In ignition::math::Color the color constants are defined like public: static const Color Cyan;. While the resulting interface is nice to use, it could cause static initialization order fiasco as C++ makes no guarantee that global variables in this form is going to be initialized in usage order. In other words, another global variable could use Color::Cyan and be initialized first.

A simple fix is to convert to a function form like the following:
public: const Color& Cyan() { static auto *c = new Color(0, 1, 1, 1); return *c; }

Another solution is more involved but it could retain the ability to refer to constants without parentheses.

1. Add a constexpr constructor to the class.
2. In another class, say, ColorConstants, use public: static constexpr Color Cyan = {0, 1, 1, 1};

Both solutions represent a API/ABI change, so I would like to hear some feedback first before sending out PRs.

The Vector classes might be affected by this too.