Bug #10167: Prime#include?(mod) hangs up

• Status: Closed
• Assignee: yugui (Yuki Sonoda)
• Target version: -
• ruby -v: ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-linux]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
• Tags: patch, lib

[nitoyon (Kenichi Saita)]

We expect Prime class implements Module#include?(mod). But Prime#include?(mod) hangs up, because it is overwritten by Enumerable#include?(obj) and tries to search mod linearly from infinite sequence of prime numbers.

Reproducible script:

$ ruby -e 'require "prime"; puts Prime.include?(Enumerable)'

• Expected: returns true
• Actual: hangs up

I found this bug by the following code (hangs up if prime is required)

enumerables = []
ObjectSpace.each_object(Class){|klass|
  if klass.include?(Enumerable) then
    enumerables.push klass
  end
}

[znz (Kazuhiro NISHIYAMA)]

workaround:

enumerables = []
module_include_p = Module.method(:include?).unbind
ObjectSpace.each_object(Class) do |klass|
  if module_include_p.bind(klass).call(Enumerable)
    enumerables.push klass
  end
end

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)

Even Prime.include?(4) hangs up too.
This method seems useless.

[nitoyon (Kenichi Saita)]

• File prime-include.diff prime-include.diff added

It's difficult to delete Prime.inlude? method because this method is included by include Enumerable.

So, I overrided Prime.include? and Prime.instance.include?. Please review my patch.

[nitoyon (Kenichi Saita)]

Review my patch, please!

[marcandre (Marc-Andre Lafortune)]

• Assignee set to yugui (Yuki Sonoda)

Instead of aliasing include? to prime?, I'd recommend instead to restore it:

 Prime.define_singleton_method(:include?, Module.instance_method(:include?))
 Prime.include?(Enumerable) # => true

Probably won't be super useful, but still beats an infinite loop :-)

Assigning to yugui, although I have not seen any activity from her in over a year on the mailing list?

[naruse (Yui NARUSE)]

• Target version deleted (2.2.0)

[jeremyevans0 (Jeremy Evans)]

I've added a pull request for this at https://github.com/ruby/prime/pull/6.

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed