Fix T49427: Drivers of Shapekeys break when Append a group.

Optimization attempt with BKE_library_idtype_can_use_idtype() was not taking into account
the fact that drivers may link virtually against any datablock...

Has to be rethinked, but for after 2.78 release, this commit is safe to backport.

1 files changed, 6 insertions, 4 deletions

diff --git a/source/blender/blenkernel/intern/library_query.c b/source/blender/blenkernel/intern/library_query.c
index cb864334208..392ac68150e 100644
--- a/source/blender/blenkernel/intern/library_query.c
+++ b/source/blender/blenkernel/intern/library_query.c
@@ -897,10 +897,12 @@ void BKE_library_update_ID_link_user(ID *id_dst, ID *id_src, const int cd_flag)
  * This is a 'simplified' abstract version of #BKE_library_foreach_ID_link() above, quite useful to reduce
  * useless iterations in some cases.
  */
+/* XXX This has to be fully rethink, basing check on ID type is not really working anymore (and even worth once
+ *     IDProps will support ID pointers), we'll have to do some quick checks on IDs themselves... */
 bool BKE_library_idtype_can_use_idtype(const short id_type_owner, const short id_type_used)
 {
-	if (id_type_used == ID_AC) {
-		return id_type_can_have_animdata(id_type_owner);
+	if (id_type_can_have_animdata(id_type_owner)) {
+		return true;  /* AnimationData can use virtually any kind of datablocks, through drivers especially. */
 	}
 
 	switch ((ID_Type)id_type_owner) {
@@ -999,10 +1001,10 @@ static int foreach_libblock_id_users_callback(void *user_data, ID *self_id, ID *
 	IDUsersIter *iter = user_data;
 
 	/* XXX This is actually some kind of hack...
-	 * Issue is, only ID pointer from shapekeys is the 'from' one, which is not actually ID usage.
+	 * Issue is, shapekeys' 'from' ID pointer is not actually ID usage.
 	 * Maybe we should even nuke it from BKE_library_foreach_ID_link, not 100% sure yet...
 	 */
-	if (GS(self_id->name) == ID_KE) {
+	if ((GS(self_id->name) == ID_KE) && (((Key *)self_id)->from == *id_p)) {
 		return IDWALK_RET_NOP;
 	}