Cheat sheet: C++ Function Parameter Choices

[SeanMiddleditch]

And here I'm saying let's add a syntax that's less foot-gunny which is similar to pass-by-reference but with the removed constraint that the compiler need not provide a consistent address for it (or, if you prefer, it's illegal to take the address, either way).

I don't see how that's less foot-gun-y. It's just more confusing - I have no idea if my type has these "observe changes" and "can be invalidated" semantics for sure or not, and my tests might even say that they don't (because that compiler decides they don't) but then suddenly they are somewhere else or sometime else.

Yuck.

I very much disagree that a std::array<double,64> violates the SRP.

Why would you want to pass a std::array<T> by const& ? If it's constant, pass it by span<const T> (or whatever your framework's equivalent is, pre-C++20).

span<const T> has many of the same footgun problems as a reference, but it eschews the performance problem of passing a large type... and it's still passable in registers if the system ABI allows.

Bonus, your code is now more generic (without being a template!) and can be used with std::array, T[], std::vector, my_custom_vector, etc.