Fix T94116: Drivers can have multiple variables with same name

The RNA setter now ensures that driver variables are uniquely named
(within the scope of the driver).

Versioning code has been added to ensure this uniqueness. The last
variable with the non-unique name retains the original name; this
ensures that the driver will still evaluate to the same value as before
this fix.

This also introduces a new blenlib function `BLI_listbase_from_link()`,
which can be used to find the entire list from any item within the list.

Manifest Task: T94116

Reviewed By: mont29, JacquesLucke

Maniphest Tasks: T94116

Differential Revision: https://developer.blender.org/D13594

1 files changed, 20 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/listbase.c b/source/blender/blenlib/intern/listbase.c
index a166c846ea7..513b08a589d 100644
--- a/source/blender/blenlib/intern/listbase.c
+++ b/source/blender/blenlib/intern/listbase.c
@@ -749,6 +749,26 @@ int BLI_findstringindex(const ListBase *listbase, const char *id, const int offs
   return -1;
 }
 
+ListBase BLI_listbase_from_link(Link *some_link)
+{
+  ListBase list = {some_link, some_link};
+  if (some_link == NULL) {
+    return list;
+  }
+
+  /* Find the first element. */
+  while (((Link *)list.first)->prev != NULL) {
+    list.first = ((Link *)list.first)->prev;
+  }
+
+  /* Find the last element. */
+  while (((Link *)list.last)->next != NULL) {
+    list.last = ((Link *)list.last)->next;
+  }
+
+  return list;
+}
+
 void BLI_duplicatelist(ListBase *dst, const ListBase *src)
 {
   struct Link *dst_link, *src_link;