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

3 files changed, 20 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index a656c767c0..1ff7010c2f 100644
--- a/activerecord/CHANGELOG.md
+++ b/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`.
 
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index a51cf4319e..f7fe968b55 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -635,6 +635,7 @@ module ActiveRecord
 
       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 @@ module ActiveRecord
         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)
diff --git a/activerecord/test/cases/relation/or_test.rb b/activerecord/test/cases/relation/or_test.rb
index 3269620987..b01801b41f 100644
--- a/activerecord/test/cases/relation/or_test.rb
+++ b/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 @@ module ActiveRecord
         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