QML: Also check for correct destroy() chaining

Check that the destroy() method of Heap::Base was called when a Managed
object needs destruction. This checks if a call to the parent's
destroy() method was accidentally omitted.

Change-Id: Id025ecd6d4744bf3eab23503fbe317ed2a461138
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 31 insertions, 7 deletions

diff --git a/src/qml/memory/qv4heap_p.h b/src/qml/memory/qv4heap_p.h
index abbe85c04e..5a3797f397 100644
--- a/src/qml/memory/qv4heap_p.h
+++ b/src/qml/memory/qv4heap_p.h
@@ -133,19 +133,41 @@ struct Q_QML_EXPORT Base {
     void *operator new(size_t, Heap::Base *m) { return m; }
     void operator delete(void *, Heap::Base *) {}
 
-    void init() { setInitialized(); }
+    void init() { _setInitialized(); }
+    void destroy() { _setDestroyed(); }
 #ifdef QML_CHECK_INIT_DESTROY_CALLS
-    bool _isInitialized;
+    enum { Uninitialized = 0, Initialized, Destroyed } _livenessStatus;
     void _checkIsInitialized() {
-        if (!_isInitialized)
+        if (_livenessStatus == Uninitialized)
             fprintf(stderr, "ERROR: use of object '%s' before call to init() !!\n",
                     vtable()->className);
-        Q_ASSERT(_isInitialized);
+        else if (_livenessStatus == Destroyed)
+            fprintf(stderr, "ERROR: use of object '%s' after call to destroy() !!\n",
+                    vtable()->className);
+        Q_ASSERT(_livenessStatus = Initialized);
+    }
+    void _checkIsDestroyed() {
+        if (_livenessStatus == Initialized)
+            fprintf(stderr, "ERROR: object '%s' was never destroyed completely !!\n",
+                    vtable()->className);
+        Q_ASSERT(_livenessStatus == Destroyed);
+    }
+    void _setInitialized() { Q_ASSERT(_livenessStatus == Uninitialized); _livenessStatus = Initialized; }
+    void _setDestroyed() {
+        if (_livenessStatus == Uninitialized)
+            fprintf(stderr, "ERROR: attempting to destroy an uninitialized object '%s' !!\n",
+                    vtable()->className);
+        else if (_livenessStatus == Destroyed)
+            fprintf(stderr, "ERROR: attempting to destroy repeatedly object '%s' !!\n",
+                    vtable()->className);
+        Q_ASSERT(_livenessStatus == Initialized);
+        _livenessStatus = Destroyed;
     }
-    void setInitialized() { Q_ASSERT(!_isInitialized); _isInitialized = true; }
 #else
     Q_ALWAYS_INLINE void _checkIsInitialized() {}
-    Q_ALWAYS_INLINE void setInitialized() {}
+    Q_ALWAYS_INLINE void _checkIsDestroyed() {}
+    Q_ALWAYS_INLINE void _setInitialized() {}
+    Q_ALWAYS_INLINE void _setDestroyed() {}
 #endif
 };
 V4_ASSERT_IS_TRIVIAL(Base)
diff --git a/src/qml/memory/qv4mm.cpp b/src/qml/memory/qv4mm.cpp
index 3d25bd1639..ad4ecfe76d 100644
--- a/src/qml/memory/qv4mm.cpp
+++ b/src/qml/memory/qv4mm.cpp
@@ -229,8 +229,10 @@ bool sweepChunk(MemoryManager::Data::ChunkHeader *header, uint *itemsInUse, Exec
                     *unmanagedHeapSize -= heapBytes;
                 }
 
-                if (m->vtable()->destroy)
+                if (m->vtable()->destroy) {
                     m->vtable()->destroy(m);
+                    m->_checkIsDestroyed();
+                }
 
                 memset(m, 0, header->itemSize);
 #ifdef V4_USE_VALGRIND