Merge pull request #66 from janekptacijarabaci/js_iterable_closures_1

 Close iterator after error in: Map, Set, WeakMap, WeakSet, Array.from, Promise.{all,race}

13 files changed, 851 insertions, 37 deletions

diff --git a/js/src/builtin/Array.js b/js/src/builtin/Array.js
index 54b47b72f..5ab0b71be 100644
--- a/js/src/builtin/Array.js
+++ b/js/src/builtin/Array.js
@@ -784,7 +784,7 @@ function ArrayKeys() {
     return CreateArrayIterator(this, ITEM_KIND_KEY);
 }
 
-// ES6 draft rev31 (2015/01/15) 22.1.2.1 Array.from(source[, mapfn[, thisArg]]).
+// ES 2017 draft 0f10dba4ad18de92d47d421f378233a2eae8f077 22.1.2.1
 function ArrayFrom(items, mapfn=undefined, thisArg=undefined) {
     // Step 1.
     var C = this;
@@ -795,43 +795,61 @@ function ArrayFrom(items, mapfn=undefined, thisArg=undefined) {
         ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(1, mapfn));
     var T = thisArg;
 
-    // Steps 4-5.
+    // Step 4.
     var usingIterator = GetMethod(items, std_iterator);
 
-    // Step 6.
+    // Step 5.
     if (usingIterator !== undefined) {
-        // Steps 6.a-c.
+        // Steps 5.a-c.
         var A = IsConstructor(C) ? new C() : [];
 
-        // Steps 6.d-e.
+        // Step 5.c.
         var iterator = GetIterator(items, usingIterator);
 
-        // Step 6.f.
+        // Step 5.d.
         var k = 0;
 
-        // Step 6.g.
+        // Step 5.e.
         // These steps cannot be implemented using a for-of loop.
         // See <https://bugs.ecmascript.org/show_bug.cgi?id=2883>.
         while (true) {
-            // Steps 6.g.i-iii.
+            // Step 5.e.i.
+            // Disabled for performance reason.  We won't hit this case on
+            // normal array, since _DefineDataProperty will throw before it.
+            // We could hit this when |A| is a proxy and it ignores
+            // |_DefineDataProperty|, but it happens only after too long loop.
+            /*
+            if (k >= 0x1fffffffffffff) {
+                IteratorCloseThrow(iterator);
+                ThrowTypeError(JSMSG_TOO_LONG_ARRAY);
+            }
+            */
+
+            // Step 5.e.iii.
             var next = callContentFunction(iterator.next, iterator);
             if (!IsObject(next))
                 ThrowTypeError(JSMSG_NEXT_RETURNED_PRIMITIVE);
 
-            // Step 6.g.iv.
+            // Step 5.e.iv.
             if (next.done) {
                 A.length = k;
                 return A;
             }
 
-            // Steps 6.g.v-vi.
+            // Steps 5.e.v.
             var nextValue = next.value;
 
-            // Steps 6.g.vii-viii.
-            var mappedValue = mapping ? callContentFunction(mapfn, thisArg, nextValue, k) : nextValue;
+            // Steps 5.e.vi-vii.
+            try {
+                var mappedValue = mapping ? callContentFunction(mapfn, thisArg, nextValue, k) : nextValue;
 
-            // Steps 6.g.ix-xi.
-            _DefineDataProperty(A, k++, mappedValue);
+                // Steps 5.e.ii (reordered), 5.e.viii.
+                _DefineDataProperty(A, k++, mappedValue);
+            } catch (e) {
+                // Steps 5.e.vi.2, 5.e.ix.
+                IteratorCloseThrow(iterator);
+                throw e;
+            }
         }
     }
 
diff --git a/js/src/builtin/Map.js b/js/src/builtin/Map.js
index 432364614..27a12bfff 100644
--- a/js/src/builtin/Map.js
+++ b/js/src/builtin/Map.js
@@ -40,11 +40,18 @@ function MapConstructorInit(iterable) {
         var nextItem = next.value;
 
         // Step 8.d.
-        if (!IsObject(nextItem))
+        if (!IsObject(nextItem)) {
+            IteratorCloseThrow(iter);
             ThrowTypeError(JSMSG_INVALID_MAP_ITERABLE, "Map");
+        }
 
         // Steps 8.e-j.
-        callContentFunction(adder, map, nextItem[0], nextItem[1]);
+        try {
+            callContentFunction(adder, map, nextItem[0], nextItem[1]);
+        } catch (e) {
+            IteratorCloseThrow(iter);
+            throw e;
+        }
     }
 }
 
diff --git a/js/src/builtin/Promise.cpp b/js/src/builtin/Promise.cpp
index 59c97e529..c781a336d 100644
--- a/js/src/builtin/Promise.cpp
+++ b/js/src/builtin/Promise.cpp
@@ -1369,7 +1369,8 @@ PromiseObject::create(JSContext* cx, HandleObject executor, HandleObject proto /
 
 static MOZ_MUST_USE bool PerformPromiseAll(JSContext *cx, JS::ForOfIterator& iterator,
                                            HandleObject C, HandleObject promiseObj,
-                                           HandleObject resolve, HandleObject reject);
+                                           HandleObject resolve, HandleObject reject,
+                                           bool* done);
 
 // ES2016, 25.4.4.1.
 static bool
@@ -1410,12 +1411,14 @@ Promise_static_all(JSContext* cx, unsigned argc, Value* vp)
     // Step 6 (implicit).
 
     // Step 7.
-    bool result = PerformPromiseAll(cx, iter, C, resultPromise, resolve, reject);
+    bool done;
+    bool result = PerformPromiseAll(cx, iter, C, resultPromise, resolve, reject, &done);
 
     // Step 8.
     if (!result) {
         // Step 8.a.
-        // TODO: implement iterator closing.
+        if (!done)
+            iter.closeThrow();
 
         // Step 8.b.
         return AbruptRejectPromise(cx, args, resultPromise, reject);
@@ -1598,8 +1601,11 @@ RunResolutionFunction(JSContext *cx, HandleObject resolutionFun, HandleValue res
 // ES2016, 25.4.4.1.1.
 static MOZ_MUST_USE bool
 PerformPromiseAll(JSContext *cx, JS::ForOfIterator& iterator, HandleObject C,
-                  HandleObject promiseObj, HandleObject resolve, HandleObject reject)
+                  HandleObject promiseObj, HandleObject resolve, HandleObject reject,
+                  bool* done)
 {
+    *done = false;
+
     RootedObject unwrappedPromiseObj(cx);
     if (IsWrapper(promiseObj)) {
         unwrappedPromiseObj = CheckedUnwrap(promiseObj);
@@ -1666,14 +1672,19 @@ PerformPromiseAll(JSContext *cx, JS::ForOfIterator& iterator, HandleObject C,
     RootedValue rejectFunVal(cx, ObjectOrNullValue(reject));
 
     while (true) {
-        bool done;
-        // Steps a, b, c, e, f, g.
-        if (!iterator.next(&nextValue, &done))
+        // Steps a-c, e-g.
+        if (!iterator.next(&nextValue, done)) {
+            // Steps b, f.
+            *done = true;
+
+            // Steps c, g.
             return false;
+        }
 
         // Step d.
-        if (done) {
+        if (*done) {
             // Step d.i (implicit).
+
             // Step d.ii.
             int32_t remainingCount = dataHolder->decreaseRemainingCount();
 
@@ -1822,7 +1833,8 @@ PromiseAllResolveElementFunction(JSContext* cx, unsigned argc, Value* vp)
 
 static MOZ_MUST_USE bool PerformPromiseRace(JSContext *cx, JS::ForOfIterator& iterator,
                                             HandleObject C, HandleObject promiseObj,
-                                            HandleObject resolve, HandleObject reject);
+                                            HandleObject resolve, HandleObject reject,
+                                            bool* done);
 
 // ES2016, 25.4.4.3.
 static bool
@@ -1863,12 +1875,14 @@ Promise_static_race(JSContext* cx, unsigned argc, Value* vp)
     // Step 6 (implicit).
 
     // Step 7.
-    bool result = PerformPromiseRace(cx, iter, C, resultPromise, resolve, reject);
+    bool done;
+    bool result = PerformPromiseRace(cx, iter, C, resultPromise, resolve, reject, &done);
 
     // Step 8.
     if (!result) {
         // Step 8.a.
-        // TODO: implement iterator closing.
+        if (!done)
+            iter.closeThrow();
 
         // Step 8.b.
         return AbruptRejectPromise(cx, args, resultPromise, reject);
@@ -1882,25 +1896,30 @@ Promise_static_race(JSContext* cx, unsigned argc, Value* vp)
 // ES2016, 25.4.4.3.1.
 static MOZ_MUST_USE bool
 PerformPromiseRace(JSContext *cx, JS::ForOfIterator& iterator, HandleObject C,
-                   HandleObject promiseObj, HandleObject resolve, HandleObject reject)
+                   HandleObject promiseObj, HandleObject resolve, HandleObject reject,
+                   bool* done)
 {
+    *done = false;
     MOZ_ASSERT(C->isConstructor());
     RootedValue CVal(cx, ObjectValue(*C));
 
     RootedValue nextValue(cx);
     RootedValue resolveFunVal(cx, ObjectOrNullValue(resolve));
     RootedValue rejectFunVal(cx, ObjectOrNullValue(reject));
-    bool done;
 
     while (true) {
         // Steps a-c, e-g.
-        if (!iterator.next(&nextValue, &done))
+        if (!iterator.next(&nextValue, done)) {
+            // Steps b, f.
+            *done = true;
+
+            // Steps c, g.
             return false;
+        }
 
         // Step d.
-        if (done) {
-            // Step d.i.
-            // TODO: implement iterator closing.
+        if (*done) {
+            // Step d.i (implicit).
 
             // Step d.ii.
             return true;
diff --git a/js/src/builtin/Set.js b/js/src/builtin/Set.js
index accc70120..c61a49ef8 100644
--- a/js/src/builtin/Set.js
+++ b/js/src/builtin/Set.js
@@ -40,7 +40,12 @@ function SetConstructorInit(iterable) {
         var nextValue = next.value;
 
         // Steps 8.d-e.
-        callContentFunction(adder, set, nextValue);
+        try {
+            callContentFunction(adder, set, nextValue);
+        } catch (e) {
+            IteratorCloseThrow(iter);
+            throw e;
+        }
     }
 }
 
diff --git a/js/src/builtin/Utilities.js b/js/src/builtin/Utilities.js
index bfb1fe7f4..2dece3801 100644
--- a/js/src/builtin/Utilities.js
+++ b/js/src/builtin/Utilities.js
@@ -154,6 +154,29 @@ function GetIterator(obj, method) {
     return iterator;
 }
 
+// ES2017 draft rev 7.4.6.
+// When completion.[[Type]] is throw.
+function IteratorCloseThrow(iter) {
+    // Steps 1-2 (implicit)
+
+    // Step 3.
+    var returnMethod = GetMethod(iter, "return");
+
+    // Step 4 (done in caller).
+    if (returnMethod === undefined)
+        return;
+
+    try {
+        // Step 5.
+        callContentFunction(returnMethod, iter);
+    } catch (e) {
+    }
+
+    // Step 6 (done in caller).
+
+    // Steps 7-9 (skipped).
+}
+
 var _builtinCtorsCache = {__proto__: null};
 
 function GetBuiltinConstructor(builtinName) {
diff --git a/js/src/builtin/WeakMap.js b/js/src/builtin/WeakMap.js
index 066a72bfe..708be8424 100644
--- a/js/src/builtin/WeakMap.js
+++ b/js/src/builtin/WeakMap.js
@@ -40,10 +40,17 @@ function WeakMapConstructorInit(iterable) {
         var nextItem = next.value;
 
         // Step 8.d.
-        if (!IsObject(nextItem))
+        if (!IsObject(nextItem)) {
+            IteratorCloseThrow(iter);
             ThrowTypeError(JSMSG_INVALID_MAP_ITERABLE, "WeakMap");
+        }
 
         // Steps 8.e-j.
-        callContentFunction(adder, map, nextItem[0], nextItem[1]);
+        try {
+            callContentFunction(adder, map, nextItem[0], nextItem[1]);
+        } catch (e) {
+            IteratorCloseThrow(iter);
+            throw e;
+        }
     }
 }
diff --git a/js/src/builtin/WeakSet.js b/js/src/builtin/WeakSet.js
index eb7c2378f..8589f9dc6 100644
--- a/js/src/builtin/WeakSet.js
+++ b/js/src/builtin/WeakSet.js
@@ -40,7 +40,12 @@ function WeakSetConstructorInit(iterable) {
         var nextValue = next.value;
 
         // Steps 8.d-e.
-        callContentFunction(adder, set, nextValue);
+        try {
+            callContentFunction(adder, set, nextValue);
+        } catch (e) {
+            IteratorCloseThrow(iter);
+            throw e;
+        }
     }
 }
 
diff --git a/js/src/js.msg b/js/src/js.msg
index cb5fc383b..2a818056f 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -579,3 +579,6 @@ MSG_DEF(JSMSG_PROMISE_CAPABILITY_HAS_SOMETHING_ALREADY, 0, JSEXN_TYPEERR, "GetCa
 MSG_DEF(JSMSG_PROMISE_RESOLVE_FUNCTION_NOT_CALLABLE,    0, JSEXN_TYPEERR, "A Promise subclass passed a non-callable value as the resolve function.")
 MSG_DEF(JSMSG_PROMISE_REJECT_FUNCTION_NOT_CALLABLE,     0, JSEXN_TYPEERR, "A Promise subclass passed a non-callable value as the reject function.")
 MSG_DEF(JSMSG_PROMISE_ERROR_IN_WRAPPED_REJECTION_REASON,0, JSEXN_INTERNALERR, "Promise rejection value is a non-unwrappable cross-compartment wrapper.")
+
+// Iterator
+MSG_DEF(JSMSG_RETURN_NOT_CALLABLE,     0, JSEXN_TYPEERR, "property 'return' of iterator is not callable")
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 2d6ff462c..a93852fa5 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -6167,6 +6167,12 @@ class MOZ_STACK_CLASS JS_PUBLIC_API(ForOfIterator) {
     bool next(JS::MutableHandleValue val, bool* done);
 
     /**
+     * Close the iterator.
+     * For the case that completion type is throw.
+     */
+    void closeThrow();
+
+    /**
      * If initialized with throwOnNonCallable = false, check whether
      * the value is iterable.
      */
diff --git a/js/src/tests/ecma_6/Array/from-iterator-close.js b/js/src/tests/ecma_6/Array/from-iterator-close.js
new file mode 100644
index 000000000..fa97ea282
--- /dev/null
+++ b/js/src/tests/ecma_6/Array/from-iterator-close.js
@@ -0,0 +1,183 @@
+var BUGNUMBER = 1180306;
+var summary = 'Array.from should close iterator on error';
+
+print(BUGNUMBER + ": " + summary);
+
+function test(ctor, { mapVal=undefined,
+                      nextVal=undefined,
+                      nextThrowVal=undefined,
+                      modifier=undefined,
+                      exceptionVal=undefined,
+                      exceptionType=undefined,
+                      closed=true }) {
+    let iterable = {
+        closed: false,
+        [Symbol.iterator]() {
+            let iterator = {
+                first: true,
+                next() {
+                    if (this.first) {
+                        this.first = false;
+                        if (nextThrowVal)
+                            throw nextThrowVal;
+                        return nextVal;
+                    }
+                    return { value: undefined, done: true };
+                },
+                return() {
+                    iterable.closed = true;
+                    return {};
+                }
+            };
+            if (modifier)
+                modifier(iterator, iterable);
+
+            return iterator;
+        }
+    };
+    if (exceptionVal) {
+        let caught = false;
+        try {
+            ctor.from(iterable, mapVal);
+        } catch (e) {
+            assertEq(e, exceptionVal);
+            caught = true;
+        }
+        assertEq(caught, true);
+    } else if (exceptionType) {
+        assertThrowsInstanceOf(() => ctor.from(iterable, mapVal), exceptionType);
+    } else {
+        ctor.from(iterable, mapVal);
+    }
+    assertEq(iterable.closed, closed);
+}
+
+// == Error cases with close ==
+
+// ES 2017 draft 22.1.2.1 step 5.e.i.1.
+// Cannot test.
+
+// ES 2017 draft 22.1.2.1 step 5.e.vi.2.
+test(Array, {
+    mapVal: () => { throw "map throws"; },
+    nextVal: { value: 1, done: false },
+    exceptionVal: "map throws",
+    closed: true,
+});
+
+// ES 2017 draft 22.1.2.1 step 5.e.ix.
+class MyArray extends Array {
+    constructor() {
+        return new Proxy({}, {
+            defineProperty() {
+                throw "defineProperty throws";
+            }
+        });
+    }
+}
+test(MyArray, {
+    nextVal: { value: 1, done: false },
+    exceptionVal: "defineProperty throws",
+    closed: true,
+});
+
+// ES 2017 draft 7.4.6 step 3.
+// if GetMethod fails, the thrown value should be used.
+test(MyArray, {
+    nextVal: { value: 1, done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                throw "return getter throws";
+            }
+        });
+    },
+    exceptionVal: "return getter throws",
+    closed: true,
+});
+test(MyArray, {
+    nextVal: { value: 1, done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                return "non object";
+            }
+        });
+    },
+    exceptionType: TypeError,
+    closed: true,
+});
+test(MyArray, {
+    nextVal: { value: 1, done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                // Non callable.
+                return {};
+            }
+        });
+    },
+    exceptionType: TypeError,
+    closed: true,
+});
+
+// ES 2017 draft 7.4.6 steps 6.
+// if return method throws, the thrown value should be ignored.
+test(MyArray, {
+    nextVal: { value: 1, done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            throw "return throws";
+        };
+    },
+    exceptionVal: "defineProperty throws",
+    closed: true,
+});
+
+test(MyArray, {
+    nextVal: { value: 1, done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            return "non object";
+        };
+    },
+    exceptionVal: "defineProperty throws",
+    closed: true,
+});
+
+// == Error cases without close ==
+
+// ES 2017 draft 22.1.2.1 step 5.e.iii.
+test(Array, {
+    nextThrowVal: "next throws",
+    exceptionVal: "next throws",
+    closed: false,
+});
+
+test(Array, {
+    nextVal: { value: {}, get done() { throw "done getter throws"; } },
+    exceptionVal: "done getter throws",
+    closed: false,
+});
+
+// ES 2017 draft 22.1.2.1 step 5.e.v.
+test(Array, {
+    nextVal: { get value() { throw "value getter throws"; }, done: false },
+    exceptionVal: "value getter throws",
+    closed: false,
+});
+
+// == Successful cases ==
+
+test(Array, {
+    nextVal: { value: 1, done: false },
+    closed: false,
+});
+
+if (typeof reportCompare === 'function')
+  reportCompare(true, true);
diff --git a/js/src/tests/ecma_6/Map/constructor-iterator-close.js b/js/src/tests/ecma_6/Map/constructor-iterator-close.js
new file mode 100644
index 000000000..ba4bee4a7
--- /dev/null
+++ b/js/src/tests/ecma_6/Map/constructor-iterator-close.js
@@ -0,0 +1,253 @@
+var BUGNUMBER = 1180306;
+var summary = 'Map/Set/WeakMap/WeakSet constructor should close iterator on error';
+
+print(BUGNUMBER + ": " + summary);
+
+function test(ctors, { nextVal=undefined,
+                       nextThrowVal=undefined,
+                       modifier=undefined,
+                       exceptionVal=undefined,
+                       exceptionType=undefined,
+                       closed=true }) {
+    function getIterable() {
+        let iterable = {
+            closed: false,
+            [Symbol.iterator]() {
+                let iterator = {
+                    first: true,
+                    next() {
+                        if (this.first) {
+                            this.first = false;
+                            if (nextThrowVal)
+                                throw nextThrowVal;
+                            return nextVal;
+                        }
+                        return { value: undefined, done: true };
+                    },
+                    return() {
+                        iterable.closed = true;
+                        return {};
+                    }
+                };
+                if (modifier)
+                    modifier(iterator, iterable);
+
+                return iterator;
+            }
+        };
+        return iterable;
+    }
+
+    for (let ctor of ctors) {
+        let iterable = getIterable();
+        if (exceptionVal) {
+            let caught = false;
+            try {
+                new ctor(iterable);
+            } catch (e) {
+                assertEq(e, exceptionVal);
+                caught = true;
+            }
+            assertEq(caught, true);
+        } else if (exceptionType) {
+            assertThrowsInstanceOf(() => new ctor(iterable), exceptionType);
+        } else {
+            new ctor(iterable);
+        }
+        assertEq(iterable.closed, closed);
+    }
+}
+
+// == Error cases with close ==
+
+// ES 2017 draft 23.1.1.1 Map step 8.d.ii.
+// ES 2017 draft 23.3.1.1 WeakMap step 8.d.ii.
+test([Map, WeakMap], {
+    nextVal: { value: "non object", done: false },
+    exceptionType: TypeError,
+    closed: true,
+});
+
+// ES 2017 draft 23.1.1.1 Map step 8.f.
+// ES 2017 draft 23.3.1.1 WeakMap step 8.f.
+test([Map, WeakMap], {
+    nextVal: { value: { get 0() { throw "0 getter throws"; } }, done: false },
+    exceptionVal: "0 getter throws",
+    closed: true,
+});
+
+// ES 2017 draft 23.1.1.1 Map step 8.h.
+// ES 2017 draft 23.3.1.1 WeakMap step 8.h.
+test([Map, WeakMap], {
+    nextVal: { value: { 0: {}, get 1() { throw "1 getter throws"; } }, done: false },
+    exceptionVal: "1 getter throws",
+    closed: true,
+});
+
+// ES 2017 draft 23.1.1.1 Map step 8.j.
+// ES 2017 draft 23.3.1.1 WeakMap step 8.j.
+class MyMap extends Map {
+    set(k, v) {
+        throw "setter throws";
+    }
+}
+class MyWeakMap extends WeakMap {
+    set(k, v) {
+        throw "setter throws";
+    }
+}
+test([MyMap, MyWeakMap], {
+    nextVal: { value: [{}, {}], done: false },
+    exceptionVal: "setter throws",
+    closed: true,
+});
+
+// ES 2017 draft 23.2.1.1 Set step 8.e.
+// ES 2017 draft 23.4.1.1 WeakSet step 8.e.
+class MySet extends Set {
+    add(v) {
+        throw "adder throws";
+    }
+}
+class MyWeakSet extends WeakSet {
+    add(v) {
+        throw "adder throws";
+    }
+}
+test([MySet, MyWeakSet], {
+    nextVal: { value: {}, done: false },
+    exceptionVal: "adder throws",
+    closed: true,
+});
+
+// ES 2017 draft 7.4.6 step 3.
+// if GetMethod fails, the thrown value should be used.
+test([MyMap, MySet, MyWeakMap, MyWeakSet], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                throw "return getter throws";
+            }
+        });
+    },
+    exceptionVal: "return getter throws",
+    closed: true,
+});
+test([MyMap, MySet, MyWeakMap, MyWeakSet], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                return "non object";
+            }
+        });
+    },
+    exceptionType: TypeError,
+    closed: true,
+});
+test([MyMap, MySet, MyWeakMap, MyWeakSet], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                // Non callable.
+                return {};
+            }
+        });
+    },
+    exceptionType: TypeError,
+    closed: true,
+});
+
+// ES 2017 draft 7.4.6 steps 6.
+// if return method throws, the thrown value should be ignored.
+test([MyMap, MyWeakMap], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            throw "return throws";
+        };
+    },
+    exceptionVal: "setter throws",
+    closed: true,
+});
+test([MySet, MyWeakSet], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            throw "return throws";
+        };
+    },
+    exceptionVal: "adder throws",
+    closed: true,
+});
+
+test([MyMap, MyWeakMap], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            return "non object";
+        };
+    },
+    exceptionVal: "setter throws",
+    closed: true,
+});
+test([MySet, MyWeakSet], {
+    nextVal: { value: [{}, {}], done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            return "non object";
+        };
+    },
+    exceptionVal: "adder throws",
+    closed: true,
+});
+
+// == Error cases without close ==
+
+// ES 2017 draft 23.1.1.1 Map step 8.a.
+// ES 2017 draft 23.3.1.1 WeakMap step 8.a.
+// ES 2017 draft 23.2.1.1 Set step 8.a.
+// ES 2017 draft 23.4.1.1 WeakSet step 8.a.
+test([Map, WeakMap, Set, WeakSet], {
+    nextThrowVal: "next throws",
+    exceptionVal: "next throws",
+    closed: false,
+});
+test([Map, WeakMap, Set, WeakSet], {
+    nextVal: { value: {}, get done() { throw "done getter throws"; } },
+    exceptionVal: "done getter throws",
+    closed: false,
+});
+
+// ES 2017 draft 23.1.1.1 Map step 8.c.
+// ES 2017 draft 23.3.1.1 WeakMap step 8.c.
+// ES 2017 draft 23.2.1.1 Set step 8.c.
+// ES 2017 draft 23.4.1.1 WeakSet step 8.c.
+test([Map, WeakMap, Set, WeakSet], {
+    nextVal: { get value() { throw "value getter throws"; }, done: false },
+    exceptionVal: "value getter throws",
+    closed: false,
+});
+
+// == Successful cases ==
+
+test([Map, WeakMap], {
+    nextVal: { value: [{}, {}], done: false },
+    closed: false,
+});
+test([Set, WeakSet], {
+    nextVal: { value: {}, done: false },
+    closed: false,
+});
+
+if (typeof reportCompare === 'function')
+  reportCompare(true, true);
diff --git a/js/src/tests/ecma_6/Promise/iterator-close.js b/js/src/tests/ecma_6/Promise/iterator-close.js
new file mode 100644
index 000000000..f17260d05
--- /dev/null
+++ b/js/src/tests/ecma_6/Promise/iterator-close.js
@@ -0,0 +1,234 @@
+// |reftest| skip-if(!xulRuntime.shell) -- needs drainJobQueue
+
+var BUGNUMBER = 1180306;
+var summary = 'Promise.{all,race} should close iterator on error';
+
+print(BUGNUMBER + ": " + summary);
+
+function test(ctor, props, { nextVal=undefined,
+                             nextThrowVal=undefined,
+                             modifier=undefined,
+                             rejectReason=undefined,
+                             rejectType=undefined,
+                             closed=true }) {
+    function getIterable() {
+        let iterable = {
+            closed: false,
+            [Symbol.iterator]() {
+                let iterator = {
+                    first: true,
+                    next() {
+                        if (this.first) {
+                            this.first = false;
+                            if (nextThrowVal)
+                                throw nextThrowVal;
+                            return nextVal;
+                        }
+                        return { value: undefined, done: true };
+                    },
+                    return() {
+                        iterable.closed = true;
+                        return {};
+                    }
+                };
+                if (modifier)
+                    modifier(iterator, iterable);
+
+                return iterator;
+            }
+        };
+        return iterable;
+    }
+    for (let prop of props) {
+        let iterable = getIterable();
+        let e;
+        ctor[prop](iterable).catch(e_ => { e = e_; });
+        drainJobQueue();
+        if(rejectType)
+            assertEq(e instanceof rejectType, true);
+        else
+            assertEq(e, rejectReason);
+        assertEq(iterable.closed, closed);
+    }
+}
+
+// == Error cases with close ==
+
+// ES 2017 draft 25.4.4.1.1 step 6.i.
+// ES 2017 draft 25.4.4.3.1 step 3.h.
+class MyPromiseStaticResolveGetterThrows extends Promise {
+    static get resolve() {
+        throw "static resolve getter throws";
+    }
+};
+test(MyPromiseStaticResolveGetterThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    rejectReason: "static resolve getter throws",
+    closed: true,
+});
+
+class MyPromiseStaticResolveThrows extends Promise {
+    static resolve() {
+        throw "static resolve throws";
+    }
+};
+test(MyPromiseStaticResolveThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    rejectReason: "static resolve throws",
+    closed: true,
+});
+
+// ES 2017 draft 25.4.4.1.1 step 6.q.
+// ES 2017 draft 25.4.4.3.1 step 3.i.
+class MyPromiseThenGetterThrows extends Promise {
+    static resolve() {
+        return {
+            get then() {
+                throw "then getter throws";
+            }
+        };
+    }
+};
+test(MyPromiseThenGetterThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    rejectReason: "then getter throws",
+    closed: true,
+});
+
+class MyPromiseThenThrows extends Promise {
+    static resolve() {
+        return {
+            then() {
+                throw "then throws";
+            }
+        };
+    }
+};
+test(MyPromiseThenThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    rejectReason: "then throws",
+    closed: true,
+});
+
+// ES 2017 draft 7.4.6 step 3.
+// if GetMethod fails, the thrown value should be used.
+test(MyPromiseThenThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                throw "return getter throws";
+            }
+        });
+    },
+    rejectReason: "return getter throws",
+    closed: true,
+});
+test(MyPromiseThenThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                return "non object";
+            }
+        });
+    },
+    rejectType: TypeError,
+    closed: true,
+});
+test(MyPromiseThenThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    modifier: (iterator, iterable) => {
+        Object.defineProperty(iterator, "return", {
+            get: function() {
+                iterable.closed = true;
+                // Non callable.
+                return {};
+            }
+        });
+    },
+    rejectType: TypeError,
+    closed: true,
+});
+
+// ES 2017 draft 7.4.6 steps 6.
+// if return method throws, the thrown value should be ignored.
+test(MyPromiseThenThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            throw "return throws";
+        };
+    },
+    rejectReason: "then throws",
+    closed: true,
+});
+
+test(MyPromiseThenThrows, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    modifier: (iterator, iterable) => {
+        iterator.return = function() {
+            iterable.closed = true;
+            return "non object";
+        };
+    },
+    rejectReason: "then throws",
+    closed: true,
+});
+
+// == Error cases without close ==
+
+// ES 2017 draft 25.4.4.1.1 step 6.a.
+test(Promise, ["all", "race"], {
+    nextThrowVal: "next throws",
+    rejectReason: "next throws",
+    closed: false,
+});
+
+test(Promise, ["all", "race"], {
+    nextVal: { value: {}, get done() { throw "done getter throws"; } },
+    rejectReason: "done getter throws",
+    closed: false,
+});
+
+// ES 2017 draft 25.4.4.1.1 step 6.e.
+test(Promise, ["all", "race"], {
+    nextVal: { get value() { throw "value getter throws"; }, done: false },
+    rejectReason: "value getter throws",
+    closed: false,
+});
+
+// ES 2017 draft 25.4.4.1.1 step 6.d.iii.2.
+let first = true;
+class MyPromiseResolveThrows extends Promise {
+    constructor(executer) {
+        if (first) {
+            first = false;
+            super((resolve, reject) => {
+                executer(() => {
+                    throw "resolve throws";
+                }, reject);
+            });
+            return;
+        }
+        super(executer);
+    }
+};
+test(MyPromiseResolveThrows, ["all"], {
+    nextVal: { value: undefined, done: true },
+    rejectReason: "resolve throws",
+    closed: false,
+});
+
+// == Successful cases ==
+
+test(Promise, ["all", "race"], {
+    nextVal: { value: Promise.resolve(1), done: false },
+    closed: false,
+});
+
+if (typeof reportCompare === 'function')
+  reportCompare(true, true);
diff --git a/js/src/vm/ForOfIterator.cpp b/js/src/vm/ForOfIterator.cpp
index 7bd521a6a..a67b36774 100644
--- a/js/src/vm/ForOfIterator.cpp
+++ b/js/src/vm/ForOfIterator.cpp
@@ -151,6 +151,57 @@ ForOfIterator::next(MutableHandleValue vp, bool* done)
     return GetProperty(cx_, resultObj, resultObj, cx_->names().value, vp);
 }
 
+// ES 2017 draft 0f10dba4ad18de92d47d421f378233a2eae8f077 7.4.6.
+// When completion.[[Type]] is throw.
+void
+ForOfIterator::closeThrow()
+{
+    MOZ_ASSERT(iterator);
+
+    RootedValue completionException(cx_);
+    if (cx_->isExceptionPending()) {
+        if (!GetAndClearException(cx_, &completionException))
+            completionException.setUndefined();
+    }
+
+    // Steps 1-2 (implicit)
+
+    // Step 3 (partial).
+    RootedValue returnVal(cx_);
+    if (!GetProperty(cx_, iterator, iterator, cx_->names().return_, &returnVal))
+        return;
+
+    // Step 4.
+    if (returnVal.isUndefined()) {
+        cx_->setPendingException(completionException);
+        return;
+    }
+
+    // Step 3 (remaining part)
+    if (!returnVal.isObject()) {
+        JS_ReportErrorNumberASCII(cx_, GetErrorMessage, nullptr, JSMSG_RETURN_NOT_CALLABLE);
+        return;
+    }
+    RootedObject returnObj(cx_, &returnVal.toObject());
+    if (!returnObj->isCallable()) {
+        JS_ReportErrorNumberASCII(cx_, GetErrorMessage, nullptr, JSMSG_RETURN_NOT_CALLABLE);
+        return;
+    }
+
+    // Step 5.
+    RootedValue innerResultValue(cx_);
+    if (!js::Call(cx_, returnVal, iterator, &innerResultValue)) {
+        if (cx_->isExceptionPending())
+            cx_->clearPendingException();
+    }
+
+    // Step 6.
+    cx_->setPendingException(completionException);
+
+    // Steps 7-9 (skipped).
+    return;
+}
+
 bool
 ForOfIterator::materializeArrayIterator()
 {