Allow `Relation#or` to accept a relation with different `references`

Note that the two relations must still have the same `includes` values
(which is the only time `references` actually does anything). It makes
sense for us to allow this, as `references` is called implicitly when
passing a hash to `where`.

Fixes #29411

activerecord/CHANGELOG.md

@@ -1,3 +1,10 @@
*   `Relation#or` now accepts two relations who have different values for
    `references` only, as `references` can be implicitly called by `where`.

    Fixes #29411.

    *Sean Griffin*

*   ApplicationRecord is no longer generated when generating models.  If you
    need to generate it, it can be created with `rails g application_record`.

activerecord/lib/active_record/relation/query_methods.rb

@@ -635,6 +635,7 @@ def or!(other) # :nodoc:

      self.where_clause = self.where_clause.or(other.where_clause)
      self.having_clause = having_clause.or(other.having_clause)
      self.references_values += other.references_values

      self
    end
@@ -1158,7 +1159,7 @@ def check_if_method_has_arguments!(method_name, args)
        end
      end

      STRUCTURAL_OR_METHODS = Relation::VALUE_METHODS - [:extending, :where, :having, :unscope]
      STRUCTURAL_OR_METHODS = Relation::VALUE_METHODS - [:extending, :where, :having, :unscope, :references]
      def structurally_incompatible_values_for_or(other)
        STRUCTURAL_OR_METHODS.reject do |method|
          get_value(method) == other.get_value(method)

activerecord/test/cases/relation/or_test.rb

@@ -1,11 +1,14 @@
# frozen_string_literal: true

require "cases/helper"
require "models/author"
require "models/categorization"
require "models/post"

module ActiveRecord
  class OrTest < ActiveRecord::TestCase
    fixtures :posts
    fixtures :authors

    def test_or_with_relation
      expected = Post.where("id = 1 or id = 2").to_a
@@ -115,5 +118,13 @@ def test_or_with_non_relation_object_raises_error
        Post.where(id: [1, 2, 3]).or(title: "Rails")
      end
    end

    def test_or_with_references_inequality
      joined = Post.includes(:author)
      actual = joined.where(authors: { id: 1 })
        .or(joined.where(title: "I don't have any comments"))
      expected = Author.find(1).posts + Post.where(title: "I don't have any comments")
      assert_equal expected.sort_by(&:id), actual.sort_by(&:id)
    end
  end
end