Apply the default scope earlier when doing calculations. Fixes #1682.

activerecord/lib/active_record/relation/calculations.rb

@@ -146,10 +146,16 @@ def calculate(operation, column_name, options = {})
       if options.except(:distinct).present?
         apply_finder_options(options.except(:distinct)).calculate(operation, column_name, :distinct => options[:distinct])
       else
-        if eager_loading? || (includes_values.present? && references_eager_loaded_tables?)
-          construct_relation_for_association_calculations.calculate(operation, column_name, options)
+        relation = with_default_scope
+
+        if relation.equal?(self)
+          if eager_loading? || (includes_values.present? && references_eager_loaded_tables?)
+            construct_relation_for_association_calculations.calculate(operation, column_name, options)
+          else
+            perform_calculation(operation, column_name, options)
+          end
         else
-          perform_calculation(operation, column_name, options)
+          relation.calculate(operation, column_name, options)
         end
       end
     rescue ThrowResult
@@ -196,7 +202,7 @@ def operation_over_aggregate_column(column, operation, distinct)
 
     def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
       # Postgresql doesn't like ORDER BY when there are no GROUP BY
-      relation = with_default_scope.reorder(nil)
+      relation = reorder(nil)
 
       if operation == "count" && (relation.limit_value || relation.offset_value)
         # Shortcut when limit is zero.
@@ -245,7 +251,7 @@ def execute_grouped_calculation(operation, column_name, distinct) #:nodoc:
         "#{field} AS #{aliaz}"
       }
 
-      relation = with_default_scope.except(:group).group(group.join(','))
+      relation = except(:group).group(group.join(','))
       relation.select_values = select_values
 
       calculated_data = @klass.connection.select_all(relation.to_sql)

activerecord/test/cases/relation_scoping_test.rb

@@ -498,4 +498,11 @@ def test_default_scope_find_last
     lowest_salary_dev = DeveloperOrderedBySalary.find(developers(:poor_jamis).id)
     assert_equal lowest_salary_dev, DeveloperOrderedBySalary.last
   end
+
+  def test_default_scope_include_with_count
+    d = DeveloperWithIncludes.create!
+    d.audit_logs.create! :message => 'foo'
+
+    assert_equal 1, DeveloperWithIncludes.where(:audit_logs => { :message => 'foo' }).count
+  end
 end

activerecord/test/models/developer.rb

@@ -91,6 +91,12 @@ class DeveloperWithSelect < ActiveRecord::Base
   default_scope select('name')
 end
 
+class DeveloperWithIncludes < ActiveRecord::Base
+  self.table_name = 'developers'
+  has_many :audit_logs, :foreign_key => :developer_id
+  default_scope includes(:audit_logs)
+end
+
 class DeveloperOrderedBySalary < ActiveRecord::Base
   self.table_name = 'developers'
   default_scope :order => 'salary DESC'