anchor.diff:    NIX_LDFLAGS = lib.optionalString (stdenv.cc.isGNU && stdenv.hostPlatform.libc == "glibc") "-lgcc_s"
                 + lib.optionalString (stdenv.isFreeBSD) "-lthr";
   
  -  configureFlags = lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
  +  configureFlags = [
  +    "ac_cv_prog_CURL_CONFIG=${lib.getDev curl}/bin/curl-config"
  +  ] ++ lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
       "ac_cv_fread_reads_directories=yes"
       "ac_cv_snprintf_returns_bogus=no"
       "ac_cv_iconv_omits_bom=no"
  -    "ac_cv_prog_CURL_CONFIG=${curl.dev}/bin/curl-config"
     ];
   
     preBuild = ''
  
positive.code:   nativeBuildInputs = [ gettext perlPackages.perl makeWrapper ]
      ++ lib.optionals withManual [ asciidoc texinfo xmlto docbook2x
           docbook_xsl docbook_xml_dtd_45 libxslt ];
    buildInputs = [curl openssl zlib expat cpio libiconv]
      ++ lib.optionals perlSupport [ perlPackages.perl ]
      ++ lib.optionals guiSupport [tcl tk]
      ++ lib.optionals withpcre2 [ pcre2 ]
  
negative.code: { fetchurl, lib, stdenv, buildPackages
  , curl, openssl, zlib, expat, perlPackages, python3, gettext, cpio
  , gnugrep, gnused, gawk, coreutils # needed at runtime by git-filter-branch etc
  , openssh, pcre2, bash
  , asciidoc, texinfo, xmlto, docbook2x, docbook_xsl, docbook_xml_dtd_45
  , libxslt, tcl, tk, makeWrapper, libiconv
  , svnSupport, subversionClient, perlLibs, smtpPerlLibs
  