El Dimecres, 9 de juliol de 2014, a les 10:58:50, David Faure va escriure: > On Thursday 12 December 2013 20:01:42 Albert Astals Cid wrote: > > El Dijous, 12 de desembre de 2013, a les 19:57:25, David Faure va escriure: > > > On Monday 11 November 2013 21:04:35 Jan Kundrát wrote: > > > > On Monday, 11 November 2013 19:17:22 CEST, Albert Astals Cid wrote: > > > > > Not sure you're understanding what i say, we have an explicit check > > > > > about > > > > > QDialog on stack+exec that says "it will crash if you dbus quit". > > > > > > > > We've chatted about this with Albert on IRC. My understanding of this > > > > is > > > > that there are many situations which can trigger destruction of the > > > > parent > > > > object; one of them involves triggering the QAction "game_quit" via > > > > DBUS. > > > > As such, I consider the EBN check a valid warning, similar to compiler > > > > warning about other dubious code constructs like no parentheses around > > > > && > > > > and ||, or unused variables -- might be valid in some circumstances, > > > > but > > > > should raise an eyebrow during review, and it might make sense to > > > > strive > > > > to > > > > make the code warning-free. > > > > > > > > However, there's another bug, probably in the kdeui code. When I > > > > trigger > > > > that QAction, this is what valgrind reports: > > > > > > > > ==355524== Invalid write of size 1 > > > > ==355524== at 0x5E3A6D7: > > > > QMenuPrivate::activateCausedStack(QList<QPointer<QWidget> > const&, > > > > QAction*, QAction::ActionEvent, bool) (qobject_p.h:321) > > > > ==355524== by 0x5E412F2: QMenuPrivate::activateAction(QAction*, > > > > QAction::ActionEvent, bool) (qmenu.cpp:1130) > > > > ==355524== by 0x5424A1A: KMenu::mouseReleaseEvent(QMouseEvent*) > > > > (kmenu.cpp:464) > > > > ==355524== by 0x5A000DB: QWidget::event(QEvent*) (qwidget.cpp:8376) > > > > ==355524== by 0x5E429DA: QMenu::event(QEvent*) (qmenu.cpp:2481) > > > > ==355524== by 0x59A03BB: > > > > QApplicationPrivate::notify_helper(QObject*, > > > > QEvent*) (qapplication.cpp:4562) > > > > ==355524== by 0x59A6168: QApplication::notify(QObject*, QEvent*) > > > > (qapplication.cpp:4105) > > > > ==355524== by 0x533F265: KApplication::notify(QObject*, QEvent*) > > > > (kapplication.cpp:311) > > > > ==355524== by 0x712AA3B: QCoreApplication::notifyInternal(QObject*, > > > > QEvent*) (qcoreapplication.cpp:949) > > > > ==355524== by 0x59A1461: > > > > QApplicationPrivate::sendMouseEvent(QWidget*, > > > > QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) > > > > (qcoreapplication.h:231) > > > > ==355524== by 0x5A31BA0: QETWidget::translateMouseEvent(_XEvent > > > > const*) > > > > (qapplication_x11.cpp:4451) > > > > ==355524== by 0x5A303B9: QApplication::x11ProcessEvent(_XEvent*) > > > > (qapplication_x11.cpp:3640) > > > > ==355524== Address 0x165b1d21 is 529 bytes inside a block of size 728 > > > > free'd > > > > ==355524== at 0x4C2AE0C: operator delete(void*) > > > > (vg_replace_malloc.c:480) > > > > ==355524== by 0x714715F: QObject::~QObject() (qscopedpointer.h:62) > > > > ==355524== by 0x59FA0C9: QWidget::~QWidget() (qwidget.cpp:1554) > > > > ==355524== by 0x54248CC: KMenu::~KMenu() (kmenu.cpp:168) > > > > ==355524== by 0x7140783: QObjectPrivate::deleteChildren() > > > > (qobject.cpp:1907) > > > > ==355524== by 0x59FA02C: QWidget::~QWidget() (qwidget.cpp:1679) > > > > ==355524== by 0x5421315: KMainWindow::~KMainWindow() > > > > (kmainwindow.cpp:467) > > > > ==355524== by 0x11A5AE: KMinesMainWindow::~KMinesMainWindow() (in > > > > /home/jkt/work/prog/kde/kmines/kmines) > > > > ==355524== by 0x7147AC7: QObject::event(QEvent*) (qobject.cpp:1175) > > > > ==355524== by 0x59FFDFA: QWidget::event(QEvent*) (qwidget.cpp:8846) > > > > ==355524== by 0x5E13C8A: QMainWindow::event(QEvent*) > > > > (qmainwindow.cpp:1478) > > > > ==355524== by 0x546E0C7: KXmlGuiWindow::event(QEvent*) > > > > (kxmlguiwindow.cpp:126) > > > > > > > > I have no idea why the DBUS calls to QAction are handled as mouse > > > > events, > > > > but I suspect something fishy is going on here. > > > > > > No, you're deleting the mainwindow while having the mouse over the menu, > > > so > > > when Qt finishes the mouse event handling it sends a mouse event to a > > > deleted widget, probably because all this happens within a nested event > > > loop, so Qt's main event loop didn't expect the widget to be already > > > deleted at that point. > > > > > > (I'm confused about the testcase though - this is "calling dbus quit > > > while > > > having the mouse over a menu?") > > > > There was no mouse over the menu at all involved. Just dbus invoking the > > action. > > Ah! Now I remember (yes, 7 months later). > This crash matches one of the items in my oversized todo list: > > "Qt bug: QMenu crashes when deleted from one of its actions. kde bug 249884, > RecursionGuard member accessed after deletion, weakpointer guard needed..."
Correct, so it still needs fixing (we all need more time i know) Or us all moving to Qt5 and hoping it's been fixed there :D Cheers, Albert > > Millian must have worked around the issue in kdevelop (the BR isn't really > clear about the fix). I guess using deleteLater().