gistfile1.txt

$ perl6-gdb-m -e 'class Foo {};  my $fb = Metamodel::ClassHOW.new_type(name => "Foo::Bar"); $fb.^add_parent(Foo); $fb.^compose;'
================================================================================================
This is Rakudo Perl 6 running in the GNU debugger, which often allwos to generate useful back-
traces to debug or report issues in Rakudo, the MoarVM backend or the currently running code.

The currently used MoarVM backend is not compiled with debugging symbols, you might want to
reconfigure and reinstall MoarVM with --debug enabled.

This Rakudo version is 2015.3.186.g.260.e.3.cd built on MoarVM version 2015.3.64.g.79.b.6087,
running on ubuntu (14.4.2.LTS.Trusty.Tahr) / linux (81.Ubuntu.SMP.Tue.Mar.24.19.29.48.UTC.2015)

Type `bt full` to generate a backtrace if applicable, type `q` to quite or `help` for help.
------------------------------------------------------------------------------------------------
Reading symbols from /home/froggs/dev/nqp/install/bin/moar...done.
Starting program: /home/froggs/dev/nqp/install/bin/moar --execname=/home/froggs/dev/nqp/install/bin/perl6-gdb-m --libpath=/home/froggs/dev/nqp/install/share/nqp/lib --libpath=/home/froggs/dev/nqp/install/share/perl6/lib --libpath=/home/froggs/dev/nqp/install/share/perl6/runtime /home/froggs/dev/nqp/install/share/perl6/runtime/perl6.moarvm -e class\ Foo\ \{\}\;\ \ my\ \$fb\ =\ Metamodel::ClassHOW.new_type\(name\ =\>\ \"Foo::Bar\"\)\;\ \$fb.\^add_parent\(Foo\)\;\ \$fb.\^compose\;
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff79995e5 in MVM_sc_get_collectable_sc (tc=<optimized out>, col=0x7ffff65f9e18) at src/6model/sc.h:69
69	    return sc_idx > 0 ? tc->instance->all_scs[sc_idx]->sc : NULL;
(gdb) p sc_idx
$1 = <optimized out>
(gdb) bt full
#0  0x00007ffff79995e5 in MVM_sc_get_collectable_sc (tc=<optimized out>, col=0x7ffff65f9e18) at src/6model/sc.h:69
No locals.
#1  MVM_sc_get_obj_sc (obj=0x7ffff65f9e18, tc=0x6036c0) at src/6model/sc.h:74
No locals.
#2  MVM_sc_wb_hit_obj (tc=0x6036c0, obj=0x7ffff65f9e18) at src/6model/sc.c:312
        comp_sc = 0x29242f0
#3  0x00007ffff79526fd in MVM_SC_WB_OBJ (obj=<optimized out>, tc=<optimized out>) at src/6model/sc.h:155
No locals.
#4  MVM_interp_run (tc=tc@entry=0x6036c0, initial_invoke=0xec6a38, invoke_data=0x61ffe0) at src/core/interp.c:2370
        obj = 0x7ffff65f9e18
        op = 65504
        LABELS = {0x7ffff79409d9 <MVM_interp_run+153>, 0x7ffff794a1cc <MVM_interp_run+39052>, 0x7ffff7940a2e <MVM_interp_run+238>, 0x7ffff7940a2e <MVM_interp_run+238>, 
          0x7ffff794a073 <MVM_interp_run+38707>, 0x7ffff794a0b6 <MVM_interp_run+38774>, 0x7ffff794a1d1 <MVM_interp_run+39057>, 0x7ffff794a216 <MVM_interp_run+39126>, 
          0x7ffff79472ad <MVM_interp_run+26989>, 0x7ffff794845f <MVM_interp_run+31519>, 0x7ffff79486f4 <MVM_interp_run+32180>, 0x7ffff79486f9 <MVM_interp_run+32185>, 
          0x7ffff79482a7 <MVM_interp_run+31079>, 0x7ffff79486ef <MVM_interp_run+32175>, 0x7ffff7948598 <MVM_interp_run+31832>, 0x7ffff7948705 <MVM_interp_run+32197>, 
          0x7ffff794a93e <MVM_interp_run+40958>, 0x7ffff794a943 <MVM_interp_run+40963>, 0x7ffff794a948 <MVM_interp_run+40968>, 0x7ffff794a955 <MVM_interp_run+40981>, 
          0x7ffff7946be1 <MVM_interp_run+25249>, 0x7ffff7940a02 <MVM_interp_run+194>, 0x7ffff7940a08 <MVM_interp_run+200>, 0x7ffff7948119 <MVM_interp_run+30681>, 
          0x7ffff79482ac <MVM_interp_run+31084>, 0x7ffff79481d8 <MVM_interp_run+30872>, 0x7ffff7948239 <MVM_interp_run+30969>, 0x7ffff7948314 <MVM_interp_run+31188>, 
          0x7ffff794837b <MVM_interp_run+31291>, 0x7ffff794816a <MVM_interp_run+30762>, 0x7ffff7948685 <MVM_interp_run+32069>, 0x7ffff794859d <MVM_interp_run+31837>, 
          0x7ffff7948619 <MVM_interp_run+31961>, 0x7ffff79483f0 <MVM_interp_run+31408>, 0x7ffff794e247 <MVM_interp_run+55559>, 0x7ffff794a84a <MVM_interp_run+40714>, 
          0x7ffff794a8c7 <MVM_interp_run+40839>, 0x7ffff79498ec <MVM_interp_run+36780>, 0x7ffff7949953 <MVM_interp_run+36883>, 0x7ffff794970d <MVM_interp_run+36301>, 
          0x7ffff7949774 <MVM_interp_run+36404>, 0x7ffff794aa22 <MVM_interp_run+41186>, 0x7ffff794aa8e <MVM_interp_run+41294>, 0x7ffff794a766 <MVM_interp_run+40486>, 
          0x7ffff794a7d2 <MVM_interp_run+40594>, 0x7ffff7940a41 <MVM_interp_run+257>, 0x7ffff7940a41 <MVM_interp_run+257>, 0x7ffff79516f7 <MVM_interp_run+69047>, 
          0x7ffff7950b51 <MVM_interp_run+66065>, 0x7ffff794efee <MVM_interp_run+59054>, 0x7ffff7950920 <MVM_interp_run+65504>, 0x7ffff794a965 <MVM_interp_run+40997>, 
          0x7ffff794a9c3 <MVM_interp_run+41091>, 0x7ffff794a0c9 <MVM_interp_run+38793>, 0x7ffff794a127 <MVM_interp_run+38887>, 0x7ffff794a185 <MVM_interp_run+38981>, 
          0x7ffff794b049 <MVM_interp_run+42761>, 0x7ffff794b09d <MVM_interp_run+42845>, 0x7ffff794b0f1 <MVM_interp_run+42929>, 0x7ffff794b145 <MVM_interp_run+43013>, 
          0x7ffff794b199 <MVM_interp_run+43097>, 0x7ffff7949f09 <MVM_interp_run+38345>, 0x7ffff794eed5 <MVM_interp_run+58773>, 0x7ffff794a268 <MVM_interp_run+39208>, 
          0x7ffff794a2b7 <MVM_interp_run+39287>, 0x7ffff794a306 <MVM_interp_run+39366>, 0x7ffff794a356 <MVM_interp_run+39446>, 0x7ffff794a3d2 <MVM_interp_run+39570>, 
          0x7ffff794aafc <MVM_interp_run+41404>, 0x7ffff794a423 <MVM_interp_run+39651>, 0x7ffff794a474 <MVM_interp_run+39732>, 0x7ffff794b572 <MVM_interp_run+44082>, 
          0x7ffff794b5c6 <MVM_interp_run+44166>, 0x7ffff794b606 <MVM_interp_run+44230>, 0x7ffff794b646 <MVM_interp_run+44294>, 0x7ffff794ab59 <MVM_interp_run+41497>, 
          0x7ffff79515a2 <MVM_interp_run+68706>, 0x7ffff79519b4 <MVM_interp_run+69748>, 0x7ffff7951a03 <MVM_interp_run+69827>, 0x7ffff794dfea <MVM_interp_run+54954>, 
          0x7ffff794e034 <MVM_interp_run+55028>, 0x7ffff794e086 <MVM_interp_run+55110>, 0x7ffff794e0d8 <MVM_interp_run+55192>, 0x7ffff794efa0 <MVM_interp_run+58976>, 
          0x7ffff79431ff <MVM_interp_run+10431>, 0x7ffff794328f <MVM_interp_run+10575>, 0x7ffff7949f5d <MVM_interp_run+38429>, 0x7ffff7949fbd <MVM_interp_run+38525>, 
          0x7ffff794a01d <MVM_interp_run+38621>, 0x7ffff794f75b <MVM_interp_run+60955>, 0x7ffff795140f <MVM_interp_run+68303>, 0x7ffff7951370 <MVM_interp_run+68144>, 
          0x7ffff794ef37 <MVM_interp_run+58871>, 0x7ffff794b1ed <MVM_interp_run+43181>, 0x7ffff794b23f <MVM_interp_run+43263>, 0x7ffff794b291 <MVM_interp_run+43345>, 
          0x7ffff794b2e3 <MVM_interp_run+43427>, 0x7ffff794af07 <MVM_interp_run+42439>, 0x7ffff794aff8 <MVM_interp_run+42680>, 0x7ffff794afa1 <MVM_interp_run+42593>, 
          0x7ffff794e150 <MVM_interp_run+55312>, 0x7ffff795102a <MVM_interp_run+67306>, 0x7ffff7950fdb <MVM_interp_run+67227>, 0x7ffff7942d6f <MVM_interp_run+9263>, 
          0x7ffff7942dbe <MVM_interp_run+9342>, 0x7ffff7942e0f <MVM_interp_run+9423>, 0x7ffff7942e5e <MVM_interp_run+9502>, 0x7ffff7942eaf <MVM_interp_run+9583>, 0x7ffff7942efe <MVM_interp_run+9662>, 
          0x7ffff7942f4d <MVM_interp_run+9741>, 0x7ffff7942fa7 <MVM_interp_run+9831>, 0x7ffff7943002 <MVM_interp_run+9922>, 0x7ffff794305b <MVM_interp_run+10011>, 
          0x7ffff79430ac <MVM_interp_run+10092>, 0x7ffff79430fd <MVM_interp_run+10173>, 0x7ffff794314c <MVM_interp_run+10252>, 0x7ffff79431a9 <MVM_interp_run+10345>, 
          0x7ffff79436ed <MVM_interp_run+11693>, 0x7ffff794373e <MVM_interp_run+11774>, 0x7ffff7951af1 <MVM_interp_run+70065>, 0x7ffff7951555 <MVM_interp_run+68629>, 
          0x7ffff7951753 <MVM_interp_run+69139>, 0x7ffff79503f1 <MVM_interp_run+64177>, 0x7ffff79516a3 <MVM_interp_run+68963>, 0x7ffff79515f1 <MVM_interp_run+68785>, 
          0x7ffff7951646 <MVM_interp_run+68870>, 0x7ffff794ee15 <MVM_interp_run+58581>, 0x7ffff794b8ee <MVM_interp_run+44974>, 0x7ffff794b93b <MVM_interp_run+45051>, 
          0x7ffff794b73d <MVM_interp_run+44541>, 0x7ffff794b793 <MVM_interp_run+44627>, 0x7ffff794b7e7 <MVM_interp_run+44711>, 0x7ffff79513c7 <MVM_interp_run+68231>, 
          0x7ffff794f448 <MVM_interp_run+60168>, 0x7ffff794f492 <MVM_interp_run+60242>, 0x7ffff794b83b <MVM_interp_run+44795>, 0x7ffff794a5d1 <MVM_interp_run+40081>, 
          0x7ffff794b4b3 <MVM_interp_run+43891>, 0x7ffff794b335 <MVM_interp_run+43509>, 0x7ffff794b3f4 <MVM_interp_run+43700>, 0x7ffff794f4e9 <MVM_interp_run+60329>, 
          0x7ffff794f53a <MVM_interp_run+60410>, 0x7ffff794f59f <MVM_interp_run+60511>, 0x7ffff794f604 <MVM_interp_run+60612>, 0x7ffff794f669 <MVM_interp_run+60713>, 
          0x7ffff794f6ce <MVM_interp_run+60814>, 0x7ffff794ec40 <MVM_interp_run+58112>, 0x7ffff794eccd <MVM_interp_run+58253>, 0x7ffff7951811 <MVM_interp_run+69329>, 
          0x7ffff7951b3b <MVM_interp_run+70139>, 0x7ffff7951152 <MVM_interp_run+67602>, 0x7ffff7951baf <MVM_interp_run+70255>, 0x7ffff795193d <MVM_interp_run+69629>, 
          0x7ffff7951c26 <MVM_interp_run+70374>, 0x7ffff79505fb <MVM_interp_run+64699>, 0x7ffff7951a52 <MVM_interp_run+69906>, 0x7ffff795189e <MVM_interp_run+69470>, 
          0x7ffff794ee72 <MVM_interp_run+58674>, 0x7ffff79511c9 <MVM_interp_run+67721>, 0x7ffff794b98f <MVM_interp_run+45135>, 0x7ffff794e2ca <MVM_interp_run+55690>, 
          0x7ffff794e1aa <MVM_interp_run+55402>, 0x7ffff794e1f3 <MVM_interp_run+55475>, 0x7ffff79506ed <MVM_interp_run+64941>, 0x7ffff7950745 <MVM_interp_run+65029>, 
          0x7ffff79507cd <MVM_interp_run+65165>, 0x7ffff7950855 <MVM_interp_run+65301>, 0x7ffff79508b6 <MVM_interp_run+65398>, 0x7ffff79517a7 <MVM_interp_run+69223>, 
          0x7ffff79512a8 <MVM_interp_run+67944>, 0x7ffff7951312 <MVM_interp_run+68050>, 0x7ffff7945c95 <MVM_interp_run+21333>, 0x7ffff7945cf6 <MVM_interp_run+21430>, 
          0x7ffff794b686 <MVM_interp_run+44358>, 0x7ffff794b6e0 <MVM_interp_run+44448>, 0x7ffff79469bb <MVM_interp_run+24699>, 0x7ffff7946a18 <MVM_interp_run+24792>, 
          0x7ffff794c271 <MVM_interp_run+47409>, 0x7ffff794beb2 <MVM_interp_run+46450>, 0x7ffff7946a74 <MVM_interp_run+24884>, 0x7ffff7946ad5 <MVM_interp_run+24981>, 
          0x7ffff7946b24 <MVM_interp_run+25060>, 0x7ffff7950d98 <MVM_interp_run+66648>, 0x7ffff7946b8e <MVM_interp_run+25166>, 0x7ffff795069a <MVM_interp_run+64858>, 
          0x7ffff79510e4 <MVM_interp_run+67492>, 0x7ffff79502e9 <MVM_interp_run+63913>, 0x7ffff795036d <MVM_interp_run+64045>, 0x7ffff7950a49 <MVM_interp_run+65801>, 
          0x7ffff7950acd <MVM_interp_run+65933>, 0x7ffff794ed5a <MVM_interp_run+58394>, 0x7ffff794ad5d <MVM_interp_run+42013>, 0x7ffff794addc <MVM_interp_run+42140>,