libmpfr causes the process to exit SIGSEGV when closing the application

[sp1ritCS]

This happens when 1 - 1 / e^2 was calculated at any time during the runtime of the app.

Based on the following backtrace,

#0  0x00007ffff5362c68 in mpfr_clear (m=0x7fffd4039ac0) at /usr/src/debug/mpfr-4.1.1/src/clear.c:29
#1  0x00007ffff539437a in mpfr_clears (x=<optimized out>) at /usr/src/debug/mpfr-4.1.1/src/clears.c:56
#2  0x00007ffff69f6ad1 in Number::~Number() (this=0x7fffd4039a98, this=<optimized out>) at /usr/src/debug/libqalculate-4.5.0/libqalculate/Number.cc:448
#3  0x00007ffff6a43692 in MathStructure::~MathStructure() (this=0x7fffd4039a30, this=<optimized out>)
    at /usr/src/debug/libqalculate-4.5.0/libqalculate/MathStructure.cc:214
#4  0x00007ffff69f0e8b in KnownVariable::~KnownVariable() (this=0x7fffe0066a60, this=<optimized out>)
    at /usr/src/debug/libqalculate-4.5.0/libqalculate/Variable.cc:291
#5  0x00007ffff69f0fb7 in DynamicVariable::~DynamicVariable() (this=<optimized out>, this=<optimized out>)
    at /usr/src/debug/libqalculate-4.5.0/libqalculate/Variable.cc:557
#6  0x00007ffff69f1297 in EVariable::~EVariable() (this=0x7fffe0066a60, this=<optimized out>)
    at /usr/src/debug/libqalculate-4.5.0/libqalculate/Variable.h:420
#7  EVariable::~EVariable() (this=0x7fffe0066a60, this=<optimized out>) at /usr/src/debug/libqalculate-4.5.0/libqalculate/Variable.h:420
#8  0x00007ffff6935c67 in Calculator::~Calculator() (this=0x7fffe00ace00, this=<optimized out>)
    at /usr/src/debug/libqalculate-4.5.0/libqalculate/Calculator.cc:603
#9  0x00007ffff6936ad9 in Calculator::~Calculator() (this=0x7fffe00ace00, this=<optimized out>)
    at /usr/src/debug/libqalculate-4.5.0/libqalculate/Calculator.cc:618
#10 0x00005555555878ba in std::_Sp_counted_ptr<Calculator*, (__gnu_cxx::_Lock_policy)2>::_M_dispose() (this=0x7fffe00d2c30)
    at /usr/include/c++/12/bits/shared_ptr_base.h:428
#11 std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() (this=0x7fffe00d2c30) at /usr/include/c++/12/bits/shared_ptr_base.h:346
#12 std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() (this=0x7fffe00d2c30) at /usr/include/c++/12/bits/shared_ptr_base.h:317
#13 std::__shared_count<(__gnu_cxx::_Lock_policy)2>::~__shared_count() (this=<optimized out>, this=<optimized out>)
    at /usr/include/c++/12/bits/shared_ptr_base.h:1071
#14 std::__shared_ptr<Calculator, (__gnu_cxx::_Lock_policy)2>::~__shared_ptr() (this=<optimized out>, this=<optimized out>)
    at /usr/include/c++/12/bits/shared_ptr_base.h:1524
#15 std::shared_ptr<Calculator>::~shared_ptr() (this=<optimized out>, this=<optimized out>) at /usr/include/c++/12/bits/shared_ptr.h:175
#16 0x00007ffff6245095 in __run_exit_handlers
    (status=0, listp=0x7ffff63ea820 <__exit_funcs>, run_list_atexit=run_list_atexit@entry=true, run_dtors=run_dtors@entry=true) at exit.c:113
#17 0x00007ffff6245220 in __GI_exit (status=<optimized out>) at exit.c:143
#18 0x00007ffff622c5b7 in __libc_start_call_main (main=main@entry=0x5555555668f0 <main(int, char**)>, argc=argc@entry=1, argv=argv@entry=0x7fffffffd0a8)
    at ../sysdeps/nptl/libc_start_call_main.h:74
#19 0x00007ffff622c679 in __libc_start_main_impl
     (main=0x5555555668f0 <main(int, char**)>, argc=1, argv=0x7fffffffd0a8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffd098) at ../csu/libc-start.c:381
#20 0x0000555555566ac5 in _start () at ../sysdeps/x86_64/start.S:115

the issue seems to be caused in the destructor of libqalculate Number class, likely by an erroneous use of mpfr_clears here.

This seems obviously more like an error with libqalculate, however I wasn't able to reproduce it in qalc, so I'm reporting it here. Feel free to forward if this isn't nasc's issue.

This happens on openSUSE Tumbleweed 20230106 with:

• NASC: nasc-0.5.4-2.17.x86_64
• libqalculate: libqalculate22-4.5.0-1.1.x86_64
• MPFR: libmpfr6-4.1.1-3.1.x86_64