Rubocop places commas into comments, generating invalid ruby code

[adfoster-r7]

When formatting the following code, rubocop will generate invalid ruby:

class Bar
  def initialize(*args)
  end
end

class Foo < Bar
  def initialize
    super(
      'firstKey' => [ 'value a', #description1
                      'value b' #description2
      ],
      'secondKey' => 'Bar'
    )
  end
end

Expected behavior

Not to generate invalid ruby code

Actual behavior

Invalid ruby code is created due to incorrectly handling the comment and placing a comma on the comment line:

class Bar
  def initialize(*args)
  end
end

class Foo < Bar
  def initialize
    super(
      'firstKey' => ['value a', # description1
                      'value b'] # description2,
      'secondKey' => 'Bar'
    )
  end
end

Steps to reproduce the problem

1. Create new ruby file
2. add original code snippet
3. bundle exec rubocop -x --safe-auto-correct new_file.rb
4. Run again, verify invalid ruby code has been generated

RuboCop version

$ [bundle exec] rubocop -V
0.80.0 (using Parser 2.7.0.2, running on ruby 2.6.5 x86_64-darwin18)

[MattBeaty]

whoever works on #7776 should also work on this issue.

[shekhar-patil]

I am working on this issue.