tag bind params with a bind param object

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -166,7 +166,7 @@ module ActiveRecord
       # Returns a bind substitution value given a +column+ and list of current
       # +binds+
       def substitute_at(column, index)
-        Arel.sql '?'
+        Arel::Nodes::BindParam.new '?'
       end
 
       # REFERENTIAL INTEGRITY ====================================

activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb

@@ -66,7 +66,7 @@ module ActiveRecord
       end
 
       def substitute_at(column, index)
-        Arel.sql "\0"
+        Arel::Nodes::BindParam.new "\0"
       end
 
       # CONNECTION MANAGEMENT ====================================

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -721,7 +721,7 @@ module ActiveRecord
       end
 
       def substitute_at(column, index)
-        Arel.sql("$#{index + 1}")
+        Arel::Nodes::BindParam.new "$#{index + 1}"
       end
 
       class Result < ActiveRecord::Result