defning extensions happens once, no need to cache

1 files changed, 3 insertions, 5 deletions

diff --git a/activerecord/lib/active_record/associations/builder/collection_association.rb b/activerecord/lib/active_record/associations/builder/collection_association.rb
index 076fedc1a9..a7f8c2af46 100644
--- a/activerecord/lib/active_record/associations/builder/collection_association.rb
+++ b/activerecord/lib/active_record/associations/builder/collection_association.rb
@@ -32,7 +32,9 @@ module ActiveRecord::Associations::Builder
 
     def define_extensions(model)
       if block_extension
-        @extension_module = mod = Module.new(&block_extension)
+        mod = Module.new(&block_extension)
+        extension_module_name = "#{model.name.demodulize}#{name.to_s.camelize}AssociationExtension"
+
         silence_warnings do
           model.parent.const_set(extension_module_name, mod)
         end
@@ -47,10 +49,6 @@ module ActiveRecord::Associations::Builder
       end
     end
 
-    def extension_module_name
-      @extension_module_name ||= "#{model.name.demodulize}#{name.to_s.camelize}AssociationExtension"
-    end
-
     def define_callback(model, callback_name)
       full_callback_name = "#{callback_name}_for_#{name}"