Another (more portable) way to get the cache line size is to use std::hardware_(destructive|constructive)_interference_size from C++17.
While it's more portable, there are some drawbacks. Drawbacks with this approach are: (1) the statically known cache line size might not be right if you deploy your code to a target CPU different from the one you compiled for, (2) using this value to define structure + member alignment in headers could end up with interesting bugs if different source files including the header are built with different flags. Also: your toolchain might not support it yet.
