Fix inconsistent creation of `NodeTreeTypeUndefined` type of node tree

Currently, when creating a new node tree ID, its `typeinfo` is set to
`NodeTreeTypeUndefined`, but its `type` enum value is left to `0`,
aka `NTREE_SHADER`.

This patch adds a new `NTREE_UNDIFINED` value, and use it for
`NodeTreeTypeUndefined` types of node trees.

NOTE: While it is not clear whether that actually fixes issues currently,
quite a bit of code still relies on the value of `type`, so think it
makes sense to sanitize this.

NOTE: Would have been ideal to reserve `0` value to undefined type,
but at this point this is not possible anymore, so chose to use `-2` instead.

Reviewed By: JacquesLucke

Differential Revision: https://developer.blender.org/D13123

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index 01889a1b0a9..53b3f07dbbc 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -12753,6 +12753,11 @@ static void rna_def_nodetree(BlenderRNA *brna)
   PropertyRNA *parm;
 
   static const EnumPropertyItem static_type_items[] = {
+      {NTREE_UNDEFINED,
+       "UNDEFINED",
+       ICON_QUESTION,
+       "Undefined",
+       "Undefined type of nodes (can happen e.g. when a linked node tree goes missing)"},
       {NTREE_SHADER, "SHADER", ICON_MATERIAL, "Shader", "Shader nodes"},
       {NTREE_TEXTURE, "TEXTURE", ICON_TEXTURE, "Texture", "Texture nodes"},
       {NTREE_COMPOSIT, "COMPOSITING", ICON_RENDERLAYERS, "Compositing", "Compositing nodes"},