Question How is constant buffer got matched between c++ and shader?

Hello,

I am learning D3D11 by myself. I am wondering how is variable in c++ got matched by variables in shader?

For example, from the tutorial of D3D11: https://docs.microsoft.com/en-us/wi...direct3d-11-resources-buffers-constant-how-to

The layout of CBuffer in c++ is exact same as layout in shader. However, in Unity, I can declare shader variable in any order. How is this achieved?