1 files changed, 51 insertions, 0 deletions
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()
 {