Allow unscoping CTEs

Author: Liamjen

activerecord/lib/active_record/relation/query_methods.rb

@@ -751,7 +751,7 @@ def reorder!(*args) # :nodoc:
     VALID_UNSCOPING_VALUES = Set.new([:where, :select, :group, :order, :lock,
                                      :limit, :offset, :joins, :left_outer_joins, :annotate,
                                      :includes, :eager_load, :preload, :from, :readonly,
-                                     :having, :optimizer_hints])
+                                     :having, :optimizer_hints, :with])
 
     # Removes an unwanted relation that is already defined on a chain of relations.
     # This is useful when passing around chains of relations and would like to

activerecord/test/cases/relation/with_test.rb

@@ -114,6 +114,15 @@ def test_raises_when_using_block
           Post.with(attributes_for_inspect: :id) { }
         end
       end
+
+      def test_unscoping
+        relation = Post.with(posts_with_comments: Post.where("legacy_comments_count > 0"))
+
+        assert_equal true, relation.values[:with].flat_map(&:keys).include?(:posts_with_comments)
+        relation = relation.unscope(:with)
+        assert_nil relation.values[:with]
+        assert_equal Post.count, relation.count
+      end
     else
       def test_common_table_expressions_are_unsupported
         assert_raises ActiveRecord::StatementInvalid do