Throw better errors for non-iterables when Symbol doesn't exist.

packages/babel-helpers/src/helpers.js

@@ -936,7 +936,7 @@ helpers.iterableToArray = helper("7.0.0-beta.0")`
     if (
       typeof iter === 'string'
       || Object.prototype.toString.call(iter) === "[object Arguments]"
-      || Symbol.iterator in Object(iter)
+      || (typeof Symbol !== "undefined" && Symbol.iterator in Object(iter))
     ) return Array.from(iter);
   }
 `;
@@ -952,9 +952,12 @@ helpers.iterableToArrayLimit = helper("7.0.0-beta.0")`
     // _e = _iteratorError
     // _i = _iterator
     // _s = _step
-    if (!(
-      Symbol.iterator in Object(arr) || Object.prototype.toString.call(arr) === "[object Arguments]"
-    )) { return }
+
+    if (
+      (typeof Symbol === "undefined" || !(Symbol.iterator in Object(arr))) &&
+      Object.prototype.toString.call(arr) !== "[object Arguments]"
+    ) return;
+
     var _arr = [];
     var _n = true;
     var _d = false;
@@ -980,9 +983,11 @@ helpers.iterableToArrayLimit = helper("7.0.0-beta.0")`
 
 helpers.iterableToArrayLimitLoose = helper("7.0.0-beta.0")`
   export default function _iterableToArrayLimitLoose(arr, i) {
-    if (!(
-      Symbol.iterator in Object(arr) || Object.prototype.toString.call(arr) === "[object Arguments]"
-    )) { return }
+    if (
+      (typeof Symbol === "undefined" || !(Symbol.iterator in Object(arr))) &&
+      Object.prototype.toString.call(arr) !== "[object Arguments]"
+    ) return;
+
     var _arr = [];
     for (var _iterator = arr[Symbol.iterator](), _step; !(_step = _iterator.next()).done;) {
       _arr.push(_step.value);
@@ -994,13 +999,17 @@ helpers.iterableToArrayLimitLoose = helper("7.0.0-beta.0")`
 
 helpers.nonIterableSpread = helper("7.0.0-beta.0")`
   export default function _nonIterableSpread() {
-    throw new TypeError("Invalid attempt to spread non-iterable instance");
+    throw new TypeError(
+      "Invalid attempt to spread non-iterable instance.\\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."
+    );
   }
 `;
 
 helpers.nonIterableRest = helper("7.0.0-beta.0")`
   export default function _nonIterableRest() {
-    throw new TypeError("Invalid attempt to destructure non-iterable instance");
+    throw new TypeError(
+      "Invalid attempt to destructure non-iterable instance.\\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."
+    );
   }
 `;
 

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/array-symbol-unsupported/exec.js

@@ -0,0 +1,13 @@
+var a = (() => [1, 2, 3])();
+
+// Simulate old environment
+let _Symbol = Symbol;
+Symbol = void 0;
+try {
+  var [first, ...rest] = a;
+
+  expect(first).toBe(1);
+  expect(rest).toEqual([2, 3]);
+} finally {
+  Symbol = _Symbol;
+}

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/array-symbol-unsupported/input.js

@@ -0,0 +1,6 @@
+var a = (() => [1, 2, 3])();
+
+// !!! In order to run this test, this shouldn't be optimized using type inference
+// If it's optimized and doesn't call toArray, please modify this test
+// and exec.js
+var [first, ...rest] = a;

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/array-symbol-unsupported/output.js

@@ -0,0 +1,8 @@
+var a = (() => [1, 2, 3])(); // !!! In order to run this test, this shouldn't be optimized using type inference
+// If it's optimized and doesn't call toArray, please modify this test
+// and exec.js
+
+
+var _a = babelHelpers.toArray(a),
+    first = _a[0],
+    rest = _a.slice(1);

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/non-iterable/exec.js

@@ -1,9 +1,22 @@
+var foo, bar;
+
 expect(
-  () => {
-    var [foo, bar] = undefined;
-  }).toThrow("Invalid attempt to destructure non-iterable instance");
+  () => [foo, bar] = undefined
+).toThrow(/destructure non-iterable/);
 
 expect(
-  () => {
-    var foo = [ ...undefined ];
-  }).toThrow("Invalid attempt to spread non-iterable instance");
+  () => [foo, bar] = {}
+).toThrow(/destructure non-iterable/);
+
+// Simulate old browser
+let _Symbol = Symbol;
+Symbol = void 0;
+try {
+
+  expect(
+    () => [foo, bar] = {}
+  ).toThrow(/destructure non-iterable/);
+
+} finally {
+  Symbol = _Symbol;
+}

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/non-iterable/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    "transform-destructuring"
+  ]
+}

packages/babel-plugin-transform-modules-commonjs/test/fixtures/regression/T7199/output.js

@@ -6,9 +6,9 @@ function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "d
 
 function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }
 
-function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }
+function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }
 
-function _iterableToArrayLimit(arr, i) { if (!(Symbol.iterator in Object(arr) || Object.prototype.toString.call(arr) === "[object Arguments]")) { return; } var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
+function _iterableToArrayLimit(arr, i) { if ((typeof Symbol === "undefined" || !(Symbol.iterator in Object(arr))) && Object.prototype.toString.call(arr) !== "[object Arguments]") return; var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
 
 function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }
 

packages/babel-plugin-transform-spread/test/fixtures/spread/array-symbol-unsupported/exec.js

@@ -0,0 +1,10 @@
+var a = (() => [2, 3])();
+
+// Simulate old environment
+let _Symbol = Symbol;
+Symbol = void 0;
+try {
+  expect([1, ...a]).toEqual([1, 2, 3]);
+} finally {
+  Symbol = _Symbol;
+}

packages/babel-plugin-transform-spread/test/fixtures/spread/array-symbol-unsupported/input.js

@@ -0,0 +1,6 @@
+var a = (() => [2, 3])();
+
+// !!! In order to run this test, this shouldn't be optimized using type inference
+// If it's optimized and doesn't call toConsumableArray, please modify this test
+// and exec.js
+[1, ...a];

packages/babel-plugin-transform-spread/test/fixtures/spread/array-symbol-unsupported/output.js

@@ -0,0 +1,6 @@
+var a = (() => [2, 3])(); // !!! In order to run this test, this shouldn't be optimized using type inference
+// If it's optimized and doesn't call toConsumableArray, please modify this test
+// and exec.js
+
+
+[1].concat(babelHelpers.toConsumableArray(a));

packages/babel-plugin-transform-spread/test/fixtures/spread/non-iterable/exec.js

@@ -0,0 +1,10 @@
+var o = {};
+
+expect(() => [...undefined]).toThrow(/spread non-iterable/);
+
+expect(() => [...o]).toThrow(/spread non-iterable/);
+
+// Simulate old browser
+Symbol = void 0;
+
+expect(() => [...o]).toThrow(/spread non-iterable/);

packages/babel-preset-env/test/fixtures/preset-options/browserslist-defaults-not-ie/output.js

@@ -2,9 +2,9 @@
 
 function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }
 
-function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }
+function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }
 
-function _iterableToArrayLimit(arr, i) { if (!(Symbol.iterator in Object(arr) || Object.prototype.toString.call(arr) === "[object Arguments]")) { return; } var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
+function _iterableToArrayLimit(arr, i) { if ((typeof Symbol === "undefined" || !(Symbol.iterator in Object(arr))) && Object.prototype.toString.call(arr) !== "[object Arguments]") return; var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
 
 function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }
 

packages/babel-preset-env/test/fixtures/sanity/block-scoping-for-of/output.js

@@ -1,8 +1,8 @@
 function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }
 
-function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }
+function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }
 
-function _iterableToArrayLimit(arr, i) { if (!(Symbol.iterator in Object(arr) || Object.prototype.toString.call(arr) === "[object Arguments]")) { return; } var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
+function _iterableToArrayLimit(arr, i) { if ((typeof Symbol === "undefined" || !(Symbol.iterator in Object(arr))) && Object.prototype.toString.call(arr) !== "[object Arguments]") return; var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }
 
 function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }
 

packages/babel-runtime-corejs2/helpers/esm/iterableToArray.js

@@ -1,5 +1,6 @@
 import _Array$from from "../../core-js/array/from";
 import _isIterable from "../../core-js/is-iterable";
+import _Symbol from "../../core-js/symbol";
 export default function _iterableToArray(iter) {
-  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || _isIterable(Object(iter))) return _Array$from(iter);
+  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || typeof _Symbol !== "undefined" && _isIterable(Object(iter))) return _Array$from(iter);
 }

packages/babel-runtime-corejs2/helpers/iterableToArray.js

@@ -2,8 +2,10 @@ var _Array$from = require("../core-js/array/from");
 
 var _isIterable = require("../core-js/is-iterable");
 
+var _Symbol = require("../core-js/symbol");
+
 function _iterableToArray(iter) {
-  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || _isIterable(Object(iter))) return _Array$from(iter);
+  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || typeof _Symbol !== "undefined" && _isIterable(Object(iter))) return _Array$from(iter);
 }
 
 module.exports = _iterableToArray;

packages/babel-runtime/helpers/esm/iterableToArray.js

@@ -1,3 +1,3 @@
 export default function _iterableToArray(iter) {
-  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || Symbol.iterator in Object(iter)) return Array.from(iter);
+  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || typeof Symbol !== "undefined" && Symbol.iterator in Object(iter)) return Array.from(iter);
 }

packages/babel-runtime/helpers/iterableToArray.js

@@ -1,5 +1,5 @@
 function _iterableToArray(iter) {
-  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || Symbol.iterator in Object(iter)) return Array.from(iter);
+  if (typeof iter === 'string' || Object.prototype.toString.call(iter) === "[object Arguments]" || typeof Symbol !== "undefined" && Symbol.iterator in Object(iter)) return Array.from(iter);
 }
 
 module.exports = _iterableToArray;