Those two functions can actually fail and leave the handle undefined.
vlc_join() and vlc_thread_join() would then crash (say, be undefined),
so errors should be taken care of explicitly.
VLC_EXPORT( void, vlc_threadvar_delete, (vlc_threadvar_t *) );
VLC_EXPORT( int, vlc_threadvar_set, (vlc_threadvar_t, void *) );
VLC_EXPORT( void *, vlc_threadvar_get, (vlc_threadvar_t) );
VLC_EXPORT( void, vlc_threadvar_delete, (vlc_threadvar_t *) );
VLC_EXPORT( int, vlc_threadvar_set, (vlc_threadvar_t, void *) );
VLC_EXPORT( void *, vlc_threadvar_get, (vlc_threadvar_t) );
-VLC_EXPORT( int, vlc_thread_create, ( vlc_object_t *, const char *, int, const char *, void * ( * ) ( vlc_object_t * ), int ) );
+VLC_EXPORT( int, vlc_thread_create, ( vlc_object_t *, const char *, int, const char *, void * ( * ) ( vlc_object_t * ), int ) LIBVLC_USED );
VLC_EXPORT( int, __vlc_thread_set_priority, ( vlc_object_t *, const char *, int, int ) );
VLC_EXPORT( void, __vlc_thread_join, ( vlc_object_t * ) );
VLC_EXPORT( int, __vlc_thread_set_priority, ( vlc_object_t *, const char *, int, int ) );
VLC_EXPORT( void, __vlc_thread_join, ( vlc_object_t * ) );
-VLC_EXPORT( int, vlc_clone, (vlc_thread_t *, void * (*) (void *), void *, int) );
+VLC_EXPORT( int, vlc_clone, (vlc_thread_t *, void * (*) (void *), void *, int) LIBVLC_USED );
VLC_EXPORT( void, vlc_cancel, (vlc_thread_t) );
VLC_EXPORT( void, vlc_join, (vlc_thread_t, void **) );
VLC_EXPORT (void, vlc_control_cancel, (int cmd, ...));
VLC_EXPORT( void, vlc_cancel, (vlc_thread_t) );
VLC_EXPORT( void, vlc_join, (vlc_thread_t, void **) );
VLC_EXPORT (void, vlc_control_cancel, (int cmd, ...));