Use single object spread call in loose mode

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

@@ -579,6 +579,16 @@ export default declare((api, opts) => {
             return;
           }
 
+          // In loose mode, we don't want to make multiple calls. We're assuming
+          // that the spread objects either don't use getters, or that the
+          // getters are pure and don't depend on the order of evaluation.
+          if (loose) {
+            if (hadProps) {
+              exp.arguments.push(obj);
+            }
+            return;
+          }
+
           exp = t.callExpression(t.cloneNode(helper), [
             exp,
             // If we have static props, we need to insert an empty object

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/expression/exec.js

@@ -0,0 +1,9 @@
+var log = [];
+
+var a = {
+  ...{ get foo() { log.push(1); } },
+  get bar() { log.push(2); }
+};
+
+// Loose mode uses regular Get, not GetOwnProperty.
+expect(log).toEqual([1, 2]);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/expression/input.js

@@ -0,0 +1,16 @@
+var a;
+var b;
+var c;
+var d;
+var x;
+var y;
+
+({ x, ...y, a, ...b, c });
+
+({ ...Object.prototype });
+
+({ ...{ foo: 'bar' } });
+
+({ ...{ foo: 'bar' }, ...{ bar: 'baz' } });
+
+({ ...{ get foo () { return 'foo' } } });

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/expression/output.js

@@ -0,0 +1,28 @@
+var a;
+var b;
+var c;
+var d;
+var x;
+var y;
+Object.assign({
+  x
+}, y, {
+  a
+}, b, {
+  c
+});
+Object.assign({}, Object.prototype);
+Object.assign({}, {
+  foo: 'bar'
+});
+Object.assign({}, {
+  foo: 'bar'
+}, {
+  bar: 'baz'
+});
+Object.assign({}, {
+  get foo() {
+    return 'foo';
+  }
+
+});

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/no-getOwnPropertyDescriptors/exec.js

@@ -0,0 +1,8 @@
+const oldGOPDs = Object.getOwnPropertyDescriptors;
+Object.getOwnPropertyDescriptors = null;
+
+try {
+  ({ ...{ a: 1 }, b: 1, ...{} });
+} finally {
+  Object.getOwnPropertyDescriptors = oldGOPDs;
+}

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/no-object-assign-exec/exec.js

@@ -0,0 +1,46 @@
+"use strict";
+const NOSET = `NOSET${__filename}`;
+const NOWRITE = `NOWRITE${__filename}`;
+
+Object.defineProperty(Object.prototype, NOSET, {
+  get(value) {
+    // noop
+  },
+});
+
+Object.defineProperty(Object.prototype, NOWRITE, {
+  writable: false,
+  value: 'abc',
+});
+
+const obj = { [NOSET]: 123 };
+// this won't work as expected if transformed as Object.assign (or equivalent)
+// because those trigger object setters (spread don't)
+expect(() => {
+  const objSpread = { ...obj };
+}).toThrow();
+
+const obj2 = { [NOWRITE]: 456 };
+// this throws  `TypeError: Cannot assign to read only property 'NOWRITE'`
+// if transformed as Object.assign (or equivalent) because those use *assignment* for creating properties
+// (spread defines them)
+expect(() => {
+  const obj2Spread = { ...obj2 };
+}).toThrow();
+
+const KEY = Symbol('key');
+const obj3Spread = { ...{ get foo () { return 'bar' } }, [KEY]: 'symbol' };
+expect(Object.getOwnPropertyDescriptor(obj3Spread, 'foo').value).toBe('bar');
+expect(Object.getOwnPropertyDescriptor(obj3Spread, KEY).value).toBe('symbol');
+
+const obj4Spread = { ...Object.prototype };
+expect(Object.getOwnPropertyDescriptor(obj4Spread, 'hasOwnProperty')).toBeUndefined();
+
+expect(() => ({ ...null, ...undefined })).not.toThrow();
+
+const o = Object.create(null);
+o.a = 'foo';
+o.__proto__ = [];
+const o2 = { ...o };
+// Loose will do o2.__proto__ = []
+expect(Array.isArray(Object.getPrototypeOf(o2))).toBe(true);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/side-effect/exec.js

@@ -0,0 +1,12 @@
+var k = { a: 1, b: 2 };
+var o = { a: 3, ...k, b: k.a++ };
+// Loose will evaluate the static `b: k.a++` before spreading `...k`.
+// It should be {a: 1, b: 1}
+expect(o).toEqual({a: 2, b: 1});
+
+var k = { a: 1, get b() { l = { z: 9 }; return 2; } };
+var l = { c: 3 };
+var o = { ...k, ...l };
+// Loose will evaluate the `l` before spreading `...k`.
+// It should be {a: 1, b: 2, z: 9}
+expect(o).toEqual({ a: 1, b: 2, c: 3 });

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/side-effect/input.js

@@ -0,0 +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,  }

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/side-effect/output.js

@@ -0,0 +1,30 @@
+var k = {
+  a: 1,
+  b: 2
+};
+var o = Object.assign({
+  a: 3
+}, k, {
+  b: k.a++
+});
+var pureA = {};
+var pureB = {};
+var pureC = {};
+var pureD = {};
+var pureE = {};
+
+function impureFunc() {
+  console.log('hello');
+}
+
+var output = Object.assign({}, pureA, {
+  get foo() {},
+
+  get bar() {}
+
+}, pureB, pureC, impureFunc(), pureD, {
+  pureD
+});
+var simpleOutput = Object.assign({}, pureA, {
+  test: '1'
+}, pureB);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/string-exec/exec.js

@@ -0,0 +1,3 @@
+expect([...'']).toHaveLength(0);
+expect([...'abc']).toHaveLength(3);
+expect([...'def']).toMatchObject(['d','e','f']);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/variable-declaration/input.js

@@ -0,0 +1 @@
+var z = { ...x };

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose-builtins/variable-declaration/output.js

@@ -0,0 +1 @@
+var z = Object.assign({}, x);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/input.js → packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/assignment/input.js

@@ -5,5 +5,3 @@ var z;
 z = { x, ...y };
 
 z = { x, w: { ...y } };
-
-const { q, ...rest } = z;

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/loose-mode/output.js → packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/assignment/output.js

@@ -1,5 +1,3 @@
-function _objectWithoutPropertiesLoose(source, excluded) { if (source == null) return {}; var target = {}; var sourceKeys = Object.keys(source); var key, i; for (i = 0; i < sourceKeys.length; i++) { key = sourceKeys[i]; if (excluded.indexOf(key) >= 0) continue; target[key] = source[key]; } return target; }
-
 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); }
 
 var x;
@@ -12,5 +10,3 @@ z = {
   x,
   w: _extends({}, y)
 };
-
-const rest = _objectWithoutPropertiesLoose(z, ["q"]);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/expression/exec.js

@@ -0,0 +1,9 @@
+var log = [];
+
+var a = {
+  ...{ get foo() { log.push(1); } },
+  get bar() { log.push(2); }
+};
+
+// Loose mode uses regular Get, not GetOwnProperty.
+expect(log).toEqual([1, 2]);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/expression/input.js

@@ -0,0 +1,16 @@
+var a;
+var b;
+var c;
+var d;
+var x;
+var y;
+
+({ x, ...y, a, ...b, c });
+
+({ ...Object.prototype });
+
+({ ...{ foo: 'bar' } });
+
+({ ...{ foo: 'bar' }, ...{ bar: 'baz' } });
+
+({ ...{ get foo () { return 'foo' } } });

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

@@ -0,0 +1,35 @@
+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); }
+
+var a;
+var b;
+var c;
+var d;
+var x;
+var y;
+
+_extends({
+  x
+}, y, {
+  a
+}, b, {
+  c
+});
+
+_extends({}, Object.prototype);
+
+_extends({}, {
+  foo: 'bar'
+});
+
+_extends({}, {
+  foo: 'bar'
+}, {
+  bar: 'baz'
+});
+
+_extends({}, {
+  get foo() {
+    return 'foo';
+  }
+
+});

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/no-getOwnPropertyDescriptors/exec.js

@@ -0,0 +1,9 @@
+const oldGOPDs = Object.getOwnPropertyDescriptors;
+Object.getOwnPropertyDescriptors = null;
+
+try {
+  ({ ...{ a: 1 }, b: 1, ...{} });
+} finally {
+  Object.getOwnPropertyDescriptors = oldGOPDs;
+}
+

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/no-object-assign-exec/exec.js

@@ -0,0 +1,46 @@
+"use strict";
+const NOSET = `NOSET${__filename}`;
+const NOWRITE = `NOWRITE${__filename}`;
+
+Object.defineProperty(Object.prototype, NOSET, {
+  get(value) {
+    // noop
+  },
+});
+
+Object.defineProperty(Object.prototype, NOWRITE, {
+  writable: false,
+  value: 'abc',
+});
+
+const obj = { [NOSET]: 123 };
+// this won't work as expected if transformed as Object.assign (or equivalent)
+// because those trigger object setters (spread don't)
+expect(() => {
+  const objSpread = { ...obj };
+}).toThrow();
+
+const obj2 = { [NOWRITE]: 456 };
+// this throws  `TypeError: Cannot assign to read only property 'NOWRITE'`
+// if transformed as Object.assign (or equivalent) because those use *assignment* for creating properties
+// (spread defines them)
+expect(() => {
+  const obj2Spread = { ...obj2 };
+}).toThrow();
+
+const KEY = Symbol('key');
+const obj3Spread = { ...{ get foo () { return 'bar' } }, [KEY]: 'symbol' };
+expect(Object.getOwnPropertyDescriptor(obj3Spread, 'foo').value).toBe('bar');
+expect(Object.getOwnPropertyDescriptor(obj3Spread, KEY).value).toBe('symbol');
+
+const obj4Spread = { ...Object.prototype };
+expect(Object.getOwnPropertyDescriptor(obj4Spread, 'hasOwnProperty')).toBeUndefined();
+
+expect(() => ({ ...null, ...undefined })).not.toThrow();
+
+const o = Object.create(null);
+o.a = 'foo';
+o.__proto__ = [];
+const o2 = { ...o };
+// Loose will do o2.__proto__ = []
+expect(Array.isArray(Object.getPrototypeOf(o2))).toBe(true);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    ["proposal-object-rest-spread", { "loose": true }]
+  ]
+}

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/side-effect/exec.js

@@ -0,0 +1,12 @@
+var k = { a: 1, b: 2 };
+var o = { a: 3, ...k, b: k.a++ };
+// Loose will evaluate the static `b: k.a++` before spreading `...k`.
+// It should be {a: 1, b: 1}
+expect(o).toEqual({a: 2, b: 1});
+
+var k = { a: 1, get b() { l = { z: 9 }; return 2; } };
+var l = { c: 3 };
+var o = { ...k, ...l };
+// Loose will evaluate the `l` before spreading `...k`.
+// It should be {a: 1, b: 2, z: 9}
+expect(o).toEqual({ a: 1, b: 2, c: 3 });

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread-loose/side-effect/input.js

@@ -0,0 +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,  }