anchor.diff:        ( if idnSupport then "--with-libidn=${libidn.dev}" else "--without-libidn" )
         ( if brotliSupport then "--with-brotli" else "--without-brotli" )
       ]
  +    ++ stdenv.lib.optional wolfsslSupport "--with-wolfssl=${wolfssl.dev}"
       ++ stdenv.lib.optional c-aresSupport "--enable-ares=${c-ares}"
       ++ stdenv.lib.optional gssSupport "--with-gssapi=${libkrb5.dev}"
          # For the 'urandom', maybe it should be a cross-system option
  
positive.code:     optional c-aresSupport c-ares ++
      optional sslSupport openssl ++
      optional gnutlsSupport gnutls ++
      optional scpSupport libssh2 ++
      optional brotliSupport brotli;
  
  
negative.code: , zlibSupport ? true, zlib ? null
  , sslSupport ? zlibSupport, openssl ? null
  , gnutlsSupport ? false, gnutls ? null
  , wolfsslSupport ? false, wolfssl ? null
  , scpSupport ? zlibSupport && !stdenv.isSunOS && !stdenv.isCygwin, libssh2 ? null
  , gssSupport ? !stdenv.hostPlatform.isWindows, libkrb5 ? null
  , c-aresSupport ? false, c-ares ? null
  