[Interest] Odd crash with QPainter + QOpenGLWidget

Thiago Macieira thiago.macieira at intel.com
Thu Mar 28 02:05:23 CET 2019

On Wednesday, 27 March 2019 14:48:16 PDT Matthew Woehlke wrote:
> ==12997==    by 0x598A728: QOpenGLVertexArrayObjectPrivate::destroy()
> (qopenglvertexarrayobject.cpp:212)
> ==12997==  Address 0x8 is not stack'd, malloc'd or (recently) free'd

Line 212:

        if (QThread::currentThread() != qGuiApp->thread()) {

There is a pointer being dereferenced on that line: qGuiApp, which is:

#define qGuiApp (static_cast<QGuiApplication *>(QCoreApplication::instance()))

That means you're somehow running this code after the application object was 
destroyed. Your backtrace wasn't long enough to tell where this was being 
called from (run valgrind with --num-callers=20), but my guess is that it's a 
global destructor keyed to the font engine.

But I also don't see how this could be *your* fault. If you can get the full 
backtrace, I think you should report as a bug.
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products

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