Fix dangling pointer

The address of the local variable controller is still referenced to by
the static variable controller_ after run() is executed and controller
has been deallocated.

Author: milsen

bandit/controller.h

@@ -146,6 +146,10 @@ namespace bandit {
         get_controller_address() = controller;
       }
 
+      static void deregister_controller() {
+        get_controller_address() = nullptr;
+      }
+
       static controller_t& registered_controller() {
         auto controller = get_controller_address();
         throw_if_nullptr(controller, "controller", "bandit::detail::register_controller()");
@@ -201,6 +205,10 @@ namespace bandit {
       controller_t::register_controller(controller);
     }
 
+    inline void deregister_controller() {
+      controller_t::deregister_controller();
+    }
+
     inline controller_t& registered_controller() {
       return controller_t::registered_controller();
     }

bandit/runner.h

@@ -110,7 +110,10 @@ namespace bandit {
     controller.set_policy(new run_policy::bandit(opt.filter_chain(), opt.break_on_failure(), opt.dry_run()));
 
     detail::register_controller(&controller);
-    return run(opt, detail::specs());
+    int result = run(opt, detail::specs());
+    detail::deregister_controller();
+
+    return result;
   }
 
   inline int run(int argc, char* argv[], bool allow_further = true) {