compatibility issue with 2.3.0 <= ruby <= 2.3.1 and 5.0.1 <= activesupport < 6

___minimal_bug_repo.rb

class Foo
  private_class_method :new

  singleton_class.prepend(Module.new)

  public_class_method :new
end

puts Foo.method(:new)

__minimal_bug_repo.rb

# Relevant code from `singleton`
module Singleton
  def self.included(klass)
    klass.private_class_method :new, :allocate
  end
end

# Relevant code from `active_support`
module ActiveSupport
  class Deprecation
    module InstanceDelegator
      def self.included(base)
        # Some other functionality is mixed in here, but the actual functionality is irrelvant
        base.singleton_class.prepend(Module.new)

        # Overrides method :new to be public
        base.public_class_method :new
      end
    end

    # Singleton makes :new method private
    include Singleton

    # InstanceDelegator makes :new method public
    include InstanceDelegator
  end
end

# This call outputs: #<ActiveSupport::Deprecation:0x007f9f4884eec0>
puts ActiveSupport::Deprecation.new

# This call hangs in ruby 2.3.1
ActiveSupport::Deprecation.method(:new)

_minimal_bug_repro.rb

require 'singleton'

module InstanceDelegator
  def self.included(base)
    base.singleton_class.prepend(Module.new)
  end
end

class Foo
  include Singleton
  include InstanceDelegator
end

Foo.method(:new)

activesupport_bug_repro.rb

# If you run the following in ruby 2.3.1, the issue `.method(:new)` call will halt the process

require 'singleton'

module ActiveSupport
  class Deprecation
    module InstanceDelegator
      def self.included(base)
        base.singleton_class.prepend(Module.new)
      end
    end
  end
end

module ActiveSupport
  class Deprecation
    include Singleton
    include InstanceDelegator
  end
end

ActiveSupport::Deprecation.method(:new)

issue narrowed down by activesupport version

Pin Ruby version at 2.3.1

andrew_pariser ~/dev/pariser/sorbet-test $ gem install activesupport -v '~> 4.0' --no-ri --no-rdoc
Successfully installed activesupport-4.2.11.1
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
4.2.11.1
#<Method: Class#new>

andrew_pariser ~/dev/pariser/sorbet-test $ gem install activesupport -v '5.0.0' --no-ri --no-rdoc
Successfully installed activesupport-5.0.0
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
5.0.0
#<Method: Class#new>

andrew_pariser ~/dev/pariser/sorbet-test $ gem install activesupport -v '5.0.1' --no-ri --no-rdoc
Successfully installed activesupport-5.0.1
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
5.0.1
^CKilled: 9

andrew_pariser ~/dev/pariser/sorbet-test $ gem install activesupport -v '~> 5.0.0' --no-ri --no-rdoc
Successfully installed activesupport-5.0.7.2
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
5.0.7.2
^CKilled: 9

andrew_pariser ~/dev/pariser/sorbet-test $ gem install activesupport -v '~> 5.1.0' --no-ri --no-rdoc
Successfully installed activesupport-5.1.7
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
5.1.7
^CKilled: 9

andrew_pariser ~/dev/pariser/sorbet-test 1 $ gem install activesupport -v '~> 5.2.0' --no-ri --no-rdoc
Successfully installed activesupport-5.2.3
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
5.2.3
^CKilled: 9

issue narrowed down by ruby version

Pin ActiveSupport version at 5.2.3

andrew_pariser ~/dev/pariser/sorbet-test $ rvm use 2.2.8
Using /Users/andrew_pariser/.rvm/gems/ruby-2.2.8
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.2.8p477 (2017-09-14 revision 59906) [x86_64-darwin18]
5.2.3
#<Method: Class#new>

andrew_pariser ~/dev/pariser/sorbet-test 137 $ rvm use 2.3.0
Using /Users/andrew_pariser/.rvm/gems/ruby-2.3.0
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin17]
5.2.3
^CKilled: 9

andrew_pariser ~/dev/pariser/sorbet-test 137 $ rvm use 2.3.1
Using /Users/andrew_pariser/.rvm/gems/ruby-2.3.1
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin18]
5.2.3
^CKilled: 9

andrew_pariser ~/dev/pariser/sorbet-test 137 $ rvm use 2.3.2
Using /Users/andrew_pariser/.rvm/gems/ruby-2.3.2
andrew_pariser ~/dev/pariser/sorbet-test $ ruby -v && ruby -e 'require "active_support"; puts ActiveSupport.version; puts ActiveSupport::Deprecation.method(:new)'
ruby 2.3.2p217 (2016-11-15 revision 56796) [x86_64-darwin18]
5.2.3
#<Method: Class#new>

Running ActiveSupport::Deprecation.method(:new) using active support version 5.2.3 causes the ruby process to hang (and disallows pry introspection). This happens in ruby 2.3.0 and 2.3.1 but not in ruby 2.3.2.