3 files changed, 19 insertions, 4 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 5ffbed28f6..6c7e2b19e7 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   `Relation#joins` is no longer affected by the target model's
+    `current_scope`, with the exception of `unscoped`.
+
+    Fixes #29338.
+
+    *Sean Griffin*
+
 *   Change sqlite3 boolean serialization to use 1 and 0
 
     SQLite natively recognizes 1 and 0 as true and false, but does not natively
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index a453ca55c7..4f53280b5c 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -219,10 +219,8 @@ module ActiveRecord
       end
 
       def klass_join_scope(table, predicate_builder) # :nodoc:
-        if klass.current_scope
-          klass.current_scope.clone.tap { |scope|
-            scope.joins_values = scope.left_outer_joins_values = [].freeze
-          }
+        if klass.current_scope && klass.current_scope.values.empty?
+          klass.unscoped
         else
           klass.default_scoped(build_scope(table, predicate_builder))
         end
diff --git a/activerecord/test/cases/scoping/default_scoping_test.rb b/activerecord/test/cases/scoping/default_scoping_test.rb
index bd05cb4787..a5061cfce7 100644
--- a/activerecord/test/cases/scoping/default_scoping_test.rb
+++ b/activerecord/test/cases/scoping/default_scoping_test.rb
@@ -377,6 +377,16 @@ class DefaultScopingTest < ActiveRecord::TestCase
                  Comment.joins(:post).count
   end
 
+  def test_joins_not_affected_by_scope_other_than_default_or_unscoped
+    without_scope_on_post = Comment.joins(:post).to_a
+    with_scope_on_post = nil
+    Post.where(id: [1, 5, 6]).scoping do
+      with_scope_on_post = Comment.joins(:post).to_a
+    end
+
+    assert_equal with_scope_on_post, without_scope_on_post
+  end
+
   def test_unscoped_with_joins_should_not_have_default_scope
     assert_equal SpecialPostWithDefaultScope.unscoped { Comment.joins(:special_post_with_default_scope).to_a },
                  Comment.joins(:post).to_a