次のようにすると core を吐きます。
% ./ruby -e '
h1 = Hash[*(1..100).map {|i| [i] }]
class << (h1.keys[0]); self end.send(:define_method, :hash) {
  callcc {|k| $k = k }
  super
}
h1.rehash
$k.call
'
-e:7: [BUG] Segmentation fault
ruby 1.8.2 (2004-09-17) [i686-linux]

zsh: abort (core dumped)  ./ruby -e 
% gdb ruby core 
GNU gdb 6.1-debian
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-linux"...Using host libthread_db library "/lib/libthread_db.so.1".

Core was generated by `./ruby -e 
h1 = Hash[*(1..100).map {|i| [i] }]
class << (h1.keys[0]); self end.'.
Program terminated with signal 6, Aborted.
Reading symbols from /lib/libdl.so.2...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/libcrypt.so.1...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libm.so.6...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
#0  0x4009e721 in kill () from /lib/libc.so.6
(gdb) bt
#0  0x4009e721 in kill () from /lib/libc.so.6
#1  0x4009e4c5 in raise () from /lib/libc.so.6
#2  0x4009f9e8 in abort () from /lib/libc.so.6
#3  0x080cb3a6 in rb_bug (fmt=0x0) at error.c:214
#4  0x080aafc2 in sigsegv (sig=11) at signal.c:446
#5  <signal handler called>
#6  0x080ad2f4 in st_insert (table=0x8129a00, key=1075606196, value=1075606156) at st.c:297
#7  0x0806f954 in rb_hash_rehash_i (key=1075606196, value=165, tbl=0xa5) at hash.c:316
#8  0x080ad877 in st_foreach (table=0x8129230, func=0x806f930 <rb_hash_rehash_i>, arg=135436800) at st.c:495
#9  0x0806f9a7 in rb_hash_rehash (hash=1075604656) at hash.c:348
#10 0x08067d61 in call_cfunc (func=0x806f960 <rb_hash_rehash>, recv=1075604656, len=1075606196, argc=135436824, argv=0x0)
    at eval.c:5378
#11 0x0805bef2 in rb_call0 (klass=1075644836, recv=1075604656, id=6825, oid=165, argc=0, argv=0x0, body=0x401d08c8, 
    nosuper=0) at eval.c:5509
#12 0x0805c748 in rb_call (klass=1075644836, recv=1075604656, mid=6825, argc=0, argv=0x0, scope=0) at eval.c:5730
#13 0x08057930 in rb_eval (self=1075673536, n=0xa5) at ruby.h:631
#14 0x08053e3b in ruby_exec () at eval.c:1456
#15 0x08053e80 in ruby_run () at eval.c:1477
#16 0x08052025 in main (argc=165, argv=0xa5, envp=0xbffff904) at main.c:50
(gdb) 
-- 
[田中 哲][たなか あきら][Tanaka Akira]