Fix invalid iterator access

src/amdis/Observer.hpp

@@ -36,7 +36,7 @@ namespace AMDiS
   public:
     virtual ~ObserverInterface() = default;
     virtual void update(Event e) = 0;
-    virtual void detach() = 0;
+    virtual void unset() = 0;
   };
 
 
@@ -65,8 +65,9 @@ namespace AMDiS
   public:
     virtual ~Notifier()
     {
+      // Remove remaining pointers to this to avoid segfaults
       for (ObserverInterface<Event>* o : observers_)
-        o->detach();
+        o->unset();
     }
 
     /// Call the \ref update method on all attached observers.
@@ -109,7 +110,8 @@ namespace AMDiS
     /// Destructor, detaches from the notifier
     virtual ~Observer()
     {
-      detach();
+      if (notifier_)
+        notifier_->detach(this);
     }
 
     /// Copy constructor. Attaches this to the copied notifier
@@ -130,13 +132,11 @@ namespace AMDiS
       return *this;
     }
 
-    void detach() final
+    /// Set the Notifier* to nullptr. Used by the Notifer to avoid segfaults when destruction occurs
+    /// out of order.
+    void unset() final
     {
-      if (notifier_)
-      {
-        notifier_->detach(this);
-        notifier_ = nullptr;
-      }
+      notifier_ = nullptr;
     }
 
     /// Implementation of the interface method \ref ObserverInterface::update.