anchor.diff:    generic =
         # dependencies
         { stdenv, lib, fetchurl, makeWrapper
  -      , glibc, zlib, readline, openssl, icu, systemd, libossp_uuid
  +      , glibc, zlib, readline, openssl, icu, lz4, systemd, libossp_uuid
         , pkg-config, libxml2, tzdata
   
         # This is important to obtain a version of `libpq` that does not depend on systemd.
  
positive.code:     buildInputs =
        [ zlib readline openssl libxml2 ]
        ++ lib.optionals icuEnabled [ icu ]
        ++ lib.optionals enableSystemd [ systemd ]
        ++ lib.optionals gssSupport [ libkrb5 ]
        ++ lib.optionals (!stdenv.isDarwin) [ libossp_uuid ];
  
negative.code:       (lib.optionalString enableSystemd "--with-systemd")
        (if stdenv.isDarwin then "--with-uuid=e2fs" else "--with-ossp-uuid")
      ] ++ lib.optionals icuEnabled [ "--with-icu" ]
        ++ lib.optionals lz4Enabled [ "--with-lz4" ]
        ++ lib.optionals gssSupport [ "--with-gssapi" ];
  
      patches =
  