Strange crash with a wrong functions stack

[mmmm1998]

I am not sure, that this is problem of Qalculate, but when I use try to use Qalculate in the program (Cantor), I have this strange crash. This is gdb log (qalculate builded manually with debug symbols)

$ gdb --args cantor -b qalculate
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Reading symbols from cantor...done.
(gdb) r
Starting program: /usr/local/bin/cantor -b qalculate
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffdf7a0700 (LWP 14991)]
[New Thread 0x7fffd5968700 (LWP 14992)]
[New Thread 0x7fffd4cf6700 (LWP 14994)]
[New Thread 0x7fffcffff700 (LWP 14995)]
dir:  "/usr/local/lib/x86_64-linux-gnu/plugins/cantor/backends"
Creating PythonBackend
Creating PythonBackend
dir:  "/usr/lib/x86_64-linux-gnu/qt5/plugins/cantor/backends"
dir:  "/usr/local/bin/cantor/backends"
[New Thread 0x7fffb92cf700 (LWP 14998)]
Backend  "Qalculate"  offers extensions:  ("HistoryExtension", "VariableManagementExtension", "CalculusExtension", "CASExtension", "LinearAlgebraExtension", "QalculatePlotExtension")
QalculateSession(0x555555dd2730) Cantor::VariableManagementExtension(0x555555a7f3c0, name = "VariableManagementExtension")

Thread 1 "cantor" received signal SIGSEGV, Segmentation fault.
__GI___libc_free (mem=0xffb2b6bbffb2b6bb) at malloc.c:3103
3103	malloc.c: Нет такого файла или каталога.
(gdb) where
#0  0x00007ffff3cc998d in __GI___libc_free (mem=0xffb2b6bbffb2b6bb) at malloc.c:3103
#1  0x00007fffed933593 in SampledFunction::~SampledFunction() () at /usr/lib/x86_64-linux-gnu/libpoppler.so.73
#2  0x00007fffed9335c9 in SampledFunction::~SampledFunction() () at /usr/lib/x86_64-linux-gnu/libpoppler.so.73
#3  0x00007fffbf3927fc in Calculator::addFunction(MathFunction*, bool, bool) (this=0x555555dd31e0, f=
    0x555555dd8fa0, force=true, check_names=true) at Calculator.cc:3378
#4  0x00007fffbf37feed in Calculator::addBuiltinFunctions() (this=0x555555dd31e0) at Calculator.cc:1285
#5  0x00007fffbf377cd8 in Calculator::Calculator() (this=0x555555dd31e0) at Calculator.cc:437
#6  0x00007fffbf7d9ac0 in QalculateSession::QalculateSession(Cantor::Backend*) (this=0x555555dd2730, backend=0x555555956390)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/backends/qalculate/qalculatesession.cpp:54
#7  0x00007fffbf7cfdef in QalculateBackend::createSession() (this=0x555555956390)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/backends/qalculate/qalculatebackend.cpp:54
#8  0x00007fffbdfc0a6b in Worksheet::initSession(Cantor::Backend*) (this=0x555555c086d0, backend=0x555555956390)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/worksheet.cpp:1284
#9  0x00007fffbdfba37e in Worksheet::Worksheet(Cantor::Backend*, QWidget*, bool) (this=0x555555c086d0, backend=0x555555956390, parent=0x555555dc7cd0, useDeafultWorksheetParameters=true) at /home/mmmm1998/Документы/Репозитории/cantor/src/worksheet.cpp:102
#10 0x00007fffbdfa95a5 in CantorPart::CantorPart(QWidget*, QObject*, QList<QVariant> const&) (this=0x555555dcf210, parentWidget=0x555555d487d0, parent=0x555555d487d0, args=..., __in_chrg=<optimized out>, __vtt_parm=<optimized out>)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/cantor_part.cpp:140
#11 0x00007fffbdfb7565 in KPluginFactory::createPartInstance<CantorPart>(QWidget*, QObject*, QList<QVariant> const&) (parentWidget=0x555555d487d0, parent=0x555555d487d0, args=...) at /usr/local/include/KF5/KCoreAddons/kpluginfactory.h:539
#12 0x00007ffff5f7fa60 in KPluginFactory::create(char const*, QWidget*, QObject*, QList<QVariant> const&, QString const&) ()
    at /usr/local/lib/x86_64-linux-gnu/libKF5CoreAddons.so.5
#13 0x000055555556f94f in KPluginFactory::create<KParts::ReadWritePart>(QObject*, QList<QVariant> const&) (this=0x555555dcf0f0, parent=0x555555d487d0, args=...) at /usr/local/include/KF5/KCoreAddons/kpluginfactory.h:551
#14 0x0000555555567d05 in CantorShell::addWorksheet(QString const&) (this=0x55555593b600, backendName=...)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/cantor.cpp:342
#15 0x00005555555632f7 in main(int, char**) (argc=3, argv=0x7fffffffda58)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/main.cpp:127
(gdb) frame 3
#3  0x00007fffbf3927fc in Calculator::addFunction (this=0x555555dd31e0, f=0x555555dd8fa0, force=true, check_names=true)
    at Calculator.cc:3378
3378				f->setName(getName(f->getName(i).name, f, force), i);
(gdb) frame 2
#2  0x00007fffed9335c9 in SampledFunction::~SampledFunction() () from /usr/lib/x86_64-linux-gnu/libpoppler.so.73
(gdb) frame 3
#3  0x00007fffbf3927fc in Calculator::addFunction (this=0x555555dd31e0, f=0x555555dd8fa0, force=true, check_names=true)
    at Calculator.cc:3378
3378				f->setName(getName(f->getName(i).name, f, force), i);
(gdb) p f
$1 = (MathFunction *) 0x555555dd8fa0
(gdb) p i
$2 = 1
(gdb) p force
$3 = true
(gdb) frame 6
#6  0x00007fffbf7d9ac0 in QalculateSession::QalculateSession (this=0x555555dd2730, backend=0x555555956390)
    at /home/mmmm1998/Документы/Репозитории/cantor/src/backends/qalculate/qalculatesession.cpp:54
54	             new Calculator();
(gdb) 

As you can see, code from Qalculate somehow go to poppler code (poppler is a library for working with pdfs, also used in Cantor).
Any ideas, why it goes like that?

[mmmm1998]

Also, maybe this is a just coincidence, but MathFunction from Qalculate placed in Function.h source file and SampledFunction from poppler place in a file with the same filename (link to file)

[mmmm1998]

Also, the problem produced only in Cantor program: using the same code, but in clear main.cpp, even with poppler library don't crash.

[hanna-kn]

I was able to fix Cantor crashing on startup (on my system) by renaming the IdentityFunction class in libqalculate (there is a class with the same name in Poppler).

[mmmm1998]

Yes, I confirm, that after c784307 the problem is gone.