Bug #7107: Ruby can no longer find constants in methods in anonymous modules

• Status: Closed
• Assignee: -
• Target version: 2.0.0
• ruby -v: ruby 2.0.0dev (2012-09-06 trunk 36915) [x86_64-darwin12.1.0]

[drbrain (Eric Hodel)]

With ruby 1.9 and newer C cannot be found if m is duplicated:

  module M
    C = 1
  
    def self.m
      C
    end
  end
  
  puts 'named module'
  M.m
  
  puts 'anonymous module'
  m = M.dup
  m.m

Ruby 1.8:

  $ ruby -v t.rb 
  ruby 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0]
  named module
  anonymous module

With Ruby 1.9:

  $ ruby19 -v t.rb 
  ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin12.2.0]
  named module
  anonymous module
  t.rb:5:in `m': uninitialized constant Module::C (NameError)
  	from t.rb:14:in `<main>'

With trunk:

    $ ruby19 -v t.rb 
    ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin12.2.0]
    named module
    anonymous module
    t.rb:5:in `m': uninitialized constant Module::C (NameError)
    	from t.rb:14:in `<main>'

m::C works in all three versions, though.

[drbrain (Eric Hodel)]

=begin
Additionally, when the module is given a name it still can't find the constant:

module M
C = 1

def self.m
  C
end

end

puts 'named module'
M.m

puts 'anonymous module'
m = M.dup
begin
m.m
rescue NameError
p $!
end

puts 're-named module'
N = m
begin
N.m
rescue NameError
p $!
end

Ruby trunk:

$ ruby20 -v t.rb
ruby 2.0.0dev (2012-09-06 trunk 36915) [x86_64-darwin12.1.0]
named module
anonymous module
#<NameError: uninitialized constant Module::C>
re-named module
#<NameError: uninitialized constant Module::C>

=end

[ko1 (Koichi Sasada)]

• Assignee set to mame (Yusuke Endoh)

[mame (Yusuke Endoh)]

• Status changed from Open to Assigned
• Assignee changed from mame (Yusuke Endoh) to nobu (Nobuyoshi Nakada)

Indeed, it looks a bug. Nobu, could you investigate?

--
Yusuke Endoh [e-mail]

[tarui (Masaya Tarui)]

hi,

I found strange behavior.

$ ruby -e "module M;C=1;def self.f;C end end;d=M.dup;p M.f;p d.f;class A;end;p d.f"
1
1
-e:1:in f': uninitialized constant Module::C (NameError) from -e:1:in '

It seems to hold the problem in InlineCache too.

[tarui (Masaya Tarui)]

additional sample.
d.f referring to M::C is correct? or d::C?

$ ruby -e "module M;C=1;def self.f;C end end;d=M.dup;p M.f;p d.f;d::C=2;p M.f;p d::C;p d.f"
1
1
-e:1: warning: already initialized constant #Module:0x007ffb39f4c860::C
-e:1: warning: previous definition of C was here
1
2
1

=begin

Nobu, I have found the cause of the bug - the cref_stack of methods are not fixed up to point to the new class/module when the class/module is duped.

Do you want me to commit it or attach it here for your review?

=end

• Assignee changed from nobu (Nobuyoshi Nakada) to Anonymous

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r38423.
Eric, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• class.c (rewrite_cref_stack, clone_method): rewrite a method's cref
  stack when cloning into a new class to allow lexical const lookup to
  work as expected [ruby-core:47834] [Bug #7107]
• test/ruby/test_class.rb (class TestClass): related test

[Eregon (Benoit Daloze)]

• Description updated (diff)