I never thought to contact them, but I might do that, thanks for the suggestion. This is something I tested almost two years ago, I have these benchmarks written down but I've since deleted the code I've used, save for the optimal implementations (though it wouldn't take too long to rewrite it).

I tested with clang on my Mac laptop and gcc on a Linux workstation. Version, not sure. If I test this again to contact the Hana people, I'll try and give all this information. I did test the constexpr ordering arrays by making sure I can pass, say, arr[0] as a template parameter. This is only possible if the value is known at compile time. Though it's also possible the compiler could be lazy in other contexts, as in not actually evaluating at compile time if it figures out the result is not necessary to be known at compile time.

Oh yeah, you're right, I was confusing translation unit and function scope.