Infinite loop in rubocop -a for ruby/csv

[ShockwaveNN]

Failure to perform RuboCop autocorrect in https://github.com/ruby/csv.git project

---

Actual behavior

Take a pretty long time

Infinite loop detected in /home/user/sources/csv/test/lib/test/unit.rb.
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:234:in `block in iterate_until_no_changes'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:230:in `loop'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:230:in `iterate_until_no_changes'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:201:in `do_inspection_loop'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:111:in `block in file_offenses'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:121:in `file_offense_cache'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:109:in `file_offenses'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:100:in `process_file'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:78:in `block in each_inspected_file'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:75:in `each'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:75:in `reduce'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:75:in `each_inspected_file'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:67:in `inspect_files'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/runner.rb:39:in `run'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/cli.rb:150:in `execute_runner'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/cli.rb:78:in `execute_runners'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/lib/rubocop/cli.rb:38:in `run'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/bin/rubocop:13:in `block in <top (required)>'
/home/user/.rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/benchmark.rb:308:in `realtime'
/home/user/.rvm/gems/ruby-2.5.0/gems/rubocop-0.52.1/bin/rubocop:12:in `<top (required)>'
/home/user/.rvm/gems/ruby-2.5.0/bin/rubocop:23:in `load'
/home/user/.rvm/gems/ruby-2.5.0/bin/rubocop:23:in `<main>'
/home/user/.rvm/gems/ruby-2.5.0/bin/ruby_executable_hooks:15:in `eval'
/home/user/.rvm/gems/ruby-2.5.0/bin/ruby_executable_hooks:15:in `<main>'

Steps to reproduce the problem

1. git clone https://github.com/ruby/csv.git
2. cd csv && git checkout 2cc4f858a2dcad54dc8c5e346ae691ac9a88f2a3
3. rubocop -a

RuboCop version

$ rubocop -V
0.52.1 (using Parser 2.5.0.0, running on ruby 2.5.0 x86_64-linux)

[pocke]

Probably it is related to #5547
I can reproduce this problem with --only BlockEndNewline option, and the related issue cause is the BlockEndNewline cop.

[ericmathison]

I was able to make a reduced test case using test/lib/test/unit.rb (from the above csv repo).

begin
  gem 'minitest', '< 5.0.0' if defined? Gem
rescue Gem::LoadError
end
require 'minitest/unit'
require 'test/unit/assertions'

def foo
  report.each {|r| 0 + \
  0 }
end

For whatever reason, this reduced case will only give the infinite loop error when explicitly specifying the --only BlockEndNewline option.

[bquorning]

I believe this issue has been fixed by #5590.

[ShockwaveNN]

Found another one infinite loop in ruby/csv - probably not related to current one, in another file #5628