c++ - How to create a compile time constant instance of a structure in C++11 -

in current project trying create compile time const static instance of structure c++11. code compiles , works fine in clang (apple llvm version 6.1.0) not work g++ (gcc) 4.8.3. gcc throws error parameter not declared 'constexpr'. there way make work in gcc?

//parameter.h struct par {     const int uniqid;     const char *name;     const char *description;     constexpr par(int uid,const char * n,const char * d)              :uniqid(uid), name(n),description(d){} };  class parameters           {     const static par param_a;     ...     const static par param_z;     printparameters(std::vector<par> parameters); };  //parameter.cpp constexpr par parameters::param_a={0,"-a","bla a"}; ...  constexpr par parameters::param_z={0,"-z","bla z"};  void parameters::printparameters(std::vector<par> parameters){      (size_t = 0; < parameters.size(); i++) {         switch (parameters[i].uniqid) {            case param_a.uniqid:                  std::cout << "a" << std::endl;                 break;         } } 

the gcc following:

parameters.cpp:11:39: error: declaration of ‘const par parameters::param_a’ outside of class not definition [-fpermissive] parameters.cpp:12:39: error: redeclaration ‘parameters::param_a’ differs in ‘constexpr’  constexpr par parameters::param_a={...};  in file included parameters.cpp:2:0:         parameters.h:190:34: note: ‘parameters::param_a’ not declared 'constexpr' const static par param_a; 

i think problem declare param_a , param_z const in parameter.h , define them constexpr in parameter.cpp. const , constexpr different things. in parameter.cpp must have this:

//parameter.cpp const par parameters::param_a={0,"-a","bla a"}; ...  const par parameters::param_z={0,"-z","bla z"};