Created attachment 251609 [details]
Example file triggering a bug

Using Gstreamer 1.0 with Vala, valac thinks that Gst.Adapter.take() and Gst.Adapter.map() have an out gsize parameter and produces invalid code. 

In C, these functions have a signature of gpointer name(GstAdapter* adapter, gsize nbytes). Valac assumes the nbytes parameter to be an out parameter containing length of returned array.

Generated C code looks like this:

gsize size;
GstAdapter* adapter = NULL;
adapter = gst_adapter_new();
guint8* arr = NULL;
arr = gst_adapter_take(adapter, &size);

Upon compilation of provided example.vala file, a warning
example.vala.c:67:2: warning: passing argument 2 of ‘gst_adapter_take’ makes integer from pointer without a cast [enabled by default]
  _tmp5_ = gst_adapter_take (adapter, &_tmp4_);
  ^
In file included from example.vala.c:10:0:
/usr/include/gstreamer-1.0/gst/base/gstadapter.h:60:25: note: expected ‘gsize’ but argument is of type ‘gsize *’
 gpointer gst_adapter_take (GstAdapter *adapter, gsize nbytes);
is generated.

I asked about this issue on #vala IRC channel and confirmed that these functions (take and map) should take one parameter in Vala.