How to initialize a static std::atomic data member

I know that the atomic types do not have copy constructors, and I assume that explains why this code does not work.

Yes, the error says that quite clearly.

Does anybody know a way to actually get this code to work?

Instead of copy-initialising from a temporary, which requires an accessible copy constructor:

std::atomic<int> order::c = std::atomic<int>(0);

use direct-initialisation, which doesn’t:

std::atomic<int> order::c(0);   // or {0} for a more C++11 experience

You should probably prefer that anyway, unless you enjoy reading unnecessarily verbose code.