Infinite loop in HeredocIndentation auto-correction

[jonas054]

Auto-correcting a file containing a heredoc with incorrect indentation, that has a line within consisting only of spaces, leads to an infinite loop.

# frozen_string_literal: true

def m
  <<~RUBY
        a
  
      the_line_above_has_2_spaces
  RUBY
end

Expected behavior

$ rubocop -a
Inspecting 1 file
C

Offenses:

file.rb:5:1: C: [Corrected] Layout/HeredocIndentation: Use 2 spaces for indentation in a heredoc.
        a ...
^^^^^^^^^

1 file inspected, 1 offense detected, 1 offense corrected

Actual behavior

$ rubocop -a
Inspecting 1 file
C

Offenses:

file.rb:5:1: C: [Corrected] Layout/HeredocIndentation: Use 2 spaces for indentation in a heredoc.
        a ...
^^^^^^^^^

0 files inspected, 1 offense detected, 1 offense corrected
Infinite loop detected in /home/jonas/dev/8108/file.rb.
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:276:in `block in iterate_until_no_changes'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:272:in `loop'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:272:in `iterate_until_no_changes'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:243:in `do_inspection_loop'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:122:in `block in file_offenses'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:146:in `file_offense_cache'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:120:in `file_offenses'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:111:in `process_file'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:90:in `block in each_inspected_file'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:89:in `each'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:89:in `reduce'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:89:in `each_inspected_file'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:78:in `inspect_files'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/runner.rb:39:in `run'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli/command/execute_runner.rb:21:in `execute_runner'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli/command/execute_runner.rb:13:in `run'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli/command.rb:10:in `run'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli/environment.rb:17:in `run'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli.rb:65:in `run_command'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli.rb:72:in `execute_runners'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/lib/rubocop/cli.rb:41:in `run'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/exe/rubocop:13:in `block in <top (required)>'
/usr/local/rvm/rubies/ruby-2.6.5/lib/ruby/2.6.0/benchmark.rb:308:in `realtime'
/usr/local/rvm/gems/ruby-2.6.5/gems/rubocop-0.85.0/exe/rubocop:12:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.6.5/bin/rubocop:23:in `load'
/usr/local/rvm/gems/ruby-2.6.5/bin/rubocop:23:in `<main>'
/usr/local/rvm/gems/ruby-2.6.5/bin/ruby_executable_hooks:24:in `eval'
/usr/local/rvm/gems/ruby-2.6.5/bin/ruby_executable_hooks:24:in `<main>'

Steps to reproduce the problem

Run rubocop -a on the example file above.

RuboCop version

Include the output of rubocop -V or bundle exec rubocop -V if using Bundler. Here's an example:

$ rubocop -V
0.85.0 (using Parser 2.7.1.3, rubocop-ast 0.0.3, running on ruby 2.6.5 x86_64-linux)