From 8b524f42b277762e20d68aa38d428fe895cf705b Mon Sep 17 00:00:00 2001
From: Zzzen <843968788@qq.com>
Date: Mon, 13 Apr 2020 00:23:11 +0800
Subject: [PATCH 1/4] Fix object spread runtime semantics

---
 .../src/index.js                              | 25 +++++++++++++++++--
 .../object-spread/expression/output.js        | 10 ++++----
 .../object-spread/side-effect/exec.js         |  4 +++
 .../object-spread/side-effect/input.js        |  2 ++
 .../object-spread/side-effect/output.js       | 16 ++++++++++++
 5 files changed, 50 insertions(+), 7 deletions(-)
 create mode 100644 packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/exec.js
 create mode 100644 packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js
 create mode 100644 packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js

diff --git a/packages/babel-plugin-proposal-object-rest-spread/src/index.js b/packages/babel-plugin-proposal-object-rest-spread/src/index.js
index 7c25ac399242..51df6bfb20ef 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/src/index.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/src/index.js
@@ -541,6 +541,7 @@ export default declare((api, opts) => {
       ObjectExpression(path, file) {
         if (!hasSpread(path.node)) return;
 
+        // a non-SpreadElement and SpreadElement striped array
         const args = [];
         let props = [];
 
@@ -579,8 +580,28 @@ export default declare((api, opts) => {
             helper = file.addHelper("objectSpread");
           }
         }
-
-        path.replaceWith(t.callExpression(helper, args));
+        // We cannot call _objectSpread with more than two elements directly, since any element could cause side effects. For
+        // example:
+        //      var k = { a: 1, b: 2 };
+        //      var o = { a: 3, ...k, b: k.a++ };
+        //      // expected: { a: 1, b: 1 }
+        // If we translate the above to `_objectSpread({ a: 3 }, k, { b: k.a++ })`, the `k.a++` will evaluate before
+        // `k` is spread and we end up with `{ a: 2, b: 1 }`.
+        // adapted from https://github.com/microsoft/TypeScript/blob/eb105efdcd6db8a73f5b983bf329cb7a5eee55e1/src/compiler/transformers/es2018.ts#L272
+        let exp = args[0];
+        for (let i = 1; i < args.length; i++) {
+          // reference: packages/babel-helpers/src/helpers.js#objectSpread2
+          if (i % 2) {
+            exp = t.callExpression(helper, [exp, args[i]]);
+          } else {
+            exp = t.callExpression(helper, [
+              exp,
+              t.objectExpression([]),
+              args[i],
+            ]);
+          }
+        }
+        path.replaceWith(exp);
       },
     },
   };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
index a172df60bd16..8f993eedf735 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
@@ -4,11 +4,11 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-_objectSpread({
+_objectSpread(_objectSpread(_objectSpread(_objectSpread({
   x
-}, y, {
+}, y), {}, {
   a
-}, b, {
+}), b), {}, {
   c
 });
 
@@ -18,9 +18,9 @@ _objectSpread({}, {
   foo: 'bar'
 });
 
-_objectSpread({}, {
+_objectSpread(_objectSpread(_objectSpread({}, {
   foo: 'bar'
-}, {}, {
+}), {}, {}), {
   bar: 'baz'
 });
 
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/exec.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/exec.js
new file mode 100644
index 000000000000..efb73e7a98ca
--- /dev/null
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/exec.js
@@ -0,0 +1,4 @@
+var k = { a: 1, b: 2 };
+var o = { a: 3, ...k, b: k.a++ };
+
+expect(o).toEqual({a: 1, b: 1});
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js
new file mode 100644
index 000000000000..2a39f42f62cf
--- /dev/null
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js
@@ -0,0 +1,2 @@
+var k = { a: 1, b: 2 };
+var o = { a: 3, ...k, b: k.a++ };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js
new file mode 100644
index 000000000000..d23ec370de81
--- /dev/null
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js
@@ -0,0 +1,16 @@
+function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); if (enumerableOnly) symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; }); keys.push.apply(keys, symbols); } return keys; }
+
+function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; if (i % 2) { ownKeys(Object(source), true).forEach(function (key) { _defineProperty(target, key, source[key]); }); } else if (Object.getOwnPropertyDescriptors) { Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); } else { ownKeys(Object(source)).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } } return target; }
+
+function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
+
+var k = {
+  a: 1,
+  b: 2
+};
+
+var o = _objectSpread(_objectSpread({
+  a: 3
+}, k), {}, {
+  b: k.a++
+});

From 032a7640a812e2c1a5112c4c132636709893c567 Mon Sep 17 00:00:00 2001
From: Zzzen <843968788@qq.com>
Date: Fri, 17 Apr 2020 00:08:43 +0800
Subject: [PATCH 2/4] limit this deoptimization

---
 .../src/index.js                              | 32 ++++++++++++++++---
 .../object-spread/assignment/output.js        |  6 ++--
 .../object-spread/expression/output.js        | 12 +++----
 .../loose-mode-builtins/output.js             |  6 ++--
 .../object-spread/loose-mode/output.js        |  6 ++--
 .../object-spread/side-effect/input.js        | 14 ++++++++
 .../object-spread/side-effect/output.js       | 23 +++++++++++++
 .../variable-declaration/output.js            |  2 +-
 8 files changed, 80 insertions(+), 21 deletions(-)

diff --git a/packages/babel-plugin-proposal-object-rest-spread/src/index.js b/packages/babel-plugin-proposal-object-rest-spread/src/index.js
index 51df6bfb20ef..63e3d3e5296a 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/src/index.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/src/index.js
@@ -541,6 +541,8 @@ export default declare((api, opts) => {
       ObjectExpression(path, file) {
         if (!hasSpread(path.node)) return;
 
+        const { scope } = path;
+
         // a non-SpreadElement and SpreadElement striped array
         const args = [];
         let props = [];
@@ -588,19 +590,39 @@ export default declare((api, opts) => {
         // If we translate the above to `_objectSpread({ a: 3 }, k, { b: k.a++ })`, the `k.a++` will evaluate before
         // `k` is spread and we end up with `{ a: 2, b: 1 }`.
         // adapted from https://github.com/microsoft/TypeScript/blob/eb105efdcd6db8a73f5b983bf329cb7a5eee55e1/src/compiler/transformers/es2018.ts#L272
-        let exp = args[0];
-        for (let i = 1; i < args.length; i++) {
+        const chunks = [];
+        let currentChunk = [];
+        for (let i = 0; i < args.length; i++) {
+          currentChunk.push(args[i]);
+          // prevent current chunk from pollution
+          if (i < args.length - 1 && !scope.isPure(args[i + 1])) {
+            chunks.push(currentChunk);
+            currentChunk = [];
+          }
+        }
+
+        if (currentChunk.length) {
+          chunks.push(currentChunk);
+          currentChunk = [];
+        }
+
+        let exp = t.callExpression(helper, chunks[0]);
+        let nthArg = chunks[0].length;
+        for (let i = 1; i < chunks.length; i++) {
           // reference: packages/babel-helpers/src/helpers.js#objectSpread2
-          if (i % 2) {
-            exp = t.callExpression(helper, [exp, args[i]]);
+          if (nthArg % 2) {
+            exp = t.callExpression(helper, [exp, ...chunks[i]]);
           } else {
             exp = t.callExpression(helper, [
               exp,
               t.objectExpression([]),
-              args[i],
+              ...chunks[i],
             ]);
           }
+
+          nthArg += chunks[i].length;
         }
+
         path.replaceWith(exp);
       },
     },
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
index a1f2970a3264..59230da9dac1 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
@@ -4,10 +4,10 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-z = _objectSpread({
+z = _objectSpread(_objectSpread({
   x
-}, y);
+}), y);
 z = {
   x,
-  w: _objectSpread({}, y)
+  w: _objectSpread(_objectSpread({}), y)
 };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
index 8f993eedf735..52727e0506ca 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
@@ -4,27 +4,27 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-_objectSpread(_objectSpread(_objectSpread(_objectSpread({
+_objectSpread(_objectSpread(_objectSpread(_objectSpread(_objectSpread({
   x
-}, y), {}, {
+}), y), {}, {
   a
 }), b), {}, {
   c
 });
 
-_objectSpread({}, Object.prototype);
+_objectSpread(_objectSpread({}), Object.prototype);
 
 _objectSpread({}, {
   foo: 'bar'
 });
 
-_objectSpread(_objectSpread(_objectSpread({}, {
+_objectSpread({}, {
   foo: 'bar'
-}), {}, {}), {
+}, {}, {
   bar: 'baz'
 });
 
-_objectSpread({}, {
+_objectSpread(_objectSpread({}), {
   get foo() {
     return 'foo';
   }
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
index 457fa6a6069d..09f770b930a7 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
@@ -1,7 +1,7 @@
-z = Object.assign({
+z = Object.assign(Object.assign({
   x
-}, y);
+}), y);
 z = {
   x,
-  w: Object.assign({}, y)
+  w: Object.assign(Object.assign({}), y)
 };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
index 1d477e3f1bb8..ce56f3ffa659 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
@@ -2,12 +2,12 @@ function _objectWithoutPropertiesLoose(source, excluded) { if (source == null) r
 
 function _extends() { _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; }; return _extends.apply(this, arguments); }
 
-z = _extends({
+z = _extends(_extends({
   x
-}, y);
+}), y);
 z = {
   x,
-  w: _extends({}, y)
+  w: _extends(_extends({}), y)
 };
 
 const rest = _objectWithoutPropertiesLoose(z, ["q"]);
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js
index 2a39f42f62cf..f2c856b9fcd4 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/input.js
@@ -1,2 +1,16 @@
 var k = { a: 1, b: 2 };
 var o = { a: 3, ...k, b: k.a++ };
+
+var pureA = {};
+var pureB = {};
+var pureC = {};
+var pureD = {};
+var pureE = {};
+
+function impureFunc() {
+  console.log('hello')
+}
+
+var output = { ...pureA, get foo() {}, get bar() {}, ...pureB, ...pureC, ...impureFunc(), ...pureD, pureD }
+
+var simpleOutput = { ...pureA, test: '1', ...pureB,  }
\ No newline at end of file
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js
index d23ec370de81..19ec3bc08cbe 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/side-effect/output.js
@@ -14,3 +14,26 @@ var o = _objectSpread(_objectSpread({
 }, k), {}, {
   b: k.a++
 });
+
+var pureA = {};
+var pureB = {};
+var pureC = {};
+var pureD = {};
+var pureE = {};
+
+function impureFunc() {
+  console.log('hello');
+}
+
+var output = _objectSpread(_objectSpread(_objectSpread({}, pureA), {}, {
+  get foo() {},
+
+  get bar() {}
+
+}, pureB, {}, pureC, {}), impureFunc(), {}, pureD, {
+  pureD
+});
+
+var simpleOutput = _objectSpread({}, pureA, {
+  test: '1'
+}, pureB);
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js
index 9fabf3047b3d..72cd13228ca6 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js
@@ -4,4 +4,4 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-var z = _objectSpread({}, x);
+var z = _objectSpread(_objectSpread({}), x);

From 8356f4a95f90e2180da1578debb013f1caa38222 Mon Sep 17 00:00:00 2001
From: Zzzen <843968788@qq.com>
Date: Sat, 18 Apr 2020 12:44:18 +0800
Subject: [PATCH 3/4] optimize empty objects

---
 .../src/index.js                                       | 10 ++++++++--
 .../test/fixtures/object-spread/assignment/output.js   |  2 +-
 .../test/fixtures/object-spread/expression/output.js   |  4 ++--
 .../object-spread/loose-mode-builtins/output.js        |  2 +-
 .../test/fixtures/object-spread/loose-mode/output.js   |  2 +-
 .../object-spread/variable-declaration/output.js       |  2 +-
 6 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/packages/babel-plugin-proposal-object-rest-spread/src/index.js b/packages/babel-plugin-proposal-object-rest-spread/src/index.js
index 63e3d3e5296a..5899233567c4 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/src/index.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/src/index.js
@@ -594,8 +594,14 @@ export default declare((api, opts) => {
         let currentChunk = [];
         for (let i = 0; i < args.length; i++) {
           currentChunk.push(args[i]);
-          // prevent current chunk from pollution
-          if (i < args.length - 1 && !scope.isPure(args[i + 1])) {
+          const isCurrentChunkEmptyObject =
+            currentChunk.length === 1 &&
+            t.isObjectExpression(args[i]) &&
+            args[i].properties.length === 0;
+          const isNextArgEffectful =
+            i < args.length - 1 && !scope.isPure(args[i + 1]);
+          // prevent current chunk from pollution unless current chunk is an empty object
+          if (!isCurrentChunkEmptyObject && isNextArgEffectful) {
             chunks.push(currentChunk);
             currentChunk = [];
           }
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
index 59230da9dac1..32a2109c8164 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
@@ -9,5 +9,5 @@ z = _objectSpread(_objectSpread({
 }), y);
 z = {
   x,
-  w: _objectSpread(_objectSpread({}), y)
+  w: _objectSpread({}, y)
 };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
index 52727e0506ca..c9c21e4d9abc 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
@@ -12,7 +12,7 @@ _objectSpread(_objectSpread(_objectSpread(_objectSpread(_objectSpread({
   c
 });
 
-_objectSpread(_objectSpread({}), Object.prototype);
+_objectSpread({}, Object.prototype);
 
 _objectSpread({}, {
   foo: 'bar'
@@ -24,7 +24,7 @@ _objectSpread({}, {
   bar: 'baz'
 });
 
-_objectSpread(_objectSpread({}), {
+_objectSpread({}, {
   get foo() {
     return 'foo';
   }
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
index 09f770b930a7..cc2b1d128d61 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
@@ -3,5 +3,5 @@ z = Object.assign(Object.assign({
 }), y);
 z = {
   x,
-  w: Object.assign(Object.assign({}), y)
+  w: Object.assign({}, y)
 };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
index ce56f3ffa659..a8b3fba4d12b 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
@@ -7,7 +7,7 @@ z = _extends(_extends({
 }), y);
 z = {
   x,
-  w: _extends(_extends({}), y)
+  w: _extends({}, y)
 };
 
 const rest = _objectWithoutPropertiesLoose(z, ["q"]);
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js
index 72cd13228ca6..9fabf3047b3d 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/variable-declaration/output.js
@@ -4,4 +4,4 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-var z = _objectSpread(_objectSpread({}), x);
+var z = _objectSpread({}, x);

From ed8067d576fd60befc34fb292ea6fdcdc323b1bd Mon Sep 17 00:00:00 2001
From: Zzzen <843968788@qq.com>
Date: Sat, 18 Apr 2020 16:56:15 +0800
Subject: [PATCH 4/4] declare variables

---
 .../test/fixtures/object-spread/assignment/input.js |  4 ++++
 .../fixtures/object-spread/assignment/output.js     |  7 +++++--
 .../test/fixtures/object-spread/expression/input.js |  7 +++++++
 .../fixtures/object-spread/expression/output.js     | 13 ++++++++++---
 .../object-spread/loose-mode-builtins/input.js      |  4 ++++
 .../object-spread/loose-mode-builtins/output.js     |  7 +++++--
 .../test/fixtures/object-spread/loose-mode/input.js |  4 ++++
 .../fixtures/object-spread/loose-mode/output.js     |  7 +++++--
 8 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/input.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/input.js
index 6f0367fb7c70..093a8e9f9351 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/input.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/input.js
@@ -1,3 +1,7 @@
+var x;
+var y;
+var z;
+
 z = { x, ...y };
 
 z = { x, w: { ...y } };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
index 32a2109c8164..9f13316b8658 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/assignment/output.js
@@ -4,9 +4,12 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-z = _objectSpread(_objectSpread({
+var x;
+var y;
+var z;
+z = _objectSpread({
   x
-}), y);
+}, y);
 z = {
   x,
   w: _objectSpread({}, y)
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/input.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/input.js
index a20f61241b3c..da4e7b689505 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/input.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/input.js
@@ -1,3 +1,10 @@
+var a;
+var b;
+var c;
+var d;
+var x;
+var y;
+
 ({ x, ...y, a, ...b, c });
 
 ({ ...Object.prototype });
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
index c9c21e4d9abc..b846f4badffe 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/expression/output.js
@@ -4,11 +4,18 @@ function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { va
 
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
 
-_objectSpread(_objectSpread(_objectSpread(_objectSpread(_objectSpread({
+var a;
+var b;
+var c;
+var d;
+var x;
+var y;
+
+_objectSpread({
   x
-}), y), {}, {
+}, y, {
   a
-}), b), {}, {
+}, b, {
   c
 });
 
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/input.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/input.js
index 6f0367fb7c70..093a8e9f9351 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/input.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/input.js
@@ -1,3 +1,7 @@
+var x;
+var y;
+var z;
+
 z = { x, ...y };
 
 z = { x, w: { ...y } };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
index cc2b1d128d61..8e9602898ed6 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode-builtins/output.js
@@ -1,6 +1,9 @@
-z = Object.assign(Object.assign({
+var x;
+var y;
+var z;
+z = Object.assign({
   x
-}), y);
+}, y);
 z = {
   x,
   w: Object.assign({}, y)
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/input.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/input.js
index 07beed075a6c..f05d6d6b8917 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/input.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/input.js
@@ -1,3 +1,7 @@
+var x;
+var y;
+var z;
+
 z = { x, ...y };
 
 z = { x, w: { ...y } };
diff --git a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
index a8b3fba4d12b..d33583d41054 100644
--- a/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
+++ b/packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js
@@ -2,9 +2,12 @@ function _objectWithoutPropertiesLoose(source, excluded) { if (source == null) r
 
 function _extends() { _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; }; return _extends.apply(this, arguments); }
 
-z = _extends(_extends({
+var x;
+var y;
+var z;
+z = _extends({
   x
-}), y);
+}, y);
 z = {
   x,
   w: _extends({}, y)