"Step into" jumps to unrelated code

1. Open project simple.pro.
   It's in tests/manual/debugger/simple/simple.pro of Creator's repository.
2. Place a breakpoint in the second line of testQStringList():

   l << "Hello ";
   

3. Start debugging.
4. When the breakpoint was hit, step into (F11).
   The debugger shows you QString's ctor in qstring.h. Fine.
5. Step into (F11).
   The debugger steps down one line. Fine.
6. Step into (F11).
   The debugger runs on and stops in the middle of void testApplicationStart(QCoreApplication *app) with an unrelated backtrace:

   1  __strlen_sse2                                          strlen.S            41   0x7ffff671fd30 
   2  ??                                                                              0x7ffff5b99bc3 
   3  ??                                                                              0x7ffff5b9b5e5 
   4  glXQueryExtensionsString                                                        0x7ffff5b94996 
   5  QXcbGlxWindow::createVisual()                                                   0x7ffff3696593 
   6  QXcbWindow::create()                                                            0x7ffff36fecf9 
   7  QXcbIntegration::createPlatformWindow(QWindow *) const                          0x7ffff36eb366 
   8  QWindowPrivate::create(bool, unsigned long long)                                0x7ffff738d424 
   9  QWidgetPrivate::create()                                                        0x7ffff7abd898 
   10 QWidget::create(unsigned long long, bool, bool)                                 0x7ffff7abde9e 
   11 QWidgetPrivate::setVisible(bool)                                                0x7ffff7acb56b 
   12 final::testApplicationStart                            simple_test_app.cpp 2301 0x5555555679a9 
   13 final::testFinal                                       simple_test_app.cpp 2347 0x555555567b1c 
   14 main                                                   simple_test_app.cpp 7244 0x555555576239 
   

I attached the debugger logs.