Adding in a local directory path for C++ header files

Hello all,

I’m creating a shell for C++ development, and I’d like to have some header files located locally on my PC included - something that has the effect of adding them to $CPATH. Is there a less or more hacky way to do this? I’ve tried (rather optimistically) adding the directory path itself to buildInputs of mkShell but that didn’t work. I presume one way would just be to directly edit the CPATH environment variable in the default.nix, by changing shellHook?

Thanks for any help.