anchor.diff:        "--sysconfdir=/etc"
         "--libdir=$(lib)/lib"
         "--with-system-tzdata=${tzdata}/share/zoneinfo"
  -      (lib.optionalString (atLeast "9.6" && !stdenv.isDarwin) "--with-systemd")
  +      (lib.optionalString enableSystemd "--with-systemd")
         (if stdenv.isDarwin then "--with-uuid=e2fs" else "--with-ossp-uuid")
       ] ++ lib.optionals icuEnabled [ "--with-icu" ];
   
  
positive.code:       { stdenv, lib, fetchurl, makeWrapper
        , glibc, zlib, readline, openssl, icu, systemd, libossp_uuid
        , pkgconfig, libxml2, tzdata
  
        # for postgreql.pkgs
        , this, self, newScope, buildEnv
  
negative.code:     buildInputs =
        [ zlib readline openssl libxml2 makeWrapper ]
        ++ lib.optionals icuEnabled [ icu ]
        ++ lib.optionals enableSystemd [ systemd ]
        ++ lib.optionals (!stdenv.isDarwin) [ libossp_uuid ];
  
      nativeBuildInputs = lib.optionals icuEnabled [ pkgconfig ];
  