Makes cancan2.0 compatible with Rails4 and optimise a view call

lib/cancan/model_adapters/active_record_adapter.rb

@@ -52,7 +52,7 @@ def self.meta_where_match?(subject_value, method, value)
       #   query(:manage, User).conditions # => "not (self_managed = 't') AND ((manager_id = 1) OR (id = 1))"
       #
       def conditions
-        if @rules.size == 1 && @rules.first.base_behavior
+        if (@rules.size == 1 || @rules.uniq{|r| r.conditions}.size == 1) && @rules.first.base_behavior
           # Return the conditions directly if there's just one definition
           tableized_conditions(@rules.first.conditions).dup
         else
@@ -87,7 +87,7 @@ def joins
 
       def database_records
         if override_scope
-          @model_class.scoped.merge(override_scope)
+          @model_class.all.merge(override_scope)
         elsif @model_class.respond_to?(:where) && @model_class.respond_to?(:joins)
           mergeable_conditions = @rules.select {|rule| rule.unmergeable? }.blank?
           if mergeable_conditions

lib/cancan/rule.rb

@@ -39,7 +39,7 @@ def matches_conditions?(action, subject, attribute)
         matches_conditions_hash?(subject)
       else
         # Don't stop at "cannot" definitions when there are conditions.
-        @conditions.empty? ? true : @base_behavior
+        (@conditions.is_a?(ActiveRecord::Relation) || @conditions.empty?) ? true : @base_behavior
       end
     end
 
@@ -48,19 +48,19 @@ def only_block?
     end
 
     def only_raw_sql?
-      @block.nil? && conditions? && [email protected]_of?(Hash)
+      @block.nil? && conditions? && [email protected]_of?(Hash) && [email protected]_a?(ActiveRecord::Relation)
     end
 
     def attributes?
       @attributes.present?
     end
 
     def conditions?
-      @conditions.present?
+      @conditions.is_a?(ActiveRecord::Relation) || @conditions.present? 
     end
 
     def instance_conditions?
-      @block || conditions?
+      @block || (!@conditions.is_a?(ActiveRecord::Relation) && conditions?)
     end
 
     def unmergeable?