anchor.diff:      INSTALL_MOD_PATH = "\${out}";
   
       NIX_CFLAGS = ["-Wno-error=cpp"];
  +
  +    buildInputs = [ libelf ];
   
       buildPhase = "make module";
     };
  
positive.code: { stdenv, fetchurl, libmnl, kernel ? null }:
  
  # module requires Linux >= 3.10 https://www.wireguard.io/install/#kernel-requirements
  assert kernel != null -> stdenv.lib.versionAtLeast kernel.version "3.10";
  
negative.code: let
    name = "wireguard-${version}";
  
    version = "0.0.20171221";
  
    src = fetchurl {
      url    = "https://git.zx2c4.com/WireGuard/snapshot/WireGuard-${version}.tar.xz";
      sha256 = "1vf5dbwc2lgcf28k1m919w94hil2gcl0l4h4da1sh6r7kdz6k5rb";
    };
  
    meta = with stdenv.lib; {
  