anchor.diff:  { lib, stdenv, fetchFromGitHub, fetchpatch, cmake, zlib, c-ares, pkg-config, re2, openssl, protobuf
  -, gflags, libnsl
  +, gflags, abseil-cpp, libnsl
   }:
   
   stdenv.mkDerivation rec {
  
positive.code:   ];
  
    nativeBuildInputs = [ cmake pkg-config ];
    propagatedBuildInputs = [ c-ares re2 zlib ];
    buildInputs = [ c-ares.cmake-config openssl protobuf gflags ]
      ++ lib.optionals stdenv.isLinux [ libnsl ];
  
  
negative.code:       "-DgRPC_SSL_PROVIDER=package"
        "-DgRPC_PROTOBUF_PROVIDER=package"
        "-DgRPC_GFLAGS_PROVIDER=package"
        "-DgRPC_ABSL_PROVIDER=package"
        "-DBUILD_SHARED_LIBS=ON"
        "-DCMAKE_SKIP_BUILD_RPATH=OFF"
        "-DCMAKE_CXX_STANDARD=17"
      ];
  
    # CMake creates a build directory by default, this conflicts with the
  