Potential leak of many QmakeEvalResult instances on session switch

diff --git a/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp b/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp
index 6cc4634375..94b59926a0 100644
--- a/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp
@@ -114,10 +114,13 @@ public:
     }
 };
 
+static std::atomic_int s_counter = 0;
+
 class QmakeEvalResult
 {
 public:
-    ~QmakeEvalResult() { qDeleteAll(directChildren); }
+    QmakeEvalResult()  { qDebug() << "QmakeEvalResult c'tor" << s_counter.fetch_add(1) + 1; }
+    ~QmakeEvalResult() { qDebug() << "QmakeEvalResult d'tor" << s_counter.fetch_sub(1) - 1; qDeleteAll(directChildren); }
 
     enum EvalResultState { EvalAbort, EvalFail, EvalPartial, EvalOk };
     EvalResultState state;