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% lldb -- ./miniruby -e0
(lldb) target create "./miniruby"
Current executable set to './miniruby' (x86_64).
(lldb) settings set -- target.run-args  "-e0"
(lldb) env RUBY_DEBUG=gc_stress
(lldb) run
Process 10265 launched: './miniruby' (x86_64)
Process 10265 stopped
* thread #1: tid = 0x7fe2a, 0x00000001001b1eea miniruby`rb_const_defined(klass=4320554240, id=3579) + 106 at variable.c:3067, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
    frame #0: 0x00000001001b1eea miniruby`rb_const_defined(klass=4320554240, id=3579) + 106 at variable.c:3067
   3064 rb_const_entry_t *
   3065 rb_const_lookup(VALUE klass, ID id)
   3066 {
-> 3067     st_table *tbl = RCLASS_CONST_TBL(klass);
   3068     st_data_t val;
   3069
   3070     if (tbl && st_lookup(tbl, (st_data_t)id, &val)) {
(lldb) bt
* thread #1: tid = 0x7fe2a, 0x00000001001b1eea miniruby`rb_const_defined(klass=4320554240, id=3579) + 106 at variable.c:3067, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
  * frame #0: 0x00000001001b1eea miniruby`rb_const_defined(klass=4320554240, id=3579) + 106 at variable.c:3067
    frame #1: 0x00000001000291c8 miniruby`rb_define_module(name="Kernel") + 40 at class.c:771
    frame #2: 0x00000001000d3717 miniruby`InitVM_Object + 263 at object.c:3412
    frame #3: 0x000000010009504d miniruby`rb_call_inits + 29 at inits.c:23
    frame #4: 0x0000000100062f5e miniruby`ruby_setup + 190 at eval.c:60
    frame #5: 0x0000000100062f89 miniruby`ruby_init + 9 at eval.c:76
    frame #6: 0x000000010020fe5d miniruby`main(argc=<unavailable>, argv=<unavailable>) + 77 at main.c:35
    frame #7: 0x00007fff972a35ad libdyld.dylib`start + 1
(lldb)