2 files changed, 7 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/associations/builder/association.rb b/activerecord/lib/active_record/associations/builder/association.rb
index 3911d1b520..f085fd1cfd 100644
--- a/activerecord/lib/active_record/associations/builder/association.rb
+++ b/activerecord/lib/active_record/associations/builder/association.rb
@@ -26,6 +26,12 @@ module ActiveRecord::Associations::Builder
     attr_reader :name, :scope, :options
 
     def self.build(model, name, scope, options, &block)
+      if model.dangerous_attribute_method?(name)
+        raise ArgumentError, "You tried to define an association named #{name} on the model #{model.name}, but " \
+                             "this will conflict with a method #{name} already defined by Active Record. " \
+                             "Please choose a different association name."
+      end
+
       builder = create_builder model, name, scope, options, &block
       reflection = builder.build(model)
       define_accessors model, reflection
diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index 62cc1e3a8d..5ccaa55a32 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -112,7 +112,7 @@ module ActiveRecord::Associations::Builder
       end
 
       record = o.send name
-      unless record.nil? || record.new_record?
+      if record && record.persisted?
         if touch != true
           record.touch touch
         else