Fix T68971: Copy As New Driver from Material node creates a bad reference.

NodeTree structures of materials and some other data blocks are
effectively node group datablock objects that are contained inside
the parent block. Thus, direct references to them are only valid
while blender is running, and are lost on save.

Fix Copy As New Driver to create a reference that goes through
the owner datablock, by adding a new ID flag to mark private
pseudo-datablocks.

Also fix functions that return full paths to structures and
properties, e.g. used in python tooltips. Functions for paths
from ID to struct or property can't be changed because of
Animation Data related code.

Reviewers: mont29

Differential Revision: https://developer.blender.org/D5559

4 files changed, 31 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index 09900651dad..e0f89024420 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -27,7 +27,7 @@
  * \note Use #STRINGIFY() rather than defining with quotes.
  */
 #define BLENDER_VERSION 281
-#define BLENDER_SUBVERSION 3
+#define BLENDER_SUBVERSION 4
 /** Several breakages with 280, e.g. collections vs layers. */
 #define BLENDER_MINVERSION 280
 #define BLENDER_MINSUBVERSION 0
diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index efc4e4fdc12..cbfc8ffc7d0 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -384,6 +384,7 @@ void ntreeUserIncrefID(struct bNodeTree *ntree);
 void ntreeUserDecrefID(struct bNodeTree *ntree);
 
 struct bNodeTree *ntreeFromID(const struct ID *id);
+struct ID *BKE_node_tree_find_owner_ID(struct Main *bmain, struct bNodeTree *ntree);
 
 void ntreeMakeLocal(struct Main *bmain,
                     struct bNodeTree *ntree,
diff --git a/source/blender/blenkernel/intern/library.c b/source/blender/blenkernel/intern/library.c
index 2dbca3b4db1..7c9f5c0ae77 100644
--- a/source/blender/blenkernel/intern/library.c
+++ b/source/blender/blenkernel/intern/library.c
@@ -1417,6 +1417,9 @@ void BKE_libblock_copy_ex(Main *bmain, const ID *id, ID **r_newid, const int fla
   const bool use_nodetree_alloc_exception = ((GS(id->name) == ID_NT) && (bmain != NULL) &&
                                              (BLI_findindex(&bmain->nodetrees, id) < 0));
 
+  /* The id->flag bits to copy over. */
+  const int copy_flag_mask = LIB_PRIVATE_DATA;
+
   BLI_assert((flag & LIB_ID_CREATE_NO_MAIN) != 0 || bmain != NULL);
   BLI_assert((flag & LIB_ID_CREATE_NO_MAIN) != 0 || (flag & LIB_ID_CREATE_NO_ALLOCATE) == 0);
   BLI_assert((flag & LIB_ID_CREATE_NO_MAIN) == 0 || (flag & LIB_ID_CREATE_NO_USER_REFCOUNT) != 0);
@@ -1448,6 +1451,8 @@ void BKE_libblock_copy_ex(Main *bmain, const ID *id, ID **r_newid, const int fla
     memcpy(cpn + id_offset, cp + id_offset, id_len - id_offset);
   }
 
+  new_id->flag = (new_id->flag & ~copy_flag_mask) | (id->flag & copy_flag_mask);
+
   if (id->properties) {
     new_id->properties = IDP_CopyProperty_ex(id->properties, flag);
   }
diff --git a/source/blender/blenkernel/intern/node.c b/source/blender/blenkernel/intern/node.c
index 206c59c110a..2eba71fa6bd 100644
--- a/source/blender/blenkernel/intern/node.c
+++ b/source/blender/blenkernel/intern/node.c
@@ -1406,6 +1406,7 @@ bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
   }
   else {
     ntree = MEM_callocN(sizeof(bNodeTree), "new node tree");
+    ntree->id.flag |= LIB_PRIVATE_DATA;
     *((short *)ntree->id.name) = ID_NT;
     BLI_strncpy(ntree->id.name + 2, name, sizeof(ntree->id.name));
   }
@@ -2172,6 +2173,7 @@ void ntreeSetOutput(bNodeTree *ntree)
    * might be different for editor or for "real" use... */
 }
 
+/* Returns the private NodeTree object of the datablock, if it has one. */
 bNodeTree *ntreeFromID(const ID *id)
 {
   switch (GS(id->name)) {
@@ -2192,6 +2194,28 @@ bNodeTree *ntreeFromID(const ID *id)
   }
 }
 
+/* Finds and returns the datablock that privately owns the given tree, or NULL. */
+ID *BKE_node_tree_find_owner_ID(Main *bmain, struct bNodeTree *ntree)
+{
+  ListBase *lists[] = {&bmain->materials,
+                       &bmain->lights,
+                       &bmain->worlds,
+                       &bmain->textures,
+                       &bmain->scenes,
+                       &bmain->linestyles,
+                       NULL};
+
+  for (int i = 0; lists[i] != NULL; i++) {
+    LISTBASE_FOREACH (ID *, id, lists[i]) {
+      if (ntreeFromID(id) == ntree) {
+        return id;
+      }
+    }
+  }
+
+  return NULL;
+}
+
 void ntreeMakeLocal(Main *bmain, bNodeTree *ntree, bool id_in_mainlist, const bool lib_local)
 {
   BKE_id_make_local_generic(bmain, &ntree->id, id_in_mainlist, lib_local);