SL-15061 Crash deleting non-zero reference in LLConversationItemSession

indra/newview/llconversationmodel.cpp

@@ -350,16 +350,24 @@ void LLConversationItemSession::clearParticipants()
 }
 
 
-void LLConversationItemSession::deleteParticipantModels()
+void LLConversationItemSession::clearAndDeparentModels()
 {
-    // Make sure that no views exist before use and that view-owned items were removed!
-    //
-    // Normally we are not supposed to delete models directly, they should be
-    // owned by views and this action will result in crashes, but LLParticipantList
-    // creates models separately from views (it probably shouldn't) and then those
-    // models wait for idle cycles to be assigned to view.
-    // this code is meant to delete 'waiting' models 
-    std::for_each(mChildren.begin(), mChildren.end(), DeletePointer());
+    std::for_each(mChildren.begin(), mChildren.end(),
+        [](LLFolderViewModelItem* c)
+        {
+            if (c->getNumRefs() == 0)
+            {
+                // LLConversationItemParticipant can be created but not assigned to any view,
+                // it was waiting for an "add_participant" event to be processed
+                delete c;
+            }
+            else
+            {
+                // Model is still assigned to some view/widget
+                c->setParent(NULL);
+            }
+        }
+    );
     mChildren.clear();
 }
 

indra/newview/llconversationmodel.h

@@ -165,7 +165,7 @@ public:
 	void removeParticipant(LLConversationItemParticipant* participant);
 	void removeParticipant(const LLUUID& participant_id);
 	void clearParticipants();
-	void deleteParticipantModels(); // do not use while there are existing participant views
+	void clearAndDeparentModels(); // will delete unowned models and deparent owned ones
 	LLConversationItemParticipant* findParticipant(const LLUUID& participant_id);
 
 	void setParticipantIsMuted(const LLUUID& participant_id, bool is_muted);

indra/newview/llconversationview.cpp

@@ -108,8 +108,7 @@ void LLConversationViewSession::destroyView()
     // Chat can create and parent models(listeners) to session's model before creating
     // coresponding views, such participant's models normally will wait for idle cycles
     // but since we are deleting session and won't be processing any more events, make
-    // sure unowned models are removed as well.
-    // Might be good idea to just have an LLPointer list somewhere in LLConversationItemSession
+    // sure unowned LLConversationItemParticipant models are removed as well.
 
     LLConversationItemSession* vmi = dynamic_cast<LLConversationItemSession*>(getViewModelItem());
 
@@ -146,9 +145,9 @@ void LLConversationViewSession::destroyView()
             folderp->destroyView();
         }
 
-        // Now everything that is left in model(listener) is unowned,
-        // it is safe to remove
-        vmi->deleteParticipantModels();
+        // Now everything that is left in model(listener) is not owned by views,
+        // only by sessions, deparent so it won't point to soon to be dead model
+        vmi->clearAndDeparentModels();
     }
 
     LLFolderViewFolder::destroyView();