anchor.diff: -{ lib, stdenv, fetchurl, openssl, kerberos, db, gettext, pam, fixDarwinDylibNames, autoreconfHook }:
  +{ lib, stdenv, fetchurl, openssl, openldap, kerberos, db, gettext, pam, fixDarwinDylibNames, autoreconfHook, enableLdap ? false }:
   
   with stdenv.lib;
   stdenv.mkDerivation rec {
  
positive.code: 
    configureFlags = [
      "--with-openssl=${openssl.dev}"
    ];
  
    # Set this variable at build-time to make sure $out can be evaluated.
    preConfigure = ''
  
negative.code: 
    buildInputs =
      [ openssl db gettext kerberos ]
      ++ lib.optional enableLdap openldap
      ++ lib.optional stdenv.isFreeBSD autoreconfHook
      ++ lib.optional stdenv.isLinux pam
      ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
  