Fix deleting of QOpenGLVersionFunctionsBackend

Since the destructor is not virtual we need to
cast to the proper class when deleting otherwise the wrong
destructor is called and the object memory is not entirely freed.

Change-Id: Ie4e0e91bfa6e802c7d72fd1f137f5c7f3f31c8a0
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

1 files changed, 12 insertions, 6 deletions

diff --git a/src/gui/opengl/qopenglversionfunctions.cpp b/src/gui/opengl/qopenglversionfunctions.cpp
index 54df2e5734..a3d3bb6bd1 100644
--- a/src/gui/opengl/qopenglversionfunctions.cpp
+++ b/src/gui/opengl/qopenglversionfunctions.cpp
@@ -74,15 +74,21 @@ QOpenGLVersionFunctionsStorage::QOpenGLVersionFunctionsStorage()
 
 QOpenGLVersionFunctionsStorage::~QOpenGLVersionFunctionsStorage()
 {
+#ifndef QT_OPENGL_ES
     if (backends) {
-        for (int i = 0; i < QOpenGLVersionFunctionsBackend::OpenGLVersionBackendCount; ++i) {
-            if (backends[i] && !--backends[i]->refs) {
-                // deleting the base class is ok, as the derived classes don't have a destructor
-                delete backends[i];
-            }
-        }
+
+        int i = 0;
+
+#define DELETE_BACKEND(X) \
+        if (backends[i] && !--backends[i]->refs) \
+            delete static_cast<QOpenGLFunctions_##X##Backend*>(backends[i]); \
+        ++i;
+
+        QT_OPENGL_VERSIONS(DELETE_BACKEND)
+#undef DELETE_BACKEND
         delete[] backends;
     }
+#endif
 }
 
 QOpenGLVersionFunctionsBackend *QOpenGLVersionFunctionsStorage::backend(QOpenGLContext *context, QOpenGLVersionFunctionsBackend::Version v)