There's some unused variables in gstsunaudiomixerctrl.c and gstsunaudiosink.c that break compilation with -Wall -Werror. There's also these warnings that I'm not sure how to get rid of:
gstsunaudiomixerctrl.c: In function `gst_sunaudiomixer_ctrl_get_volume':
gstsunaudiomixerctrl.c:179: warning: 'gain' might be used uninitialized in this function
gstsunaudiomixerctrl.c:179: warning: 'balance' might be used uninitialized in this function
The code in question is:
  gint gain, balance;
[stuff, doesn't touch gain or balance]
  switch (sunaudiotrack->track_num) {
    case GST_SUNAUDIO_TRACK_OUTPUT:
      gain = (int) audioinfo.play.gain;
      balance = audioinfo.play.balance;
      break;
    case GST_SUNAUDIO_TRACK_LINE_IN:
      gain = (int) audioinfo.record.gain;
      balance = audioinfo.record.balance;
      break;
    case GST_SUNAUDIO_TRACK_MONITOR:
      gain = (int) audioinfo.monitor_gain;
      balance = audioinfo.record.balance;
      break;
  }
so I guess because there's no default case gcc complains.