Make exception thrown via v8 public API propagate to v8::TryCatch as JS thrown exceptions do.

src/messages.cc

Index: src/messages.cc
diff --git a/src/messages.cc b/src/messages.cc
index cab982cecc5d9f82632218278ed032264809de1f..5e15b93193db06b483f5a80f0beef2a908d37409 100644
--- a/src/messages.cc
+++ b/src/messages.cc
@@ -106,14 +106,34 @@ Handle<JSMessageObject> MessageHandler::MakeMessageObject(
 }
 
 
-void MessageHandler::ReportMessage(MessageLocation* loc,
+void MessageHandler::ReportMessage(Isolate* isolate,
+                                   MessageLocation* loc,
                                    Handle<Object> message) {
+  // If we are in process of message reporting, just ignore all other requests
+  // to report a message as they are due to unhandled exceptions thrown in
+  // message callbacks.
+  if (isolate->in_exception_reporting()) {
+    ReportMessage("uncaught exception thrown while reporting");
+    return;
+  }
+  isolate->set_in_exception_reporting(true);
+
+  // We are calling into embedder's code which can throw exceptions.
+  // Thus we need to save current exception state, reset it to the clean one
+  // and ignore scheduled exceptions callbacks can throw.
+  Isolate::ExceptionScope exception_scope(isolate);
+  isolate->clear_pending_exception();
+  isolate->set_external_caught_exception(false);
+
   v8::Local<v8::Message> api_message_obj = v8::Utils::MessageToLocal(message);
 
   v8::NeanderArray global_listeners(FACTORY->message_listeners());
   int global_length = global_listeners.length();
   if (global_length == 0) {
     DefaultMessageReport(loc, message);
+    if (isolate->has_scheduled_exception()) {
+      isolate->clear_scheduled_exception();
+    }
   } else {
     for (int i = 0; i < global_length; i++) {
       HandleScope scope;
@@ -124,8 +144,13 @@ void MessageHandler::ReportMessage(MessageLocation* loc,
           FUNCTION_CAST<v8::MessageCallback>(callback_obj->proxy());
       Handle<Object> callback_data(listener.get(1));
       callback(api_message_obj, v8::Utils::ToLocal(callback_data));
+      if (isolate->has_scheduled_exception()) {
+        isolate->clear_scheduled_exception();
+      }
     }
   }
+
+  isolate->set_in_exception_reporting(false);
 }