Having a constexpr static string gives a linker error

The following program gives me a link-time error:

#include <iostream> struct Test { static constexpr char text[] = "Text"; }; int main() { std::cout << Test::text << std::endl; // error: undefined reference to `Test::text' } 

The error message is

/tmp/main-35f287.o: In function `main': main.cpp:(.text+0x4): undefined reference to `Test::text' main.cpp:(.text+0x13): undefined reference to `Test::text' clang: error: linker command failed with exit code 1 (use -v to see invocation) 

Ok. Let's try to fix that: I add a definition outside the struct body:

#include <iostream> struct Test { static constexpr char text[] = "Text"; }; constexpr char Test::text[] = "Text"; int main() { std::cout << Test::text << std::endl; } 

Clang gives me the following error message.

main.cpp:4:35: error: static data member 'text' already has an initializer constexpr char Test::text[] = "Text"; ^ main.cpp:3:50: note: previous initialization is here struct Test { static constexpr char text[] = "Text"; }; 

Oh, well, I thought, now I know what you want:

#include <iostream> struct Test { static constexpr char text[]; }; constexpr char Test::text[] = "Text"; int main() { std::cout << Test::text << std::endl; } 

And again an error:

main.cpp:3:41: error: declaration of constexpr static data member 'text' requires an initializer struct Test { static constexpr char text[]; }; 

And there the dog bites its own tail. :(

Is there a way to use compile-time constant character arrays that are declared inside a class? The reason, I want the data inside a class, is that I need a type traits class that helps me do template stuff.