`Rails/HasManyOrHasOneDependent` false-positive when using Prism

[owst]

class Thing < ApplicationRecord
  has_many :other_thing, through: :yet_another_thing
end

triggers a Rails/HasManyOrHasOneDependent, despite having a :through kwarg when using ParserEngine: parser_prism

---

Steps to reproduce the problem

Using parser_prism parse the above example file.

Expected behavior

No offense due to :through kwarg:

      # It doesn't register an offense if `:through` or `dependent: nil`
      # is specified, or if the model is read-only.

Actual behavior

False positive offense.

The node in question is

=> s(:send, nil, :has_many,
  s(:sym, :other_thing),
  s(:kwargs,
    s(:pair,
      s(:sym, :through),
      s(:sym, :yet_another_thing))))

RuboCop version

$ [rubocop -V
1.79.2 (using Parser 3.3.7.4, Prism 1.5.1, rubocop-ast 1.46.0, analyzing as Ruby 3.4, running on ruby 3.4.7) [arm64-darwin24]
  - rubocop-rails 2.33.4
  - rubocop-factory_bot 2.26.1
  - rubocop-performance 1.19.1
  - rubocop-rake 0.6.0
  - rubocop-rspec 3.4.0
  - rubocop-sorbet 0.8.7
  - rubocop-thread_safety 0.5.1

[Earlopain]

You seem to be getting "modern" ast, as shown by the kwargs node. That should be emitted as a hash node instead, rubocop does not handle it otherwise.

Can you provide full reproduction steps?

[owst]

Sorry, my repro was rather lacking. The key requirement seems to be to run

RuboCop::AST::BuilderPrism.modernize

which we do as part of our internal cop setup. We have a comment there saying

+# This enables rubocop to correctly handle keyword argument behavior in Ruby 2.7+
+# It enabled differentiation between keyword arguments and hash literals passed
+# as positional arguments.
+# https://github.com/whitequark/parser/pull/769

and we seem to have changed

-RuboCop::AST::Builder.modernize
+RuboCop::AST::BuilderPrism.modernize

at some point, hence the original comment referencing the parser repo but calling a method on BuilderPrism.

A full repro is this script:

rm -rf repro

mkdir repro
cd repro

echo 3.4.7 > .ruby-version

bundle init
bundle add rails --version 7.2.2.2
bundle install

bundle exec rails new --minimal .

bundle add rubocop --version 1.79.2
bundle add rubocop-ast --version 1.46.0
bundle add rubocop-rails --version 2.33.4
bundle add prism --version 1.5.1
bundle install

cat > app/models/thing.rb <<EOF
class Thing < ApplicationRecord
  has_many :other_thing, through: :yet_another_thing
end
EOF

cat > cop-setup.rb <<EOF
# This enables rubocop to correctly handle keyword argument behavior in Ruby 2.7+
# It enabled differentiation between keyword arguments and hash literals passed
# as positional arguments.
# https://github.com/whitequark/parser/pull/769
RuboCop::AST::BuilderPrism.modernize
EOF

cat > .rubocop.yml <<EOF
require:
- ./cop-setup.rb

plugins:
- rubocop-rails

inherit_mode:
  merge:
    - Include
    - Exclude

AllCops:
  TargetRubyVersion: 3.4
  DisplayCopNames: true
  NewCops: enable
EOF
bundle exec rubocop --only Rails/HasManyOrHasOneDependent app/models/thing.rb

Press n to not overwrite the .ruby-version and y to overwrite the Gemfile.

[Earlopain]

That would explain it, yeah. modernize is not a supported mode for rubocop. It's unfortunate but necessary for backwards compatibility.

You should just remove that, Rubocop does handle keywords arguments correctly. Perhaps it wasn't equipped to when they were rather new but today that is not the case anymore.