making stream::flush synchronous to avoid circular event dep

Author: PietroGhg

sycl/source/detail/stream_impl.cpp

@@ -116,11 +116,7 @@ void stream_impl::flush(const EventImplPtr &LeadEvent) {
       fflush(stdout);
     });
   });
-  if (LeadEvent) {
-    LeadEvent->attachEventToComplete(detail::getSyclObjImpl(Event));
-    LeadEvent->getSubmittedQueue()->registerStreamServiceEvent(
-        detail::getSyclObjImpl(Event));
-  }
+  Event.wait();
 }
 
 void stream_impl::flush() { flush(nullptr); }

sycl/unittests/scheduler/CommandsWaitForEvents.cpp

@@ -159,16 +159,16 @@ TEST_F(SchedulerTest, StreamAUXCmdsWait) {
           [=]() { Out << "Hello, World!" << endl; });
     });
 
-    ASSERT_TRUE(QueueImplProxy->MStreamsServiceEvents.size() == 1)
-        << "Expected 1 service stream event";
+    ASSERT_TRUE(QueueImplProxy->MStreamsServiceEvents.size() == 0)
+        << "Expected 0 service stream event";
 
     std::shared_ptr<sycl::detail::event_impl> EventImpl =
         detail::getSyclObjImpl(Event);
 
     auto EventImplProxy = std::static_pointer_cast<EventImplProxyT>(EventImpl);
 
-    ASSERT_TRUE(EventImplProxy->MPostCompleteEvents.size() == 1)
-        << "Expected 1 post complete event";
+    ASSERT_TRUE(EventImplProxy->MPostCompleteEvents.size() == 0)
+        << "Expected 0 post complete event";
 
     Q.wait();