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 990000a32ea84aa4d605562912afb3440c871354..18dec54cf052f03eedf3272c722f91a7819eb1a3 100644
--- a/src/messages.cc
+++ b/src/messages.cc
@@ -109,12 +109,32 @@ Handle<JSMessageObject> MessageHandler::MakeMessageObject(
 
 void MessageHandler::ReportMessage(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.
+  static int in_process = false;

[Mads Ager (chromium), 2011/03/21 10:33:22]

This will not work with isolates. You need this to be store in the isolate
somewhere. Also, it will probably not work with Lockers either. There might be a
thread switch while reporting messages with on thread. 

I think this should be added to the archived thread state that is part of the
isolate (make it part of Top like the rest of the exception state).

[antonm, 2011/03/21 18:15:48]

Done.

+  if (in_process) {
+    ReportMessage("uncaught exception thrown while reporting");
+    return;
+  }
+  in_process = 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.
+  Top::ExceptionScope exception_scope;
+  Top::clear_pending_exception();
+  Top::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 (Top::has_scheduled_exception()) {
+      Top::clear_scheduled_exception();
+    }
   } else {
     for (int i = 0; i < global_length; i++) {
       HandleScope scope;
@@ -125,8 +145,13 @@ 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 (Top::has_scheduled_exception()) {
+        Top::clear_scheduled_exception();
+      }
     }
   }
+
+  in_process = false;
 }