Bug #2788: nil.instance_eval pushes nil onto cref
http://redmine.ruby-lang.org/issues/show/2788

Author: Shugo Maeda
Status: Assigned, Priority: Low
Assigned to: Yukihiro Matsumoto, Category: core
ruby -v: ruby 1.9.2dev (2010-02-18 trunk 26704) [i686-linux]

A singleton class definition of nil pushes NilClass onto cref.
It is reasonable because NilClass has nil as the only instance.
However, nil.instance_eval pushes nil onto cref, which means that method definitions are not permitted in that context.

  defiant:ruby$ ruby-trunk -ve 'class <<nil; def foo; puts "foo" end; end; nil.foo'
  ruby 1.9.2dev (2010-02-18 trunk 26704) [i686-linux]
  foo
  defiant:ruby$ ruby-trunk -ve 'nil.instance_eval {|i| def foo; puts "foo" end }; nil.foo'  
  ruby 1.9.2dev (2010-02-18 trunk 26704) [i686-linux]
  -e:1:in `block in <main>': no class/module to add method (TypeError)
  	from -e:1:in `instance_eval'
  	from -e:1:in `<main>'

The behavior is the same in Ruby 1.8.7.
Is it intended or a bug?


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