I've found a very strange (and serious) miscompilation of QImage with g++
In qimage.cpp there is a simple line (3584 in Qt-5.3.2):
d->paintEngine = paintEngine ? paintEngine : new
QRasterPaintEngine(paintDevice);
which results in 0(!). The return value of this method QImage::paintEngine() is
then 0 -
which should never happen.I can reproduce with a slightly modified "minimal" platform plugin, and only if it has a second QImage member, which gets its mImage member assigned. I have created a very small reproducible example program and I verified that this only happens when compiling QtGui with gcc (4.8.3 or 4.9.0), but it does not happen with clang (3.5.0). All tests are done on x86/64bit Linux (openSuse 13.2) with a self-compiled Qt5.3.2 (with a namespace, in debug mode). I also see the problem compiled with gcc-4.8.2 in release mode compiled on a CentOS-7 Testprogram/diff attached. Simply run with ./splash -platform minimal and in case of the bug it prints: created new QImage paint engine 0x0 returning QImage paint engine 0x0 QWidget::paintEngine: Should no longer be called QPainter::begin: Paint device returned engine == 0, type: 1 QPainter::setPen: Painter not active Can anyone please tell me if you can reproduce this ? Is this really a gcc bug ? Shall I create a gcc bug report with this example/description or is this much too large for a testcase ? -- Best regards/Schöne Grüße Martin A: Because it breaks the logical sequence of discussion Q: Why is top posting bad? () ascii ribbon campaign - against html e-mail /\ - against proprietary attachments Geschenkideen, Accessoires, Seifen, Kulinarisches: www.lillehus.at
--- qminimalbackingstore.h 2015-02-04 11:00:39.495064795 +0100
+++ new/qminimalbackingstore.h 2015-02-04 11:00:27.635152101 +0100
@@ -59,7 +59,7 @@
void resize(const QSize &size, const QRegion &staticContents);
private:
- QImage mImage;
+ QImage mImage, old;
const bool mDebug;
};
--- qminimalbackingstore.cpp 2015-02-04 11:00:34.051104837 +0100
+++ new/qminimalbackingstore.cpp 2015-02-04 11:00:27.635152101 +0100
@@ -50,11 +50,12 @@
QT_BEGIN_NAMESPACE
QMinimalBackingStore::QMinimalBackingStore(QWindow *window)
- : QPlatformBackingStore(window)
+ : QPlatformBackingStore(window), mImage(QSize(100, 100), QGuiApplication::primaryScreen()->handle()->format())
, mDebug(QMinimalIntegration::instance()->options() & QMinimalIntegration::DebugBackingStore)
{
if (mDebug)
qDebug() << "QMinimalBackingStore::QMinimalBackingStore:" << (quintptr)this;
+ old = mImage;
}
QMinimalBackingStore::~QMinimalBackingStore()
--- qimage.cpp 2014-09-23 14:32:27.201254640 +0200
+++ qimage.cpp 2015-02-04 10:50:16.810025578 +0100
@@ -3582,8 +3582,10 @@
if (platformIntegration)
paintEngine = platformIntegration->createImagePaintEngine(paintDevice);
d->paintEngine = paintEngine ? paintEngine : new QRasterPaintEngine(paintDevice);
+ qDebug() << "created new QImage paint engine" << d->paintEngine;
}
+ qDebug() << "returning QImage paint engine" << d->paintEngine;
return d->paintEngine;
}
#include <QSplashScreen>
#include <QApplication>
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QPixmap pix(100, 100);
QSplashScreen *s = new QSplashScreen(pix);
s->show();
return app.exec();
}
splash.pro
Description: application/vnd.nokia.qt.qmakeprofile
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