Deprecate InstanceMethods namespace handling in ActiveSupport::Concern.

This avoids the unnecessary "yo dawg, I heard you like include, so I put a module that includes your module when it is included" approach when building extensions.

Author: josevalim

activesupport/lib/active_support/concern.rb

@@ -4,17 +4,12 @@ module ActiveSupport
   #   module M
   #     def self.included(base)
   #       base.extend ClassMethods
-  #       base.send(:include, InstanceMethods)
   #       scope :disabled, where(:disabled => true)
   #     end
   #
   #     module ClassMethods
   #       ...
   #     end
-  #
-  #     module InstanceMethods
-  #       ...
-  #     end
   #   end
   #
   # By using <tt>ActiveSupport::Concern</tt> the above module could instead be written as:
@@ -31,10 +26,6 @@ module ActiveSupport
   #     module ClassMethods
   #       ...
   #     end
-  #
-  #     module InstanceMethods
-  #       ...
-  #     end
   #   end
   #
   # Moreover, it gracefully handles module dependencies. Given a +Foo+ module and a +Bar+
@@ -118,7 +109,11 @@ def append_features(base)
         @_dependencies.each { |dep| base.send(:include, dep) }
         super
         base.extend const_get("ClassMethods") if const_defined?("ClassMethods")
-        base.send :include, const_get("InstanceMethods") if const_defined?("InstanceMethods")
+        if const_defined?("InstanceMethods")
+          base.send :include, const_get("InstanceMethods")
+          ActiveSupport::Deprecation.warn "The InstanceMethods module inside ActiveSupport::Concern will be " \
+            "no longer included automatically. Please define instance methods directly in #{base} instead.", caller
+        end
         base.class_eval(&@_included_block) if instance_variable_defined?("@_included_block")
       end
     end

activesupport/test/concern_test.rb

@@ -19,9 +19,6 @@ def included_ran
       end
     end
 
-    module InstanceMethods
-    end
-
     included do
       self.included_ran = true
     end
@@ -74,7 +71,7 @@ def test_class_methods_are_extended
   def test_instance_methods_are_included
     @klass.send(:include, Baz)
     assert_equal "baz", @klass.new.baz
-    assert @klass.included_modules.include?(ConcernTest::Baz::InstanceMethods)
+    assert @klass.included_modules.include?(ConcernTest::Baz)
   end
 
   def test_included_block_is_ran
@@ -92,6 +89,6 @@ def test_modules_dependencies_are_met
 
   def test_dependencies_with_multiple_modules
     @klass.send(:include, Foo)
-    assert_equal [ConcernTest::Foo, ConcernTest::Bar, ConcernTest::Baz::InstanceMethods, ConcernTest::Baz], @klass.included_modules[0..3]
+    assert_equal [ConcernTest::Foo, ConcernTest::Bar, ConcernTest::Baz], @klass.included_modules[0..2]
   end
 end