Don't try to get the subclass if the inheritance column doesn't exist

The `subclass_from_attrs` method is called even if the column specified by
the `inheritance_column` setting doesn't exist. This prevents setting associations
via the attributes hash if the association name clashes with the value of the setting,
typically `:type`. This worked previously in Rails 3.2.

3 files changed, 18 insertions, 1 deletions

diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index 7fd7d42354..d2b5a06b55 100644
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -1,10 +1,11 @@
-require "cases/helper"
+require 'cases/helper'
 require 'models/company'
 require 'models/person'
 require 'models/post'
 require 'models/project'
 require 'models/subscriber'
 require 'models/vegetables'
+require 'models/shop'
 
 class InheritanceTest < ActiveRecord::TestCase
   fixtures :companies, :projects, :subscribers, :accounts, :vegetables
@@ -367,4 +368,10 @@ class InheritanceComputeTypeTest < ActiveRecord::TestCase
   ensure
     ActiveRecord::Base.store_full_sti_class = true
   end
+
+  def test_sti_type_from_attributes_disabled_in_non_sti_class
+    phone = Shop::Product::Type.new(name: 'Phone')
+    product = Shop::Product.new(:type => phone)
+    assert product.save
+  end
 end
diff --git a/activerecord/test/models/shop.rb b/activerecord/test/models/shop.rb
index 81414227ea..607a0a5b41 100644
--- a/activerecord/test/models/shop.rb
+++ b/activerecord/test/models/shop.rb
@@ -5,6 +5,11 @@ module Shop
 
   class Product < ActiveRecord::Base
     has_many :variants, :dependent => :delete_all
+    belongs_to :type
+
+    class Type < ActiveRecord::Base
+      has_many :products
+    end
   end
 
   class Variant < ActiveRecord::Base
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index ddfc1ac0d6..9a7d918a25 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -557,9 +557,14 @@ ActiveRecord::Schema.define do
 
   create_table :products, force: true do |t|
     t.references :collection
+    t.references :type
     t.string     :name
   end
 
+  create_table :product_types, force: true do |t|
+    t.string :name
+  end
+
   create_table :projects, force: true do |t|
     t.string :name
     t.string :type