Example of a weird ruby bug (https://bugs.ruby-lang.org/issues/9967)

block_weirdness.rb

puts RUBY_DESCRIPTION

class SuperClass
  def foo
    "foo"
  end
end

class SubClass < SuperClass
  def foo(arg)
    arg.bar { super() }
  end
end

class Arg
  def bar(&block)
    Class.new { define_method(:some_method, &block) } if $define_method
    yield
  end
end

print "Without define_method: "
puts SubClass.new.foo(Arg.new)

$define_method = true
print "With define_method: "
puts SubClass.new.foo(Arg.new)

output

➜  code  chruby 2.1.1
➜  code  ruby block_weirdness.rb
ruby 2.1.1p76 (2014-02-24 revision 45161) [x86_64-darwin12.0]
Without define_method: foo
With define_method: block_weirdness.rb:11:in `block in foo': super called outside of method (NoMethodError)
	from block_weirdness.rb:18:in `bar'
	from block_weirdness.rb:11:in `foo'
	from block_weirdness.rb:27:in `<main>'
➜  code  chruby 2.0
➜  code  ruby block_weirdness.rb
ruby 2.0.0p353 (2013-11-22 revision 43784) [x86_64-darwin12.5.0]
Without define_method: foo
With define_method: block_weirdness.rb:11:in `block in foo': super called outside of method (NoMethodError)
	from block_weirdness.rb:18:in `bar'
	from block_weirdness.rb:11:in `foo'
	from block_weirdness.rb:27:in `<main>'
➜  code  chruby 1.9.3
➜  code  ruby block_weirdness.rb
ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-darwin12.4.0]
Without define_method: foo
With define_method: block_weirdness.rb:11:in `block in foo': super called outside of method (NoMethodError)
	from block_weirdness.rb:18:in `bar'
	from block_weirdness.rb:11:in `foo'
	from block_weirdness.rb:27:in `<main>'
➜  code  chruby 1.9.2
➜  code  ruby block_weirdness.rb
ruby 1.9.2p320 (2012-04-20 revision 35421) [x86_64-darwin12.4.0]
Without define_method: foo
With define_method: block_weirdness.rb:11:in `block in foo': super called outside of method (NoMethodError)
	from block_weirdness.rb:18:in `bar'
	from block_weirdness.rb:11:in `foo'
	from block_weirdness.rb:27:in `<main>'
➜  code  chruby 1.8.7
➜  code  ruby block_weirdness.rb
ruby 1.8.7 (2013-06-27 patchlevel 374) [i686-darwin12.4.0]
Without define_method: foo
With define_method: foo