GString related signature generation needs extra Option?

[russel]

In the GStreamer MPEGTS library is a function:

GST_MPEGTS_API
gboolean gst_mpegts_descriptor_parse_dvb_short_event (const GstMpegtsDescriptor *descriptor,
                                                       gchar **language_code,
                                                       gchar **event_name,
                                                       gchar **text);

when gir is applied to the GstMpegts-1.0.gir file it generates a method in Descriptor with signature:

parse_dvb_short_event(&self) -> Option<(GString, GString, GString>

There are though situations in which gboolean gst_mpegts_descriptor_parse_dvb_short_event does not set event_name and text but instead leaves them null. This leads to a fail of is_null in the GString constructor which leads to a panic. Experiment indicates that the signature:

parse_dvb_short_event(&self) -> Option<(GString, Option<GString>, Option<GString>)>

solves all the problems I see in this situation. I guess consistency ought to lead to:

parse_dvb_short_event(&self) -> Option<(Option<GString>, Option<GString>, Option<GString>)>

so should signatures where there is a gchar* out parameter leading to a GString be Option<GString> instead?

[sdroege]

It's missing annotations in the C code: the nullable annotation should be applied to the ones that can return NULL, the not nullable for the others. (And the current allow-none annotation should become the non-deprecated optional)

And then gir needs to be extended to actually handle this situation.

[russel]

I'll have a look at doing the necessary annotation on the GStreamer MPEG-TS library, there are other GStreamer libraries already annotated to use as examples.