Ensure `apply_join_dependency` for subqueries in `from` and `where`

Fixes #21577.

3 files changed, 19 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation/predicate_builder/relation_handler.rb b/activerecord/lib/active_record/relation/predicate_builder/relation_handler.rb
index f51ea4fde0..c8bbfa5051 100644
--- a/activerecord/lib/active_record/relation/predicate_builder/relation_handler.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder/relation_handler.rb
@@ -4,6 +4,10 @@ module ActiveRecord
   class PredicateBuilder
     class RelationHandler # :nodoc:
       def call(attribute, value)
+        if value.eager_loading?
+          value = value.send(:apply_join_dependency)
+        end
+
         if value.select_values.empty?
           value = value.select(value.arel_attribute(value.klass.primary_key))
         end
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 9c5be4ad9b..34554450dd 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -963,6 +963,9 @@ module ActiveRecord
         name = from_clause.name
         case opts
         when Relation
+          if opts.eager_loading?
+            opts = opts.send(:apply_join_dependency)
+          end
           name ||= "subquery"
           opts.arel.as(name.to_s)
         else
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 844be0d0bf..e44533cf60 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -195,6 +195,18 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal(relation.map(&:post_count).sort, subquery.values.sort)
   end
 
+  def test_finding_with_subquery_with_eager_loading_in_from
+    relation = Comment.includes(:post).where("posts.type": "Post")
+    assert_equal relation.to_a, Comment.select("*").from(relation).to_a
+    assert_equal relation.to_a, Comment.select("subquery.*").from(relation).to_a
+    assert_equal relation.to_a, Comment.select("a.*").from(relation, :a).to_a
+  end
+
+  def test_finding_with_subquery_with_eager_loading_in_where
+    relation = Comment.includes(:post).where("posts.type": "Post")
+    assert_equal relation.to_a, Comment.where(id: relation).to_a
+  end
+
   def test_finding_with_conditions
     assert_equal ["David"], Author.where(name: "David").map(&:name)
     assert_equal ["Mary"],  Author.where(["name = ?", "Mary"]).map(&:name)