Fix T83411: Crash when using a workspace/layout data path in a driver

Building IDs which are not covered by copy-on-write process was not
implemented, which was causing parameters block not present, and, hence
causing crashes in areas which expected parameters to present.

First part of this change is related on making it so Copy-on-Write is
optional for ID nodes in the dependency graph.

Second part is related on using a generic builder for all ID types
which were not covered by Copy-on-Write before.

The final part is related on making it so build_id() is properly
handling ParticleSettings and Grease Pencil Data. Before they were not
covered there at all, and they need special handling because they do
have own build functions.

Not sure it worth trying to split those parts, as they are related to
each other and are not really possible to be tested standalone. Open
for a second opinion though.

Possible nut-tightening is to re-organize build_id() function so
that every branch does return and have an assert at the end, so that
missing ID type in the switch statement is easier to spot even when
using compilers which do not report missing switch cases.

As for question "why not use default" the answer is: to make it more
explicit and clear what is a decision when adding new ID types. We do
not want to quietly fall-back to a non-copy-on-write case for a newly
added ID types.

Differential Revision: https://developer.blender.org/D10075

6 files changed, 83 insertions, 8 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
index dcdf2f48607..f5298acc498 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
@@ -388,7 +388,9 @@ void DepsgraphNodeBuilder::build_id(ID *id)
   if (id == nullptr) {
     return;
   }
-  switch (GS(id->name)) {
+
+  const ID_Type id_type = GS(id->name);
+  switch (id_type) {
     case ID_AC:
       build_action((bAction *)id);
       break;
@@ -478,13 +480,39 @@ void DepsgraphNodeBuilder::build_id(ID *id)
     case ID_SIM:
       build_simulation((Simulation *)id);
       break;
-    default:
-      fprintf(stderr, "Unhandled ID %s\n", id->name);
-      BLI_assert(!"Should never happen");
+    case ID_PA:
+      build_particle_settings((ParticleSettings *)id);
+      break;
+    case ID_GD:
+      build_gpencil((bGPdata *)id);
+      break;
+
+    case ID_LI:
+    case ID_IP:
+    case ID_SCR:
+    case ID_VF:
+    case ID_BR:
+    case ID_WM:
+    case ID_PAL:
+    case ID_PC:
+    case ID_WS:
+      BLI_assert(!deg_copy_on_write_is_needed(id_type));
+      build_generic_id(id);
       break;
   }
 }
 
+void DepsgraphNodeBuilder::build_generic_id(ID *id)
+{
+  if (built_map_.checkIsBuiltAndTag(id)) {
+    return;
+  }
+
+  build_idproperties(id->properties);
+  build_animdata(id);
+  build_parameters(id);
+}
+
 static void build_idproperties_callback(IDProperty *id_property, void *user_data)
 {
   DepsgraphNodeBuilder *builder = reinterpret_cast<DepsgraphNodeBuilder *>(user_data);
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
index 174f9b129f9..a7033c8c8f3 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
@@ -152,6 +152,9 @@ class DepsgraphNodeBuilder : public DepsgraphBuilder {
 
   virtual void build_id(ID *id);
 
+  /* Build function for ID types that do not need their own build_xxx() function. */
+  virtual void build_generic_id(ID *id);
+
   virtual void build_idproperties(IDProperty *id_property);
 
   virtual void build_scene_render(Scene *scene, ViewLayer *view_layer);
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index df48cb91ce7..556b60b930b 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -484,7 +484,9 @@ void DepsgraphRelationBuilder::build_id(ID *id)
   if (id == nullptr) {
     return;
   }
-  switch (GS(id->name)) {
+
+  const ID_Type id_type = GS(id->name);
+  switch (id_type) {
     case ID_AC:
       build_action((bAction *)id);
       break;
@@ -560,13 +562,40 @@ void DepsgraphRelationBuilder::build_id(ID *id)
     case ID_SIM:
       build_simulation((Simulation *)id);
       break;
-    default:
-      fprintf(stderr, "Unhandled ID %s\n", id->name);
-      BLI_assert(!"Should never happen");
+    case ID_PA:
+      build_particle_settings((ParticleSettings *)id);
+      break;
+    case ID_GD:
+      build_gpencil((bGPdata *)id);
+      break;
+
+    case ID_LI:
+    case ID_IP:
+    case ID_SCR:
+    case ID_VF:
+    case ID_BR:
+    case ID_WM:
+    case ID_PAL:
+    case ID_PC:
+    case ID_WS:
+      BLI_assert(!deg_copy_on_write_is_needed(id_type));
+      build_generic_id(id);
       break;
   }
 }
 
+void DepsgraphRelationBuilder::build_generic_id(ID *id)
+{
+
+  if (built_map_.checkIsBuiltAndTag(id)) {
+    return;
+  }
+
+  build_idproperties(id->properties);
+  build_animdata(id);
+  build_parameters(id);
+}
+
 static void build_idproperties_callback(IDProperty *id_property, void *user_data)
 {
   DepsgraphRelationBuilder *builder = reinterpret_cast<DepsgraphRelationBuilder *>(user_data);
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.h b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
index 5587379089c..21d1d4b6268 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
@@ -198,6 +198,9 @@ class DepsgraphRelationBuilder : public DepsgraphBuilder {
 
   virtual void build_id(ID *id);
 
+  /* Build function for ID types that do not need their own build_xxx() function. */
+  virtual void build_generic_id(ID *id);
+
   virtual void build_idproperties(IDProperty *id_property);
 
   virtual void build_scene_render(Scene *scene, ViewLayer *view_layer);
diff --git a/source/blender/depsgraph/intern/depsgraph.cc b/source/blender/depsgraph/intern/depsgraph.cc
index 17eeba55a27..3d30e7e79b9 100644
--- a/source/blender/depsgraph/intern/depsgraph.cc
+++ b/source/blender/depsgraph/intern/depsgraph.cc
@@ -142,6 +142,14 @@ static void clear_id_nodes_conditional(Depsgraph::IDDepsNodes *id_nodes, const F
        * datablock for her own dirty needs. */
       continue;
     }
+    if (id_node->id_cow == id_node->id_orig) {
+      /* Copy-on-write version is not needed for this ID type.
+       *
+       * NOTE: Is important to not de-reference the original datablock here because it might be
+       * freed already (happens during main database free when some IDs are freed prior to a
+       * scene). */
+      continue;
+    }
     if (!deg_copy_on_write_is_expanded(id_node->id_cow)) {
       continue;
     }
diff --git a/source/blender/depsgraph/intern/depsgraph_tag.cc b/source/blender/depsgraph/intern/depsgraph_tag.cc
index 95ee8234ef3..c60ec4351bc 100644
--- a/source/blender/depsgraph/intern/depsgraph_tag.cc
+++ b/source/blender/depsgraph/intern/depsgraph_tag.cc
@@ -265,6 +265,10 @@ void depsgraph_update_editors_tag(Main *bmain, Depsgraph *graph, ID *id)
 void depsgraph_id_tag_copy_on_write(Depsgraph *graph, IDNode *id_node, eUpdateSource update_source)
 {
   ComponentNode *cow_comp = id_node->find_component(NodeType::COPY_ON_WRITE);
+  if (cow_comp == nullptr) {
+    BLI_assert(!deg_copy_on_write_is_needed(GS(id_node->id_orig->name)));
+    return;
+  }
   cow_comp->tag_update(graph, update_source);
 }