../tests/check/pipelines/gl-launch-lines.c:314:12: error: variable 'have_gldifferencematte' set but not used [-Werror,-Wunused-but-set-variable] gboolean have_gldifferencematte; ^ 1 error generated. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4741>