Bug #14267: Lazy proc allocation introduced in #14045 creates regression

• Status: Open
• Priority: Normal
• Assignee: -
• Target version: -
• ruby -v: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin15]
• Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN
• Tags: core, notbug

[myronmarston (Myron Marston)]

The following script consistently prints Proc equality: true on versions of Ruby before 2.5, but prints Proc equality: false on Ruby 2.5:

# regression.rb
def return_proc(&block)
  block
end

def return_procs(&block)
  block.inspect if ENV['INSPECT_BLOCK']

  proc_1 = return_proc(&block)
  proc_2 = return_proc(&block)

  return proc_1, proc_2
end

proc_1, proc_2 = return_procs { }

puts RUBY_VERSION
puts "Proc equality: #{proc_1 == proc_2}"

Here's the output on Ruby 2.4 and 2.5:

$ chruby 2.4
$ ruby regression.rb
2.4.2
Proc equality: true
$ chruby 2.5
$ ruby regression.rb
2.5.0
Proc equality: false

As the output shows, the two procs were equal on 2.4 but are no longer equal on 2.5. I believe this is due to the lazy proc allocation introduced in #14045. Note that if I call a method on the proc (such as inspect) it defeats the lazy allocation and "fixes" the regression:

$ chruby 2.5
$ INSPECT_BLOCK=1 ruby regression.rb
2.5.0
Proc equality: true

This caused a bug in RSpec, which I've worked around for now by calling __id__ on the proc.

Is there a way to keep the lazy proc allocation while fixing this regression?

[duerst (Martin Dürst)]

• Related to Feature #14045: Lazy Proc allocation for block parameters added