(In reply to Erik Quaeghebeur from comment #0)
> Application: kbibtex ( (), near 0.7.90)
The Git version information is missing. If you go to Help -> About KBibTeX, does it show a version number like "Version 1f432e58 (master), near 0.8.50"?

> The crash does not seem to be reproducible.
So, you yourself cannot reproduce this crash?

The bracktrace you provide is very detailed, but it stops at a point where I doubt the problem is actually caused. Therefore, to address the problem I need a clear path on how to reproduce the crash.

(In reply to Thomas Fischer from comment #1)
> (In reply to Erik Quaeghebeur from comment #0)
> > Application: kbibtex ( (), near 0.7.90)
> The Git version information is missing. If you go to Help -> About KBibTeX,
> does it show a version number like "Version 1f432e58 (master), near 0.8.50"?

No, it shows "versie (), near 0.7.90". But in the ebuild, I see "COMMIT=32bf659581e1c6a02a6f97bd714b44456c654783" and the ebuild version is "0.8_pre20180222"

> > The crash does not seem to be reproducible.
> So, you yourself cannot reproduce this crash?

Indeed, so it appears that what I was doing at the time (as described in the original report) is not the cause.

> The bracktrace you provide is very detailed, but it stops at a point where I
> doubt the problem is actually caused. Therefore, to address the problem I
> need a clear path on how to reproduce the crash.

In case there is not enough information here, then I guess closing this is best. In case I hit this again, I can always reopen with (hopefully) new info.

(In reply to Erik Quaeghebeur from comment #2)
> (In reply to Thomas Fischer from comment #1)
> > (In reply to Erik Quaeghebeur from comment #0)
> > > Application: kbibtex ( (), near 0.7.90)
> > The Git version information is missing. If you go to Help -> About KBibTeX,
> > does it show a version number like "Version 1f432e58 (master), near 0.8.50"?
> 
> No, it shows "versie (), near 0.7.90". But in the ebuild, I see
> "COMMIT=32bf659581e1c6a02a6f97bd714b44456c654783" and the ebuild version is
> "0.8_pre20180222"
> 
> > > The crash does not seem to be reproducible.
> > So, you yourself cannot reproduce this crash?
> 
> Indeed, so it appears that what I was doing at the time (as described in the
> original report) is not the cause.
> 
> > The bracktrace you provide is very detailed, but it stops at a point where I
> > doubt the problem is actually caused. Therefore, to address the problem I
> > need a clear path on how to reproduce the crash.
> 
> In case there is not enough information here, then I guess closing this is
> best. In case I hit this again, I can always reopen with (hopefully) new
> info.

I again got a segfault; my feeling is that it may be the same bug. Now it happened after saving upon closing KBibTeX. I'm not reopening, as I cannot reproduce it.

-- Backtrace:
Application: KBibTeX (kbibtex), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fd4db425800 (LWP 13942))]

Thread 4 (Thread 0x7fd4af4a3700 (LWP 13958)):
#0  0x00007fd4d658c1a2 in ?? () from /usr/lib64/libQt5Core.so.5
#1  0x00007fd4d677da2a in ?? () from /usr/lib64/libQt5Core.so.5
#2  0x00007fd4d00bc1a9 in g_main_context_check () from /usr/lib64/libglib-2.0.so.0
#3  0x00007fd4d00bc744 in ?? () from /usr/lib64/libglib-2.0.so.0
#4  0x00007fd4d00bc8bc in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#5  0x00007fd4d677db4b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#6  0x00007fd4d672c0ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#7  0x00007fd4d6588da3 in QThread::exec() () from /usr/lib64/libQt5Core.so.5
#8  0x00007fd4d658d2c1 in ?? () from /usr/lib64/libQt5Core.so.5
#9  0x00007fd4d18278b7 in start_thread () from /lib64/libpthread.so.0
#10 0x00007fd4d5e2e5cf in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x7fd4bcbbd700 (LWP 13944)):
#0  0x00007fd4d5e2322d in poll () from /lib64/libc.so.6
#1  0x00007fd4d00bc7a6 in ?? () from /usr/lib64/libglib-2.0.so.0
#2  0x00007fd4d00bc8bc in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#3  0x00007fd4d677db4b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#4  0x00007fd4d672c0ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#5  0x00007fd4d6588da3 in QThread::exec() () from /usr/lib64/libQt5Core.so.5
#6  0x00007fd4d49f6ec5 in ?? () from /usr/lib64/libQt5DBus.so.5
#7  0x00007fd4d658d2c1 in ?? () from /usr/lib64/libQt5Core.so.5
#8  0x00007fd4d18278b7 in start_thread () from /lib64/libpthread.so.0
#9  0x00007fd4d5e2e5cf in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7fd4c5d8c700 (LWP 13943)):
#0  0x00007fd4d5e2322d in poll () from /lib64/libc.so.6
#1  0x00007fd4cfe55860 in ?? () from /usr/lib64/libxcb.so.1
#2  0x00007fd4cfe57419 in xcb_wait_for_event () from /usr/lib64/libxcb.so.1
#3  0x00007fd4c7ea5119 in ?? () from /usr/lib64/libQt5XcbQpa.so.5
#4  0x00007fd4d658d2c1 in ?? () from /usr/lib64/libQt5Core.so.5
#5  0x00007fd4d18278b7 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fd4d5e2e5cf in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7fd4db425800 (LWP 13942)):
[KCrash Handler]
#6  QHash<QString, QVariant>::findNode (this=this@entry=0x55e0aec80c30, akey=..., ahp=ahp@entry=0x0) at /usr/include/qt5/QtCore/qhash.h:922
#7  0x00007fd4d95ead88 in QHash<QString, QVariant>::contains (akey=..., this=0x55e0aec80c30) at /usr/include/qt5/QtCore/qhash.h:897
#8  File::property (this=0x55e0af442670, key=...) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/data/file.cpp:292
#9  0x00007fd4dadb0e97 in FieldLineEdit::FieldLineEditPrivate::updateURL (text=..., this=0x55e0b0867240) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/field/fieldlineedit.cpp:390
#10 FieldLineEdit::FieldLineEditPrivate::textChanged (text=..., this=0x55e0b0867240) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/field/fieldlineedit.cpp:402
#11 FieldLineEdit::slotTextChanged (this=<optimized out>, text=...) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/field/fieldlineedit.cpp:472
#12 0x00007fd4d675628e in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQt5Core.so.5
#13 0x00007fd4dae28ce2 in MenuLineEdit::textChanged (this=this@entry=0x55e0b0856210, _t1=...) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.8_pre20180504_build/src/gui/kbibtexgui_autogen/IMAN36LHMA/moc_menulineedit.cpp:139
#14 0x00007fd4dadf2f44 in MenuLineEdit::slotTextChanged (this=0x55e0b0856210) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/widgets/menulineedit.cpp:315
#15 0x00007fd4d675628e in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQt5Core.so.5
#16 0x00007fd4d77d1f05 in ?? () from /usr/lib64/libQt5Widgets.so.5
#17 0x00007fd4d6755f39 in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQt5Core.so.5
#18 0x00007fd4d77ea97d in ?? () from /usr/lib64/libQt5Widgets.so.5
#19 0x00007fd4d77eac80 in QWidgetTextControl::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib64/libQt5Widgets.so.5
#20 0x00007fd4d67560bb in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQt5Core.so.5
#21 0x00007fd4d6ff84d4 in QTextDocumentPrivate::finishEdit() () from /usr/lib64/libQt5Gui.so.5
#22 0x00007fd4d70305a1 in QSyntaxHighlighter::setDocument(QTextDocument*) () from /usr/lib64/libQt5Gui.so.5
#23 0x00007fd4d7030779 in QSyntaxHighlighter::~QSyntaxHighlighter() () from /usr/lib64/libQt5Gui.so.5
#24 0x00007fd4d2119459 in Sonnet::Highlighter::~Highlighter() () from /usr/lib64/libKF5SonnetUi.so.5
#25 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#26 0x00007fd4d675dc1f in QObject::~QObject() () from /usr/lib64/libQt5Core.so.5
#27 0x00007fd4d8e909c3 in ?? () from /usr/lib64/libKF5TextWidgets.so.5
#28 0x00007fd4d8e8c29b in KTextEdit::~KTextEdit() () from /usr/lib64/libKF5TextWidgets.so.5
#29 0x00007fd4d8e8c369 in KTextEdit::~KTextEdit() () from /usr/lib64/libKF5TextWidgets.so.5
#30 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#31 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#32 0x00007fd4dadb29c9 in FieldLineEdit::~FieldLineEdit (this=0x55e0b0856210, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/field/fieldlineedit.cpp:419
#33 0x00007fd4dadaed22 in FieldInput::~FieldInput (this=0x55e0b0855e10, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/field/fieldinput.cpp:280
#34 0x00007fd4dadaed59 in FieldInput::~FieldInput (this=0x55e0b0855e10, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/field/fieldinput.cpp:281
#35 0x00007fd4dade4a7b in EntryConfiguredWidget::~EntryConfiguredWidget (this=0x55e0b07c1320, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/element/elementwidgets.cpp:94
#36 0x00007fd4dade4b29 in EntryConfiguredWidget::~EntryConfiguredWidget (this=0x55e0b07c1320, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/element/elementwidgets.cpp:99
#37 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#38 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#39 0x00007fd4d77b5b59 in QStackedWidget::~QStackedWidget() () from /usr/lib64/libQt5Widgets.so.5
#40 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#41 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#42 0x00007fd4dae2d40b in HidingTabWidget::~HidingTabWidget (this=0x55e0aff60a40, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.8_pre20180504_build/src/gui/kbibtexgui_autogen/IMAN36LHMA/../../../../../kbibtex-0.7.90/src/gui/widgets/hidingtabwidget.h:32
#43 HidingTabWidget::~HidingTabWidget (this=0x55e0aff60a40, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.8_pre20180504_build/src/gui/kbibtexgui_autogen/IMAN36LHMA/../../../../../kbibtex-0.7.90/src/gui/widgets/hidingtabwidget.h:32
#44 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#45 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#46 0x00007fd4dadd92a7 in ElementEditor::~ElementEditor (this=0x55e0aff3cd90, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/element/elementeditor.cpp:467
#47 0x00007fd4dadd9359 in ElementEditor::~ElementEditor (this=0x55e0aff3cd90, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/element/elementeditor.cpp:471
#48 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#49 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#50 0x00007fd4dadc5aba in ElementEditorDialog::~ElementEditorDialog (this=0x55e0aff55570, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/file/fileview.cpp:52
#51 ElementEditorDialog::~ElementEditorDialog (this=0x55e0aff55570, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/file/fileview.cpp:52
#52 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#53 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#54 0x00007fd4dae2d803 in FileView::~FileView (this=0x55e0af878740, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.8_pre20180504_build/src/gui/kbibtexgui_autogen/O3FNYGJQRT/../../../../../kbibtex-0.7.90/src/gui/file/fileview.h:39
#55 FileView::~FileView (this=0x55e0af878740, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.8_pre20180504_build/src/gui/kbibtexgui_autogen/O3FNYGJQRT/../../../../../kbibtex-0.7.90/src/gui/file/fileview.h:39
#56 0x00007fd4d675cb1c in QObjectPrivate::deleteChildren() () from /usr/lib64/libQt5Core.so.5
#57 0x00007fd4d7644beb in QWidget::~QWidget() () from /usr/lib64/libQt5Widgets.so.5
#58 0x00007fd4dadc5f59 in PartWidget::~PartWidget (this=0x55e0af86a900, __in_chrg=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/gui/file/partwidget.cpp:62
#59 0x00007fd4da375ca2 in KParts::Part::~Part() () from /usr/lib64/libKF5Parts.so.5
#60 0x00007fd4afc65bc6 in KBibTeXPart::~KBibTeXPart (this=0x55e0af869500, __in_chrg=<optimized out>, __vtt_parm=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/parts/part.cpp:766
#61 0x00007fd4afc65c29 in KBibTeXPart::~KBibTeXPart (this=0x55e0af869500, __in_chrg=<optimized out>, __vtt_parm=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/parts/part.cpp:769
#62 0x00007fd4d6756f18 in QObject::event(QEvent*) () from /usr/lib64/libQt5Core.so.5
#63 0x00007fd4d7609d6c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQt5Widgets.so.5
#64 0x00007fd4d76115d1 in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQt5Widgets.so.5
#65 0x00007fd4d672d38a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib64/libQt5Core.so.5
#66 0x00007fd4d672fffd in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib64/libQt5Core.so.5
#67 0x00007fd4d677dd43 in ?? () from /usr/lib64/libQt5Core.so.5
#68 0x00007fd4d00bc5a7 in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0
#69 0x00007fd4d00bc810 in ?? () from /usr/lib64/libglib-2.0.so.0
#70 0x00007fd4d00bc8bc in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#71 0x00007fd4d677db2f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#72 0x00007fd4d672c0ca in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5
#73 0x00007fd4d6734654 in QCoreApplication::exec() () from /usr/lib64/libQt5Core.so.5
#74 0x000055e0ad753719 in main (argc=<optimized out>, argv=<optimized out>) at /var/tmp/portage/app-text/kbibtex-0.8_pre20180504/work/kbibtex-0.7.90/src/program/program.cpp:123

I still have problems to reproduce this problem, but thanks to your detailed backtrace I now have an idea what may caused the problem. In EntryConfiguredWidget::~EntryConfiguredWidget (src/gui/element/elementwidgets.cpp) the code deletes Qt Widgets that should/will be automatically deleted by the QObject hierarchy. This double delete may be the cause of the crash.
Try to remove the for-loop in the constructor but keep
delete[] listOfLabeledFieldInput;
Deletion of gridLayout may be removed without harm, too.

Keep me updated if that fixes the crash. If it works, I'll commit a fix.

What is the status of this issue?

(In reply to Christoph Feck from comment #6)
> What is the status of this issue?
I haven't had the opportunity to really look at this yet.

@Thomas:
I see that in the mean time the Gentoo devs have updated kbibtex to a 20180526 release (of master, I guess). In case the suggested change is included there, I can easily test this in the coming week.