c++ - Demangling and <sstream> results in "ambiguous reference to __gnu_gxx namespace" -

when need print type info @ runtime, apply demangling std::type_info::name() result. implementation gcc, uses abi::__cxa_demangle():

#include <cxxabi.h>  gcc demangling implementation std::string demangle(  const std::string& name ) {      int status;      return std::string( abi::__cxa_demangle( name.c_str() , 0 , 0 , &status ) );      return name; } 

today writting to_string template allows me print content of typelist. avoid std::stringconcatenations, used string stream, std::ostringstream:

template<typename t> struct to_string_t {     operator std::string()     {         return demangle( typeid( t ).name() );     } };  template<typename... ts> struct to_string_t<mpl::list<ts...>> {     operator std::string()     {         std::ostringstream os;          os << '[' << _to_string<mpl::list<ts...>>() << ']';          return os.str();     } }; 

_to_string class template implements operator<<to print recursively content of typelist stream. (i don't include not bloat post non-related metaprogramming code).

this works without demangling. when include <cxxabi> implement demangling, compiler shows ambiguous reference __gnu_gxx namespace error in sstream.h.

what reason?