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List:       kde-frameworks-devel
Subject:    Re: Review Request 126725: prevent crash-on-exit in KSelectAction::~KSelectAction
From:       "David Faure" <faure () kde ! org>
Date:       2016-01-14 7:50:38
Message-ID: 20160114075038.14175.69389 () mimi ! kde ! org
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> On Jan. 12, 2016, 9:49 p.m., David Faure wrote:
> > Can I see the backtrace, with a description of how this gets triggered? I'm not \
> > sure the issue is fully understood (as shown by the use of "might" in the \
> > description...). 
> > Is the action being destroyed by clicking into a submenu of the action? Otherwise \
> > I don't get the relation with the fix.
> 
> René J.V. Bertin wrote:
> A CrashReporter backtrace I still had logged:
> 
> ```
> Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
> Exception Codes: EXC_I386_GPFLT
> 
> Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
> 0   org.qt-project.QtCore         	0x000000010cbac886 QObject::property(char \
> const*) const + 150 (qlist.h:105) 1   libqcocoa.dylib               \
> 0x000000011189e37a QCocoaMenuItem::~QCocoaMenuItem() + 58 (qcocoamenuitem.mm:109) 2 \
> libqcocoa.dylib               	0x000000011189e52e QCocoaMenuItem::~QCocoaMenuItem() \
> + 14 (qcocoamenuitem.mm:106) 3   org.qt-project.QtWidgets      	0x000000010b2989bd \
> QMenu::actionEvent(QActionEvent*) + 749 (qmenu.cpp:3224) 4   \
> org.qt-project.QtWidgets      	0x000000010b1643d0 QWidget::event(QEvent*) + 1232 \
> (qwidget.cpp:9044) 5   org.qt-project.QtWidgets      	0x000000010b296bdc \
> QMenu::event(QEvent*) + 1164 (qmenu.cpp:2678) 6   org.qt-project.QtWidgets      \
> 0x000000010b12653b QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251 \
> (qapplication.cpp:3716) 7   org.qt-project.QtWidgets      	0x000000010b1298f4 \
> QApplication::notify(QObject*, QEvent*) + 8212 (qapplication.cpp:3681) 8   \
> org.qt-project.QtCore         	0x000000010cb7b433 \
> QCoreApplication::notifyInternal(QObject*, QEvent*) + 115 (qthread_p.h:291) 9   \
> org.qt-project.QtWidgets      	0x000000010b1582ed QWidget::removeAction(QAction*) + \
> 125 (qcoreapplication.h:224) 10  org.qt-project.QtWidgets      	0x000000010b11c711 \
> QAction::~QAction() + 97 (qaction.cpp:566) 11  org.qt-project.QtWidgets      \
> 0x000000010b16d16c QWidgetAction::~QWidgetAction() + 444 (qwidgetaction.cpp:122) 12 \
> libKF5WidgetsAddons.5.dylib   	0x000000010acddd80 KSelectAction::~KSelectAction() + \
> 64 (kselectaction.cpp:99) 13  org.qt-project.QtCore         	0x000000010cba3d75 \
> QObjectPrivate::deleteChildren() + 245 (qobject.cpp:1943) 14  \
> org.qt-project.QtWidgets      	0x000000010b153ee1 QWidget::~QWidget() + 1441 \
> (qwidget.cpp:1658) 15                                	0x00000001093c16bb \
> Bin::~Bin() + 1067 (bin.cpp:456) 16                                \
> 0x00000001093c181e Bin::~Bin() + 14 (bin.cpp:438) 17                                \
> 0x0000000109443d3e Core::~Core() + 62 (core.cpp:43) 18                              \
> 0x000000010940c95f MainWindow::~MainWindow() + 207 (mainwindow.cpp:549) 19          \
> 0x000000010940cd45 MainWindow::~MainWindow() + 21 (mainwindow.cpp:542) 20  \
> org.qt-project.QtCore         	0x000000010cba4748 QObject::event(QEvent*) + 776 \
> (qobject.cpp:4455) 21  org.qt-project.QtWidgets      	0x000000010b164d26 \
> QWidget::event(QEvent*) + 3622 (qwidget.cpp:9105) 22  org.qt-project.QtWidgets      \
> 0x000000010b26c45f QMainWindow::event(QEvent*) + 911 (qmainwindow.cpp:1495) 23  \
> libKF5XmlGui.5.dylib          	0x000000010a81e810 KMainWindow::event(QEvent*) + 624 \
> (kmainwindow.cpp:829) 24  libKF5XmlGui.5.dylib          	0x000000010a856398 \
> KXmlGuiWindow::event(QEvent*) + 24 (kxmlguiwindow.cpp:118) 25  \
> org.qt-project.QtWidgets      	0x000000010b12653b \
> QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251 (qapplication.cpp:3716) \
> 26  org.qt-project.QtWidgets      	0x000000010b1298f4 \
> QApplication::notify(QObject*, QEvent*) + 8212 (qapplication.cpp:3681) 27  \
> org.qt-project.QtCore         	0x000000010cb7c0db \
> QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) + 971 \
> (qthread_p.h:291) 28  org.qt-project.QtCore         	0x000000010cb7ba2c \
> QCoreApplication::exec() + 412 (qcoreapplication.cpp:1240) 29                       \
> 0x00000001093f3761 main + 10257 (main.cpp:118) 30  libdyld.dylib                 \
> 0x00007fff8508c5fd start + 1 ```
> 
> When I say crash-on-exit, I mean that the crash occurs after selecting the Quit \
> menu item, or closing the main window. 
> René J.V. Bertin wrote:
> Here's a backtrace obtained in the debugger:
> 
> ```
> * thread #1: tid = 0x3727c3, 0x0000000103c4e886 QtCore`QObject::property(char \
> const*) const [inlined] QListData::size() const + 4 at qlist.h:105, queue = \
> 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT) frame \
> #0: 0x0000000103c4e886 QtCore`QObject::property(char const*) const [inlined] \
> QListData::size() const + 4 at qlist.h:105 102      void remove(int i);
> 103      void remove(int i, int n);
> 104      void move(int from, int to);
> -> 105      inline int size() const { return d->end - d->begin; }
> 106      inline bool isEmpty() const { return d->end  == d->begin; }
> 107      inline void **at(int i) const { return d->array + d->begin + i; }
> 108      inline void **begin() const { return d->array + d->begin; }
> (lldb) bt
> * thread #1: tid = 0x3727c3, 0x0000000103c4e886 QtCore`QObject::property(char \
> const*) const [inlined] QListData::size() const + 4 at qlist.h:105, queue = \
>                 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS \
>                 (code=EXC_I386_GPFLT)
> * frame #0: 0x0000000103c4e886 QtCore`QObject::property(char const*) const \
> [inlined] QListData::size() const + 4 at qlist.h:105 frame #1: 0x0000000103c4e882 \
> QtCore`QObject::property(char const*) const [inlined] \
> QList<QByteArray>::indexOf(this=0x0000000118b9a1c0, t=0x0000000118b9a1c0, \
> from=<unavailable>) const at qlist.h:940 frame #2: 0x0000000103c4e882 \
> QtCore`QObject::property(this=<unavailable>, name=0x000000010af1799a) const + 146 \
> at qobject.cpp:3884 frame #3: 0x000000010ae9e37a \
> libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 58 at \
> qcocoamenuitem.mm:109 frame #4: 0x000000010ae9e52e \
> libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem() [inlined] \
> QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 14 at \
> qcocoamenuitem.mm:106 frame #5: 0x000000010ae9e529 \
> libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 9 at \
> qcocoamenuitem.mm:106 frame #6: 0x00000001022339bd \
> QtWidgets`QMenu::actionEvent(this=0x00000001069bce00, e=<unavailable>) + 749 at \
> qmenu.cpp:3224 frame #7: 0x00000001020ff3d0 \
> QtWidgets`QWidget::event(this=0x00000001069bce00, event=0x00007fff5fbfde30) + 1232 \
> at qwidget.cpp:9044 frame #8: 0x0000000102231bdc \
> QtWidgets`QMenu::event(this=0x00000001069bce00, e=0x00007fff5fbfde30) + 1164 at \
> qmenu.cpp:2678 frame #9: 0x00000001020c153b \
> QtWidgets`QApplicationPrivate::notify_helper(this=<unavailable>, \
> receiver=0x00000001069bce00, e=0x00007fff5fbfde30) + 251 at qapplication.cpp:3716 \
> frame #10: 0x00000001020c48f4 QtWidgets`QApplication::notify(this=<unavailable>, \
> receiver=<unavailable>, e=<unavailable>) + 8212 at qapplication.cpp:3681 frame #11: \
> 0x0000000103c1d433 QtCore`QCoreApplication::notifyInternal(this=<unavailable>, \
> receiver=<unavailable>, event=<unavailable>) + 115 at qcoreapplication.cpp:970 \
> frame #12: 0x00000001020f32ed QtWidgets`QWidget::removeAction(QAction*) [inlined] \
> QCoreApplication::sendEvent(receiver=<unavailable>, event=0x00000001037c1480) + 125 \
> at qcoreapplication.h:224 frame #13: 0x00000001020f32ce \
> QtWidgets`QWidget::removeAction(this=<unavailable>, action=0x0000000106a7eff0) + 94 \
> at qwidget.cpp:3317 frame #14: 0x00000001020b7711 \
> QtWidgets`QAction::~QAction(this=0x0000000106a7eff0) + 97 at qaction.cpp:568 frame \
> #15: 0x000000010210816c \
> QtWidgets`QWidgetAction::~QWidgetAction(this=0x0000000106a7eff0) + 444 at \
> qwidgetaction.cpp:122 frame #16: 0x0000000101db9d80 \
> libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction() [inlined] \
> KSelectAction::~KSelectAction(this=0x0000000106a7eff0) + 64 at \
> kselectaction.cpp:107 frame #17: 0x0000000101db9d49 \
> libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction() [inlined] \
> KSelectAction::~KSelectAction(this=0x0000000106a7eff0) at kselectaction.cpp:99 \
> frame #18: 0x0000000101db9d49 \
> libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction(this=0x0000000106a7eff0) \
> + 9 at kselectaction.cpp:99 frame #19: 0x0000000103c45d75 \
> QtCore`QObjectPrivate::deleteChildren(this=0x0000000106a78e30) + 245 at \
> qobject.cpp:1946 frame #20: 0x00000001020eeee1 \
> QtWidgets`QWidget::~QWidget(this=0x0000000106a78c80) + 1441 at qwidget.cpp:1658 \
> frame #21: 0x0000000100363e6b kdenlive`Bin::~Bin(this=0x0000000106a78c80) + 1067 at \
> bin.cpp:458 frame #22: 0x0000000100363fce kdenlive`Bin::~Bin() [inlined] \
> Bin::~Bin(this=0x0000000106a78c80) + 14 at bin.cpp:440 frame #23: \
> 0x0000000100363fc9 kdenlive`Bin::~Bin(this=0x0000000106a78c80) + 9 at bin.cpp:440 \
> frame #24: 0x00000001003e8bed kdenlive`Core::~Core() [inlined] \
> Core::~Core(this=0x0000000106a6ba60) + 68 at core.cpp:47 frame #25: \
> 0x00000001003e8ba9 kdenlive`Core::~Core() [inlined] \
> Core::~Core(this=0x0000000106a6ba60) at core.cpp:43 frame #26: 0x00000001003e8ba9 \
> kdenlive`Core::~Core(this=0x0000000106a6ba60) + 9 at core.cpp:43 frame #27: \
> 0x00000001003bbb8f kdenlive`MainWindow::~MainWindow(this=0x0000000106b4df40, \
> vtt=0x00000001004e1850) + 207 at mainwindow.cpp:614 frame #28: 0x00000001003bbf75 \
> kdenlive`MainWindow::~MainWindow() [inlined] \
> MainWindow::~MainWindow(this=0x0000000106b4df40) + 12 at mainwindow.cpp:608 frame \
> #29: 0x00000001003bbf69 kdenlive`MainWindow::~MainWindow(this=0x0000000106b4df40) + \
> 9 at mainwindow.cpp:608 frame #30: 0x0000000103c46748 \
> QtCore`QObject::event(QEvent*) [inlined] \
> qDeleteInEventHandler(o=0x0000000106b4df40) + 14 at qobject.cpp:4455 frame #31: \
> 0x0000000103c4673a QtCore`QObject::event(this=0x0000000106b4df40, e=<unavailable>) \
> + 762 at qobject.cpp:1230 frame #32: 0x00000001020ffd26 \
> QtWidgets`QWidget::event(this=0x0000000106b4df40, event=0x00000001236a90d0) + 3622 \
> at qwidget.cpp:9105 frame #33: 0x000000010220745f \
> QtWidgets`QMainWindow::event(this=0x0000000106b4df40, event=0x00000001236a90d0) + \
> 911 at qmainwindow.cpp:1495 frame #34: 0x0000000101925810 \
> libKF5XmlGui.5.dylib`KMainWindow::event(this=0x0000000106b4df40, \
> ev=0x00000001236a90d0) + 624 at kmainwindow.cpp:829 frame #35: 0x000000010195d398 \
> libKF5XmlGui.5.dylib`KXmlGuiWindow::event(this=0x0000000106b4df40, \
> ev=0x00000001236a90d0) + 24 at kxmlguiwindow.cpp:118 frame #36: 0x00000001020c153b \
> QtWidgets`QApplicationPrivate::notify_helper(this=<unavailable>, \
> receiver=0x0000000106b4df40, e=0x00000001236a90d0) + 251 at qapplication.cpp:3716 \
> frame #37: 0x00000001020c48f4 QtWidgets`QApplication::notify(this=<unavailable>, \
> receiver=<unavailable>, e=<unavailable>) + 8212 at qapplication.cpp:3681 frame #38: \
> 0x0000000103c1e0db QtCore`QCoreApplicationPrivate::sendPostedEvents(QObject*, int, \
> QThreadData*) [inlined] QCoreApplication::notifyInternal(this=<unavailable>, \
> receiver=<unavailable>, event=<unavailable>) + 95 at qcoreapplication.cpp:970 frame \
> #39: 0x0000000103c1e07c QtCore`QCoreApplicationPrivate::sendPostedEvents(QObject*, \
> int, QThreadData*) [inlined] QCoreApplication::sendEvent(receiver=<unavailable>, \
> event=0x00000001236a90d0) + 28 at qcoreapplication.h:224 frame #40: \
> 0x0000000103c1e060 \
> QtCore`QCoreApplicationPrivate::sendPostedEvents(receiver=0x0000000000000000, \
> event_type=0, data=0x0000000106a00e70) + 848 at qcoreapplication.cpp:1598 frame \
> #41: 0x0000000103c1da2c QtCore`QCoreApplication::exec() + 412 at \
> qcoreapplication.cpp:1240 frame #42: 0x00000001003a13b1 kdenlive`main(argc=1, \
> argv=<unavailable>) + 9841 at main.cpp:126 frame #43: 0x00007fff8508c5fd \
> libdyld.dylib`start + 1 frame #44: 0x00007fff8508c5fd libdyld.dylib`start + 1
> ```

Ok I see clearly what's happening. ~KSelectAction deletes QAction::menu() (the child \
menu), then (in ~QAction) the action is removed from its own (parent) menu, and the \
implementation of that on OSX is to delete a "platform menuitem", which has this code \
if (m_menu && COCOA_MENU_ANCESTOR(m_menu) == this)  SET_COCOA_MENU_ANCESTOR(m_menu, \
0); i.e. reparent any child menu. At this point m_menu is dangling, hence the crash. \
(technically m_menu is a "platform menu" but 

So 1) moving the "delete d_ptr" of KSelectAction is completely useless and unrelated. \
The crash happens *after* ~KSelectAction itself is done. 2) setMenu(0), and just \
that, is a possible fix 3) menu()->deleteLater, and just that, is a possible fix

(oh crap I forgot to submit this yesterday morning).

Let's see how this matches your new comment. Yep, it does.
I vote for 3), to avoid the overhead of 2).


- David


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/126725/#review90980
-----------------------------------------------------------


On Jan. 12, 2016, 1:14 p.m., René J.V. Bertin wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/126725/
> -----------------------------------------------------------
> 
> (Updated Jan. 12, 2016, 1:14 p.m.)
> 
> 
> Review request for KDE Frameworks and Christoph Feck.
> 
> 
> Repository: kwidgetsaddons
> 
> 
> Description
> -------
> 
> I was seeing a systematic crash on exitting kdenlive5, on OS X deep under the \
> `delete menu()` instruction in `KSelectAction::~KSelectAction`. The backtrace \
> suggested this might be due to a pending event (or an event due to the menu \
> deletion) being delivered post-mortem to an instance of a QMenu related class. 
> My fix is based on 3 principles:
> 1) release the "foreign" member instance (`menu()`) before releasing the own d-ptr
> 2) Remove the QMenu instance from ourselves before deleting it to have one less \
> potential dangling reference to it 3) QMenu is a QObject descendent that \
> corresponds to a UI element: on OS X it is safer to dispose these through \
> `deleteLater()` rather than directly. 
> 
> Diffs
> -----
> 
> src/kselectaction.cpp 1381099 
> 
> Diff: https://git.reviewboard.kde.org/r/126725/diff/
> 
> 
> Testing
> -------
> 
> On OS X 10.9.5, Qt 5.5.1 and KF5 Frameworks 5.16.0, built for installation under \
> /opt/local . 
> It seems that points 1) and 2) above already solve the crash issue in kdenlive on \
> OS X, but the general principle stands so I suggest keeping 3) in library code like \
> this. 
> 
> Thanks,
> 
> René J.V. Bertin
> 
> 


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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;">  <p style="margin-top: 0;">On January 12th, 2016, 9:49 p.m. UTC, <b>David \
Faure</b> wrote:</p>  <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;">  <pre style="white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Can I see the backtrace, with a description of how \
this gets triggered? I'm not sure the issue is fully understood (as shown by the use \
of "might" in the description...).</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">Is the action being \
destroyed by clicking into a submenu of the action? Otherwise I don't get the \
relation with the fix.</p></pre>  </blockquote>




 <p>On January 13th, 2016, 1:20 a.m. UTC, <b>René J.V. Bertin</b> wrote:</p>
 <blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;">  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">A \
CrashReporter backtrace I still had logged:</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;"><div class="codehilite" \
style="background: #f8f8f8"><pre style="line-height: 125%">Exception Type:  \
EXC_BAD_ACCESS (SIGSEGV) Exception Codes: EXC_I386_GPFLT

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   org.qt-project.QtCore           0x000000010cbac886 QObject::property(char const*) \
const + 150 (qlist.h:105) 1   libqcocoa.dylib                 0x000000011189e37a \
QCocoaMenuItem::~QCocoaMenuItem() + 58 (qcocoamenuitem.mm:109) 2   libqcocoa.dylib    \
0x000000011189e52e QCocoaMenuItem::~QCocoaMenuItem() + 14 (qcocoamenuitem.mm:106) 3   \
org.qt-project.QtWidgets        0x000000010b2989bd QMenu::actionEvent(QActionEvent*) \
+ 749 (qmenu.cpp:3224) 4   org.qt-project.QtWidgets        0x000000010b1643d0 \
QWidget::event(QEvent*) + 1232 (qwidget.cpp:9044) 5   org.qt-project.QtWidgets        \
0x000000010b296bdc QMenu::event(QEvent*) + 1164 (qmenu.cpp:2678) 6   \
org.qt-project.QtWidgets        0x000000010b12653b \
QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251 (qapplication.cpp:3716) 7 \
org.qt-project.QtWidgets        0x000000010b1298f4 QApplication::notify(QObject*, \
QEvent*) + 8212 (qapplication.cpp:3681) 8   org.qt-project.QtCore           \
0x000000010cb7b433 QCoreApplication::notifyInternal(QObject*, QEvent*) + 115 \
(qthread_p.h:291) 9   org.qt-project.QtWidgets        0x000000010b1582ed \
QWidget::removeAction(QAction*) + 125 (qcoreapplication.h:224) 10  \
org.qt-project.QtWidgets        0x000000010b11c711 QAction::~QAction() + 97 \
(qaction.cpp:566) 11  org.qt-project.QtWidgets        0x000000010b16d16c \
QWidgetAction::~QWidgetAction() + 444 (qwidgetaction.cpp:122) 12  \
libKF5WidgetsAddons.5.dylib     0x000000010acddd80 KSelectAction::~KSelectAction() + \
64 (kselectaction.cpp:99) 13  org.qt-project.QtCore           0x000000010cba3d75 \
QObjectPrivate::deleteChildren() + 245 (qobject.cpp:1943) 14  \
org.qt-project.QtWidgets        0x000000010b153ee1 QWidget::~QWidget() + 1441 \
(qwidget.cpp:1658) 15                                  0x00000001093c16bb Bin::~Bin() \
+ 1067 (bin.cpp:456) 16                                  0x00000001093c181e \
Bin::~Bin() + 14 (bin.cpp:438) 17                                  0x0000000109443d3e \
Core::~Core() + 62 (core.cpp:43) 18                                  \
0x000000010940c95f MainWindow::~MainWindow() + 207 (mainwindow.cpp:549) 19            \
0x000000010940cd45 MainWindow::~MainWindow() + 21 (mainwindow.cpp:542) 20  \
org.qt-project.QtCore           0x000000010cba4748 QObject::event(QEvent*) + 776 \
(qobject.cpp:4455) 21  org.qt-project.QtWidgets        0x000000010b164d26 \
QWidget::event(QEvent*) + 3622 (qwidget.cpp:9105) 22  org.qt-project.QtWidgets        \
0x000000010b26c45f QMainWindow::event(QEvent*) + 911 (qmainwindow.cpp:1495) 23  \
libKF5XmlGui.5.dylib            0x000000010a81e810 KMainWindow::event(QEvent*) + 624 \
(kmainwindow.cpp:829) 24  libKF5XmlGui.5.dylib            0x000000010a856398 \
KXmlGuiWindow::event(QEvent*) + 24 (kxmlguiwindow.cpp:118) 25  \
org.qt-project.QtWidgets        0x000000010b12653b \
QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251 (qapplication.cpp:3716) \
26  org.qt-project.QtWidgets        0x000000010b1298f4 QApplication::notify(QObject*, \
QEvent*) + 8212 (qapplication.cpp:3681) 27  org.qt-project.QtCore           \
0x000000010cb7c0db QCoreApplicationPrivate::sendPostedEvents(QObject*, int, \
QThreadData*) + 971 (qthread_p.h:291) 28  org.qt-project.QtCore           \
0x000000010cb7ba2c QCoreApplication::exec() + 412 (qcoreapplication.cpp:1240) 29      \
0x00000001093f3761 main + 10257 (main.cpp:118) 30  libdyld.dylib                   \
0x00007fff8508c5fd start + 1 </pre></div>
</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">When I say crash-on-exit, I mean that the crash occurs \
after selecting the Quit menu item, or closing the main window.</p></pre>  \
</blockquote>





 <p>On January 13th, 2016, 6:49 p.m. UTC, <b>René J.V. Bertin</b> wrote:</p>
 <blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;">  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Here's a backtrace obtained in the debugger:</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;"><div \
class="codehilite" style="background: #f8f8f8"><pre style="line-height: 125%">* \
thread #1: tid = 0x3727c3, 0x0000000103c4e886 QtCore`QObject::property(char const*) \
const [inlined] QListData::size() const + 4 at qlist.h:105, queue = \
&#39;com.apple.main-thread&#39;, stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)  \
frame #0: 0x0000000103c4e886 QtCore`QObject::property(char const*) const [inlined] \
QListData::size() const + 4 at qlist.h:105  102      void remove(int i);
   103      void remove(int i, int n);
   104      void move(int from, int to);
-&gt; 105      inline int size() const { return d-&gt;end - d-&gt;begin; }
   106      inline bool isEmpty() const { return d-&gt;end  == d-&gt;begin; }
   107      inline void **at(int i) const { return d-&gt;array + d-&gt;begin + i; }
   108      inline void **begin() const { return d-&gt;array + d-&gt;begin; }
(lldb) bt
* thread #1: tid = 0x3727c3, 0x0000000103c4e886 QtCore`QObject::property(char const*) \
const [inlined] QListData::size() const + 4 at qlist.h:105, queue = \
                &#39;com.apple.main-thread&#39;, stop reason = EXC_BAD_ACCESS \
                (code=EXC_I386_GPFLT)
  * frame #0: 0x0000000103c4e886 QtCore`QObject::property(char const*) const \
[inlined] QListData::size() const + 4 at qlist.h:105  frame #1: 0x0000000103c4e882 \
QtCore`QObject::property(char const*) const [inlined] \
QList&lt;QByteArray&gt;::indexOf(this=0x0000000118b9a1c0, t=0x0000000118b9a1c0, \
from=&lt;unavailable&gt;) const at qlist.h:940  frame #2: 0x0000000103c4e882 \
QtCore`QObject::property(this=&lt;unavailable&gt;, name=0x000000010af1799a) const + \
146 at qobject.cpp:3884  frame #3: 0x000000010ae9e37a \
libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 58 at \
qcocoamenuitem.mm:109  frame #4: 0x000000010ae9e52e \
libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem() [inlined] \
QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 14 at \
qcocoamenuitem.mm:106  frame #5: 0x000000010ae9e529 \
libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 9 at \
qcocoamenuitem.mm:106  frame #6: 0x00000001022339bd \
QtWidgets`QMenu::actionEvent(this=0x00000001069bce00, e=&lt;unavailable&gt;) + 749 at \
qmenu.cpp:3224  frame #7: 0x00000001020ff3d0 \
QtWidgets`QWidget::event(this=0x00000001069bce00, event=0x00007fff5fbfde30) + 1232 at \
qwidget.cpp:9044  frame #8: 0x0000000102231bdc \
QtWidgets`QMenu::event(this=0x00000001069bce00, e=0x00007fff5fbfde30) + 1164 at \
qmenu.cpp:2678  frame #9: 0x00000001020c153b \
QtWidgets`QApplicationPrivate::notify_helper(this=&lt;unavailable&gt;, \
receiver=0x00000001069bce00, e=0x00007fff5fbfde30) + 251 at qapplication.cpp:3716  \
frame #10: 0x00000001020c48f4 \
QtWidgets`QApplication::notify(this=&lt;unavailable&gt;, \
receiver=&lt;unavailable&gt;, e=&lt;unavailable&gt;) + 8212 at qapplication.cpp:3681  \
frame #11: 0x0000000103c1d433 \
QtCore`QCoreApplication::notifyInternal(this=&lt;unavailable&gt;, \
receiver=&lt;unavailable&gt;, event=&lt;unavailable&gt;) + 115 at \
qcoreapplication.cpp:970  frame #12: 0x00000001020f32ed \
QtWidgets`QWidget::removeAction(QAction*) [inlined] \
QCoreApplication::sendEvent(receiver=&lt;unavailable&gt;, event=0x00000001037c1480) + \
125 at qcoreapplication.h:224  frame #13: 0x00000001020f32ce \
QtWidgets`QWidget::removeAction(this=&lt;unavailable&gt;, action=0x0000000106a7eff0) \
+ 94 at qwidget.cpp:3317  frame #14: 0x00000001020b7711 \
QtWidgets`QAction::~QAction(this=0x0000000106a7eff0) + 97 at qaction.cpp:568  frame \
#15: 0x000000010210816c \
QtWidgets`QWidgetAction::~QWidgetAction(this=0x0000000106a7eff0) + 444 at \
qwidgetaction.cpp:122  frame #16: 0x0000000101db9d80 \
libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction() [inlined] \
KSelectAction::~KSelectAction(this=0x0000000106a7eff0) + 64 at kselectaction.cpp:107  \
frame #17: 0x0000000101db9d49 \
libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction() [inlined] \
KSelectAction::~KSelectAction(this=0x0000000106a7eff0) at kselectaction.cpp:99  frame \
#18: 0x0000000101db9d49 \
libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction(this=0x0000000106a7eff0) + \
9 at kselectaction.cpp:99  frame #19: 0x0000000103c45d75 \
QtCore`QObjectPrivate::deleteChildren(this=0x0000000106a78e30) + 245 at \
qobject.cpp:1946  frame #20: 0x00000001020eeee1 \
QtWidgets`QWidget::~QWidget(this=0x0000000106a78c80) + 1441 at qwidget.cpp:1658  \
frame #21: 0x0000000100363e6b kdenlive`Bin::~Bin(this=0x0000000106a78c80) + 1067 at \
bin.cpp:458  frame #22: 0x0000000100363fce kdenlive`Bin::~Bin() [inlined] \
Bin::~Bin(this=0x0000000106a78c80) + 14 at bin.cpp:440  frame #23: 0x0000000100363fc9 \
kdenlive`Bin::~Bin(this=0x0000000106a78c80) + 9 at bin.cpp:440  frame #24: \
0x00000001003e8bed kdenlive`Core::~Core() [inlined] \
Core::~Core(this=0x0000000106a6ba60) + 68 at core.cpp:47  frame #25: \
0x00000001003e8ba9 kdenlive`Core::~Core() [inlined] \
Core::~Core(this=0x0000000106a6ba60) at core.cpp:43  frame #26: 0x00000001003e8ba9 \
kdenlive`Core::~Core(this=0x0000000106a6ba60) + 9 at core.cpp:43  frame #27: \
0x00000001003bbb8f kdenlive`MainWindow::~MainWindow(this=0x0000000106b4df40, \
vtt=0x00000001004e1850) + 207 at mainwindow.cpp:614  frame #28: 0x00000001003bbf75 \
kdenlive`MainWindow::~MainWindow() [inlined] \
MainWindow::~MainWindow(this=0x0000000106b4df40) + 12 at mainwindow.cpp:608  frame \
#29: 0x00000001003bbf69 kdenlive`MainWindow::~MainWindow(this=0x0000000106b4df40) + 9 \
at mainwindow.cpp:608  frame #30: 0x0000000103c46748 QtCore`QObject::event(QEvent*) \
[inlined] qDeleteInEventHandler(o=0x0000000106b4df40) + 14 at qobject.cpp:4455  frame \
#31: 0x0000000103c4673a QtCore`QObject::event(this=0x0000000106b4df40, \
e=&lt;unavailable&gt;) + 762 at qobject.cpp:1230  frame #32: 0x00000001020ffd26 \
QtWidgets`QWidget::event(this=0x0000000106b4df40, event=0x00000001236a90d0) + 3622 at \
qwidget.cpp:9105  frame #33: 0x000000010220745f \
QtWidgets`QMainWindow::event(this=0x0000000106b4df40, event=0x00000001236a90d0) + 911 \
at qmainwindow.cpp:1495  frame #34: 0x0000000101925810 \
libKF5XmlGui.5.dylib`KMainWindow::event(this=0x0000000106b4df40, \
ev=0x00000001236a90d0) + 624 at kmainwindow.cpp:829  frame #35: 0x000000010195d398 \
libKF5XmlGui.5.dylib`KXmlGuiWindow::event(this=0x0000000106b4df40, \
ev=0x00000001236a90d0) + 24 at kxmlguiwindow.cpp:118  frame #36: 0x00000001020c153b \
QtWidgets`QApplicationPrivate::notify_helper(this=&lt;unavailable&gt;, \
receiver=0x0000000106b4df40, e=0x00000001236a90d0) + 251 at qapplication.cpp:3716  \
frame #37: 0x00000001020c48f4 \
QtWidgets`QApplication::notify(this=&lt;unavailable&gt;, \
receiver=&lt;unavailable&gt;, e=&lt;unavailable&gt;) + 8212 at qapplication.cpp:3681  \
frame #38: 0x0000000103c1e0db \
QtCore`QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) \
[inlined] QCoreApplication::notifyInternal(this=&lt;unavailable&gt;, \
receiver=&lt;unavailable&gt;, event=&lt;unavailable&gt;) + 95 at \
qcoreapplication.cpp:970  frame #39: 0x0000000103c1e07c \
QtCore`QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) \
[inlined] QCoreApplication::sendEvent(receiver=&lt;unavailable&gt;, \
event=0x00000001236a90d0) + 28 at qcoreapplication.h:224  frame #40: \
0x0000000103c1e060 QtCore`QCoreApplicationPrivate::sendPostedEvents(receiver=0x0000000000000000, \
event_type=0, data=0x0000000106a00e70) + 848 at qcoreapplication.cpp:1598  frame #41: \
0x0000000103c1da2c QtCore`QCoreApplication::exec() + 412 at qcoreapplication.cpp:1240 \
frame #42: 0x00000001003a13b1 kdenlive`main(argc=1, argv=&lt;unavailable&gt;) + 9841 \
at main.cpp:126  frame #43: 0x00007fff8508c5fd libdyld.dylib`start + 1
    frame #44: 0x00007fff8508c5fd libdyld.dylib`start + 1
</pre></div>
</p></pre>
 </blockquote>








</blockquote>

<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Ok I \
see clearly what's happening. ~KSelectAction deletes QAction::menu() (the child \
menu), then (in ~QAction) the action is removed from its own (parent) menu, and the \
implementation of that on OSX is to delete a "platform menuitem", which has this code \
if (m_menu &amp;&amp; COCOA_MENU_ANCESTOR(m_menu) == this)  \
SET_COCOA_MENU_ANCESTOR(m_menu, 0); i.e. reparent any child menu. At this point \
m_menu is dangling, hence the crash. (technically m_menu is a "platform menu" but \
</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">So 1) moving the "delete d_ptr" of KSelectAction is \
completely useless and unrelated. The crash happens <em style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
normal;">after</em> ~KSelectAction itself is done. 2) setMenu(0), and just that, is a \
possible fix 3) menu()-&gt;deleteLater, and just that, is a possible fix</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">(oh crap I forgot to submit this yesterday \
morning).</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Let's see how this matches your new comment. Yep, it \
does. I vote for 3), to avoid the overhead of 2).</p></pre>
<br />










<p>- David</p>


<br />
<p>On January 12th, 2016, 1:14 p.m. UTC, René J.V. Bertin wrote:</p>








<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; \
-webkit-border-radius: 6px;">  <tr>
  <td>

<div>Review request for KDE Frameworks and Christoph Feck.</div>
<div>By René J.V. Bertin.</div>


<p style="color: grey;"><i>Updated Jan. 12, 2016, 1:14 p.m.</i></p>









<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
kwidgetsaddons
</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">I was seeing a systematic crash on exitting kdenlive5, \
on OS X deep under the <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: inherit;">delete menu()</code> \
instruction in <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: \
inherit;">KSelectAction::~KSelectAction</code>. The backtrace suggested this might be \
due to a pending event (or an event due to the menu deletion) being delivered \
post-mortem to an instance of a QMenu related class.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">My \
fix is based on 3 principles: 1) release the "foreign" member instance (<code \
style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: \
0;line-height: inherit;">menu()</code>) before releasing the own d-ptr 2) Remove the \
QMenu instance from ourselves before deleting it to have one less potential dangling \
reference to it 3) QMenu is a QObject descendent that corresponds to a UI element: on \
OS X it is safer to dispose these through <code style="text-rendering: inherit;color: \
#4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">deleteLater()</code> rather than directly.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">On OS X 10.9.5, Qt 5.5.1 and KF5 Frameworks 5.16.0, \
built for installation under /opt/local .</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">It seems that points 1) \
and 2) above already solve the crash issue in kdenlive on OS X, but the general \
principle stands so I suggest keeping 3) in library code like this.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>src/kselectaction.cpp <span style="color: grey">(1381099)</span></li>

</ul>

<p><a href="https://git.reviewboard.kde.org/r/126725/diff/" style="margin-left: \
3em;">View Diff</a></p>






  </td>
 </tr>
</table>







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</html>


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