Dear Maintainer, I tried to have a look at this issue.
This is the stack with debug symbols: (gdb) bt #0 QByteArray::QByteArray (a=..., this=0x7fffffffd4e8) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qbytearray.h:492 #1 QList<QByteArray>::takeLast (this=0x7fffffffd4e0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:565 #2 ConsoleHtml::updateView (this=0x555555ab9ac0) at ./src/consolehtml.cpp:182 #3 0x0000555555572dd6 in ConsoleHtml::clear (this=<optimized out>) at ./src/consolehtml.cpp:227 #4 0x0000555555577da5 in ConsoleHtml::qt_static_metacall (_o=<optimized out>, _id=<optimized out>, _a=0x7fffffffd6a0, _c=<optimized out>) at ./obj-x86_64-linux-gnu/src/kalgebra_autogen/EWIEGA46WW/moc_consolehtml.cpp:134 #5 0x00007ffff69df28b in QMetaObject::activate(QObject*, int, int, void**) () at kernel/qobject.cpp:3771 #6 0x00007ffff69df8a7 in QMetaObject::activate (sender=sender@entry=0x555555be7820, m=m@entry=0x7ffff77f5840 <QAction::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7fffffffd6a0) at kernel/qobject.cpp:3633 #7 0x00007ffff7325ee2 in QAction::triggered (this=this@entry=0x555555be7820, _t1=<optimized out>) at .moc/moc_qaction.cpp:376 #8 0x00007ffff73284f0 in QAction::activate (this=0x555555be7820, event=<optimized out>) at kernel/qaction.cpp:1166 #9 0x00007ffff7498e1c in QMenuPrivate::activateCausedStack (this=this@entry=0x555555be3bb0, causedStack={...}, action=action@entry=0x555555be7820, action_e=action_e@entry=QAction::Trigger, self=self@entry=true) at widgets/qmenu.cpp:1371 #10 0x00007ffff74a03f0 in QMenuPrivate::activateAction (this=this@entry=0x555555be3bb0, action=action@entry=0x555555be7820, action_e=action_e@entry=QAction::Trigger, self=self@entry=true) at widgets/qmenu.cpp:1448 #11 0x00007ffff74a141b in QMenu::mouseReleaseEvent (this=<optimized out>, e=0x7fffffffdcb0) at widgets/qmenu.cpp:2942 #12 0x00007ffff736a7c8 in QWidget::event (this=this@entry=0x555555bbd0a0, event=event@entry=0x7fffffffdcb0) at kernel/qwidget.cpp:8925 #13 0x00007ffff74a3aab in QMenu::event (this=0x555555bbd0a0, e=0x7fffffffdcb0) at widgets/qmenu.cpp:3064 #14 0x00007ffff732c491 in QApplicationPrivate::notify_helper (this=this@entry=0x555555784680, receiver=receiver@entry=0x555555bbd0a0, e=e@entry=0x7fffffffdcb0) at kernel/qapplication.cpp:3727 #15 0x00007ffff7333d18 in QApplication::notify(QObject*, QEvent*) () at kernel/qapplication.cpp:3203 #16 0x00007ffff69b6039 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at ../../include/QtCore/5.11.2/QtCore/private/../../../../../src/corelib/thread/qthread_p.h:307 #17 0x00007ffff7333019 in QCoreApplication::sendEvent (event=<optimized out>, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:234 #18 QApplicationPrivate::sendMouseEvent (receiver=receiver@entry=0x555555bbd0a0, event=event@entry=0x7fffffffdcb0, alienWidget=0x0, alienWidget@entry=0x555555bbd0a0, nativeWidget=0x555555bbd0a0, buttonDown=buttonDown@entry=0x7ffff7824870 <qt_button_down>, lastMouseReceiver=..., spontaneous=true) at kernel/qapplication.cpp:2695 #19 0x00007ffff73856c3 in QWidgetWindow::handleMouseEvent(QMouseEvent*) () at kernel/qwidgetwindow.cpp:556 #20 0x00007ffff7387e8e in QWidgetWindow::event (this=0x7fffd8007910, event=0x7fffffffe0b0) at kernel/qwidgetwindow.cpp:281 #21 0x00007ffff732c491 in QApplicationPrivate::notify_helper (this=this@entry=0x555555784680, receiver=receiver@entry=0x7fffd8007910, e=e@entry=0x7fffffffe0b0) at kernel/qapplication.cpp:3727 #22 0x00007ffff7333ad0 in QApplication::notify(QObject*, QEvent*) () at kernel/qapplication.cpp:3486 #23 0x00007ffff69b6039 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at ../../include/QtCore/5.11.2/QtCore/private/../../../../../src/corelib/thread/qthread_p.h:307 #24 0x00007ffff6d5fb2b in QCoreApplication::sendSpontaneousEvent (event=0x7fffffffe0b0, receiver=0x7fffd8007910) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:237 #25 QGuiApplicationPrivate::processMouseEvent (e=0x555556940e70) at kernel/qguiapplication.cpp:2081 #26 0x00007ffff6d61a25 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x555556940e70) at kernel/qguiapplication.cpp:1816 #27 0x00007ffff6d3bd8b in QWindowSystemInterface::sendWindowSystemEvents (flags=...) at kernel/qwindowsysteminterface.cpp:1032 #28 0x00007fffddc4985b in QPAEventDispatcherGlib::processEvents (this=0x555555800360, flags=...) at qeventdispatcher_glib.cpp:70 #29 0x00007ffff69b4d0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at ../../include/QtCore/../../src/corelib/global/qflags.h:140 #30 0x00007ffff69bce82 in QCoreApplication::exec() () at ../../include/QtCore/../../src/corelib/global/qflags.h:120 #31 0x00005555555661a9 in main (argc=<optimized out>, argv=<optimized out>) at ./src/main.cpp:43 In ConsoleHtml::clear is unconditionally the last element retrieved, even when the log is empty. 182 const auto newEntry = log.takeLast(); It looks like upstream have fixed this in commit [1]. This is contained in branch Applications/18.08. Have not found a matching upstream bug. Kind regards, Bernhard [1] https://cgit.kde.org/kalgebra.git/commit/src/consolehtml.cpp?id=aaf3ffd1e1e874ebadae29d846bee18ad0b912a7
apt update apt dist-upgrade apt install xserver-xorg lightdm openbox systemd-coredump gdb valgrind kalgebra systemctl start lightdm export LANG=C export DISPLAY=:0 kalgebra ########### benutzer@debian:~$ gdb -q --args kalgebra Reading symbols from kalgebra...(no debugging symbols found)...done. (gdb) run Starting program: /usr/bin/kalgebra [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [New Thread 0x7fffdce9e700 (LWP 13068)] ... [New Thread 0x7fff3b5ff700 (LWP 13119)] [Thread 0x7fff3b5ff700 (LWP 13119) exited] Thread 1 "kalgebra" received signal SIGSEGV, Segmentation fault. 0x0000555555572691 in ?? () (gdb) bt #0 0x0000555555572691 in ?? () #1 0x0000555555577da5 in ?? () #2 0x00007ffff69e228b in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #3 0x00007ffff7328ee2 in QAction::triggered(bool) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #4 0x00007ffff732b4f0 in QAction::activate(QAction::ActionEvent) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #5 0x00007ffff749be1c in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #6 0x00007ffff74a33f0 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #7 0x00007ffff74a441b in QMenu::mouseReleaseEvent(QMouseEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #8 0x00007ffff736d7c8 in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #9 0x00007ffff74a6aab in QMenu::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #10 0x00007ffff732f491 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #11 0x00007ffff7336d18 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #12 0x00007ffff69b9039 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #13 0x00007ffff7336019 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #14 0x00007ffff73886c3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #15 0x00007ffff738ae8e in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #16 0x00007ffff732f491 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #17 0x00007ffff7336ad0 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5 #18 0x00007ffff69b9039 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #19 0x00007ffff6d62b2b in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5 #20 0x00007ffff6d64a25 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5 #21 0x00007ffff6d3ed8b in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5 #22 0x00007fffddc4f85b in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 #23 0x00007ffff69b7d0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #24 0x00007ffff69bfe82 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 #25 0x00005555555661a9 in ?? () #26 0x00007ffff6430b17 in __libc_start_main (main=0x555555565f00, argc=1, argv=0x7fffffffe648, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffe638) at ../csu/libc-start.c:310 #27 0x000055555556622a in _start () ############### apt install xserver-xorg lightdm openbox systemd-coredump gdb valgrind git kalgebra kalgebra-dbgsym libqt5core5a-dbgsym libqt5gui5-dbgsym libqt5widgets5-dbgsym qtbase5-dev mkdir .gdb cd .gdb git clone https://github.com/Lekensteyn/qt5printers.git cat << EOF > qt5-gdbinit python import sys, os.path sys.path.insert(0, os.path.expanduser('~/.gdb')) import qt5printers qt5printers.register_printers(gdb.current_objfile()) end EOF cd .. mkdir kalgebra/orig -p cd kalgebra/orig apt source kalgebra cd ../.. benutzer@debian:~$ gdb -q --args kalgebra Reading symbols from kalgebra...Reading symbols from /usr/lib/debug/.build-id/db/c25dd2c87a837265a5fccb742e0b65684c3166.debug...done. done. (gdb) set width 0 (gdb) set pagination off (gdb) directory /home/benutzer/kalgebra/orig/kalgebra-17.08.3 Source directories searched: /home/benutzer/kalgebra/orig/kalgebra-17.08.3:$cdir:$cwd (gdb) source .gdb/qt5-gdbinit (gdb) display/i $pc 1: x/i $pc <error: No registers.> (gdb) run Starting program: /usr/bin/kalgebra [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [New Thread 0x7fffdce9d700 (LWP 21893)] [New Thread 0x7fffd3078700 (LWP 21894)] [New Thread 0x7fffd2877700 (LWP 21895)] [New Thread 0x7fffd2076700 (LWP 21896)] [New Thread 0x7fffd1875700 (LWP 21897)] [New Thread 0x7fffd1074700 (LWP 21898)] [New Thread 0x7fffd0873700 (LWP 21899)] [New Thread 0x7fffbbfff700 (LWP 21900)] [New Thread 0x7fffbb7fe700 (LWP 21901)] [New Thread 0x7fffbaffd700 (LWP 21902)] [New Thread 0x7fffb9f92700 (LWP 21904)] [New Thread 0x7fffb9791700 (LWP 21906)] [New Thread 0x7fffb8f90700 (LWP 21907)] [New Thread 0x7fff9bfff700 (LWP 21908)] [New Thread 0x7fff9b7fe700 (LWP 21909)] [New Thread 0x7fff9affd700 (LWP 21910)] [New Thread 0x7fff9a7fc700 (LWP 21911)] [New Thread 0x7fff99ffb700 (LWP 21912)] [New Thread 0x7fff997fa700 (LWP 21913)] [New Thread 0x7fff98ff9700 (LWP 21914)] [New Thread 0x7fff83fff700 (LWP 21915)] [New Thread 0x7fff837fe700 (LWP 21916)] [New Thread 0x7fff82ffd700 (LWP 21917)] [New Thread 0x7fff827fc700 (LWP 21918)] [New Thread 0x7fff81ffb700 (LWP 21919)] [New Thread 0x7fff817fa700 (LWP 21920)] [New Thread 0x7fff80ff9700 (LWP 21921)] [New Thread 0x7fff7bfff700 (LWP 21922)] [New Thread 0x7fff7b7fe700 (LWP 21923)] [New Thread 0x7fff7affd700 (LWP 21924)] [New Thread 0x7fff7a7fc700 (LWP 21925)] [New Thread 0x7fff79ffb700 (LWP 21926)] [New Thread 0x7fff797fa700 (LWP 21934)] [New Thread 0x7fff43fff700 (LWP 21943)] [Thread 0x7fff43fff700 (LWP 21943) exited] Thread 1 "kalgebra" received signal SIGSEGV, Segmentation fault. QByteArray::QByteArray (a=..., this=0x7fffffffd4e8) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qbytearray.h:492 warning: Source file is more recent than executable. 492 inline const char *QByteArray::constData() const 1: x/i $pc => 0x555555572691 <ConsoleHtml::updateView()+257>: mov (%rdx),%eax (gdb) bt #0 QByteArray::QByteArray (a=..., this=0x7fffffffd4e8) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qbytearray.h:492 #1 QList<QByteArray>::takeLast (this=0x7fffffffd4e0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:565 #2 ConsoleHtml::updateView (this=0x555555ab9ac0) at ./src/consolehtml.cpp:182 #3 0x0000555555572dd6 in ConsoleHtml::clear (this=<optimized out>) at ./src/consolehtml.cpp:227 #4 0x0000555555577da5 in ConsoleHtml::qt_static_metacall (_o=<optimized out>, _id=<optimized out>, _a=0x7fffffffd6a0, _c=<optimized out>) at ./obj-x86_64-linux-gnu/src/kalgebra_autogen/EWIEGA46WW/moc_consolehtml.cpp:134 #5 0x00007ffff69df28b in QMetaObject::activate(QObject*, int, int, void**) () at kernel/qobject.cpp:3771 #6 0x00007ffff69df8a7 in QMetaObject::activate (sender=sender@entry=0x555555be7820, m=m@entry=0x7ffff77f5840 <QAction::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7fffffffd6a0) at kernel/qobject.cpp:3633 #7 0x00007ffff7325ee2 in QAction::triggered (this=this@entry=0x555555be7820, _t1=<optimized out>) at .moc/moc_qaction.cpp:376 #8 0x00007ffff73284f0 in QAction::activate (this=0x555555be7820, event=<optimized out>) at kernel/qaction.cpp:1166 #9 0x00007ffff7498e1c in QMenuPrivate::activateCausedStack (this=this@entry=0x555555be3bb0, causedStack={...}, action=action@entry=0x555555be7820, action_e=action_e@entry=QAction::Trigger, self=self@entry=true) at widgets/qmenu.cpp:1371 #10 0x00007ffff74a03f0 in QMenuPrivate::activateAction (this=this@entry=0x555555be3bb0, action=action@entry=0x555555be7820, action_e=action_e@entry=QAction::Trigger, self=self@entry=true) at widgets/qmenu.cpp:1448 #11 0x00007ffff74a141b in QMenu::mouseReleaseEvent (this=<optimized out>, e=0x7fffffffdcb0) at widgets/qmenu.cpp:2942 #12 0x00007ffff736a7c8 in QWidget::event (this=this@entry=0x555555bbd0a0, event=event@entry=0x7fffffffdcb0) at kernel/qwidget.cpp:8925 #13 0x00007ffff74a3aab in QMenu::event (this=0x555555bbd0a0, e=0x7fffffffdcb0) at widgets/qmenu.cpp:3064 #14 0x00007ffff732c491 in QApplicationPrivate::notify_helper (this=this@entry=0x555555784680, receiver=receiver@entry=0x555555bbd0a0, e=e@entry=0x7fffffffdcb0) at kernel/qapplication.cpp:3727 #15 0x00007ffff7333d18 in QApplication::notify(QObject*, QEvent*) () at kernel/qapplication.cpp:3203 #16 0x00007ffff69b6039 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at ../../include/QtCore/5.11.2/QtCore/private/../../../../../src/corelib/thread/qthread_p.h:307 #17 0x00007ffff7333019 in QCoreApplication::sendEvent (event=<optimized out>, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:234 #18 QApplicationPrivate::sendMouseEvent (receiver=receiver@entry=0x555555bbd0a0, event=event@entry=0x7fffffffdcb0, alienWidget=0x0, alienWidget@entry=0x555555bbd0a0, nativeWidget=0x555555bbd0a0, buttonDown=buttonDown@entry=0x7ffff7824870 <qt_button_down>, lastMouseReceiver=..., spontaneous=true) at kernel/qapplication.cpp:2695 #19 0x00007ffff73856c3 in QWidgetWindow::handleMouseEvent(QMouseEvent*) () at kernel/qwidgetwindow.cpp:556 #20 0x00007ffff7387e8e in QWidgetWindow::event (this=0x7fffd8007910, event=0x7fffffffe0b0) at kernel/qwidgetwindow.cpp:281 #21 0x00007ffff732c491 in QApplicationPrivate::notify_helper (this=this@entry=0x555555784680, receiver=receiver@entry=0x7fffd8007910, e=e@entry=0x7fffffffe0b0) at kernel/qapplication.cpp:3727 #22 0x00007ffff7333ad0 in QApplication::notify(QObject*, QEvent*) () at kernel/qapplication.cpp:3486 #23 0x00007ffff69b6039 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at ../../include/QtCore/5.11.2/QtCore/private/../../../../../src/corelib/thread/qthread_p.h:307 #24 0x00007ffff6d5fb2b in QCoreApplication::sendSpontaneousEvent (event=0x7fffffffe0b0, receiver=0x7fffd8007910) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:237 #25 QGuiApplicationPrivate::processMouseEvent (e=0x555556940e70) at kernel/qguiapplication.cpp:2081 #26 0x00007ffff6d61a25 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x555556940e70) at kernel/qguiapplication.cpp:1816 #27 0x00007ffff6d3bd8b in QWindowSystemInterface::sendWindowSystemEvents (flags=...) at kernel/qwindowsysteminterface.cpp:1032 #28 0x00007fffddc4985b in QPAEventDispatcherGlib::processEvents (this=0x555555800360, flags=...) at qeventdispatcher_glib.cpp:70 #29 0x00007ffff69b4d0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at ../../include/QtCore/../../src/corelib/global/qflags.h:140 #30 0x00007ffff69bce82 in QCoreApplication::exec() () at ../../include/QtCore/../../src/corelib/global/qflags.h:120 #31 0x00005555555661a9 in main (argc=<optimized out>, argv=<optimized out>) at ./src/main.cpp:43 (gdb) print this $1 = (QByteArray * const) 0x7fffffffd4e8 (gdb) print *this $2 = <error reading variable: Cannot access memory at address 0x10> (gdb) up #1 QList<QByteArray>::takeLast (this=0x7fffffffd4e0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:565 warning: Source file is more recent than executable. 565 { T t = std::move(last()); removeLast(); return t; } (gdb) print this $3 = (QList<QByteArray> * const) 0x7fffffffd4e0 (gdb) print *this $4 = <empty> (gdb) up #2 ConsoleHtml::updateView (this=0x555555ab9ac0) at ./src/consolehtml.cpp:182 182 const auto newEntry = log.takeLast(); (gdb) list ConsoleHtml::updateView 173 void ConsoleHtml::updateView() 174 { 175 QByteArray code; 176 code += "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>\n"; 177 code += "<html xmlns=\"http://www.w3.org/1999/xhtml\" xml:lang=\"en\">\n<head>\n\t<title> :) </title>\n"; 178 code += m_model->css(); 179 code += "</head>\n<body>"; 180 181 auto log = m_model->htmlLog(); 182 const auto newEntry = log.takeLast(); 183 foreach(const QString &entry, log) 184 code += "<p class='normal'>" + entry + "</p>\n"; 185 186 code += m_optionsString.toUtf8(); 187 if (newEntry.startsWith("<ul class='error'>")) 188 code += newEntry; 189 else 190 code += "<p class='last'>" + newEntry + "</p>\n"; 191 code += "</body></html>"; 192 193 page()->setHtml(code); 194 195 emit changed(); 196 197 QObject* o = new QObject; 198 connect(this, &QWebEngineView::loadFinished, o, [this, o](){ 199 page()->runJavaScript(QStringLiteral("window.scrollTo(0, document.body.scrollHeight);")); 200 delete o; 201 }); 202 } 203 ########### set width 0 set pagination off directory /home/benutzer/kalgebra/orig/kalgebra-17.08.3 source .gdb/qt5-gdbinit display/i $pc run b ConsoleHtml::clear record cont ########### https://cgit.kde.org/kalgebra.git/commit/src/consolehtml.cpp?id=aaf3ffd1e1e874ebadae29d846bee18ad0b912a7