Bug #12923: Accessing singleton_class of fstring cause assertion failure

• Status: Closed
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -
• Backport: 2.2: DONTNEED, 2.3: DONE, 2.4: DONTNEED

[naruse (Yui NARUSE)]

以下のワンライナーが「Assertion Failed: string.c:343:register_fstring:RBASIC_CLASS(ret) == rb_cString」します。

./miniruby -e'#encoding:us-ascii' -e'ObjectSpace.each_object{|o| o.singleton_class if o.is_a?(String)}; "hoge".intern'

クラッシュログは自分で走らせてもらうとして、何が起きているかというと、
(1) 文字列リテラルをはじめとして、何らかのかたちでシンボルを作らずにrb_fstringからfrozenなStringを作る
(2) その文字列に対してsingleton_classを呼ぶ。するとそのRVALUE->klassにsingleton_classが代入される
(3) 同じ内容の文字列でString#internする（1.でシンボルを作っているとlookup_str_sym()にひっかかる）
(4) register_fstringの"assert(RBASIC_CLASS(ret) == rb_cString);"で落ちる

しかし、どう直しましょうかね。

[naruse (Yui NARUSE)]

• Related to Bug #11386: taint flag about rb_fstring() added

[nobu (Nobuyoshi Nakada)]

RBASIC_CLASSをrb_obj_classにしてassertionを緩めましょうか。

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r56747.

---

class.c: no fstring singleton class

• class.c (singleton_class_of): prohibit fstrings from creating
  singleton classes.
  temporary measure for [ruby-dev:49867] [Bug #12923]

[nobu (Nobuyoshi Nakada)]

• Status changed from Closed to Assigned
• Assignee set to matz (Yukihiro Matsumoto)

ひとまずSEGVはしないようにfstringはsingleton classを作れないようにします。
笹田さんと話したのですが、frozen object全般でsingleton classの追加を禁止したほうがよさそうという結論になりました。
まつもとさんはどうでしょうか。

[nobu (Nobuyoshi Nakada)]

• Status changed from Assigned to Closed

Applied in changeset r56754.

---

test_fstring.rb: fix exception

• test/-ext-/string/test_fstring.rb (test_singleton_class): fix
  expected exception class. [ruby-dev:49867] [Bug #12923]

[matsuda (Akira Matsuda)]

• Related to Bug #12930: instance_eval, instance_exec raises TypeError on a frozen String added

[nobu (Nobuyoshi Nakada)]

• Backport changed from 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN to 2.2: DONTNEED, 2.3: REQUIRED, 2.4: DONTNEED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: DONTNEED, 2.3: REQUIRED, 2.4: DONTNEED to 2.2: DONTNEED, 2.3: WONTFIX, 2.4: DONTNEED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: DONTNEED, 2.3: WONTFIX, 2.4: DONTNEED to 2.2: DONTNEED, 2.3: REQUIRED, 2.4: REQUIRED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: DONTNEED, 2.3: REQUIRED, 2.4: REQUIRED to 2.2: DONTNEED, 2.3: DONE, 2.4: REQUIRED

ruby_2_3 r58157 merged revision(s) 56747,56754,56777.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: DONTNEED, 2.3: DONE, 2.4: REQUIRED to 2.2: DONTNEED, 2.3: DONE, 2.4: DONTNEED