Fix: confusion in QImage paintEngine creation on shared images

During the creation of a raster paint engine in QImage::paintEngine(),
the QImage will be detached. At least old gcc versions would get
confused so that the newly created paintengine would end up in the old
QImage copy insteads of the newly detached one. Work around by
dropping the temporary engine pointer.

Fixes: QTBUG-79383
Change-Id: I27b1f24312269bc2bcc641dc4334397a92e3bfbb
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index dda407181a..2779b97fbd 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -4145,11 +4145,11 @@ QPaintEngine *QImage::paintEngine() const
 
     if (!d->paintEngine) {
         QPaintDevice *paintDevice = const_cast<QImage *>(this);
-        QPaintEngine *paintEngine = 0;
         QPlatformIntegration *platformIntegration = QGuiApplicationPrivate::platformIntegration();
         if (platformIntegration)
-            paintEngine = platformIntegration->createImagePaintEngine(paintDevice);
-        d->paintEngine = paintEngine ? paintEngine : new QRasterPaintEngine(paintDevice);
+            d->paintEngine = platformIntegration->createImagePaintEngine(paintDevice);
+       if (!d->paintEngine)
+            d->paintEngine = new QRasterPaintEngine(paintDevice);
     }
 
     return d->paintEngine;