anchor.diff:    # applications that use Curl.
     propagatedBuildInputs = with lib;
       optional http2Support nghttp2 ++
  -    optional idnSupport libidn ++
  +    optional idnSupport libidn2 ++
       optional ldapSupport openldap ++
       optional zlibSupport zlib ++
       optional gssSupport libkrb5 ++
  
positive.code:       (lib.withFeatureAs scpSupport "libssh2" (lib.getDev libssh2))
        (lib.enableFeature ldapSupport "ldap")
        (lib.enableFeature ldapSupport "ldaps")
        (lib.withFeatureAs idnSupport "libidn" (lib.getDev libidn))
        (lib.withFeature brotliSupport "brotli")
      ]
      ++ lib.optional wolfsslSupport "--with-wolfssl=${lib.getDev wolfssl}"
  
negative.code: # files.
  
  assert http2Support -> nghttp2 != null;
  assert idnSupport -> libidn2 != null;
  assert ldapSupport -> openldap != null;
  assert zlibSupport -> zlib != null;
  assert opensslSupport -> openssl != null;
  