c_g_output_stream_vprintf

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
int function(GOutputStream* stream, size_t* bytesWritten, GCancellable* cancellable, GError** error, const(char)* format, void* args) c_g_output_stream_vprintf;

Meta