Bug 1331585 - Allow falsy "done" values for IteratorClose due to exception during array destructuring

Issue mcp-graveyard/UXP%74

3 files changed, 25 insertions, 8 deletions

diff --git a/js/src/jit/JitFrames.cpp b/js/src/jit/JitFrames.cpp
index 30bbd0b9b..7c3f0d120 100644
--- a/js/src/jit/JitFrames.cpp
+++ b/js/src/jit/JitFrames.cpp
@@ -353,11 +353,11 @@ CloseLiveIteratorIon(JSContext* cx, const InlineFrameIterator& frame, JSTryNote*
     RootedObject iterObject(cx, &v.toObject());
 
     if (isDestructuring) {
-        Value v = si.read();
-        MOZ_ASSERT(v.isBoolean());
+        RootedValue doneValue(cx, si.read());
+        bool done = ToBoolean(doneValue);
         // Do not call IteratorClose if the destructuring iterator is already
         // done.
-        if (v.isTrue())
+        if (done)
             return;
     }
 
@@ -654,9 +654,9 @@ ProcessTryNotesBaseline(JSContext* cx, const JitFrameIterator& frame, Environmen
             uint8_t* framePointer;
             uint8_t* stackPointer;
             BaselineFrameAndStackPointersFromTryNote(tn, frame, &framePointer, &stackPointer);
-            Value doneValue(*(reinterpret_cast<Value*>(stackPointer)));
-            MOZ_ASSERT(doneValue.isBoolean());
-            if (doneValue.isFalse()) {
+            RootedValue doneValue(cx, *(reinterpret_cast<Value*>(stackPointer)));
+            bool done = ToBoolean(doneValue);
+            if (!done) {
                 Value iterValue(*(reinterpret_cast<Value*>(stackPointer) + 1));
                 RootedObject iterObject(cx, &iterValue.toObject());
                 if (!IteratorCloseForException(cx, iterObject)) {
diff --git a/js/src/tests/ecma_6/Destructuring/array-iterator-close.js b/js/src/tests/ecma_6/Destructuring/array-iterator-close.js
index f7805540d..ed35135db 100644
--- a/js/src/tests/ecma_6/Destructuring/array-iterator-close.js
+++ b/js/src/tests/ecma_6/Destructuring/array-iterator-close.js
@@ -43,6 +43,22 @@ function test() {
     }, "in lhs");
     assertEq(returnCalled, ++returnCalledExpected);
 
+    // throw in lhs ref calls IteratorClose with falsy "done".
+    iterable[Symbol.iterator] = makeIterator({
+        next: function() {
+            // "done" is undefined.
+            return {};
+        },
+        ret: function() {
+            returnCalled++;
+            return {};
+        }
+    });
+    assertThrowsValue(function() {
+        0, [...{}[throwlhs()]] = iterable;
+    }, "in lhs");
+    assertEq(returnCalled, ++returnCalledExpected);
+
     // throw in iter.next doesn't call IteratorClose
     iterable[Symbol.iterator] = makeIterator({
         next: function() {
diff --git a/js/src/vm/Interpreter.cpp b/js/src/vm/Interpreter.cpp
index 9a8c6777f..7f8ff8445 100644
--- a/js/src/vm/Interpreter.cpp
+++ b/js/src/vm/Interpreter.cpp
@@ -1205,8 +1205,9 @@ ProcessTryNotes(JSContext* cx, EnvironmentIter& ei, InterpreterRegs& regs)
             // stack. The iterator object is second from the top.
             MOZ_ASSERT(tn->stackDepth > 1);
             Value* sp = regs.spForStackDepth(tn->stackDepth);
-            MOZ_ASSERT(sp[-1].isBoolean());
-            if (sp[-1].isFalse()) {
+            RootedValue doneValue(cx, sp[-1]);
+            bool done = ToBoolean(doneValue);
+            if (!done) {
                 RootedObject iterObject(cx, &sp[-2].toObject());
                 if (!IteratorCloseForException(cx, iterObject)) {
                     SettleOnTryNote(cx, tn, ei, regs);