Rubocop: Rails/RedundantAllowNil stumbles upon validation

[Medvezo]

Actual behavior

Newly added Rails/RedundantAllowNil errors out after encountering validates keyword

5 errors occurred:
An error occurred while Rails/RedundantAllowNil cop was inspecting /home/app/models/user.rb:9:2.
An error occurred while Rails/RedundantAllowNil cop was inspecting /home/app/models/user.rb:10:2.
An error occurred while Rails/RedundantAllowNil cop was inspecting /home/app/models/user.rb:11:2.
An error occurred while Rails/RedundantAllowNil cop was inspecting /home/app/models/user.rb:12:2.
An error occurred while Rails/RedundantAllowNil cop was inspecting /home/app/models/user.rb:13:2.

Steps to reproduce the problem

The file in question app/models/user.rb:

class User < ApplicationRecord
  belongs_to :account, optional: true

  before_save { self.email = email.downcase }

  has_secure_password
  has_secure_token :confirmation_token

  validates :email, format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i }
  validates :email, length: { maximum: 256 }
  validates :email, presence: true
  validates :email, uniqueness: { case_sensitive: false }
  validates :password, length: { minimum: 8 }
end

RuboCop version

$ [bundle exec] rubocop -V
0.67.0 (using Parser 2.6.2.0, running on ruby 2.6.2 x86_64-linux)

[Medvezo]

Identified the culprit after running rubocop -d:

An error occurred while Rails/RedundantAllowNil cop was inspecting /home/app/models/user.rb:10:2.
undefined method `children' for nil:NilClass
.../rubocop-0.67.0/lib/rubocop/cop/rails/redundant_allow_nil.rb:42:in `on_send'

[koic]

Thanks for the feedback. I opened a PR #6886.

[connorshea]

I just got the same error in my Rails project :D

[rafasoares]

Same, still getting it on 0.67.1.

1 error occurred:
An error occurred while Rails/RedundantAllowNil cop was inspecting /path/to/rails/app/models/user.rb:9:2.
Errors are usually caused by RuboCop bugs.
Please, report your problems to RuboCop's issue tracker.
https://github.com/rubocop-hq/rubocop/issues

Mention the following information in the issue report:
0.67.1 (using Parser 2.6.2.0, running on ruby 2.6.2 x86_64-darwin18)
Finished in 5.799085999955423 seconds

[rossjones]

Sorry, just noticed the changelog mentions the fix isn't released yet but the PR is on master.

[rafasoares]

You're right. I completely misread the release page. I should probably go to bed. lol

But thanks for pointing it out, I've disabled the cop for now to get rid of the error,

[koic]

Hi there. We RuboCop core team released RuboCop 0.67.2.
https://github.com/rubocop-hq/rubocop/blob/v0.67.2/CHANGELOG.md#0672-2019-04-05

[rossjones]

@koic you're amazing, thank you!

[connorshea]

Thanks!

[koerneml]

1 error occurred:
An error occurred while Rails/RedundantAllowNil cop was inspecting /path/to/rails/app/models/model.rb:12:8.
Errors are usually caused by RuboCop bugs.
Please, report your problems to RuboCop's issue tracker.
https://github.com/rubocop-hq/rubocop/issues

Mention the following information in the issue report:
0.67.2 (using Parser 2.6.2.0, running on ruby 2.6.1 x86_64-linux)

It seems that some of the issue still persists in 0.67.2

in this case, it was a klass.validates-call in a self.inherited(klass) callback if that information is of any help

[koic]

@koerneml Could you open a new issue based on the issue template?
https://github.com/rubocop-hq/rubocop/blob/v0.67.2/.github/ISSUE_TEMPLATE/bug_report.md