1 files changed, 9 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index fc6f15206a..0fcd288fc5 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -61,6 +61,12 @@ module ActiveRecord
     end
   end
 
+  class HasAndBelongsToManyAssociationWithPrimaryKeyError < ActiveRecordError #:nodoc:
+    def initialize(reflection)
+      super("Primary key is not allowed in a has_and_belongs_to_many join table (#{reflection.options[:join_table]}).")
+    end
+  end
+
   class HasAndBelongsToManyAssociationForeignKeyNeeded < ActiveRecordError #:nodoc:
     def initialize(reflection)
       super("Cannot create self referential has_and_belongs_to_many association on '#{reflection.class_name rescue nil}##{reflection.name rescue nil}'. :association_foreign_key cannot be the same as the :foreign_key.")
@@ -1675,7 +1681,6 @@ module ActiveRecord
 
         def create_has_and_belongs_to_many_reflection(association_id, options, &extension)
           options.assert_valid_keys(valid_keys_for_has_and_belongs_to_many_association)
-
           options[:extend] = create_extension_modules(association_id, extension, options[:extend])
 
           reflection = create_reflection(:has_and_belongs_to_many, association_id, options, self)
@@ -1685,6 +1690,9 @@ module ActiveRecord
           end
 
           reflection.options[:join_table] ||= join_table_name(undecorated_table_name(self.to_s), undecorated_table_name(reflection.class_name))
+          if connection.supports_primary_key? && (connection.primary_key(reflection.options[:join_table]) rescue false)
+             raise HasAndBelongsToManyAssociationWithPrimaryKeyError.new(reflection)
+          end
 
           reflection
         end