anchor.diff: -{ stdenv, fetchzip, boost, cmake, ncurses, python2
  +{ stdenv, fetchzip, boost, cmake, ncurses, python3, coreutils
   , z3Support ? true, z3 ? null, cvc4Support ? true, cvc4 ? null
   , cln ? null, gmp ? null
   }:
  
positive.code:     pushd ..
      # IPC tests need aleth avaliable, so we disable it
      sed -i "s/IPC_ENABLED=true/IPC_ENABLED=false\nIPC_FLAGS=\"--no-ipc\"/" ./scripts/tests.sh
      for i in ./scripts/*.sh; do
        patchShebangs "$i"
      done
      for i in ./scripts/*.py; do
        patchShebangs "$i"
      done
      for i in ./test/*.sh; do
        patchShebangs "$i"
      done
      TERM=xterm ./scripts/tests.sh
  
negative.code: stdenv.mkDerivation rec {
  
    pname = "solc";
    version = "0.6.8";
  
    # upstream suggests avoid using archive generated by github
    src = fetchzip {
      url = "https://github.com/ethereum/solidity/releases/download/v${version}/solidity_${version}.tar.gz";
      sha256 = "1nxds6c10hjqjjk893qw2yljws57li0xigbf3ih85y8y6d587ph0";
    };
  
    postPatch = ''
  