こんにちは sheepman です。
次のようにすると core を吐きます。

$ ./miniruby -ve 'defined?(1.hoge)'
ruby 1.9.0 (2005-08-19) [i686-linux]
YARVCore 0.3.1 (rev: 256) [opts: ]
-e:1: warning: useless use of defined? in void context
-e:1: [BUG] unimplemented defined: NODE_LIT
ruby 1.9.0 (2005-08-19) [i686-linux]

zsh: abort      ./miniruby -ve 'defined?(1.hoge)'

以下はバックトレースです。

(gdb) bt
#0  0x4009ac11 in kill () at finddomain.c:145
#1  0x4009a895 in raise (sig=6) at ../linuxthreads/sysdeps/unix/sysv/linux/raise.c:32
#2  0x4009c008 in abort () at ../sysdeps/generic/abort.c:88
#3  0x080ccfc6 in rb_bug (fmt=0x80f3a63 "unimplemented defined: %s") at ../yarv/error.c:214
#4  0x080d1392 in defined_expr () at ../yarv/compile.c:2014
#5  0x080d1075 in defined_expr (self=1075621320, iseqobj=0x813f348, ret=0xbfffe9a0,
    node=0x401cae2c, lfinish=0x813f530, needstr=2) at ../yarv/compile.c:1995
#6  0x080d61fe in iseq_compile_each (self=1075621320, ret=0xbfffe9a0, node=0x401cae18, poped=0)
    at ../yarv/compile.c:3708
#7  0x080cf1c5 in iseq_compile (self=1075621320, narg=1075621400) at ../yarv/compile.c:221
#8  0x080bf899 in iseq_init (self=1075621320, node=1075621400, name=1075621340,
    file_name=1075621360, parent=0, type=3) at ../yarv/yarvcore.c:412
#9  0x080be5ee in call_cfunc (func=0x80bf864 <iseq_init>, recv=1075621320, len=1075480936, argc=5,
    argv=0x6) at call_cfunc.h:37
#10 0x080bafa9 in th_call0 (th=0x810f978, klass=0, recv=1075621320, id=0, oid=3001, argc=5,
    argv=0xbfffeb70, body=0x401cb494, nosuper=0) at ../yarv/vm.c:280
#11 0x08059b0c in rb_call (klass=1075623180, recv=1075621320, mid=3001, argc=5, argv=0xbfffeb70,
    scope=1) at ../yarv/eval.c:3668
#12 0x08059e25 in rb_funcall2 (recv=0, mid=3001, argc=5, argv=0xbfffeb70) at ruby.h:647
#13 0x0805bc62 in rb_obj_call_init (obj=1075621320, argc=5, argv=0xbfffeb70) at ../yarv/eval.c:4966
#14 0x0807cbe0 in rb_class_new_instance (argc=5, argv=0xbfffeb70, klass=1075623180)
    at ../yarv/object.c:1524
#15 0x080bf3c9 in yarvcore_eval_parsed (node=0, file=0) at ../yarv/yarvcore.c:247
#16 0x08056d44 in ruby_exec_internal () at ../yarv/eval.c:1562
#17 0x08056d60 in ruby_exec () at ../yarv/eval.c:1574
#18 0x08056d9b in ruby_run () at ../yarv/eval.c:1591
#19 0x080551c1 in main () at ../yarv/main.c:38
#20 0x40087c1f in __libc_start_main (main=0x80551a0 <main>, argc=3, ubp_av=0x3,
    init=0x80d7424 <__libc_csu_init>, fini=0x80d746c <__libc_csu_fini>,
    rtld_fini=0x400144a0 <_rtld_local>, stack_end=0x401a8968)

-- 
sheepman / TAMURA Takashi
sheepman sheepman.sakura.ne.jp http://sheepman.parfait.ne.jp/
   

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