Issue #12492 has been updated by Shyouhei Urabe.


なお当方の環境はgccversion 6.0.0 20160320 (experimental) (Homebrew gcc6 6-20160320)です。

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Bug #12492: RUBY_DEBUG=gc_stress dumps core
https://bugs.ruby-lang.org/issues/12492#change-59247

* Author: Shyouhei Urabe
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.4.0dev (2016-05-09 trunk 55419) [x86_64-darwin15]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
次のようにすると core を吐きます。

```
zsh % PATH="/usr/bin:$PATH" RUBY_DEBUG=gc_stress /usr/bin/lldb -- ./ruby -e 'p GC.stress'
(lldb) target create "./ruby"
Current executable set to './ruby' (x86_64).
(lldb) settings set -- target.run-args  "-e" "p GC.stress"
(lldb) run
Process 15385 launched: './ruby' (x86_64)
Process 15385 stopped
* thread #1: tid = 0x5a843, 0x00000001001b4dda ruby`rb_const_defined(klass=4320291960, id=3643) + 106 at variable.c:3082, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
    frame #0: 0x00000001001b4dda ruby`rb_const_defined(klass=4320291960, id=3643) + 106 at variable.c:3082
   3079 st_table *
   3080 rb_st_copy(VALUE obj, struct st_table *orig_tbl)
   3081 {
-> 3082     st_table *new_tbl = st_copy(orig_tbl);
   3083     st_foreach(new_tbl, tbl_copy_i, (st_data_t)obj);
   3084     return new_tbl;
   3085 }
(lldb) bt
* thread #1: tid = 0x5a843, 0x00000001001b4dda ruby`rb_const_defined(klass=4320291960, id=3643) + 106 at variable.c:3082, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
  * frame #0: 0x00000001001b4dda ruby`rb_const_defined(klass=4320291960, id=3643) + 106 at variable.c:3082
    frame #1: 0x000000010002d6b8 ruby`rb_define_module(name="Kernel") + 40 at class.c:773
    frame #2: 0x00000001000d4287 ruby`InitVM_Object + 263 at object.c:3407
    frame #3: 0x000000010009853d ruby`rb_call_inits + 29 at inits.c:23
    frame #4: 0x000000010006789b ruby`ruby_setup + 155 at eval.c:60
    frame #5: 0x0000000100067909 ruby`ruby_init + 9 at eval.c:76
    frame #6: 0x000000010021369d ruby`main(argc=<unavailable>, argv=<unavailable>) + 77 at main.c:35
    frame #7: 0x00007fff9c00f5ad libdyld.dylib`start + 1
    frame #8: 0x00007fff9c00f5ad libdyld.dylib`start + 1
(lldb)
```

[ruby-dev:41536](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-dev/41536) が再発しているのではないでしょうか。



-- 
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