-template<> struct need_promotion<char > : true_type {};
-template<> struct need_promotion<signed char > : true_type {};
-template<> struct need_promotion<unsigned char > : true_type {};
-template<> struct need_promotion<signed short int > : true_type {};
-template<> struct need_promotion<unsigned short int> : true_type {};
+template<> struct need_promotion<char > : public true_type {};
+template<> struct need_promotion<signed char > : public true_type {};
+template<> struct need_promotion<unsigned char > : public true_type {};
+template<> struct need_promotion<signed short int > : public true_type {};
+template<> struct need_promotion<unsigned short int> : public true_type {};