Revert "Removing composed_of from ActiveRecord."

This reverts commit 14fc8b34521f8354a17e50cd11fa3f809e423592.

Reason: we need to discuss a better path from this removal.

Conflicts:
	activerecord/lib/active_record/reflection.rb
	activerecord/test/cases/base_test.rb
	activerecord/test/models/developer.rb

1 files changed, 2 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 803d68187c..df8d805c8c 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -266,6 +266,7 @@ module ActiveRecord
         @changed_attributes[attr] = orig_value if _field_changed?(attr, orig_value, @attributes[attr])
       end
 
+      @aggregation_cache = {}
       @association_cache = {}
       @attributes_cache  = {}
 
@@ -390,6 +391,7 @@ module ActiveRecord
 
       @attributes[pk] = nil unless @attributes.key?(pk)
 
+      @aggregation_cache       = {}
       @association_cache       = {}
       @attributes_cache        = {}
       @previously_changed      = {}