c++ - g++ and clang++ different behaviour with variadic container -

in order practice c++11, i'm playing variadic templates.

in particular, i'm playing sort of recursive variadic container class (onion) , function returns number of template types (func()).

i came across case clang++ (3.5.0) can't compile while g++ (4.9.2) compiles , runs no problems.

i have simplified follows

#include <iostream>  template <typename f, typename ... o> struct onion;  template <typename f, typename s, typename ... o> struct onion<f, s, o...>  {    f               first;    onion<s, o...>  others;  };  template <typename l> struct onion<l>  { l  last; };   template <typename ... args> std::size_t func (onion<args...> const &)  { return sizeof...(args); }   int main()  {    auto o = onion<int, char const *, float> { 23, { "abcd", {34.0f}} };     std::cout << func(o) << '\n';     return 0;  } 

clang++ (3.5.0) gives me following compiler error

test.cpp:28:17: error: no matching function call 'func'    std::cout << func(o) << '\n';                 ^~~~ test.cpp:20:13: note: candidate template ignored: substitution       failure [with args = <>]: few template arguments class template       'onion' std::size_t func (onion<args...> const &)             ^     ~~~~~ 1 error generated. 

g++ (4.9.2) compiles without problem and, running, output 3.

my question is: who's right?

clang++, giving error, or g++, compiling?

i add if rewrite func() in way

template <typename x, typename ... args> std::size_t func (onion<x, args...> const &)  { return 1u + sizeof...(args); } 

or if redefine onion in way

template <typename ... o> struct onion; 

both clang++ , g++ compile without errors.

this looks compiler bug in clang 3.5. if run code trunk version compiles nicely.