Documentation: how to setup a LLVM development environment

[SchrodingerZhu]

Problem

I found it is not trivial to setup a usable LLVM development environment.

I hope something like the following should work:

environment.systemPackages = with pkgs; [
     llvmPackages_latest.clangUseLLVM
     llvmPackages_latest.llvm
     llvmPackages_latest.openmp
     llvmPackages_latest.lld
     llvmPackages_latest.bintools
     llvmPackages_latest.libcxx
     llvmPackages_latest.libcxxabi
     llvmPackages_latest.compiler-rt
     llvmPackages_latest.libunwind
];

But this does not give the dev headers like:

/nix/store/mg7dmdj9nbijkys9ink0qi6gl5cpshk6-openmp-14.0.6-dev

Only when I enter the nix shell would the *-dev being populated.

How to correctly setup the development environment?

[aaronmondal]

I think we have something that comes close to what you want in our rules_ll flake.

See #213144 and #214524.