 }
 
 function a2(_ref2) {
@@ -57,7 +57,7 @@ function a7(_ref8 = {}) {
 }
 
 function a8([_ref9]) {
-  let a1 = babelHelpers.objectWithoutProperties(_ref9, []);
+  let a1 = babelHelpers.extends({}, _ref9);
 }
 
 function a9([_ref10]) {
@@ -68,7 +68,7 @@ function a9([_ref10]) {
 }
 
 function a10([a1, _ref11]) {
-  let a2 = babelHelpers.objectWithoutProperties(_ref11, []);
+  let a2 = babelHelpers.extends({}, _ref11);
 } // Unchanged
 
 

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/variable-destructuring/output.js

@@ -1,10 +1,10 @@
 var z = {};
-var x = babelHelpers.objectWithoutProperties(z, []);
+var x = babelHelpers.extends({}, z);
-var a = babelHelpers.objectWithoutProperties({
+var a = babelHelpers.extends({}, {
   a: 1
-}, []);
+});
-var x = babelHelpers.objectWithoutProperties(a.b, []);
+var x = babelHelpers.extends({}, a.b);
-var x = babelHelpers.objectWithoutProperties(a(), []);
+var x = babelHelpers.extends({}, a());
 var {
   x1
 } = z,
@@ -36,7 +36,7 @@ let {
   }
 } = complex,
     asdf = babelHelpers.objectWithoutProperties(complex.x, ["a", d].map(babelHelpers.toPropertyKey)),
-    d = babelHelpers.objectWithoutProperties(complex.y, []),
+    d = babelHelpers.extends({}, complex.y),
     g = babelHelpers.objectWithoutProperties(complex, ["x"]);
 let {} = z,
-    y4 = babelHelpers.objectWithoutProperties(z.x4, []);
+    y4 = babelHelpers.extends({}, z.x4);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/regression/T7178/output.js

@@ -5,6 +5,6 @@ var _props = babelHelpers.interopRequireDefault(require("props"));
 console.log(_props.default);
 
 (function () {
-  const props = babelHelpers.objectWithoutProperties(this.props, []);
+  const props = babelHelpers.extends({}, this.props);
   console.log(props);
 })();

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/regression/gh-5151/output.js

@@ -3,7 +3,7 @@ const {
 } = a,
       y = babelHelpers.objectWithoutProperties(a, ["x"]),
       z = foo(y);
-const s = babelHelpers.objectWithoutProperties(r, []),
+const s = babelHelpers.extends({}, r),
       t = foo(s); // ordering is preserved
 
 var l = foo(),

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/regression/gh-7304/output.js

@@ -7,7 +7,7 @@ exports.default = void 0;
 
 class _default {
   method(_ref) {
-    let object = babelHelpers.objectWithoutProperties(_ref, []);
+    let object = Object.assign({}, _ref);
   }
 
 }

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"]);