anchor.diff:          "--disable-init-state"
           "--enable-gc"
         ]
  -      ++ lib.optionals (!is112) [
  +      ++ lib.optionals (!is20) [
           "--with-dbi=${perlPackages.DBI}/${perl.libPrefix}"
           "--with-dbd-sqlite=${perlPackages.DBDSQLite}/${perl.libPrefix}"
           "--with-www-curl=${perlPackages.WWWCurl}/${perl.libPrefix}"
  -      ] ++ lib.optionals (is112 && stdenv.isLinux) [
  +      ] ++ lib.optionals (is20 && stdenv.isLinux) [
           "--with-sandbox-shell=${sh}/bin/busybox"
         ];
   
  
positive.code:     inherit name src;
      version = lib.getVersion name;
  
      is112 = lib.versionAtLeast version "1.12pre";
  
      VERSION_SUFFIX = lib.optionalString fromGit suffix;
  
  
negative.code:   }) // { perl-bindings = nixStable; };
  
    nixUnstable = (lib.lowPrio (common rec {
      name = "nix-2.0${suffix}";
      suffix = "pre5889_c287d731";
      src = fetchFromGitHub {
        owner = "NixOS";
        repo = "nix";
        rev = "c287d7312103bae5e154c0c4dd493371a22ea207";
        sha256 = "1dwhz93dlk62prh3wfwf8vxfcqjdn21wk0ms65kf5r8ahkfgpgq4";
      };
      fromGit = true;
    })) // { perl-bindings = perl-bindings { nix = nixUnstable; }; };
  